Underground Space. Vol. 1, pp. 309-315. ©Pergamon Press 1977 . Printed in Great Britain.
Assessing Environmental Impact of
Earth Covered Buildings*
ROYCE LaNIER
American Institute of Planners
Washington, D. C.
THE PROCESS of environmental impact analysis
which has developed in response to federal and state
legislation has had a number of beneficial effects. It
has stimulated a dramatic increase in the level of
public involvement in decision-making with regards to
specific projects by making information about
proposed development accessible and encouraging
public debate on the anticipated effects. This process
has provided a valuable opportunity for reappraisal of
individual projects by forcing documentation of
potentially adverse effects,consideration of shortterm return in relationship to long term productivity
and evaluation of development alternatives. This
process has been particularly effective in increasing
professional as well as public awareness of long-range
impacts and of linkages among seemingly unrelated
actions. Yet for all of its potential contributions to
the planning process environmental impact analysis
(EIA) remains a separate function.
The evaluation of a project's environmental impact
is generally begun late in the development process
after many decisions have been made concerning the
project. It often becomes an elaborate mechanism for
justifying intended actions and succeeds in modifying
those actions only through actual or threatened
judicial processes. Particularly restrictive is the
project by project approach which considers each
situation unique. Although some generalizations are
possible for all similar projects, current methodologies encourage an emphasis on the unique set of
conditions which characterize each project. The
project by proj ct approach to environmental impact
analysis also fails to consider cumulative effects of a
number of independent actions and generally pays
too little attention to off-site impacts.
Any evaluation of the environmental impact of
earth covered buildings if limited strictly to current
EIA methodologies will provide little transferable
* Revised from
information. Therefore this paper will look not only
at project impact analysis, but at the potential for
minimizing the environmental impact of urbanization
by greater use of earth covered architecture as an
alternative form of development.
At a micro or project scale it should be useful to
outline ways in which enviromental factors might
differ when an earth covered project is substituted for
an above ground project _ on the same site. Of broader
significance, though perhaps more difficult to
quantify, are the environmental implications of
extensive use of earth covered buildings. An
evaluation of environmental impact at the macroscale of an urban region will require an assessment of
the cumulative effects of current development
practices as well _ as analysis of the degree of
modification likely should earth covered buildings
become commonplace.
Project Analysis
In terms of environmental impact analysis it is not
particularly important whether the use of an earth
covered structure is being considered as a development alternative or as the primary action proposed.
In either case, evaluation of impact at the project
level will focus initially on assessing existing
conditions on the site. As each site will present a
different set of conditions it should be helpful to
identify conditions where the use of an earth covered
building would have the greatest potential negative
impact and those where the positive benefits are most
likely to be realized. Only under the most exceptional
circumstance could an earth covered structure be
completed without drastic alteration to the original
wildlife population, vegetation cover, soil structure
and hydrological characteristics of the site. This
would involve use of tunneling or mining technology
rather than the more common cut and cover methods
generally used in near-surface underground development. - In most cases any construction activity will
produce an impact on the original site characteristics
whatever fmal form the project takes.
While the original vegetation cover can not in most
Earth Covered Buildings and Environ-
in the conference proceedings
Alternatives in Energy Conservation: The Use of
Earth Covered Buildings, National Science Foundation, NSF/RA-760006, p. 269-278 (1975).
mental
Impact
309
Royce LaNier
310
cases be retained, the agricultural or horticultural
productivity of a site may actually be improved by
the decreased loss of nutrients through leaching and
by the increased moisture retention time of the soil
caused by the subsurface barrier. Hydrological
conditions should be given particular attention when
considering structures below grade. Any structure will
affect soil permeability and surface runoff as well as
ground water recharge rates but structures below
grade may also interrupt
the lateral flow of
underground water through the soil.
The principal benefit of earth covered buildings
may well be the fact that the ground surface remains
open. Depending upon the particular site characteristics, the significance of this face will vary
considerably. In the open countryside maintaining a
rural character to the landscape may make it desirable
to locate some new facility underground. In a densely
developed urban setting the obstruction of air
movement or light may be of critical importance to
surrounding properties. Preservation of a particular
open space may be of aesthetic or historical
significance or scarce open land may be needed as a
park, a playground, a civic plaza or for other public
activities. In such cases the negative impacts of an
earth covered building would be considerably less
than any surface structure.
At the micro-scale the most important environmental benefit of earth covered buildings is the
potential uses of the surface area . The most
significant environmental impacts will probably be
those derived from the decision of how to use this
space. Determination
of broader environmental
impacts must be at the macro-scale.
Regional Scale Analysis
Assessment of the environmental impacts of
alternative forms of urban development is not
Table 1. Climatic Changes Produced By Cities (from Landsberg, 1962) [ 1}
Element
Comparison with rural environs
Contaminants:
dust particles
10 times more
sulfur dioxide
5 times more
carbon dioxide ................................................... 10 times more
carbon monoxide
25 times more
Radiation:
total on horizontal surface
15 to 20% less
ultraviolet, winter .............................................
30% less
ultraviolet, summer .............................................
5% less
Ooudiness:
clouds
5 to 10% more
fog, winter ............................................................
100% more
fog, summer
30% more
Precipitation:
amounts
days with 0.2 in.
Temperature: annual
mean winter
minima
Relative humidity:
annual mean .........................................................
winter
..................................................................
summer
5 to 10% more
10% more
1 to 1.5°F more
2 to 3° more
6% less
2% less
8% less
Wind speed:
annual mean
extreme gusts
calms
20 to 30% less
10 to 20% less
5 to 20% more
310
Royce Covered
LaNier Buildings
Assessing Environmental Impact of Earth
presently a part of the EIA process. Ideally such
broad assessments should be a part of the
comprehensive planning process thus providing a basis
for decisions on individual projects. Only at the
macro-scale of regional analysis is it possible to give
consideration to the cumulative effects of various
land use alternatives and forms of urban development. In the same manner that planners now
determine the level of demand for new housing and
classrooms for fire protection, water and sewer
service, recreational and other public facilities based
on the projected changes in the demographic
structure of a community, there is a need to estimate
the effect of these anticipated changes on such
environmental factors as hydrology and climate
including air movement which affects air quality and
heat absorption or reflectivity which will modify the
urban heat island effect. An environmental impact
analysis at the regional level would also consider
changes in the rates of material and energy
utilization, modifications to the life-cycle or longterm maintenance costs of community infrastructure,
sociopsychological and economic implications and
indirect or secondary effects of various alternatives.
The following sections look at the primary
environmental factors affected by urbanization and
hypotheses modifications to these effects which
might result from extensive use of underground
space.
311
Changes Resulting from Urbanization" reported by
Changnon (1974) [3] which is reproduced as Table 2.
With regards to the potential effects of various land
use alternatives, temperature, precipitation, wind and
humidity are discussed individually.
Temperature
Without a doubt the most significant climatic
changes resulting from urbanization are those linked
directly or indirectly with the "urban heat island".
The work of Duckworth and Sandberg (1954) [4]
added a spatial dimension to the consensus that
urbanization was responsible for a reduction in the
diurnal temperature variation as shown in Fig. 1 and a
general warming within the city as shown in Tables 1
and 2. The proftle of the "urban heat island" is by
general agreement a dome rising over the center or
more heavily built up area to a height of 200-300
meters although regional winds produce an "urban
heat plume", or downwind draft of heated air (Clarke
and McElroy, 1970) [5]. Chandler (1968) [6] based
on observations in English towns and cities indicates
that a close statistical relationship exists between the
intensity of the urban heat island and the urban
development density within a radius of up to 500
meters. This would suggest that the effects are highly
localized. Further study of the significance of various
land use patterns on local temperature variations were
reported by McElroy (1972) [7] based on mathe-
URBAN CLIMATE
Climatologists usually employ the term urban
climate with reference to the differences in
precipitation, air movement, and temperature levels
observed at urban sites and in nearby rural areas.
Although this does not take into account local
variations in weather which can be significant, nor
does it consider the effects which urban areas have on
surrounding rural areas, one does get a reasonably
accurate picture of the incremental changes in climate
which occur due to urbanization.
While cautioning against generalizing the effects of
urban areas on local climates, Landsberg (1962) [1]
offers a set of climatic variables on which he has
placed rather specific measures of the urban -rural
differences. This list, reproduced as Table 1,
represents the consensus of urban climatologists in
the early 1960's. These differences were attributed by
Landsberg (1956) [2] to physical changes in the
surface of urbanization, addition of heat to the
atmosphere by the city and changes in the aerosal
content of the air.
A decade of intense research activity has produced
some modification in this consensus particularly with
regards to causes; but the magnitude of changes
remains remarkably similar in the set of "Weather
..... 100
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20
0 6 12 18 24 30
-
HOURS
Weather Bureau
Airport Station
---Weather Bureau
City Station
FIG. 1. Diurnal temperature traces from urban and
rural stations. Richmond, Virginia, clear day in
summer (from Langsberg, 195 6) [2}.
Table 2. Weather Changes Resulting From Urbanization (from Changnon, 1974) [ 3}
Average changes expressed as percent or
magnitude of rural conditions
Annual
Cold season
Warm season
+1000%
+2000
+500
-22%
-34
-20
Temperature
(oF)
+20
+40
+10
Humidity
(relative)
-6%
-2
-8
Visibility
(frequency)
-26%
-34
-17
Fog
(frequency)
+60%
+100
+30
Wind speed
(mph)
-25%
-20
-30
+6%
+5
+10
Rainfall
(amount)
+14%
+13
+15
Snowfall
(amount)
+10%
+10
Thunderstorms
+16%
+5
Con taminants
(volume)
Solar radiation
(Langleys)
Cloudiness
(frequency)
matical
simulation. this report suggests that
differences in location of green areas and paved areas
produces differences in location of cool and warm
areas in the temperature gradients between them but
no change in the level of contrast found within the
city. The extremely localized nature of micro-climatic
modifications places a special importance on land use
decisions particularly the location of open space in
planning for livable communities.
In order to reduce the overall intensity of the
urban heat island and consequently, modify its
general effect on the temperature within the city, it is
necessary to consider several factors simultaneously.
According to Lowry (1975) [8] the average value of
intensities are seldom related to population alone, or
to season or latitude alone but to all of these and to
the general level of heat producing activities, i.e.,
degree of indutrial development and intensity of
+ 30
energy use within the city and its society. Thus the
reduction in energy utilization which is possible with
earth covered buildings could have a significant
impact on the regional temperature by modifying the
intensity of the urban heat island while the
introduction of surface vegetation on a particular site
will most directly affect the local micro-climate.
Precipitation
Present consensus holds that urban effects on
precipitation totals are regional, e.g., mostly felt
outside and "downwind" of the urban area. The
effect seems to be on the order of 15% excess
precipitation in the affected area over the surrounding area. The increase is thought to be in the high
intensity storms rather than the low intensity
"drizzly" or "showery" weather as had been
previously assumed - but the evidence is not clear.
312
Assessing Environmental Impact of Earth
RoyceCovered
LaNier Buildings
This change in consensus came about largely due to
a n analysis by Changnon (1968) [9] of the
precipitation records of LaPorte, Indiana which lies
downward from Chicago and the steel plants of Gary,
Indiana. If the intensity of the urban heat island is
indeed a primary factor in the changes which have
been observed, then reduced energy use should have a
modifying effect.
Wind
The effect of urbanization on wind speed is rather
dramatic. The annual mean speed is redvced by 20 to
30% but previous understanding of this effect is
recognized to have been oversimplified. It is now
widely held that when moderate to strong winds are
blowing in the region, the roughness of the surface
profile of the city retards the air flow, and wind
speeds in the city center are reduced by as much as
I 0 to 20%. When there are only light winds blowing
in the region, it is likely that the thermal and
mechanical turbulence produced by the city enhances
the momentum of heat exchange and produces 5 to
I 0% greater speeds at ground level in the city than in
rural areas nearby . Such a phenomena should be
minirnized by simplifying the surface profile of the
city through extensive use of earth covered buildings.
Humidity
Consensus holds that relative humidity is less in
urban areas than surrounding areas due to high
temperatures and reduced availability of water for
evaporation.
Depending on
geographic locale
increased humidity can be beneficial in one region
and detrimental in another in terms of human
comfort. Extensive use of earth covered buildings
could modify this aspect of the urban climate by
increasing moisture holding evaporative surfaces but
the practice would have to be wide spread to have
any appreciable effect. The annual decrease in
humidity due to urbanization is estimated at 6%, 2%
in cold and 8% in warm seasons.
URBAN HYDROLOGY
Another primary effect of urbanization is on the
hydrological cycles. The natural cycle includes two
networks for collecting precipitation. The surface
system collects runoff into streams, rivers, lakes and
eventually empties into the oceans. There is a similar
network of underground aquifers. Such factors as
vegetation cover, soil characteristics and land form
drastically affect crossover between the two systems.
Urbanization adds a thrid system of distribution and
collection and dramatically affects flows in the
natural systems.
313
Climatic Effects
The effects of urbanization on precipitation are
discussed in detail in the preceding section. This is the
primary climatic effect on the hydrological cycle and
is related to the intensity of the urban heat island.
Reduced use of energy, e.g., radiant heat emission to
the atmosphere, should reduce this effect.
Changes in Surface and Groundwater Flows
Urbanization increases the impervious cover of the
surface and thus tends to reduce infiltration and
evapotranspiration causing drastic changes to the
natural precipitation -runoff relationships. The artificial catchment network often facilitates rapid
removal of water which increases high water levels
and aggravating downstream flooding. Base flows of
streams are reduced as recharge is denied or diverted
and over-exploitations of groundwater reserves
diminish overall yield. Although the use of earth
covered buildings will not eliminate these interruptions, groundwater recharge might be facilitated
depending on the surface treatment used.
Water Supply and Conservation
The availability of an adequate water supply is
generally the paramount prerequisite for urbanization. Yet the concentration of large numbers of
people in urban areas inevitably results in water
demands which exceed the level of withdrawals
which are sustainable from yields of the local
catchment area. This requires importing water from
distant sources which, according to Lindh (1972)
[10], has significant effects on regional water balance
and associated water quality. Table 3 contains
estimates of the magnitude of demand for water on a
global scale. These estimates by Lvovich (1969) [11]
indicate dramatic increases are anticipated in
municipal water use and for industry and energy
production which are for the most part related to
urbanization. While agricultural utilization is projected
to double between 1965 and the year 2000, urban
related demand is expected to increase more than
20-fold . According to Lvovich, about one half the
total urban related demand in the year 2000 would
be for energy production. Should these projections
prove accurate, the environmental consquences will
be massive.
The use of earth covered buildings would probably
not affect domestic utilization of water nor would
increased efficiency of domestic utilization have any
dramatic impact on the overall level of demand. It is
in the area of energy utilization that the greatest
conservation potential exists. The extensive use of
earth covered buildings could, by reducing the size of
the increased demand for energy, also decrease the
demand for water dramatically. This secondary effect
could prove to be far more significant in environ-
Table 3. A Summary of Recent Estimates by Lvovich ( I969) [II] of Principal Global Water Uses
1965, Km3 /Year
Uses and Needs
Municipal Water Supply
Withdrawal
2000, Km'/Year
Return
Withdrawal
Return
98
56
950
760
Irrigation
2300
600
4250
400
Industry
200
160
3000
2400
Energy
250
235
4500
4230
12700
7790
Totals
2845
mental terms than the direct micro-clirna tic and
hydrological modifications.
Water Quality and Pollution
Increased pollution of surface water bodies related
to urbanization are well documented. These include
increased storm runoff and soil erosion, combined
sewer overflow, seepage from septic systems and
effluent overflows from waste treatment plants,
discharge from industrial plants and return of heated
effluent from energy conversion processes. Several of
these are particularly subject to modification as a
result of using earth covered buildings.
Significant negative impact can be anticipated as a
result of additional excavation. The most critical
direct impact would be the increased stream sediment
loads, but indirect impacts would also result from the
practice of filling wet land areas with excavated
materials. This practice could have even greater
impacts on water quality than the direct impacts
from sedimentation. The major positive benefits
would be related to decreased thermal pollution levels
which should result from the decreased energy
demands resulting from the use of earth covered
buildings.
CONCLUSIONS
Although it appears reasonable to assume that a
number of negative environmental impacts would be
minimized by extensive use of earth covered
buildings, there is little basis on which to estimate the
magnitude of change. Until a number of studies have
been completed
which analyze the accumulative
environmental effects of many projects within the
context of base line studies on the existing ecological
conditions in various types of urbanized areas, any
meaningful assessment of the macro-scale effects of
alternative forms of urban development will be
difficult. The primary conclusions to be drawn from
this review of potential impacts is that reductions in
1051
energy utilization may be the most promising aspect
to pursue. Consequently, it is recommended that
urban energy budget studies be undertaken in a
number of communities of varying size and physical
layout.
All human activity requires energy, all systems are
operated by some form of energy whether it be
biological processes which use somatic energy
captured by green plants and passed through the food
chain to "fuel" other living organisms or industrial
processes fueled by energy released in burning coal or
natural gas. It might be helpful to undertake research
on cities as complex energy degrading systems where
materials are brought in and processed to provide
goods for the inhabitants and for sale to other
communities. As energy is essential for every process,
every service, the efficiency with which various
communities provide their inhabitants with essential
goods and services as well as comforts and pleasures
might well be measured in terms of energy utilization.
In order to construct such an energy budget for a
city, three distinct forms of energy should be
considered: atmospheric, somatic and extra-somatic.
Atmospheric energy refers to the radiant energy of the
sun and to the mechanical energy of wind caused by
the temperature differences which result from uneven
distribution of radiant energy. Somatic energy is that
captured through photosynthesis in green plants,
which become food and eventually human energy.
Extra-somatic energy is that released from fuels
whether it be wood, coal, oil, gas or uranium.
As energy can not be conserved but is degraded
into radiant heat in use, the efficiency with which it
is used and transformed become critical. Of equal
importance in determining the efficiency of the
system is the rate of conversion or capture of
atmospheric and somatic energy in a city and the
degree to which these forms of energy can be used to
off-set the need for extra-somatic energy. In theory,
the use of earth covered buildings would dramatically
alter the energy budget of a city by increasing the
vegetation cover thus the capture of somatic energy
314
Royce LaNier
Assessing Environmental Impact of Earth Covered Buildings
by green plants; and by making use of the
atmospheric energy captured by the earth, to modify
the need for extra-somatic energy to heat and cool
315
buildings. Energy budget studies on this scale are
essential to understanding the overall impact of
alternative patterns of urban development.
REFERENCES
1 . Air Over Cities , U.S. Public Health Service Technical Reports A62-5, Washington,
D.C., pp. 1-22 (1962).
2. Landsberg H. in Man's Role in Changing the Face of the Earth, University of Chicago
Press, Chicago, pp . 5 84-603 (1956).
3. Proceedings 4th Conference on Weather Modification, Fort Lauderdale, American
Meteorological Society, pp . 347 -352 (1974).
4. Duckworth F. and Sandberg, J. Bulletin of the American Meteorological Society. 35,
pp. 198-207 (1954).
5. Clarke J . and McElroy J. Proceedings of the Symposium on Urban Climates and
Building Climatology, Brussels, Technical Note No. 108, World Meteorological
Organization; Geneva, pp. 1-14 ( 1970).
6. Chandler T. Proceedings of the Symposium on Urban Climates and Building
Climatology (1968); Brussels Technical Note No. 108 , World Meteorological
Organization, Geneva, 1970, pp. 1-14.
7. McElroy J . in Proceedings of the Conference on Urban Environment, Philadelphia,
American Meteorological Society, pp. 185-190 ( 1972).
8. Lowry W. "N orth American Research Concerning the Effects of Urbanization on
Local and Regional Weather Climate," paper presented at symposium on
Geographical Characteristics of Urban Development, Budapest, Association of
A merican Geographers and Hungarian Geographical Research Institute, proceedings
to be published in Hungary (197 5).
9. Changnon S. Bulletin of the American Meteorological Society , 49, pp. 4-11 (1968).
10. Lindh G. "U rbanization: A Hydrological Headache ," ABBIO 1, No . 6, December
1972, pp. 190 -199.
11 . Lvovich M. I. Vodnie Resoursi Buduschevo, (Water Resources of the Future)
Prosreschenie, editor, Moskow, in Russian (1969) ; as reproduced in Inadvertent
Climate Modification, Massachusetts Institute of Technology Press, Cambridge, 1971,
p. 178.