University of Groningen
The sustainability of conventional houses, passive houses and earthships, based on
legislation, environmental impact energy and operating energy.
Kuil, Elena
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CIO, Center for Isotope Research
IVEM, Center for Energy and Environmental Studies
Master Programme Energy and Environmental Sciences
University of Groningen
The sustainability of conventional houses,
passive houses and earthships, based on
legislation, environmental impact energy
and operating energy
Elena Kuil
EES 2012-155 T
Training report of Elena Kuil
Supervised by: Dr. R.M.J. Benders (IVEM)
Dr. C. Visser (IVEM)
University of Groningen
CIO, Center for Isotope Research
IVEM, Center for Energy and Environmental Studies
Nijenborgh 4
9747 AG Groningen
The Netherlands
http://www.rug.nl/fmns-research/cio
http://www.rug.nl/fmns-research/ivem
PREFACE
This report has been written as part of the Master program Energy & Environmental Sciences (EES).
The Master’s degree programme has two specialization, which are ‘System studies on Energy and
Environment’ and ‘Experimental studies of Energy and Climate’.
Goal of this Training Thesis is to design, organize and carry out a research in the field of ‘Systems studies on Energy and Environment’. This includes the collection of data, the correct application
of research methods, the analysis of results, the derivation of recommendations and lastly to be able to
clearly report and communicate these findings.
Many thanks go to Rene Benders, my first supervisor at the University of Groningen. A thank you
also for Cindy Visser for being my second supervisor at the University of Groningen. Furthermore, I
would like to thank the Dutch earthship association (Vereninging Aardehuis) for answering questions
about their project, particularly Estella Franssen. A second last thank you goes to Mischa Hewitt for
providing insights into the Brighton Earthship. Lastly, I would like to thank my fellow students for
their good advice, and not to forget, my family and friends for always supporting me.
TABLE OF CONTENTS
Summary .......................................................................................................................... 5
Samenvatting ................................................................................................................... 7
1. Introduction ............................................................................................................... 9
1.1 Dutch Energy Policies .................................................................................................... 9
1.1.1 NMP ......................................................................................................................... 9
1.1.2 The Dutch Building Decree ...................................................................................... 9
1.1.3 LTA, EPN and EPC ................................................................................................ 10
1.2 Problem definition ........................................................................................................ 10
1.3 Research question ......................................................................................................... 11
1.4 Reading guide ............................................................................................................... 11
2. Construction types................................................................................................... 13
2.1 Conventional house ...................................................................................................... 13
2.2 Low energy buildings ................................................................................................... 13
2.2.1 Passive house ......................................................................................................... 14
2.2.2 Passive design ........................................................................................................ 15
2.3 Earthship ....................................................................................................................... 15
2.3.1 Earthship Biotecture .............................................................................................. 15
2.3.2 Mapping of earthships in Europe ........................................................................... 17
2.3.3 Earthships in the Netherlands ................................................................................ 18
2.3.4 Earthship Europe ................................................................................................... 18
3. Building materials ................................................................................................... 21
3.1 Conventional house ...................................................................................................... 21
3.1.1 Wood and timber .................................................................................................... 21
3.1.2 Sand, gravel and concrete ..................................................................................... 21
3.1.3 Clay, bricks and tiles .............................................................................................. 22
3.1.4 Glass wool and plastic ........................................................................................... 22
3.2 Low energy buildings ................................................................................................... 22
3.2.1 Rock wool ............................................................................................................... 22
3.2.2 Cellulose fibres....................................................................................................... 23
3.2.3 Oriented Strand Board ........................................................................................... 23
3.3 Earthship ....................................................................................................................... 23
3.3.1 Scrap tires .............................................................................................................. 23
3.3.2 Steel and aluminium cans....................................................................................... 24
3.3.3 Glass bottles ........................................................................................................... 25
3.3.4 Loam....................................................................................................................... 25
4. Methods – Environmental impact (SimaPro) ....................................................... 27
4.1 Conventional house ...................................................................................................... 27
4.2 Low energy buildings ................................................................................................... 28
4.3 Earthship ....................................................................................................................... 29
4.3.1 Steel and aluminium cans....................................................................................... 30
4.3.2 Glass bottles ........................................................................................................... 30
4.4 SimaPro ........................................................................................................................ 31
4.4.1 ReCiPe Endpoint indicator .................................................................................... 31
5. Methods – Operating energy (Excel & DoMUS) .................................................. 33
5.1 Excel model .................................................................................................................. 33
5.1.1 Conventional house ................................................................................................ 34
5.1.2 Low energy building ............................................................................................... 34
5.1.3 Earthship ................................................................................................................ 34
5.1.4 Comparison construction types .............................................................................. 34
5.2 DoMUS ........................................................................................................................ 35
5.2.1 Conventional house ................................................................................................ 35
5.2.2 Low energy building ............................................................................................... 35
5.2.3 Earthship ................................................................................................................ 35
5.3 Excel and DoMUS ........................................................................................................ 36
6. Results – Environmental impact (SimaPro) ......................................................... 37
6.1
6.2
6.3
Weighting of the three construction types .................................................................... 37
Comparison construction types .................................................................................... 38
Different earthships ...................................................................................................... 39
7. Results – Operating energy (Excel & DoMUS) .................................................... 41
7.1 Excel ............................................................................................................................. 41
7.1.1 Conventional house ................................................................................................ 41
7.1.2 Low energy building ............................................................................................... 41
7.1.3 Earthship ................................................................................................................ 41
7.1.4 Comparison construction types .............................................................................. 42
7.2 Excel and DoMUS ........................................................................................................ 42
8. Discussion ................................................................................................................. 45
9. Conclusion ................................................................................................................ 49
10. References ................................................................................................................ 51
SUMMARY
Buildings demand energy in their life cycle. Energy use is, among others, restricted by the Energy
Performance Standard (EPN), which is a standard determining the quantity of energy that new buildings are allowed to use, compelling them to comply with a required energy performance. The output
of an energy performance calculation is the energy performance coefficient (EPC), which expresses
the energy efficiency of a building. In 1996, the EPC for residential buildings was set at 1.4. Currently, the EPC is set at 0.6 and expectations are that the EPC will increase even further.
To address current building standards, the building practices of conventional houses are adjusted. Meanwhile, the demand for even more sustainable houses rises. A renowned sustainable house
is the passive house, which aims at minimizing the building’s operating energy. A more unusual sustainable construction type is an earthship, which is designed to operate on a self-sufficient basis and is
largely constructed from recycled and reclaimed materials.
This research compares conventional houses, passive houses and earthship based on legislation, environmental impact and operating energy. In this research the environmental impact is calculated based on the energy needed to manufacture all the building materials used in a building. The
operating energy is defined as the energy used for heating of a building during is operational phase.
First of all, the rules on sustainable building and legislation were researched. Secondly, the most important building materials used in the three construction types are investigated with respect to their
availability and recyclability. Subsequently, a SimaPro model is used to assess the environmental impact of the building materials. The results will indicate the environmental impact on human health,
ecosystems and resources. Furthermore, an Excel model and a DoMUS model are used to look at the
operating energy. The results give the transmission losses of the different construction types.
Literature shows that all construction types fit within the Dutch rules and regulations, although for earthships some adjustments are made. Therefore, based on legislation, it is concluded that
all three construction types are sustainable. The SimaPro model shows that the conventional house has
the lowest and the earthship the highest environmental impact. It can be concluded that, conventional
houses are more sustainable than passive houses and earthships.
As the general idea behind passive houses and earthship is that they recover the extra energy
used for the production of building materials when the houses are in use, it interesting to look at the
operating energy. The Excel and DoMUS model show that passive houses lose significantly less heat
than conventional houses. Earthships perform roughly the same as conventional houses, provided that
they have insulation in the floor. In general, it can be concluded that passive house are more sustainable than conventional houses and earthship with XPS insulation in the floor. Presumably, an earthship
performs better than a conventional house when thermal storage in the earthship walls is taken into
account.
Based on the results, it can be concluded that in relative terms both conventional houses and
passive houses are more sustainable and thus suitable for the Dutch market than earthship. With regard to earthships, this research gives a cautious negative advise.
5
6
SAMENVATTING
Gebouwen verbruiken energie. Hun energieverbruik wordt onder andere gereguleerd door de Energie
Prestatie Norm (EPN), die nieuwe gebouwen dwingt te voldoen aan een vereiste energieprestatie. De
uitkomst van een energie prestatie berekening wordt uitgedrukt in de energie-efficiëntie van gebouwen uit, oftewel de Energie Prestatie Coëfficiënt (EPC). In 1996 werd de EPC voor residentiële gebouwen vastgesteld op 1,4. De huidige EPC is 0,6 en de verwachting is dat de EPC verder zal toenemen.
Om te voldoen aan de huidige bouwnorm, worden er steeds zuinigere conventionele woningen ontwikkeld. Ondertussen neemt ook de vraag naar nog duurzamere woningen toe. Een gerenommeerd duurzaam huis is het passieve huis, dat gericht is op het minimaliseren van operationele energie. Een ander, meer ongebruikelijk duurzaam huis, is een aardehuis. Aardehuizen zijn zelfvoorzienend en zijn grotendeels opgebouwd uit gerecycleerde en geregenereerde materialen.
Dit onderzoek vergelijkt conventionele huizen, passieve huizen en aardehuizen op basis van
wetgeving, milieu-impact en operationele energie. In dit onderzoek wordt de milieu-impact berekend
op basis van de energie die nodig is om alle bouwmaterialen die gebruikt worden in een huis te vervaardigen. De operationele energie wordt gedefinieerd als de energie die wordt gebruikt om een gebouw warm te houden tijdens zijn operationele fase.
Allereerst is de wetgeving voor duurzaam bouwen onderzocht. Vervolgens is er gekeken naar
de beschikbaarheid en recycleerbaarheid van de belangrijkste bouwmaterialen gebruikt in de drie huizen. Het SimaPro model is gebruikt om de milieu-impact van de bouwmaterialen te modelleren. De
resultaten geven de milieu-impact op gebied van volksgezondheid, ecosystemen en hulpbronnen. Een
Excel model en het DoMUS model zijn gebruikt om de operationele energie te onderzoeken. De resultaten geven het transmissieverlies van de onderzochte huizen.
Uit de literatuur blijkt dat alle drie de huizen passen binnen de Nederlandse wet- en regelgeving, alhoewel er voor aardehuizen wel enkele aanpassingen zijn gedaan (aansluiting gas, water, licht
en riool). Op basis van wetgeving, worden in dit onderzoek alle drie de huizen daarom als duurzaam
aangemerkt. Het SimaPro model toont aan dat een conventioneel huis de laagste en een aardehuis de
hoogste milieu-impact heeft. Geconcludeerd kan worden dat conventionele huizen duurzamer zijn dan
passieve huizen en aardehuizen.
Aangezien het algemene idee achter passieve huizen en aardehuizen is dat ze de extra energie
die ze gebruiken voor de productie van bouwmaterialen terugwinnen wanneer ze in gebruik zijn, is
het interessant om te kijken naar de operationele energie. De Excel en DoMUS modellen tonen aan
dat passieve huizen aanzienlijk minder warmte verliezen dan conventionele huizen. Aardehuizen presteren grofweg hetzelfde als conventionele woningen, mits ze isolatie in de vloer te hebben. In het algemeen kan worden geconcludeerd dat passieve huizen duurzaam zijn, dan aardehuizen en conventionele huizen. Aardehuizen met XPS isolatie in de vloer en conventionele huizen zijn duurzamer dan
een aardehuis zonder isolatie in de vloer. Vermoedelijk presteren aardehuizen beter dan conventionele
huizen, wanneer warmteopslag in de muren wordt meegenomen.
Gebaseerd op de resultaten kan worden geconcludeerd conventionele huizen en passiefhuizen
duurzamer en dus geschikter zijn voor de Nederlandse woningmarkt dan aardehuizen. Met betrekking
tot de aardehuizen, geeft dit onderzoek een voorzichtig negatief advies.
7
8
1. INTRODUCTION
Buildings demand energy in their life cycle, both directly and indirectly. The direct energy is the energy used for operation (operating energy), in the form of for example gas or electricity. Indirect energy is the energy used for the production of goods and services, thus, among others, for the production of building materials (embodied energy).
1.1 Dutch Energy Policies
The first serious concerns regarding the energy and environmental aspects of buildings stocks in the
Netherlands took place in 1973, when the Organization of Petroleum Exporting Countries (OPEC)
imposed an oil embargo against Western nations, reducing oil exports to some nations and banning it
completely to the United States and the Netherlands (Melchert 2007, Beerepoot and Beerepoot 2007).
The crisis brought about a growing social anxiety regarding energy security and environmental protection in the Netherlands (Melchert 2007). As a result, the Dutch building policymaking radically
changed .
1.1.1 NMP
In 1974, the Dutch government published its first energy policy in order to restrict energy use and to
consider future energy supply related to environmental impact (Energienota 1974). In 1976, the Dutch
Energy Council was founded; an independent advisory body that advises the Dutch government and
parliament on energy policy (AER 2012). The first National Environmental Policy Plan (NMP1) was
issued in 1989, followed by the National Environmental Policy Plan Plus in 1990. Together, these
reports represented a new phase in the institutionalisation of sustainable building practices in the
Netherlands, introducing the idea of closed loops for material, energy saving and efficiency, the promotion of quality, partnerships between government, business and civil society, and a preference for
market-based solutions as central policy lines (Melchert 2007, Smith and Kern 2009). The second and
third National Environmental Policy Plans (NMP2 and NMP3) further institutionalised the new approach (Keijzers 2000).
Less important for sustainable building is the Fourth National Environmental Policy Plan
(NMP4), which the Dutch government adopted in 2001. NMP4 is not a comprehensive environmental
policy like NMP3. The design is such that NMP3 remains in effect unless NMP4 states otherwise.
NMP4 defines seven persistent environmental problems, which are biodiversity, climate change, natural resources, health, external safety, living environment and potential uncontrollable risks. In relation
to biodiversity, climate change and natural resources it introduced long-term transition management
(until 2030). It aims to provide an end to the shift of environmental burdens on future generations and
people in poor countries. On the remaining topics it introduced policy innovations (SER 2012).
1.1.2 The Dutch Building Decree
A Dutch Building Decree was announced in 1992. Until 1992 building rules differed from one municipality to another. The objective of the Dutch Building Decree was to preclude dissimilarities between
municipalities relating to their building codes. A general set of requirements for all buildings was introduced to create clarity and uniformity in the building regulations. As the Building Decree of 1992
failed to address its goals, a new version came into being. The Building Decree of 2003 introduced a
table in which all decisions that form the Building Decree of 2003 are included. This made it possible
to easily determine how the Building Decree of 2003 heralded at any time after 1 January 2003. Furthermore, it comprised more sections and regulations than the Building Decree of 1992 (Heijden et al.
2006).
In April 2012, the Building Decree of 2012 came into force. The aim of the new Building Decree is to increase the cohesion within the building regulations, to reduce regulatory pressure and to
improve accessibility. It summarizes various rules and decisions. Structural requirements are thus
more readable, easier and less ambiguous. The new Building Decree contains the provisions that are
included in the Building Decree of 2003, the accompanying ministerial decree, the Occupancy Decree
(‘Gebruiksbesluit’; since November 2008), the municipal building codes and the Decree additional
safety rules on road tunnels. Also the new European regulations and the European commitments to the
9
House of Commons are taken into account. The largest change in the new Building Decree is that
there is now one set of technical requirements for the demolition, (re)building and use of buildings
and other structures such as bridges and tunnels.
1.1.3 LTA, EPN and EPC
Besides the NMPs and the Dutch Building Decree, specific programs introduced building standards
regarding the energy use of buildings. In 1995, a program was proclaimed, known as Long-Term
Agreement (LTA), requiring existing buildings to reduce their energy consumption by 25%, based on
the 1995 levels within a period of 10 years. At the same time, the Energy Performance Standard
(EPN) was announced, which is a standard determining the quantity of energy that new industrial and
office buildings were allowed to use, compelling them to comply with a required energy performance
(Melchert 2007). The output of an energy performance calculation became known as the energy performance coefficient (EPC), which expresses the energy efficiency of a building.
In 1996, the EPC for residential buildings was set at 1.4, which more or less represented the standard
building practice at that time (Beerepoot and Beerepoot 2007). The increased awareness of environmental problems related to energy processes led to the implementation of building codes that are more
and more stringent on energy requirements. During the years, the EPC enhanced to 1.2 in 1998, 1.0 in
2000 (Beerepoot and Beerepoot 2007), 0.8 in 2006 (Noailly and Batrakova 2010), and 0.6 in 2011
(BZK 2011, EL&I 2011). Expectations are that the EPC will increase even further to 0.4 in 2015
(EL&I 2011). The Dutch government’s ambition is to make energy-neutral housing the norm by 2020
(BuildDesk 2011). Since 2003, the energy performance coefficient is stated in the Dutch Building Decree.
1.2 Problem definition
To address current building standards, building practices of conventional houses are adjusted. Passive
technologies are applied, including increased insulation, better performing windows, reduction of infiltration losses and heat recovery from ventilation air/or waste water (Sartori and Hestnes 2007). In
recognition of the potential of sustainable houses in reducing dependence on fossil fuels and generating less environmental damage, the demand for even more sustainable houses rises.
A renowned sustainable house is the passive house, which aims at minimizing the building’s
operating energy. A more unusual sustainable construction type is an earthship, which is designed to
operate on a self-sufficient basis and is largely constructed from recycled and reclaimed materials (Ip
and Miller 2009). In passive houses and earthships not only passive, but also active technologies are
common. Examples include heat pumps coupled with air or ground/water heat sources, solar thermal
collectors, solar photovoltaic panels and biomass burners (Sartori and Hestnes 2007).
The energy embodied in each house, that is, the sum of all the energy needed to manufacture
the structure, varies, as type of building, type of construction or size differs. Also, the operating energy, which is the energy used in a structure during its operational phase (heating, cooling, ventilation,
hot water, lighting and other electrical appliances), is diverse (Sartori and Hestnes 2007).
Although studies exist that have researched the embodied energy of houses, the thermal performance of houses, or the influence of the installation of passive and active technologies on the energy use of houses, not many were found that combine the different aspects. Moreover, most studies
compare conventional houses with low-energy houses, sometimes mentioning passive houses, or sporadic mentioning solar houses. However, little research has been performed on earthships, especially
comparing them to other construction types. Few have examined if earthships can contribute to a
more sustainable (Dutch) society, which can meet the needs of present and future generations. Therefore, the objective of this research is to compare conventional houses, passive houses and earthships
on multiple aspects.
10
1.3 Research question
The central question of this Trainings Thesis is therefore:
How sustainable are conventional houses, passive houses and earthships, based on legislation,
environmental impact and operating energy?
The following subquestions can be formulated:
• How can conventional houses, passive houses and earthships be defined and described?
All three construction types will be discussed. More attention is paid to the sustainable houses
as they are less known. As this is one of the few studies that includes earthships, the main focus lies with this construction type.
•
Which building materials are characteristic for conventional houses, passive houses and
earthships and what is their environmental impact (especially for earthships as they are built
from recycled materials)?
The embodied energy of a house is the sum of all the energy needed to manufacture the structure, thus the sum of all energy needed to obtain the building materials. The operating energy,
which is the energy used in a structure during its operational phase, depends on the building
materials used in a construction type. Before modelling the relation between building materials and embodied energy (in relation to environmental impact) and operating energy, first a
literature study is performed on the building materials itself. In conventional and passive
houses, new building materials are used. Which building materials are used? Is the mining or
harvesting harmful to the environment? Is it possible to reuse the building materials after their
period of use? In earthships, waste is reused as building material. Which waste is used? What
are the consequences of the waste / building materials when not used for earthships? If the
waste is recycled, what are the recycle rates?
•
What is the environmental impact of a conventional house, a passive house and an earthship?
For each construction type the building materials (and quantities) used for the floor, outer
walls and roof are inserted in SimaPro. SimaPro calculates the energy needed for the production stage of the building materials. The results show the energy use translated in an environmental impact in three main areas of protection, that is human health, ecosystems and resources.
•
What is the operating energy of a conventional house, a passive house and an earthship?
In the first model, which is a model in Excel, it is assumed that the operating energy is the energy used to maintain the temperature by compensating for the heat losses through the floor,
the walls and the roof. For each surface area of all three construction type, heat loss is calculated. In the second model, which is the DoMUS model (Domestic Metabolism User friendly
Simulated model), insulation data of walls, floors, roofs and windows is entered. The three
construction types are compared based on the function ‘heating’.
1.4 Reading guide
This report is set up as follows. After the introduction, a review of the three relevant construction
types is given in chapter 2. A more detailed discussion of the various building materials used in the
three construction types and their recycle facts can be found in chapter 3. The models and the data
analysed in this study are presented in chapter 4 and 5. Results are provided in chapter 7 and 8. Chapter 9 pays attention to the discussions. Finally, concluding remarks are given in chapter 10.
11
12
2. CONSTRUCTION TYPES
Worldwide, there are many building types and construction types which satisfy or can meet the current EPC values. There are five main types of houses based on the way of building, which are detached houses, semi-detached houses, terraced houses/row houses, end of terrace houses and flats.
Flats are part of an apartment building. Examples are an apartment, a porch house or a maisonette.
Although many different types exist, people often prefer to live in houses that fit within traditions and
culture. Furthermore, the type of housing is often associated with the nearest available material, skills
and level of technology. The most common building types in the Netherlands are flats and terraced
houses or row house (Table 1).
Table 1: Number of houses (x1000) per building type in the Netherlands (CBS 2010).
Detached
1998
1999
2000
2002
2006
2009
954.0
964.0
957.0
959.5
1020.5
1013.0
Semidetached
755.0
744.0
788.0
840.3
840.1
899.8
Terraced /
Row house
1829.0
1808.0
1871.0
1858.4
1836.5
1872.9
End of terrace
865.0
809.0
836.0
818.4
837.3
881.8
Flats
Remaining
1957.0
2118.0
2053.0
2062.4
2178.3
2202.3
.
.
.
87.7
87.9
126.6
As for construction type, most buildings are built in a conventional way. However, lesser-used construction methods have gained popularity in recent years and the development of a number of lowenergy building types continues. The following text focuses on three construction types, specifically
conventional houses, passive houses and earthships.
2.1 Conventional house
As mentioned in section 1.1.3, buildings must meet the standard the EPN sets. Buildings that are built
according to the common practice of a specific country in a specific period, that is, meeting the minimal legally required energy standards are referred to with the term ‘conventional house’ (Sartori and
Hestnes 2007, Audenaert et al. 2008). The EPC is calculated by dividing the characteristic energy by
the normalized energy, in which the characteristic energy is based on living area and surface loss,
while the normalized energy is based on primary energy consumption and primary energy gain. The
principle is such that the EPC of a large house is approximately the same as the EPC of a small house,
assuming equal facilities and location. Similar measures to improve the energy performance lead to
more or less the same performance, regardless of the type, shape or size of the house. In other words,
large houses may use more energy to meet the same performance requirements as small houses.
Therefore, the energy consumption of both houses is clearly different (Novem 2000).
2.2 Low energy buildings
There are also buildings that go beyond addressing the current building standards. Buildings that have
a better energy performance than the standard energy efficiency requirements in buildings codes are
called low energy buildings. A global definition for low energy buildings is lacking. In fact, low energy buildings are known under different names across Europe. In 2008, a survey identified 17 different
terms in use, among which the terms low energy house, high-performance house, passive
house/Passivhaus, zero carbon house, zero energy house, energy savings house, energy positive house
and 3-litre house. Furthermore, concepts that take into account more parameters than energy demand
use special terms such as eco-building or green building (European Commission 2009).
Variations exist not only with regard to the terms chosen, but also what energy use is included
in the definition. Ideally, the minimum performance requirements should take into account all types of
energy use, that is, demand for space heating and cooling, water heating, air conditioning as well as
consumption of electricity. This is often not the case (European Commission 2009).
13
2.2.1 Passive house
As passive houses are studied in this research, the term should be defined better. The definitions for
passive houses are even more heterogeneous than the definitions for low energy buildings. In southern
Europe (e.g. Spain, Italy, Portugal, Greece) a passive house is defined as a house that has been constructed using passive technologies. In central Europe (Germany, Austria, Sweden etc.) the term refers
to a certain standardized type of low energy buildings as developed in Germany. It is a special type of
low energy building for which thermal comfort can be achieved solely by post-heating or post-cooling
of the fresh air mass without a need for a conventional heating system.
German passive house technologies typically include passive solar gain, super glazing, airtight
building envelope and thermal bridge-free construction. This reduces the annual demand for space
heating (and possibly cooling) to 15 kWh/m². The limit for total primary energy (energy used to produce the energy delivered to the building) use, which is calculated based on heating, hot water and
electricity, is set at 120kWh/m². Switzerland has a similar standard as the one in Germany. In the
United States, a house built with the passive house standard uses between 75 and 95% less energy for
space heating and cooling than current new buildings that meet today’s US energy efficiency codes
(European Commission 2009).
In this research a house is defined as a passive house when the energy demand for heating is net
less than 15 kWh/m2 (Schnieders and Hermelink 2006, Mlecnik et al. 2007, Mlecnik et al. 2010), the
total primary energy demand is less than 120 kWh/m2 (Mlecnik et al. 2007, Mlecnik et al. 2010) and
the air-tightness (n50) is ≤ 0.6 h-1. Design should aim at minimizing the building’s operating energy
while maximizing exploitation of passive technologies (Sartori and Hestnes 2007). For comparison,
the annual demand for space heating of a newly built conventional house from 2010 is 100 kWh/m2.
The annual demand for space heating of an older home (before 1960) is around 200 kWh/m2 (Praktisch Duurzaam 2012).
Figure 1: Passive house principles (Green Hammer 2012).
Numerous successful passive house schemes have been built in Germany, Austria, Sweden, Belgium,
France and other Central European countries (Boonstra et al. 2006). In 2009, more than 12,000 houses
were built in Europe (European Commission 2009). Although there is no large scale implementation
in the Netherlands yet, the concept seems to be suitable for the Dutch market (Boonstra et al. 2006).
14
The Passive House Holland Foundation puts the number of realized passive houses in the Netherlands
in sharp contrast to developments abroad. In recent years, however, a reasonable number of passive
houses were built.
Also a large number of homes are renovated, making them highly efficient (PH Holland 2008).
It should be noted that the standard for a house renovated into a passive house is slightly different
from a newly built passive house. The annual demand for space heating may not exceed 20 kWh/m2,
while the limit for primary energy lies at 130 kWh/m2.
2.2.2 Passive design
Design is essential for each building that is based on passive techniques, because design is tied to specific conditions (Figure 1). A design must have a limited cooling outer surface and a proper surface/volume ratio. It must be oriented to the sun and represent new opportunities. In order to realize a
passive house, its insulation must be of high quality. The objective of passive houses is to build a full
heat bridge-free construction, which means that there are no components that are able to conduct heat
to the outside. Furthermore, it is important that a passive house has no cracks and other openings
through which air, moisture or heat can enter or leave the house. All buildings and houses built using
the passive house concept must be implemented consistently with insulated passive frames, windows
and doors and are always provided with triple glazing. Because of the clear energy-saving measures
and balanced ventilation, little extra warmth is needed for a healthy and constant indoor climate. The
use of efficient systems for ventilation, water and space heating, air filtration and heat recovery reduces energy consumption and thus energy bills. Energy bills can be reduced even further by using renewable solar energy, for example PV panels (PH Holland 2008).
2.3 Earthship
Another construction type designed to have minimum adverse impacts on the built and natural environment is known as an earthship. The term earthship refers to a type of dwelling designed by the architect Michael Reynolds. It is a sustainable, ecologically built house that can provide for all needs of
its residents, without assistance from outside. It strives for integral quality in a broad way. Autonomy
is achieved by the fact that earthships are not connected to the usual grids, such as electricity, water,
gas or a sewage system. Sustainable technologies are applied to prevent strains on the environment
(Earthship Europe 2012). Examples of these technologies are photovoltaic cells, wind turbines and a
rainwater harvesting systems (Ip and Miller 2009).
Striking is the use of alternative building materials, as earthships are constructed largely from
recycled and reclaimed materials. Building materials must serve their intended function not only when
newly installed but also for some acceptable length of time. When new materials are to be developed
or considered, or when traditional materials are to be used in an untried situation, the ability to predict
their performance may be greatly limited. The exact prediction of performance requires a complete
understanding of the material properties, the processes involved in the interaction of the materials
with its environment, and the environmental factors to which it will be subjected (John et al. 2005).
2.3.1 Earthship Biotecture
Michael Reynolds has always been a critic of the profession of architecture for its failure to deal with
the amount of waste that building design creates. He realized that any object can become a powerful
and durable insulation material when it is filled with dirt. After graduating from the University of
Cincinnati in 1969 he founded Earthship Biotecture, copyrighting the term for use only in structures
designed by him. Concerned with all the waste being produced and the on-going oil crisis in the
1970s, he started to build with cans and later added tires rammed with earth as new building blocks.
He combined these techniques with enough glazing, water catchment and energy production, after
which the first earthships were born.
15
Figure 2: The development of earthship models. Illustrations by W.
Raets (Earthship Europe, 2012).
His first can and rammed tire buildings where hut types, followed by U shaped models and combinations of both. When the greenhouse was added, the modular earthship was born. Another model was
the packaged model (without a greenhouse); a rectangular building with the south side glazed and the
rest imbedded in soil. A combination of the models led to the birth of the global model (Figure
2Figure 2).
The greenhouse mentioned, characteristically faces south. It plays an important role in seasonal thermal storage (Grindley and Hutchinson 1996). The latter is achieved by means of sloped
glazing of the greenhouse. During the winter months, the low angle of the sun allows passive solar
heat to be absorbed into the floors and walls. Both masses are storage batteries for temperature. Heat
absorbed during the day is released during the night. The greater the mass, the greater the storage capacity. During the summer months the angle of the sun is too steep to reach inside the earthship. This
allows the mass of the earth to cool the earthship (Figure 3).
Figure 3: Sloped glazing plays an important role in seasonal thermal store (Grindley and Hutchinson 1996)
As earthships are not dependent on infrastructure, it is possible to build on distant locations and therefore also on cheap parcels. By now, about a 1000 earthships have been built worldwide, whereof some
in Europe (Earthship Europe 2012). Earthship Biotecture is a global company, offering a proven, totally sustainable design and construction services worldwide.
16
2.3.2 Mapping of earthships in Europe
The first earthship to be built in Europe was planned in the year 2000 in Boingt, Belgium. A journalist
(Josephine) had convinced the municipality to have an earthship built with the help of Michael Reynolds. While the team of Earthship Biotecture was on its way to Europe, the council of the municipality
put their veto on the project. To deal with this setback, it was decided that a small demonstration
earthship without energy and water systems would be built in the backyard of Josephine’s home in
Strombeek, Belgium.
In July 2002, the building of the second earthship in Europe started in Fife, Scotland. Earthship Fife was initiated by Sustainable Communities Initiatives (SCI) as a demonstration and test in the
Scottish climate. The U-model has important adaptations that were done on request of SCI, which is
double glazing, thermal wrap insulation all around the building and a waterproof membrane. Building
finished in August 2004.
Figure 4: Earthships built or being built in Europe (Earthship Europe 2012)
The third earthship in Europe designed by Reynolds is the earthship Valencia, Spain. Building started
in spring 2003 and finished in 2008. To deal with too much water and too much sun, some small adjustments were made in April 2011, which solved the problems.
The fourth earthship project started in spring 2004 in Brighton, UK. Worth mentioning is the
fact that the University of Brighton placed sensors in the wall to research the thermal build up. Furthermore, as in Scotland, thermal wrap insulation was applied. The Brighton earthship is a modular
model and was finished in autumn 2006.
17
In April 2007, the building of earthship Ger, France, started. Earthship Ger is the first global model
built in Europe and included the thermal wrap insulation also applied in Fife and Brighton. In spring
2008 the building was finished.
In the summer of 2008 another project of Reynolds started in Zwolle, the Netherlands. Building was finished summer 2009. More earthships were built in Sweden, Portugal and Estonia; however
these were not designed by Michael Reynolds (Earthship Europe 2012). Figure 4 gives an overview of
the earthships built or being built in Europe.
2.3.3 Earthships in the Netherlands
As mentioned above, the first earthship that was built in the Netherlands is earthship Zwolle. Locating
a suitable piece of land, designing an earthship, gaining the planning permission and especially resolving building control issues was not that easy. As earthships are autonomous they conflict with the
Dutch Building Decree (as mentioned in 1.1.2). The Dutch Building Decree does not allow people to
live in earthships, as it requires that buildings are connected to the sewer and to public utilities. After
concessions were made, permission was granted for the realisation of an “autonomous” earthship in
Zwolle. Earthship Zwolle is based on a global model, but with an entrance in the North wall. Because
of the high ground water levels and a lack of stable ground a big concrete foundation was poured and
the earthship was lifted instead of being dug into the ground. The earthship is not off grid either but
connected to sewage, water and electricity (Earthship Europe 2012).
Currently, the Dutch earthship association (Vereniging Aardehuis 2012) is realizing another
earthship project, unique for Europe. An eco-district of 23 earthships plus a number of related projects
and enterprises is to be built in Olst. Twenty earthships will be built and paid for by individual households. The other three are to be built by the association for rental accommodation. The related projects
and enterprises that are planned are a visitor’s centre, a community centre, permaculture gardens and a
playground for children, which will include small animals.
The purpose of the visitor’s centre is to share knowledge of how to build and live in a sustainable manner with the world. It can be rented by people from outside the project and will have smallscale overnight accommodation and a teashop. The community centre will serve as a meeting point
for the community. It will accommodate for birthday celebrations, meetings, eating together and other
common activities. The aim of permaculture is to create a collaborative and harmonious relationship
between man and his natural surroundings. In practice, edible vegetables are grown in the local environment and animals are taken into consideration as to their place and supportive roles. As animals
provide food and eat left-over food, they are considered to be part of a biological life cycle. A natural
playground is expected to invite children to be adventurous and to play together.
For the building project in Olst it was sorted out on which aspects a prototype Earthship did
not meet the building regulation requirements. These aspects were further examined on health and
safety. After the concept was modified, the earthships fulfilled the framework of the Dutch building
regulations. In terms of utilities, only an electricity connection is planned to be installed. Consequently, an excess of self-generation solar energy can be distributed through the grid. Homes will not be
individually connected to drinking water. Probably one service pipe will be installed for the community in case of dry periods. In general, house roofs will collect rainwater in large reservoirs, which will
then be purified to drinking water. After use, the water is again purified by a wetland. Research has
demonstrated the quality and reliability of the through the wetland purified water. Therefore, the water does not need to be discharged to the sewer, thus the earthship will not be connected to the sewer
(Vereniging Aardehuis 2010).
2.3.4 Earthship Europe
The central point for volunteers, European earthship communities, European earthship projects and
European non-profit earthship organizations is Earthship Europe. Earthship Europe tries to get more
coordination and cooperation on a European level. Set up with different needs in mind, Earthship Europe is organized in departments (Figure 5), which are Flagship Europe, the European Earthship Circle of Organizations (EECO), the European Earthship Builders United (EEBU) and the European
Earthship Communities Network (EECN).
18
Figure 5: The organization of Earthship Europe (Earthship Europe 2012).
Flagship Europe is the research and development department of Earthship Europe. At the same time,
it is a title an actual building can hold for a while for getting nearest to the flagship criteria. The
EECO rose out of the idea that having a circle of similar-minded organizations with common goals is
a good way to spread information on self-sustainable building in a fast way in different languages.
Earthship Belgium, the founding organization, soon was accompanied by the newly formed Earthship
Sweden. Within a year after starting with the EECO, the countries Denmark, Spain and Moldova
joined the circle. The EEBU is a web-based platform that provides information for project owners and
people that want to build. It is a place where people can discuss with builders elsewhere in Europe,
can share knowhow, and can sign up for volunteer work. The EECN means to provide a web-based
platform for earthship or earthship-inspired communities. A place where they can get to know each
other and share their information on building and running a community and life in the community
(Earthship Europe 2012).
19
20
3. BUILDING MATERIALS
To realize different construction types, including those mentioned in the previous chapter, building
materials are needed. The mining of raw materials used to produce building materials is limited to the
stock. The generation of the raw materials by the Earth takes much longer than the lifespan of the
technical and economic materials made of it. Besides the fact that the availability of raw materials is
limited, the mining of the substances is often very harmful to the environment and has great consequences for the local community. Furthermore, after their period of use, materials become waste and
they are dumped to be buried in landfills or incinerated at waste incineration plants, resulting in pollution and polluting emissions (Tulp 2009). In order to restrict the environmental impact of building
materials, materials should be used in such a way that no material is spilled. Additionally, materials
should be reusable or biodegradable.
However, the latter is often not the case, as in construction among others PVC pipes, plastic
frames and oil-based insulating materials are used. In the next chapter (chapter 4), a model is discussed that looks at the environmental impact of building materials based on quantities. As an introduction to this model, the current chapter will look at what is known in literature about the extraction,
application and processing (after use) of some of the building materials used in a conventional house,
a passive house and an earthship.
3.1 Conventional house
Careful selection of environmental sustainable building materials is the easiest way for architects to
begin incorporating sustainable design principles in buildings. Natural materials (e.g. wood, sand,
gravel) are generally lower in embodied energy and toxicity than materials modified by man (John et
al. 2005), thus have a lower environmental impact. However, in today's construction mostly modified
materials are used. Important building materials of a conventional house are timber, concrete, bricks,
tiles, glass wool and plastic (EPS), thus they will be discussed below. Also different types of metals
are used for construction, but they will not be discussed as they are not assumed to be the same for all
construction types.
3.1.1 Wood and timber
Wood (the material in its natural state) is renewable, can be reused and recycled in certain applications and is biodegradable in others. It is used in different forms in the production of a wide range of
products as well as being a source of energy. Wood and wood-based fibres are among others used for
furniture, books, packaging of products and documentation. Wood is also widely used as construction
material. In comparison with other materials, wood has a relatively low weight with high strengths
values, allowing the realisation of very large spans. Furthermore, it has a naturally high chemical resistance. Known applications of wood in construction are doors, window frames, battens, facade elements and cladding systems. Wood is then referred to as timber to indicate that it was modified by
man.
Whether the use of timber in construction is sustainable, is dependent on its life cycle phase.
With regard to sourcing and harvesting, about 90% of the timber used in wood products sold on the
European market originates from European forests, which are largely sustainably managed. Just over
60% of the net annual increment is harvested, hence, in most areas their surface area grows. With regard to recycling, increasingly, recycled materials are used for the production of paper and wood
products (RF 2010).
3.1.2 Sand, gravel and concrete
The Dutch construction industry does not only need a constant supply of wood, but also a continuous
supply of sand and gravel. Sand and gravel are erosion products derived from stone. The world contains a vast resource of stone and volcanic activity leads to new resources constantly. However, stone
does not grow at a visible speed. Therefore, extraction of stone and the environmental impact of the
stone extraction process should be minimized. In the Netherlands alone, annually 40 million tons of
sand and gravel are used in concrete and concrete products (Van Nieuwpoort Groep 2012).
21
Concrete has a variety of appearance as a building material, is compatible with various other
structural materials and can be processed in many ways (pump, pour, cast, spray, trowel, mold, form
and carve). Concrete can be recycled, but the resource-saving potential is limited, as it has been calculated that on a European scale, even a full utilisation of recyclable aggregates will account for maximum 10% of the annual consumption. Currently, the amount of stone/concrete demolition rubble being recycled varies significantly across Europe. The amount of concrete recycling in Italy and Spain is
about 10%, while France has a recycle rate of 20%. The German recycle rate is much higher, reaching
80%. The Netherlands, Belgium and Denmark have recycle rates over 90% (ECOserve 2012).
3.1.3 Clay, bricks and tiles
Whereas sand and gravel are used to produce concrete, a lot of clay is used to produce bricks and tiles.
Also clay is composed of fragments of weathered and eroded rock. Tiles and Bricks of Europe (TBE)
states that the extraction of clay for construction is only a small percentage (5%) of the total mineral
extraction. In estuaries, the extraction is performed with minimal disruption of the environment. In
case of deep deposits the required footprint is modest. The energy used for the transport of raw materials is kept limited, as brick and tile factories are usually located along clay deposits or sand quarries.
The factories are committed to maintain the appearance of the site, to prevent pollution and to reduce
the environmental impact. Although the extraction of clay has an effect on the environment, it also
has potential benefits, such as the creation of nature reserves, lakes and the formation of repositories
for different types of waste.
Once extracted, the clay enters the production process. Among others, ceramic building materials are produced. It is claimed that ceramic building materials have a very long life, require little or
no maintenance and help cover the cost of heating and cooling. They contribute to a pleasant room
climate thanks to the porous structure and have a high resistance to fire and moisture. The amount of
brick demolition waste that is reused varies across Europe. Utilising bricks from demolition sites is
difficult, as they may be contaminated with concrete, mortar, plaster and other materials. When bricks
are reused it is often for low-grade application. European standards for bricks are very strict, thus it is
extremely difficult to ensure that bricks from demolished buildings will be durable when used in new
structures. Roof tiles, however, can be easily extracted and reused, thus this is done regularly (TBE
2012).
3.1.4 Glass wool and plastic
In addition to the above-mentioned materials, also specific materials for insulation are used in construction. A well-known insulation material is glass wool. Glass wool insulation is lightweight and its
long strand fibre gives good tear strength. Furthermore, it is non-combustible, water repellent and rot
proof. Glass wool is made from natural sand to which recycled glass (cullet) and fluxing agents are
added. At the end of its useful life, glass mineral wool is itself infinitely recyclable (Isover 2012). In
construction also plastic is used for insulation. A well-known insulator against heat and cold is expanded polystyrene (EPS). EPS is extracted from oil and is 100% recyclable (EPS 2012).
3.2 Low energy buildings
Passive house construction is mainly based on the building materials of the conventional house.
Therefore, careful selection of environmental sustainable materials also applies for passive houses.
However, the building materials are used in a different manner to standard methodology. Main difference in passive houses is that the volumes of insulation are considerable greater. It is said that the energy which is necessary to produce, transport and recycle the additional insulation material is recovered within a few months. Hereafter, better insulation of buildings is a cost-effective way to reduce
CO2 emissions (Rockwool 2012). In addition, some other building materials are used, which will be
discussed below. These materials are rock wool, cellulose fibres and oriented strand board (OSB).
3.2.1 Rock wool
Rock wool is mainly made of dolerite, which is volcanic rock. Annually, volcanoes and tectonic
plates produce 38,000 times more rock material than is used to make rock wool, thus (from the material point of view) the harvest of rock wool is sustainable. Furthermore, basalt, recycled rock wool and
22
other residues are used as raw materials for production. In the production of rock wool, environmental
aspects are taken into account. During production, production residues like mineral wool waste and
packaging film are fed back into the production process. With regard to packaging materials, less environmentally harmful materials, such as cardboard and recyclable polyethylene film are used. In addition, the use of packaging materials is minimized.
In construction, rock wool is used as heat insulation. It envelops air and therefore it has a high
natural insulation. Furthermore, it is fire-resistant and tolerates high temperatures (above 1000 °C). It
fits seamlessly, retains its shape, is resistant to aging, germfree, inorganic (no breeding ground for
fungi or bacteria) and ensures soundproofing (Rockwool 2012).
3.2.2 Cellulose fibres
Cellulose fibres are mainly made of waste paper (80%). The theoretical maximum collection rate of
paper is 81%, as the share of non-collectable and non-recyclable paper (libraries, archives, sanitary
paper) is estimated to be 19% of the total paper and board consumption. However, lower paper recycle rates are reached, as in 2010 the recycle rate was 68.9% (ERPC 2012). Cellulose is popular for
house insulation in for example the roof and walls of a passive house, because of its sustainability and
low embodied energy. When removed from a building, it may be used again or disposed of safely
without creating toxic waste (LEH 2012).
3.2.3 Oriented Strand Board
Oriented Strand Board (OSB) is the main innovation in the wood industry. The remarkable qualities
of OSB are due to the unique manufacturing process. Wood flakes are veneered and then sprinkled on
each other in several layers, each layer perpendicular to the previous layer, so that a maximum
strength and stability is obtained. OSB has a low environmental impact as there are no mature trees
used in OSB production. Only thin stems from ecologically managed forests responsibly replanted are
used. OSB itself is fully recyclable (OSB 2012).
3.3 Earthship
It is said that another way to incorporate sustainable design is to use waste as building material, as
with earthships. Consequently, the consumption of fresh raw materials, the energy usage during production, the air pollution from incineration and the water pollution from landfills are reduced. Striking materials that are reused in earthships are scrap tires, steel and aluminium cans, glass bottles and
loam, thus they will be discussed in the following section. Whilst some of the materials used in the
earthship construction are recycled, there are significant amounts that are not. Information mentioned
earlier, about for example concrete and rock wool also applies to earthships.
3.3.1 Scrap tires
In Earthships, discarded tires are used to build walls. Originally this was a way to keep the tires out of
landfills. European countries were allowed to decided themselves how to process their scrap tires. Recovery rates varied. In 2003, the EU was the second largest scrap tire generator (after the United
States), generating 2.6 million tons of used tires in 2003. The leading scrap tire generator was Germany (24%), followed by the UK (17%), France (14%), Italy (14%) and Spain (11%). Not only did
Germany generate the most scrap tires, it also recycled most of them (78%). The UK recycled 59%,
France recycled 52%, Italy recycled 70%, and Spain recycled only 25%. In 2003, the main endmarkets for scrap tires were tire-derived fuel, ground rubber applications, cut/punched/stamped rubber
products and civil engineering applications. Examples of areas of application are the cement industry,
the paper industry, rubber modified asphalt, new tire manufacturing, landfill construction and operation, and sub-grade insulation for roads. Tires that were not recycled were among others sent to landfills or were left on vehicles in scrap yards (Irevna 2005).
Since 2003, much has changed. The EU has toughened its stance towards environmental hazards. It has laid down strict requirements for landfills to prevent and reduce the negative effect of car
tires on the environment. From 2003 onwards, whole scrap tires are banned from being landfilled,
while from 2006 onwards shredded tires are banned from being landfilled (Irevna 2005, European
Union 2012). Accordingly, recovery rates have dramatically increased. In 2010, the enlarged Europe
23
was faced with the challenge of managing about 3.3 million tons of used tires. Of the EU countries
(plus Norway and Switzerland), 23 countries recovered 90% and more of their annually used tires
output. Of those 23 countries, 18 countries recovered 100% (Figure 6). The average used tire recovery
rate of the EU27 (plus Norway and Switzerland) was 96% (ETRma 2011). As a result, it is not very
logical to use tires as building material in earthships.
Figure 6: Recovery rates of used tires in Europe. Countries with recovery rates that exceed 100% have collected more than their obligation.
3.3.2 Steel and aluminium cans
Other waste that is used in the walls of his Earthship are steel and aluminium cans. They are used to
fill the empty spots in the outer walls made of tires. In addition, they can also be used for inner walls,
in combination with concrete (Figure 7).
In 2008, steel supply for the packaging market to the European Union (EU) countries was
4,312 tons, from which 70% was recycled. The country with the highest recycling rates was Belgium
(98%), followed by Germany (92%) and the Netherlands (87%). In 2010, 72% of the steel packaging
was recycled in Europe. This makes steel the most recycled packaging material. In theory steel is
100% recyclable without any loss in quality. Its magnetic properties make it the easiest and most economical packaging material to sort and recover (APEAL 2012).
In 2010, the main producer of aluminium globally was China (41%), while Europe produced
10% of the total production. EU’s production of primary aluminium was 2.3 million tons (21% of the
total production). Its production of recycled aluminium reached 4.3 million tons (33% of the total
production). Import levels reached 5.1 million tons (46% of the total production). The main end-use
markets for the aluminium products in Europe are building (26%) and transport (37%). The remaining
part goes into engineering, packaging, and other applications.
Aluminium has impressive recycling rates of over 90% in transport and building applications.
However, other applications reach lower levels. As to packaging, in 2008, 65% of all metal beverage
cans consumed in the EU countries, the European Free Trade Association (EFTA) countries and Turkey was made of aluminium. The average aluminium beverage can recycling rate stood at 63%. Dif24
ferent initiatives try to further reduce the environmental footprint of aluminium packaging. The current aim is a 75% recycle rate for Europe in 2015 (EAA 2012). Also aluminium is 100% recyclable
with no downgrading of its qualities.
As steel and aluminium are 100% recyclable, they cannot be regarded as waste. It can be concluded that the use of steel and aluminium cans in earthships conflicts with the idea behind earthships.
Figure 7: The use of steel and aluminium cans and the use of glass bottles in Earthship walls
3.3.3 Glass bottles
Also glass bottles are used in Earthship walls. They serve as decoration and light source, while simultaneously giving firmness to the wall (Figure 7). Their use is intended to combat waste, but it can be
discussed whether glass bottles are waste, as glass is 100% recyclable in a closed loop system. The
European Container Glass Federation (FEVE) claims that in 2009 the EU glass consumption totalled
16,323 tons, while 11,004 tons was collected the same year. Thus, the recycle rate of the EU in 2009
equalled 67.42%. In 2010, this recycle rate equalled 67.56%. According to the latest glass recycling
estimates (March 2012), the average glass recycling rate in the EU remains stable at 68%. Because of
this recycling rate, more than 12 million tons of raw materials (sand, soda ash, limestone) were saved
and more than 7 million tons of CO2 was avoided. As there is still 32% of glass that is not collected,
the EU commission has announced a new legal status for cullet, which is, giving it a status of nonwaste. Their goal is to help further increase glass recycling rates.
3.3.4 Loam
Loam is a construction material that consists of 3 main components, namely sand, clay and water.
Furthermore, some additives (e.g. straw, hemp wood or paper pulp) can be added according to the
expected end result. It is a material that originated many centuries ago and it was frequently used until
cement was discovered. Nowadays, loam is rapidly gaining popularity again. Loam has a moisturising
effect and is able to keep humidity in a house at a constant level. Additionally, a heat wall with loam
ensures an even heat distribution and delivery over the entire wall. Also it can be used to create all
desired forms and it can be applied on almost any surface. However, most important is that loam is a
100% environmentally friendly material without chemical additives (Leemstuc 2012).
25
26
4. METHODS – ENVIRONMENTAL IMPACT (SIMAPRO)
One goal of this research is to compare conventional houses, passive houses and earthships based on
environmental impact. This chapter will discuss the SimaPro model used to look at the environmental
impact based on the embodied energy. As mentioned earlier, the energy embodied in each structure is
the sum of all the energy needed to manufacture the structure (Sartori and Hestnes 2007). Thus, the
energy embodied in each of the construction types mentioned is the sum of all the energy needed to
produce the different building materials for one construction type.
In this research however, it is assumed that the energy embodied in each construction type
mentioned is the sum of all the energy needed to produce the different building materials for the floor,
the outer walls and the roof of a construction type. The SimaPro model does not take into account inner walls, basements, balconies, pipes, windows etc. as these data were hard to obtain. Although the
environmental impact of building materials is influenced by the source of the building materials in
relation to transport, transport is also not included in the model due to a limited amount of time.
The embodied energy of a structure varies, as type of building, type of construction or size
differs (Sartori and Hestnes 2007). To prevent type of building and size from influencing the model,
the amount of each building material needed for a construction type was first calculated in m3 or kg
per m2 roof, wall or floor (Table 2, Table 3 and Table 4) and entered in SimaPro (see 4.4). Subsequently, in SimaPro, the amounts were multiplied with the surface areas of a model house, respectively 90 m2 floor, 100.8 m2 wall and 90 m2 roof (Figure 8).
Figure 8: Model house; length 15m, width 6m, height 2.4m
4.1 Conventional house
The intention of this research was to base the construction data of a conventional house on a conventional house built in the Netherlands. Unfortunately, these data were not available. Therefore, the
building materials of a conventional house as cited in Table 2 Error! Reference source not
found.are based on numbers from the BUtgb, or in English the UBAtc, which is Belgium’s only authority offering technical approval of construction materials, products, systems and installers.
27
Table 2: Buildings materials used in a conventional house per m2 surface area (BUtgb 2008, Kort 2009)
Material SimaPro
Amount Unit
Roof (pitched)
Battens (horizontal)
Battens (vertical)
Fibre cement board
Insulation glass wool
Vapor barrier (aluminium foil)
Particle board, cement bonded, at plant/RER S
Glass wool mat, at plant/CH S
Chipboard ceiling
Tiles
3
0.0032
2.2
m
kg
Particle board, indoor use, at plant/RER S
Roof tile, at plant/RER S
0.018
41
m
kg
Interior chipboard
Vapor barrier (PE)
Insulation EPS
Particle board, indoor use, at plant/RER S
Polyethylene, LDPE, granulate, at plant/RER S
Expandable polystyrene (EPS) E
0.018
0.188
2.475
m
kg
kg
Exterior cladding mineral fiber cement board
Lintel (frame with window / door)
Cladding brick
Particle board, cement bonded, at plant/RER S
0.0032
m
3
Walls
Frame (wood)
Floor
Moisture barrier
Concrete
EPS
PE-film (polyethyleen)
Screed (Assumtion: cement
Brick, at plant/RER S
Concrete block, at plant/DE S
Expandable polystyrene (EPS) E
Polyethylene, LDPE, granulate, at plant/RER S
Cement cast plaster floor, at plant/CH S
3
3
180
kg
380
2.475
0.188
90
kg
kg
kg
kg
4.2 Low energy buildings
It was intended to base the construction data of a passive house on a passive house built in the Netherlands. Again, the data could not be obtained. Therefore, the building materials of a passive house as
cited in Table 3 are based on data from the VIBE, which stands for “Vlaams Instituut voor BioEcologisch bouwen en wonen”. It is a non-profit organisation that promotes natural building and living and educates its principles (Kort 2009, Eurabo 2012, VIBE 2007).
Table 3: Buildings materials used in a passive house per m2 surface area (Kort 2009, Eurabo 2012, VIBE
2007)
Material SimaPro
Amount Unit
Roof (Pitched)
3
Wood finish
Sawn timber, hardwood, planed, air / kiln dried, u=10%, at plant/RER S
0.012
m
Pipe cavity (ceiling battens)
Vapor barrier
Insulation (paper flakes)
Sawn timber, softwood, planed, kiln dried, at plant/RER S
0.024
m
Cellulose fibre, inclusive blowing in, at plant/CH S
Insulation (celit) on roof
Tiles
Fibreboard soft, without adhesives, at plant (u=7%)/CH S
Roof tile, at plant/RER S
Walls
Gypsum fibreboard
Pipe cavity with insulation (wood)
Gypsum fibre board, at plant/CH S
OSB
Insulation (paper flakes)
Insulation (celit) on timber frame
Air cavity
Bricks
3
18
kg
0.044
41
m
kg
12.6
0.04
kg
Oriented strand board, at plant/RER S
Cellulose fibre, inclusive blowing in, at plant/CH S
0.015
8.55
m
kg
Fibreboard soft, without adhesives, at plant (u=7%)/CH S
0.066
m
3
3
3
Brick, at plant/RER S
162
kg
Floorboards
Sawn timber, hardwood, planed, air / kiln dried, u=10%, at plant/RER S
0.02
m
OSB
Insulation (paper flakes)
Insulation (EPS)
Concrete slab
Oriented strand board, at plant/RER S
Cellulose fibre, inclusive blowing in, at plant/CH S
Expandable polystyrene (EPS) E
Concrete block, at plant/DE S
0.18
8.55
4.125
240
m
kg
kg
kg
Floor
28
3
3
4.3 Earthship
The building materials of an earthship are not based on a Dutch earthship, but on the earthship in
Brighton. This is because the Netherlands has no earthships that are built to serve as a dwelling.
Numbers as cited in Table 4 are based on the article of Hewitt (Hewitt 2009). For the record, the dry
limestone subsoil is the dirt with which the tires are filled. Apparently, this is the type of soil that was
available at the Brighton Earthship.
Table 4: Building materials used in an earthship per m2 surface area (Kort 2009, Hewitt 2009, Rockwool (2)
2012)
Material SimaPro
Amount Unit
Roof (Nest)
Surface Rse
CA 32 1000r steel profile roof
Tyvek Supro roofing membrane
Hard Rock Dual Density board
Chromium steel 18/8, at plant/RER S
Polyethylene, HDPE, granulate, at plant/RER S
Rock wool, packed, at plant/CH S
15.8
0.98
3.6
kg
kg
kg
18mm CDX Ply deck
Rockwool Roll
Visqueen 1200 heavy gauge plastic
Plywood, outdoor use, at plant/RER S
Rock wool, packed, at plant/CH S
Polyethylene, LDPE, granulate, at plant/RER S
0.018
10.8
0.94
m
6mm Birch ply
Surface Rsi
Plywood, outdoor use, at plant/RER S
0.006
m
23.036
kg
12
3024
120
3.75
2.82
kg
kg
kg
kg
kg
300
192
kg
kg
Walls
Surface Rse
Adobe plaster finish
Earth rammed tyres
> Rubber (tyres)
> Dry limestone subsoil
> London clay
Yelofoam X2i
Visqueen 1200 heavy gauge plastic x 3
Surface Rsi
Floor
Surface Rse
Cast concrete
Stone
Surface Rsi
Clay plaster, at plant/CH S
Synthetic rubber, at plant/RER S
Limestone, milled, packed, at plant/CH S
Clay plaster, at plant/CH S
Polystyrene, extruded (XPS), at plant/RER S
Polyethylene, LDPE, granulate, at plant/RER S
Concrete block, at plant/DE S
Natural stone plate, cut, at regional storage/CH S
3
kg
kg
3
Noticeable is the lack of insulation materials in the floor of the Brighton earthship. As the concept of
earthships aims at retaining heat, it does not seem logical that the floor is not better insulated. On the
website of the Dutch earthship association (Vereniging Aardehuis 2012) is mentioned that the floors
of the earthships built in Olst will be insulated with polystyrene. To investigate the influence of polystyrene insulation, the model does not only look at a scenario with the construction materials from the
article by Hewitt (hereafter referred to as the reference scenario), but also to the reference scenario in
which polystyrene insulation has been added to the floor. Since the type and thickness of the polystyrene used are not mentioned, numbers are based on the Yelofoam X2i (10 cm) used in the earthship
wall. For the second scenario, the data of the floor are depicted in Table 5.
Table 5: Buildings materials used in an earthship floor per m2 surface area: Polystyrene included
Floor
Surface Rse
Cast concrete
Yelofoam X2i
Stone
Surface Rsi
Concrete block, at plant/DE S
Polystyrene, extruded (XPS), at plant/RER S
Natural stone plate, cut, at regional storage/CH S
300
3.75
192
kg
kg
kg
Accept for the lack of insulation in the floor, it is striking that tires are mentioned, while cans and
glass bottles are left out. In 3.3, it is explained that tires, cans and glass bottles used in earthship are
all reclaimed building materials. In relation to embodied energy, one could assume that the initial affliction of nature (human health, ecosystems, resources) during the production of tires, cans and glass
bottles is distributed over the years that a tire is in position as a car tire and cans and glass bottles are
used to drink from. Their application after this periods of use is then burden free. From this point of
29
view, tires, cans and bottles should not be taken into account within the SimaPro model. Although the
tires, cans and bottles are used, they do not contribute to the environmental impact calculated in the
model.
One could also say that the initial affliction of nature during the production of tires, can and
glass bottles remains the same during all the years of use. From this point of view, tires, cans and bottles should all be taken into account within the SimaPro model.
As involving tires, while excluding cans and bottles seems wrong, the model does not only
look at the reference scenario and the reference scenario with polystyrene insulation. Four other scenarios are developed. One scenario will exclude tires from the reference scenario, thereby assuming
that the initial affliction of nature during the production has ‘perished’. One scenario will include cans
in the reference scenario, hence assuming that the initial affliction of nature during the production remains the same. Another scenario will include glass bottles in the reference scenario, also assuming
that the initial affliction of nature during het production remains the same. The last scenario will include cans and glass bottles in the reference scenario, assuming that the initial affliction of nature during het production remains the same. Subsequently, the different scenarios can be compared based on
environmental impact. It should be noted, that the cans and bottles do not replace the tires in the wall.
In practice, they replace some of the dirt used in the walls. In the model, no adjustments were made to
the amount of dirt.
4.3.1 Steel and aluminium cans
As steel and aluminium cans are interesting to look at in this research as they are used in outer walls, a
separate calculation for these cans is made based on earthship Fife. Earthship Fife is a single 6 by 5
meter U module. In the project, over 1500 cans are used (Hewitt 2009). When it is assumed that the
height of an earthship is 2.4 meter and all walls are made of tyres, the surface area of the walls of
earthship Fife is (6+6+5+5)*2.4 = 52.8 m2. This means that 1 m2 wall contains around 1500/52.8 = 28
cans. Assuming that the ratio aluminium cans and steel cans is equal, 1 m2 wall contains around 14
steel cans and 14 aluminium cans. One aluminium can weighs around 14.9 gram (IAI 2012). One steel
can weighs around 21.4 gram (SCRIB 2006). The following data can be entered in SimaPro.
Table 6: Aluminium and steel cans used in an earthship per m2 surface area
Material SimaPro
Recycled Material (Cans)
Aluminium cans
Steel cans
Aluminium, production mix, at plant/RER S
Steel, low-alloyed, at plant/RER S
Amount Unit
0.209
0.300
kg
kg
4.3.2 Glass bottles
As this research is also interested in results with regard to the use of recycled glass bottles in earthships, a calculation is made on glass bottles. The number of glass bottles used in an earthship varies
with the design. Based on numbers of earthship Zwolle (Vereniging Aardehuis 2012) it is assumed
that during the construction of an earthship 4000 glass bottles are needed. It must be noted that the
4000 bottles are not used in total, but are cut in half, after which the bottom sides are taped together to
form bottle bricks. Therefore, in further calculations on the total weight of the glass bottles only 2000
bottles are used. The weight of the glass bottles is based on the weight of wine bottles. Wine bottles
vary in weight, but it is assumed that the average weight of a wine bottle is 500 gram, thus 0.5 kilogram. This would mean that an earthship contains 2000*0.5 = 1000 kg glass. The following data can
be entered in SimaPro.
Table 7: Glass bottles used in an earthship
Material SimaPro
Recycled Material (Glass bottles)
Glass bottles
Packaging glass, white, at regional storage/CH S
Amount Unit
1000
kg
It should be noted that the amount of glass entered is not per 1 m2 of surface area as before. When
used in a calculation within SimaPro, the number should not be multiplied with the surface areas of
the model house. Furthermore, it is assumed that the application of glass bottles is in outer walls. In
practice, their application is mainly in inner walls, which are not included in the model. Also note that
30
when glass bottles are used for excessive decoration in for instance garden walls, glass use in an
earthship can be much higher.
4.4 SimaPro
SimaPro is a Life Cycle Analysis (LCA) software program with an extensive database holding information about the environmental impact of materials and about processing techniques. SimaPro can be
used to analyse the environmental impact of a product throughout its lifecycle. The product’s life cycle includes all processes which can be related to the production, use and disposal of the product. This
part of the research however, focuses not on the total lifecycle of a product, but only on the environmental impact of the production stage of the building materials used in the different construction
types. To compare the environmental impact of the production stages of the building materials used in
the different construction types, a method and an impact indicator must be chosen. The following text
explains the choice made for this research.
4.4.1 ReCiPe Endpoint indicator
In this research, the ReCiPe method is used as it is the newest method in SimaPro to calculate the environmental impact of materials. Subsequently, two types of impact indicators are available, respectively midpoint indicators and endpoint indicators. A midpoint indicator reflects the relative importance of emissions or extractions within an impact category. An endpoint or damage indicator has
a relatively high environmental relevance, allows aggregation of different effects and is considered to
be more understandable to decision makers, but is also inherently more uncertain (De Schryver 2010).
In this research, the later impact indicator is used because of its high environmental relevance.
Three different perspectives can be selected; that of an individualist (I), an egalitarian (E) or a
hierarchist (H). An individualist is a self-seeking person, who wants to control the environment
around him and the people in it. An egalitarian has a strong group loyalty and acts solely upon the
rules imposed to him by nature. A hierarchist tries to solve an environmental problem by introducing
boundaries for emissions of pollutants and other environmental treats. As the Netherlands is a typical
example of a country that is governed hierarchistically, in this research the perspective of the hierarchist is used (De Schryver et al. 2011). What remains is the choice between different normalisation/weighting sets. In this research the Europe ReCiPe H/A is used, as this set used the normalisation
values of Europe and is recommended by SimaPro.
Results are expressed in three main areas of protection, that is ‘human health’, ‘ecosystems’
and ‘resources’. The area of protection ‘human health’ is quantified by changes in mortality and morbidity (sickness rate). It has the unit DALY, which stands for ‘disability adjusted life years’. The area
of protection ‘ecosystems’ is computed in terms of changes in quality of natural ecosystems (biodiversity) as a consequence of exposure to chemicals or physical interventions. It has the unit species/yr.
The area of protection ‘resources’ refers to the extraction of scarce resources and covers the concern
about limited resource availability and the future possibilities to enjoy the resources we have today
(De Schryver 2010). It has money ($) as unit.
31
32
5. METHODS – OPERATING ENERGY (EXCEL & DOMUS)
Another goal of this research is to compare conventional houses, passive houses and earthships based
on operating energy. The operating energy is the energy used in a structure during its operational
phase (Sartori and Hestnes 2007). In this research however, it is assumed that the operating energy is
the energy needed for heating to compensate for heat losses. The heat losses are calculated with an
Excel model and a DoMUS model.
5.1 Excel model
In this research it is assumed that the inside temperature of a Dutch house is 20 ºC (Ta). The average
outside temperature in the Netherlands is set at 10.5 ºC (Tb) . This number is based on average temperatures from the KNMI (Royal Netherlands Meteorological Institute) which can be found in Table
8. In the first model used to calculate the operating energy, which is a model in Excel, it is assumed
that the operating energy is the energy used to maintain the temperature by compensating for heat
losses through the floor, the walls and the roof. To calculate the heat flow/loss through a floor, wall or
roof having a surface area of 1 m2 (Q), the following formula is used:
Q = (Ta – Tb) / Rtot (Anonymous 2012)
In which:
Q = the flow of heat through a floor, wall or roof having a surface area of 1 m2 in Watts (W)
Ta and Tb = the temperature on both sides of the wall in degrees Celsius (ºC)
Rtot = the thermal resistance of a floor, wall or roof having a surface area of 1 m2 (m2 ºC/W)
Table 8: Average temperature (ºC) in the Netherlands per season from the year 2001 up to 2012 (KNMI 2012)
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
Average
Average Temp. Average Temp. Average Temp. Average Temp. Average Temp.
Spring (°C)
Summer (°C)
Autumn (°C)
Winter (°C)
Year (°C)
9.1
17.4
11.6
4.1
10.6
10.0
17.6
10.7
4.8
10.8
10.1
18.6
9.8
2.4
10.2
9.5
17.0
10.9
4.1
10.4
9.8
16.9
12.0
3.6
10.6
9.1
18.5
13.6
2.8
11.0
11.7
17.2
10.3
6.5
11.4
10.2
17.3
10.2
5.1
10.7
10.8
17.4
11.7
2.2
10.5
8.9
17.7
9.9
1.1
9.4
11.0
16.3
11.4
2.3
10.3
10.5
The total thermal resistance (Rtot) of a floor, wall or roof with a surface area of 1 m2 is calculated by
adding up the R values of the different building materials within a floor, wall or roof. The Rtot values
calculated can be found in Table 9, Table 10 and Table 11. The R values of the different buildings
materials within the conventional house are calculated by the following formula:
R = t / λ (Anonymous 2012)
In which:
R = the thermal resistance of a building material (m2 ºC /W)
T = the thickness in meters (m)
λ = the thermal conductivity (W/m ºC)
33
5.1.1 Conventional house
The thicknesses of the building materials used are based on the data from BUtgb (BUtgb 2008, Kort
2009). The thermal conductivity of the different building materials are based on numbers from Kort
(BUtgb 2008, Kort 2009).
Table 9: Calculation of Q (W) of the different surface areas of a conventional house
Conventional house Temp In (°C) Temp Out (°C) Rtot (m2K/W)
Roof
20
10.5
3.3
Wall
2.9
Floor
2.7
5.1.2 Low energy building
The thicknesses of the building materials used are based on the data from VIBE (Kort 2009, Eurabo
2012, VIBE 2007). The thermal conductivity values are based on numbers from Kort (BUtgb 2008,
Kort 2009).
Table 10: Calculation of Q (W) of the different surface areas of a passive house
Passive house
Roof
Wall
Floor
Temp In (°C) Temp Out (°C) Rtot (m2K/W)
20
10.5
10.9
5.7
10.8
5.1.3 Earthship
The Rtot values in Table 11 are based on the article of Hewitt (Hewitt 2009). No calculation with
thickness and the thermal conductivity was needed.
Table 11: Calculation of Q (W) of the different surface areas of an earthship
Earthship
Roof
Wall
Floor
Temp In (°C) Temp Out (°C) Rtot (m2K/W)
20
10.5
4.6
5.6
0.3
Also for the operating energy the influence of polystyrene insulation in the floor is examined. When
polystyrene insulation is added to the earthship floor, the Rtot value becomes 3.8 (Table 12).
Table 12: Calculation of Q (W) of the different surface areas of an earthship: Polystyrene included
Earthship
Roof
Wall
Floor
Temp In (°C) Temp Out (°C) Rtot (m2K/W)
20
10.5
4.6
5.6
3.8
5.1.4 Comparison construction types
To calculate the total loss of heat by a house, the heat flow per m2 can be multiplied by the total surface of the roof, wall and floor in m2. In this research, the numbers are multiplied by the dimensions
of the model house (Figure 8).
34
5.2 DoMUS
The second model used to compare conventional houses, passive houses and earthships based on operating energy is the DoMUS (Domestic Metabolism User friendly Simulated) model. “DoMUS can
be used to gain insights in the energy use of households. On the one hand the model offers the possibility to determine the yearly total (direct and indirect) energy use. On the other hand it is possible to
determine the consequences of a change in household expenditures” (Benders and Kok 1999).
Although DoMUS can be used to calculate domestic energy use for different functions of energy
(heating, house, appliances, transport, food, holiday, others), this research concerns only the category
of heating. Within the category of heating, the item of transmission losses, thus insulation, is altered
in such a way that a conventional house, a passive house and an earthship can be compared in this
respect. It must be noted, that not only data on walls, floors and roofs, but also on windows are entered. The insulation data entered for the different construction types can be found in Table 13, Table
14 and Table 15Error! Reference source not found.. Furthermore, is should be noted that the standard DoMUS model assumes a house volume of 250 m3. This value is edited to correspond with the
model house used in SimaPro and the Excel model, thus 215 m3.
5.2.1 Conventional house
Based on the data from BUtgb (BUtgb 2008, Kort 2009), four insulation types were chosen to represent the insulation data of a conventional house (Table 13). No further calculations were needed.
Table 13: Insulation data of a conventional house (BUtgb 2008, Kort 2009)
Insulation Conventional house
Wall
EPS plates 10 cm
Floor
EPS foam 10 cm
Roof
Mineral wool 10 cm (also insul. later on)
Window Double window pane high effcient (HE)
U-value
0.35
0.37
0.31
1.85
5.2.2 Low energy building
Based on the data from VIBE (Kort 2009, Eurabo 2012, VIBE 2007), one insulation type already present in DoMUS was chosen to represent the insulation data of a passive house (Table 14), which is
the ‘double window pane HE++’. Insulation data on the passive wall, floor and roof were added. The
U-value (in DoMUS K-value) was calculated by dividing 1 by the total R value of the insulation materials. As the research focuses on the direct energy part of the operating energy (gas and electricity)
and not on the indirect energy part, the indirect energy values are not relevant. Since results related to
costs and life time are not considered, these values are not specified.
Table 14: Insulation data of a passive house (* = data added in DoMUS)
Insulation Passive house
U-value
Wall*
Cellulose 19 cm + Celit 6.6 cm + OSB 1.5 cm
0.17
Floor* Cellulose 19 cm + EPS 15 cm
0.09
Roof*
Cellulose 40 cm + celit 4.4 cm
0.09
Window double window pane HE++
1.1
5.2.3 Earthship
Based on the data from the article of Hewitt (Hewitt 2009), the insulation types for the earthship were
entered (Table 15). As the floor of the Brighton earthship contains no EPS, XPS, mineral wool or other specific insulation materials, but only cement and concrete, one could say that the ‘no insulation’
option in DoMUS can represent the insulation data of an earthship floor. However, the U values of
DoMUS and the available data do not match. DoMUS uses a standard U-value of 2 for a floor with no
insulation, which means an R-value of 0.5 (R is 1 divided by U). The Excel model assumes (based on
35
the insulation qualities of cement and concrete) an R-value of 0.33, thus an U value of 2.99 is assumed. Again, the indirect energy, life time and cost values are treated as not relevant for the calculations in this research.
Table 15: Insulation data of an earthship (* = data added in DoMUS)
Insulation Earthship
Wall*
Yelofoam (XPS) 10 cm
Floor
No insulation
Roof*
Rockwool 60 cm
Window* Double window pane
U-value
0.18
2.99
0.22
2.5
Also, in the DoMUS model the influence of polystyrene insulation in the floor is examined. As the R
value of polystyrene insulation is 3.4, the total R value of the earthship floor (with the 0.33 from the
Excel model) becomes 3.73 and the U-value 0.26 (Table 16).
Table 16: Insulation data of an earthship (* = data added in DoMUS): Polystyrene included
Insulation Earthship
Wall*
Yelofoam (XPS) 10 cm
Floor
Yelofoam (XPS) 10 cm (thus polystyrene)
Roof*
Rockwool 60 cm
Window* Double window pane
U-value
0.18
0.26
0.22
2.5
5.3 Excel and DoMUS
As both the Excel model and DoMUS calculate transmission losses, they can be compared. Before
doing so, it should be noted that there are some differences. The Excel model calculates the transmission losses by adding up the heat losses that occur through the walls, the roof and the floor. Transmission losses through the windows are not included. To calculate Q, the indoor temperature (Ta) is set at
20 ºC and the average outside temperature is set at 10.5 ºC.
The DoMUS model calculates the transmission losses by adding up the heat losses that occur
through the walls, the roof, the floor and in addition though the windows. To calculate the space heating demand, the model uses a degree-days method. It is assumed that a house needs space heating
when the average total day and night temperature drops below 15.5 ºC. A house is additionally heated
by means of internal heat sources and the sun, so that at an outdoor temperature of 15.5 ºC, the average indoor temperature is 18 ºC. Days and nights as well as seasons are taken into account. Heat demand is calculated by the transmission losses, plus the ventilation losses, minus the internal heat production and minus the heat gains by solar radiation (Benders and Kok 1999).
36
6. RESULTS – ENVIRONMENTAL IMPACT (SIMAPRO)
The three main areas of protection in SimaPro embrace different subareas of protection, like for example climate change, terrestrial acidification and metal depletion, but this research leaves that aside.
Several graphs and tables can be generated to do an impact assessment. Important for this research are
the damage assessment and the weighting method. The damage assessment gives the relative contribution (%) of the used materials and processes to the three main areas of protection. The weighting
method shows the weighted contributions (Pt) of the different processes and materials to the environmental effects. It assumes that not every environmental effect is as important or serious as another.
The importance of different effects changes regularly as a result of scientific debate. Main purpose of
the points is to compare relative differences between products or components. The scale is chosen in
such a way that the value of 1 Pt is representative for one thousandth of the yearly environmental load
of one average European inhabitant.
6.1 Weighting of the three construction types
The weighting method is used to analyse 1 m2 floor (blue), wall (red) and roof (green) of a conventional house, a passive house and an earthship without floor insulation (Figure 9Table 9)., the embodied energy of the tires is taken into account in the calculation of the environmental impact. The embodied energy of the cans and bottles is not included in the calculation.
Figure 9: Weighting of a conventional house, a passive house and an earthship: 1 m2 floor, wall and roof compared
It can be concluded that a conventional house has the lowest environmental impact in all three main
areas of protection. This result meets the expectations. In passive houses more insulation materials are
used, that, in general, have a higher environmental impact. In earthships, among others, a lot of dirt
and clay is used that cause a higher environmental impact. The conventional roof scores the lowest.
Possibly, this is due to the fact that in the conventional roof no EPS is used, in contrast with the conventional floor and roof.
The passive house mainly has a higher environmental impact due to the passive house floor.
Furthermore, the passive house roof scores high ecosystems. It is striking that in both the roof and the
floor sawn timber is used. This might explain the high environmental impact on ecosystems. The environmental impact of the floor in the main areas of protection human health and resources seems to
be caused by the use of OSB. Concrete, EPS and cellulose fibre cannot be the cause of the peaks.
Concrete shows no peak for the floor in the graph of the conventional house and the earthship. EPS
shows no peak for the floor of the conventional house. Cellulose fibre is used in the floor, wall and
roof of the passive house. The environmental impact of the passive house wall and roof is not high in
all three main areas of protection.
The Earthship has a high environmental impact for the wall and the roof. Probably the large
amounts of clay and dirt in the wall have their influence. Furthermore, the environmental impact of
the earthship roof is possibly high due to the use of rock wool and/or steel. The earthship floor scores
relatively low with respect to the earthship’s wall and roof. However, note that the earthship floor
scores higher when compared to a conventional floor. The difference can only be explained by the use
37
of natural stone in an earthship floor. It should be noted that the environmental impact of the floor is
even higher when insulation materials are used. In Figure 10, the impact of 1 m2 floor with XPS is
compared with the impact of 1 m2 floor of the reference scenario (without insulation).
Figure 10: Weighting of an earthship: 1 m2 floor (reference scenario )and 1 m2 floor with XPS
6.2 Comparison construction types
The SimaPro model can also be used to compare the three construction types to each other (Figure
11). Results show the environmental impact of the different construction types based on the dimensions of the model house. The environmental impact of the earthship with XPS in the floor is illustrated by the dark green lines.
Figure 11: Weighting of a conventional house, a passive house and an earthship
In all three areas of protection, the conventional house (blue bars) has the lowest environmental impact and the earthship (green bars) has the highest environmental impact. Based on the environmental
impact alone, conventional houses are more sustainable than passive houses. Passive houses are in
their turn, more sustainable than earthships. However, the general idea behind passive houses and
earthships is that they recover the extra energy used for the production of building materials when the
houses are in use. If passive houses and earthships have a higher energy efficiency than conventional
houses once in use, eventually they will be net more economically favorable and are thus sustainable.
38
6.3 Different earthships
Previously, it has been stated that the inclusion or omission of recycled materials (tires, cans and glass
bottles) in Earthship would be modeled separately. Figure 12 shows the damage assessment of 5 different scenarios.
Figure 12: Damage assessment of 5 Earthships
The chart shows that the environmental impact of the reference scenario without tires is significantly
lower than that of the reference scenario. So it really matters whether it is assumed that the application
of tires after their use under a car is burden free or not. If it is assumed that the application of tires in
earthships is burden free, the reference scenario without tires represents de environmental impact of
earthships. If it is assumed that the application of tires in earthships is not burden free, the reference
scenario represents the environmental impact of earthships.
With regard to the scenarios including cans, bottles or cans and bottles in the reference scenario, the chart shows that the environmental impacts do not differ so much from the environmental
impact of the reference scenario (deviations between 0.1 and 3.4%). Especially, considering the fact
that it is not taken into account that cans and bottles replace some of the dirt used in walls. It is expected that the environmental impact is lower when less dirt is used. Whether it is assumed that the
application of cans and bottles in earthships is burden free or not, is less important for the calculation
of the environmental impact based on the embodied energy.
39
40
7. RESULTS – OPERATING ENERGY (EXCEL & DOMUS)
First, the results of the Excel model are given (7.1), followed by the result of the DoMUS model (7.2).
7.1 Excel
The Excel model is used to calculate the heat flow/loss through a floor, wall or roof having a surface
area of 1 m2 in Watt (Figure 13).
Figure 13: Q (W) of the different surface areas of a conventional house, a passive house and an earthship
7.1.1 Conventional house
The results of a conventional house reveal that the heat flow/loss of all three surface areas are alike.
The heat loss through 1 m2 roof is 2.9 W, while that of a 1 m2 wall is 3.3 W and that of 1 m2 floor is
3.5 W.
7.1.2 Low energy building
The passive house shows that the heat loss through 1 m2 floor and roof is the same. However, heat
loss through 1 m2 wall is almost double that of the floor and roof. Put side by side with a conventional
house it would be expected that heat loss is lower as insulation in passive houses is better. The heat
loss is indeed less. In fact, the number for the heat loss through 1 m2 wall is halved, while the values
for the heat loss through the floor and the roof are respectively a fourth and a third of the values of a
conventional house.
7.1.3 Earthship
In Figure 13, it can be seen that the heat loss through the three different surface areas of an earthship
is far from the same. Although the heat loss through 1 m2 roof (2.1 W) and 1 m2 wall (1.7 W) is in the
same order of magnitude, the heat loss through 1 m2 floor is not (28.8 W). This can explained by the
lack of insulation in the floor, as the data concerning the earthship is based on the data of Hewitt. To
illustrate the effect of insulation, the Excel model is also used to calculate the heat low/loss through an
earthship floor isolated with XPS having a surface area of 1 m2 (Figure 14). It can be seen that the
heat flow through 1 m2 floor of an earthship isolated with XPS is similar to the heat flow through 1 m2
floor of a conventional house. The roof and wall perform better than the roof and wall of a conventional house, which was expected. They perform, however, relatively bad when compared to the roof
and wall of a passive house, which was less expected. The difference can be explained by the fact that
the Excel model does not include thermal storage in the walls of an Earthship. In 7.2 this will be elaborated further.
41
Figure 14: Q (W) of the different surface areas of an earthship with XPS in the floor
7.1.4 Comparison construction types
Not only heat loss through 1 m2 surface areas can be shown. When the heat loss of each 1 m2 surface
area is multiplied with the dimensions of the model house (Figure 8), a rough estimation can be made
of the heat loss of each construction type. In Figure 15, it can be seen that the Excel model calculates
the heat loss of a model conventional house at 912 W. For the model passive house, a heat loss of 325
W is calculated. The heat loss of the model earthship is much higher. The calculated value is 2946 W.
Again, this can be explained by the lack of insulation in the earthship floor. Therefore, also the heat
loss of an earthship with XPS insulation in the floor is shown. It can be seen that the heat loss of an
earthship with XPS insulation in the floor is much lower, being 697 W. When the heat loss of the
model conventional house is set as a standard, thus at 100%, the relative heat loss of the passive house
is 36%, the relative heat loss of the earthship is 323% and the relative heat loss of an earthship with
XPS insulation in the floor is 76% .
Figure 15: Total heat loss (W) of the 3 construction types, based on the dimensions of the model house.
7.2 Excel and DoMUS
The DoMUS model is also used to compare all three construction types, based on operating energy.
The transmission losses of the different construction types are calculated in GJ/yr (Figure 16). To investigate whether the transmission losses of the different construction types relate in the same way,
the results of the Excel model are transformed from Watt to GJ/yr and also added to the chart. It
should be noted that the models themselves cannot be compared in a fair way, because they calculate
the transmission losses differently, as explained earlier in 5.3.
42
Figure 16: Transmission losses (GJ/yr) of 3 construction types – The Excel model
and the DoMUS model compared.
Indeed, the results show that the transmission losses relate in the same way. The values found with the
DoMUS model are respectively 32, 15, 51 and 38 GJ/yr. The values found with the Excel model are
respectively 29, 10, 93 and 22 GJ/yr. The passive house loses significantly less heat than the conventional house, which was expected. The earthship, however, loses significantly more heat. The earthship with XPS in the floor, gives a more realistic view of the transmission losses of an earthship. As
earthships are claimed to be energy-efficient, it was expected that the earthship would perform better
than the conventional house.
The fact that the earthship (with XPS insulation in the floor) performs roughly similar and not
better than the conventional house can be explained by the fact that in reality earthships are designed
to take advantage of thermal storage in the walls. When thermal storage is included in the models, the
earthships will lose net less heat through transmission. Presumably, in this case the earthship (with
XPS insulation in the floor) will outperform the conventional house. How much difference thermal
storage can make has not been demonstrated yet. Measurements have been carried out on the Brighton
Earthship. It was demonstrated that the rammed tire wall exhibits thermal “battery” behavior. However, the real potential of thermal storage can only be calculated after long-term monitoring, since an
earthship must be in use for a few years, before a thermal equilibrium is reached (Ip and Miller
2009).
In general, it can be concluded that based on transmissions losses, passive house are more
sustainable than conventional houses and earthship with XPS insulation in the floor. Earthship without insulation in the floor are the least sustainable. Admittedly, earthships will be more sustainable
when thermal storage is taken into account.
43
44
8. DISCUSSION
In this chapter, the findings of this research are discussed. First, the availability of the data will be
discussed, followed by a discussion on the building materials used in the models. Then, some comment will be made concerning the models, after which the results will be reviewed. The chapter will
conclude with recommendations for future research.
In this research, conventional houses, passive houses and earthships were analysed based on legislation, environmental impact and operating energy. In order to do so, information on the different construction types had to be gathered, with respect to used building materials and their quantities. The
initial idea was to collect information on multiple houses of each construction type from houses within the Netherlands. Subsequently, the three most comparable houses (among others based on building
type and living surface) would be used for further modelling, after which the imported models could
be enhanced with other types of insulation for comparison. Potentially, the ideas for these other types
of insulation could be derived from the houses already found but not used in the model. However,
research revealed that contractors are not always willing or able to provide information, thus information on multiple houses was not found at all and the set up was not feasible.
A new plan was developed, based on the available information. For each construction type
one set of data was collected laboriously. The data on a conventional house and a passive house originate from Belgium (BUtgb and VIBE), while the building materials of an earthship are based on the
earthship of Brighton, UK. Quantities of building materials of each construction type were calculated
per 1 m2 surface area floor, outer wall or roof and used for modelling. Inner walls, basements, balconies, pipes, windows, etc. were excluded from the models, since it is assumed that the used quantities
are equivalent for each house, thus will not make any difference. There is just one exception, as the
DoMUS model does include windows. To obtain results that are based on the total building materials
of a house, quantities were multiplied with the dimensions of a model house. With this approach, to
some extent the research could go ahead as conceived. Nonetheless, the data entered are less accurate
as intended.
As mentioned, building materials used in the models are based on existing houses from Belgium and
the United Kingdom. Within the lists of building materials there are a few things that stand out. Both
in the conventional and the passive house there is no concrete used in the outer walls. The expectation
was that there would be concrete in the outer walls of the conventional and passive house, since this is
not uncommon. However, as concrete walls are not required in houses, it was decided to make no adjustments to the list.
Furthermore, the floor of the earthship contain no insulation, but includes only concrete and
cement. As an earthship aims at retaining heat, it does not seem logical that the floor is not better insulated. Therefore, a scenario with insulation in the earthship floor was developed. In addition, the glass
bottles and steel and aluminium cans known to be used in earthships are not brought up in the list of
earthship building materials. As this research is interested in the influence of recycled materials, scenarios were developed that investigate the exclusion and/or inclusion of recycled materials. By means
of this additional scenarios, the few things that stand out are covered.
In addition to the above, it is important to mention that the building materials of the conventional and the passive house are based on a pitched roof, whereas the building materials of the earthship are based on a roof that tends more towards flat. Although information was available on a pitched
roof of an earthship, an earthship is predominantly flat. Therefore, it would not have been realistic to
base the building materials of an earthship roof on a pitched roof. Another approach would be to base
the building materials of the other construction types on a flat roof, but these data could not be obtained. As the models used the same surface areas for the roof, the effect on the model will be small.
For the earthship also a choice had to be made between different types of wall. It would have been
more precise to take into account both types of roof and walls to the extent of occurrence. The major
type of wall was chosen, therefore the effect on the model will be small.
Regarding the models the following needs to be said. SimaPro is a software program that can be used
to analyse the environmental impact of a product throughout its lifecycle. In this research it is used to
45
look at the environmental impact of the production stage of the building materials used in the different
construction types. It would have been more precise to look at the total lifecycles, however, the environmental impact of the production stage of the building materials gives a reasonable insight in the
environmental impact of the different construction types.
The Excel model assumes that the heat flow/loss (W) through a floor, wall or roof having a
surface area of 1 m2 can be calculated by dividing the difference in temperature on both sides of the
wall (ºC) by the thermal resistance of a floor, wall or roof having a surface area of 1 m2 (m2.ºC /W).
This formula is originally only intended to calculate the heat flow/loss through a wall having a surface
area of 1 m2. Therefore it is possible that the formula is not fully applicable to a floor or a roof. Given
that the roof of the model house is flat (no influence of an attic), it is assumed that the formula is still
reasonably applicable. Given that the average temperature of groundwater is 10 degrees, the assumption for the outside temperature of the floor (10.5 ºC) seems reasonable. Should the results of the three
design types deviate, then this has no effect on the relative outcome.
The DoMUS model takes into account the location, the number of people, the orientation of
the house, heating equipment, appliances, transport, holidays, food and others. Although it could be
interesting to vary for example the number of people, the heating equipment or the appliance, this research kept all this factors constant. Therefore, differences in results are only due to differences in
insulation. When it is decided to adjust heating equipment and appliances in the DoMUS model, the
model first needs to be adapted. The possibility of heat storage (such as storage in the earthship walls)
is not included in the model. Furthermore, nothing is done with the angle of the windows, although it
is known that this influences the demand for heating as well. It can be expected that when the angle of
the windows and for the earthship the thermal storage in the walls is included in the model, the passive house and the earthship will perform better on operating energy.
When looking at the results of SimaPro it can be stated that they give a global view of the environmental impact of the different construction types. The fact that the houses in which more material
(e.g. insulation, dirt) is used have a greater environmental impact, was to be expected. It can be discussed whether an earthship has a greater environmental impact than a passive house. Maybe if the
model had taken transportation into account, the result would be different. The materials in the walls
are responsible for a large part of the high environmental impact. If these materials are obtained in the
neighbourhood, while the materials for passive houses come from far, it may be possible that the environmental impact of the earthship materials is relative lower. A brief examination on the influence of
transport seems to indicate that inland transport of construction materials contributes 7 to 10% to the
total environmental impact. When materials are imported from abroad, it seems that transport contributes around 20% to the total environmental impact. Thus, the influence on the results seems to be acceptable.
When looking at the heat loss per 1 m2 surface area, the results from the Excel model are to a
large extent as expected. Compared to a conventional house, a passive house is much better insulated,
thus heat loss through all different surface areas is lower. The results with respect to the earthship fall
somewhere in between, which was to be expected as earthships must generate their own energy, thus
do not want to lose too much energy, but are not as good insulated as passive houses. An exception is
the result for the earthship floor. Heat loss through the earthship floor is extremely high as no insulation is incorporated. It is striking that a building which aims to keep the heat inside, has a floor that is
so poorly insulated. It seems more natural, that in general, earthship floors are better insulated. It has
been shown by the scenario with earthship with XPS insulation in the floor that insulation can make a
big difference
DoMUS shows the same patterns for transmission losses of the three construction types as the
Excel model. The passive house has the lowest and the earthship the highest transmission losses. Also
in DoMUS the earthship floor has a large impact. Again, it is shown that XPS insulation in the earthship floor influences the result a lot. In general, the results from the DoMUS and the Excel model
show that the transmission losses relate in the same way. It is believed that the earthship with XPS in
the floor, gives a more realistic view of the transmission losses of an earthship.
This study has shown that the data needed to compare different construction types are difficult to obtain. Data are not available or not released. Therefore, assumptions are made. Although this research
46
was very useful to give an insight in the performance of an earthship compared to a conventional
house and a passive house, a comparison of entire houses is not recommended. It seems more convenient to compare components (outer walls, inner walls, floors, roofs) of different construction methods.
Consequently, the research can look at the details of the construction methods. SimaPro could be used
to do a whole lifecycle analysis. Once all separate components have been investigated, they can be
combined again.
Furthermore, this research has only looked at the suitability of different construction types.
Thus, this research has examined the different construction types with a limited gaze. It would be also
interesting to look at the feasibility and the acceptability, especially for earthships. With respect to
earthships it did not consider the bigger picture in which reduced water consumption and locally generated renewable energy play a role too. Also, use of space and social aspects are disregarded.
It can be discussed whether we have enough (building) ground to only build earthships. Furthermore,
it can be questioned whether people want to build their own earthship, when they know that it is
heavy and time consuming work. In addition, it is interesting to examine to what extent people want
to live in a house made of tires, can and bottles.
47
48
9. CONCLUSION
The main question of this research was: ‘How sustainable are conventional houses, passive houses
and earthships, based on legislation, environmental impact and operating energy?’ In order to answer
this question, knowledge had to be obtained on the current Dutch energy policies, the position of the
three construction types within Europe and the Netherlands and the current status of the most important building materials used in the three construction types with respect to their availability and
recyclability. The findings in literature regarding these topics will be presented first.
The short literature study on Dutch energy policies has shown that Dutch policymaking supports sustainable building for quite some time now. Over the years policies are introduced in order to restrict
energy use and to reduce the environmental impact of residential dwellings. The Dutch Building Decree has ensured clarity and uniformity in the building regulations. The Energy Performance Standard
makes sure that houses become increasingly energy efficient.
All three construction types that are investigated in this research fit within the Dutch policies,
as not only conventional houses, but also passive houses and earthships have already been realised in
the Netherlands. Therefore, it is said that all three construction types are sustainable based on legislation. It should be noted however, that in order to make the realisation of earthships possible, some
adjustments have been made within the design and some exceptions have been made within the Dutch
policies. Considering this, it can be concluded that passive houses fit best alongside conventional
houses. This applies not only to the Netherlands but also to Europe, since only a few earthships have
been realised in Europe in relation to many passive houses.
With regard to the building materials used in the different construction types it can be concluded that with almost all building materials high recycle rates can be achieved. In construction there are
two potential moments to fit in reuse of materials. One moment is when a house is demolished. Building materials can be extracted and reused, provided that the materials are not contaminated as is the
case with bricks. In practice this does not happen very often yet, which is a shame. The other moment
is when a house is being built. Materials that have been used already can be reused as building materials.
An example from practice is an earthship. Although it is good ambition to reuse materials in an
earthship, it is questionable whether all materials that are reused in earthships contribute to the reduction of the environmental impact. The glass bottles and the steel and aluminium cans are 100% recyclable. Therefore, it seems better to collect the bottles and cans and to reuse them to create new objects instead of reusing them as building block in an earthship.
In addition to the performance of building materials in literature, there is also the performance of the
materials in the models. Based on the SimaPro program it can be concluded that conventional houses
are more sustainable than passive houses and earthships. Whether the application of recycled glass
bottles and steel and aluminium cans is burden free or not, does not really influence the environmental
impact of earthships. Whether the application of recycled tires is burden free or not, does influence
the environmental impact of earthships. However, when it is assumed that recycled tires are burden
free and do not contribute to the environmental impact, still, the earthship remains unsustainable
compared to the conventional house and the passive house.
The general idea behind passive houses and earthships is that they recover the extra energy
used for the production of building material through lower transmission losses when the houses are in
use. Therefore, it is interesting to look at the operating energy. Both the Excel model and the DoMUS
model show that the transmission losses of the passive house are the lowest, thus it is concluded that
the passive house is more sustainable based on transmission losses. The conventional house and the
earthship with XPS insulation in the floor are less sustainable. The earthship with XPS insulation is
expected to be more sustainable, as thermal storage is not taken into account. The earthship without
insulation in the floor is the least sustainable.
The research can be summjarised in a table, after which the answer to the main question: ‘How sustainable are conventional houses, passive houses and earthship, based on legislation, environmental
impact and operating energy’ can be formulated.
49
Table 17: An overview of the sustainability of the different construction types based on legislation, environmental impact and operating energy
Literature
SimaPro
DoMUS/Excel
Total
Conventional
house
+
+
+/+
Passive house
Earthship
+
+/+
+
+/-
Earthship (with
XPS)
+/+/- (+)
+/-
Based on the results displayed in Table 17, it can be concluded that both conventional houses and passive houses more sustainable, thus suitable for the Dutch market than earthship. With regard to earthships, this research gives a cautious negative advise.
50
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