University of Texas at El Paso
Sustainable Engineering
Final Report: Life Cycle Assessment
Víctor Domínguez
Karla Gámez
Jose Lafon
Jorge Silva
July 8, 2013
Introduction
The Life Cycle Assessment is a systematic approach used to evaluate the total weight
released to the environment either by a product, process or system. A complete or full Life Cycle
Assessment is called from cradle-to-grave, where cradle is the beginning of the product while
grave is the last life phase of the product. This methodology is really good on the evaluation of
the environmental impacts associated with a product, process or system. This analysis has four
components: Goal definition and scope; Inventory analysis; Impact Evaluation and
Interpretation. Figure 1 illustrates a diagram of the Life Cycle Assessment with its four
components. For this report a Life Cycle Assessment of the Inca Empire is carried out explaining
in detail how they applied the four components in their constructions.
Figure 1. Life Cycle Assessment Diagram
Goal Definition and Scope
The Inca Empire was the largest empire in pre-Columbian America which lasted about
three centuries. The Inca people were a pastoral tribe first in Cusco, under the command of
Capac they form the kingdom of Cusco considered to be a state. After this, Pachacuti decided to
reorganize the kingdom of Cusco, leaving in charge four leaders. Pachacuti is thought to have
built what is now Machu Picchu.
Machu Picchu is found to be the most astounding urban creation of the Inca Empire. It is
still a mystery on how the inca engineers built this structures. By the time they were constructing
this there was no iron, steel, wheel, was not discovered yet, and there was not written language
either. However, Incas had a really good understanding on urban planning, hydraulics, drainage,
hydrology, and construction methods.
The incas are well known to work with the environment, not altering anything. The
construction was set accordingly to what they were facing in that moment. The goals and scope
of the incas has to deal with civilization. They needed to find a way to survive and grow as
civilized persons.
Their goal and scope was to create a place where to live and survive. Aside from this,
they needed to become with an idea to produce goods and food. But there were some limitations
to reach these goals. The area and space where they were living were not too convenient for
them, lack of tools, materials such as metals to make the construction easy, and disadvantages
that the natural environment can bring with it like rains.
However, for the Incas all of these obstacles were not a problem. They thought of how to
overcome the adversities of the Andean terrain and weather. The structures on their living spaces
are well constructed. These structures were made out of fieldstones laid over stone foundations.
These stones were cut into rectangular pieces or different shapes that would lay perfectly into
one and other forming a puzzle. Also, there was no cement or other material used to glue the
stones together. For agriculture, they built some andenes. Andenes are terraces dig into the
slopes of the mountains to provide cultivable hillsides. The incas then took advantage of the soil,
and work with these andenes to be productive in agriculture having a great turn out. Another
remarkable achievement of the incas was their water supply and drainage system. For this, the
incas would had to plan precisely Machu Picchu. Then Incas build a water canal on a steady
grade considering gravity flow to carry the water form the spring to the city center. This canal
descends from the top of the mountain, passing through the agricultural fields, and then to the
city center crossing inner walls supplying the town with water.
There is not much known about the construction methods used by the incas. There are still
unanswered questions on how the incas accomplished all these goals having limited materials. It
is fascinating to see some of the inca’s goals achieved. The engineering applied on their
structures, and the methods they used to construct on an environmental friendly manner.
Inventory Analysis
Next step in the Life Cycle Assessment is the inventory analysis. On this step, an analysis
of all the inputs and outputs of a process, product or system are quantified in order to be
analyzed in following steps. Examples of the inputs may be the water consumption while an
example of the output could be the emissions of carbon dioxide to the atmosphere. This step is
the one that takes more time because you need to look at all the possible inputs and outputs a
process may have. For example, if you look at the production of ethanol, you need to look also at
the transportation of the product. This requires that the input to build the tank where the oil is
transported should be also included in the inventory analysis. Therefore, the system boundary
has an important role in order to determine which inputs can be included in the inventory
analysis. It is assumed that any material production that contributes to 5% or less to the total
product weight can be excluded of the Life Cycle Assessment. The best component to illustrate
an inventory analysis is the flowchart.
The Empire Inca had several inputs and outputs which can be analyzed in the Life Cycle
Assessment. Let’s start doing an analysis of the inputs in the Empire Inca. One of the most
important inputs in the civilization was the water consumption obtained mainly from the rain and
rivers. This water was used to irrigate their crops and for the consumption of their people. It is
really difficult to estimate how much water they used but surely it had to be big quantities since
the agriculture was really valuable for them. Also, in terms of the agriculture the solar energy
was necessary for the crop work. There is no more evidence of any other type of energy that the
Incas could use. Next is the raw material that the Inca people used as an input for their system.
For the construction of their houses and temples they only used rocks. These rocks were huge
and weighed a lot. It is estimated that in order to move one of the biggest rocks in their
constructions it was needed thousands of people because of the extreme weight. Moreover, this
civilization did not have any kind of slaves, which means that all the work was made by them.
Another raw material used in the construction of the Empire Inca was the use of clay. This
material was used to join the big block of rock together. It is important to state that the Incas had
to types of construction. One of them was the one where they allocated rocks over rocks without
using any type of adhesive or glue. This type of structure was sustained only by the weight of the
rocks. The other type of construction was the one where they use rocks but also the addition of
clay to maintain the structures together. The rocks were also used for the construction of the
terraces where the Incas plant their crops. The use of some wood was also used to sustain these
terraces but mainly was only the use of the rocks.
Another type of input in the inventory analysis is the material used to build the
instruments used for construction. In this aspect the most important instrument used by the Incas
was the rock. They used the rocks to shape the bigger rocks until obtaining the adequate figure.
This process used to take a lot of time to the Incas. It is believed that the Incas may use other
type of metals as instruments for their construction. However, it is not completely known which
metals they could have used. Gold and silver were used for jewelry and decoration of their
temples and palaces. In terms of the transportation of material Incans moved their materials
either by themselves or with the llamas. Something that made more complicated the
transportation was that the Incas did not know the wheel. That is why they had to move all their
materials applying a lot of energy, which made the work harder too.
The Empire Inca also had some outputs to the environment. However, since the Incas
adapted their constructions to the environment, the emissions were few. One output is the
evidence of mercury in the rivers. This output brought troubles to the environment and people
from the region.
Impact Evaluation
One of the phases of the life cycle is the impact evaluation. This step is made to identify
and evaluate the actual quantity and significance of all the possible environmental impacts. This
phase helps to compare two or more different products. For example, a company that wants to
protect the environment must take into consideration all the emissions a product causes when this
is manufactured. Also, the emissions this product will continue to produce during its useful life
and when is not useful any more. After the evaluation is complete, then the company can choose
what material or what method of manufacturing is more environmental friendly. In this part of
the report, we analyze what the Incas did to apply this important phase of the life cycle.
The Incas ruins in Machu Picchu in Peru are very impressive because it is hard to believe
how they could make such constructions. They lived in the mountains, making communication
difficult especially for the translation of big rocks that they would use to build their houses and
temples. Some rocks weighted hundreds of tons or even more, without any kind of machinery or
wheels they found the way to put those rocks on top of the mountains, it is a mystery how they
did that. One of the things we observed and that we could relate to the impact evaluation is the
material they chose for construction.
They did not have a lot of materials to choose from, but they chose the most resistant one. If they
would have chosen wood, their cities could have been destroyed more easily by fire, the sun
itself or by the humans. Because of their good comparison of materials, their cities are still in
good condition after thousands of years.
The Incas were agricultures, even though they lived in mountains where no plain lands
exist to plant. They had to come up with a method never seen before. They would cut the
mountains and make perfect straight lands where they could plant their food. They did not have
to waste their energies to go down the mountains and find a good land to plant. Emissions for
this are minimum but they saved a lot of energy and time. This way, Incas developed the most
efficient method for farming along the inclined slope of the Andes. These terraces where they
used to plant were sustained by walls of rocks, which would retain heat from the day and keep
the roots of plants warm during freezing nights at high altitudes. This would also conserve water
and make farming seasons longer. Since Incas depended of natural resources, they had to take
care of their environment. They developed water channels to conduct water down the hill. Water
would pass through these farming staircases one by one until falling into another channel or
river.
The Incas were miners too; they used gold and silver for personal jewelry, to cover their
temples and palaces. The minerals from the Andes gave the Incas the opportunity to develop
these metals. Now and days evidence shows particles of mercury in lakes that killed so many
people in these times. The Incas were not aware of the damage they were doing to the rivers and
lakes. Maybe they could have used a different method to mine without damaging the
environment, that is why is very important to make an impact evaluation before designing and
creating new innovations or devices.
The Incas did not know this important phase of the life cycle that we now know in the
present, but they used common sense on developing their technologies and methods to survive.
The Incas created their cities along the Andes where weather and natural resources were in their
favor. They chose the right way of doing things, that’s why their temples are still up for us to
admire.
Interpretation
The stage of interpretation is a systematic process which is used on the identification,
description, evaluation and presentation of all the information that have been resultant from the
three other stages. The purpose of this stage is to analyze the results, to give references and to
guide to conclusions and proposals that allow taking future decisions. It is a rational and
systematic evaluation of the needs and opportunities to reduce environmental troubles, in terms
of energy and material consumption and waste emissions by a product, process or activity (PPA).
The final output of the analysis should be a set of improvement scenarios, which will help reduce
the environmental burdens or problems brought on by a product or by a process.
Normally, the activities that are done by the humans have a negative impact on the
environment. The Inca’s activities were not the exception, although their impact to the
environment was minimum. This civilization caused lake pollution with the mercury and also
caused an increment on carbon dioxide on the atmosphere. Nevertheless, it is imperative to recall
that the Inca civilization tried to make all their constructions taking as a base the environment;
they used their environment and nature on their favor and construct according to this factor, so
their impact was reduced because of this way of construction of collaboration with the
environment. The Inca civilization, since they had a great respect and admiration to nature, they
tried to be friendly with nature causing to be one of the first civilizations which applied the
principles of sustainability. This way of construction friendly with the environment caused also
positive impacts on the environment, for example the way the Incas treated the land and how
they took advantage of all the soil, the Incas harvest ten times more compared with the actual
harvest in Peru. This treatment on the land also decreased erosion and the surface runoff.
The type of material the Incas chose was an important aspect when calculating the impact
on the environment, the Incas used a strong material, rocks which have last hundreds of years
and still are on foot. This material is obviously renewable so it does not affect the ecosystem, the
only thing the Incas did on their constructions was to mold the rock and accommodate them to
form majesties of constructions. This right choice of material has had an incredible positive
impact, and as a result the construction is still perdurable during the years and resisting all types
of earthquakes, this proves the Incas build according to their environment and this construction
does not have any negative impact on the environment.
It can be stated that the materials the Incas utilized for their constructions were of the
same area of the construction itself. From the Inventory Analysis it can be stated that with the
material used there were some impact on the environment, the wood which was used for the
construction may cause a problem with Global Warming. The energy the Incas utilized,
mechanic and kinetic certainly helped on the reduction of Carbon Dioxide produced for the
environment. With this Life Cycle Analysis it can be stated that there was not a considerable
negative effect on the environment with the construction of Machu Picchu, another point to
consider is that the city has no need of maintenance, as a proof how much it has lasted on this
many years.
As a conclusion, every product, process or activity affects the eco-system and the
environment. However the way the Incas viewed nature and how they worked with the
environment makes them a pioneer on the sustainability subject. Their construction of the Machu
Picchu has the main idea of sustainability, it met the objective at that time, but this construction
did not compromise the future of nature on that area. Our society need to learn from the Incas in
some aspects and one is respect nature and work with nature for a benefit of us and Earth,
reaching the objectives of today but not compromising the future.
References
Cooke, C., Balcom, P. H., Biester, H. & Wolfe, A. P. Proc. Natl Acad. Sci. USA
doi:10.1073/pnas.0900517106 (2009).