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PREPARED FOR PRESENTATION AS A KEYNOTE LECTURE AT
“HEALTHY BUILDINGS ‘95,” MILAN, ITALY, SEPTEMBER 10-15, 1995
BUILDING ECOLOGY:
AN ARCHITECT’S PERSPECTIVE ON HEALTHY BUILDINGS
Hal Levin
INTRODUCTION
A healthy building is one that adversely affects neither the health of its occupants nor
the larger environment. Indoor air quality (IAQ) concerns are among many indoor
environmental issues that must be addressed to avoid adverse impacts on occupants’ health
and well being. Among the other indoor environmental factors that must be considered are
the quality of thermal, light, acoustic, privacy, security, and functional suitability. In
addition to concerns about indoor environmental quality and its affect on occupants,
buildings must not adversely affect the larger environment. The construction, operation,
use, and ultimate disposition of a building must have minimal adverse effects on the
natural environment or ultimately it will adversely affect people whether indoors or out.
Buildings are healthy only if their effects on their occupants and the larger environment are
benign.
This paper addresses both indoor environment, especially indoor air quality concerns,
as well as general environmental concerns. It discusses recent work evaluating the impacts
of buildings on the larger environment. It also reviews data available to determine norms
for important building parameters and analyzes major studies of building impacts on
occupant health. The analysis presented here is intended to help buildings designers’
prioritize design alternatives that minimize harmful impacts on indoor and general
environments.
Very little analysis has been done to form the basis of design of environmentally
benign buildings. At best, designers have simply attempted to apply known design
solutions to decrease the negative impacts buildings have on the environment. This paper
discusses methodological approaches to establishing priorities for environmental problems
that can be addressed by building design. In order to study buildings’ impacts on their
occupants and the larger environment, building ecology has been proposed as an
interdisciplinary, systematic approach (Levin, 1981, 1989, 1991).
The scope of “designing healthy buildings” is far too extensive for thorough treatment
in the limited space available here. Therefore, this paper focuses on methodologies for
developing design guidance rather than on the detailed guidance that can result. Previous
publications (mentioned below) have addressed design issues related to indoor air quality
and to “sustainable architecture.” However, these have generally not been established on a
sound analytical basis. The emphasis here is to explore analytical methods and sources for
developing sound design guidance for healthy buildings.
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Definition of “Healthy Building”
Indoor Environmental Quality. Indoor environmental quality refers to all aspects of
the indoor environment that affect the health and well-being of occupants. This must
include not only air quality but also light, thermal, acoustic, vibration, and other aspects of
the indoor environment (Levin, 1995). With respect to the indoor environment, a healthy
building is one that does not adversely affect the occupants. Some authors suggest that it
should even enhance the occupants’ productivity and sense of well-being to be considered
healthy. Thus, it is not only the absence of harmful environmental characteristics but also
the presence of beneficial ones that defines a healthy building. Thus, designers should
begin by avoiding harmful elements and attempt to incorporate supportive, beneficial ones.
General Environmental Quality. The general environment (as used in this paper)
refers to the environment of the entire planet Earth. This is obviously an enormously large
and complex subject. Nevertheless, the concept of a healthy building must include concern
for the impacts of the building on the total environment. Environmental degradation
ultimately limits the healthiness of any building. Some environmental problems, although
caused by local or regional pollution or resource consumption, result in impacts with
important global implications. These include destruction of the ozone layer, global
warming, loss of biodiversity, and destruction of unique habitats. Resource consumption
and pollution emission result in important localiz impacts such as contamination of surface
and groundwater, destruction or consumption of natural resources, photochemical smog,
acidification, eutrophication, soil degradation and soil erosion. A healthy building is
defined as one that has minimal impacts on the local and global environment.
Criteria for Healthy Buildings
Table 1. Important factors for which ‘Healthy Building’ criteria should be established
Environmental focus Criteria focus
Indoor environmental quality Thermal environmental quality
Indoor air quality
Illumination
Acoustics
Functional support
Security
Privacy
Way-finding
General environmental quality Mineral resource consumption
Energy consumption
Natural resource consumption
Habitat destruction, Biodiversity loss
Land use
Atmospheric pollution
Water pollution
Soil pollution
Determination of a building’s healthfulness must be based on specific criteria that can
be evaluated by measurement or by informed, structured judgment. Table 1 contains a list
of factors for which such criteria should be established and used in the design of healthy
buildings.
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DESIGNING HEALTHY BUILDINGS
The impacts of buildings on the quality of the indoor environment and the general
environment are determined by numerous factors during design, construction, operation,
maintenance, and ultimate disposal of a building. They are also determined by occupant
behaviors and activities, sources introduced by cooking, cleaning, personal hygiene, office
products, decoration, plants, and numerous other sources. Designers only control the
intended construction; builders, users, managers, and others determine many building
factors that determine indoor air quality. However, designers can improve the likelihood a
building will be healthy with respect to indoor air quality by anticipating the use of the
building and providing for it in their designs. Where building use cannot be anticipated,
general principles can be applied and flexibile designs can provide for various potential
uses.
The indoor air factors under the control of the designers are the materials and systems,
the ventilation, the environmental control scheme, the layout, etc. All of these
significantly affect indoor air quality and other environmental factors. However, any
dysfunction in the indoor environment potentially affects occupant health and well-being.
When buildings fail to do what they are intended to do, indoor environmental pollution in
the form of indoor air pollution, noise, glare, etc. cause occupant discomfort, health
problems, and poor performance. Space does not permit discussion of the whole range of
design issues in the indoor environment; this paper focuses on indoor air quality. A healthy
building is one that works well to provide for the intended users and activities.
Building design and material selection for IAQ
The most important building design and material selection IAQ considerations have
been discussed extensively (Levin, 1981, 1987, 1989a, 1991, 1992, 1994; Seppänen,
1993). A rational process for building design decisions on building-related environmental
factors most critical to occupant health and comfort should be based on the following:
1. The most significant health and comfort outcomes (based on frequency and
gravity);
2. The plausible causal environmental factors; and,
3. The building design elements that control those factors.
A scientific basis for building design and material selection to achieve good indoor air
quality is still available only to those willing to draw inferences from their studies (Platt,
1964). Scientific studies of indoor air quality (IAQ) and occupant health and comfort
usually identify only associations of risk factors but do not demonstrate causality. Logical
analysis and examination of the dominant evidence can be used to hypothesize certain root
or primary risk factors. Designers implicitly hypothesize causality in determining what
factors are important and how to address them. Designers can best target their IAQ control
efforts based on analysis of identified risk factors and logical plausibility. The process
described here will help design efforts have maximum impact on primary or root building
factors contributing to the prevalence of sick building syndrome (SBS) and building-
related illness (BRI) (Levin, 1994).
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Identifying the Most Important IAQ Design Factors
Discussion of building design and material selection in the context of IAQ should be
based on the best available knowledge. There are three fundamental approaches to
identifying the most important factors and to establishing criteria for design. They are
shown in Table 2.
Table 2. Three approaches to identify important IAQ design factors
Approach Method/Comment
Characterize factors important to indoor air Review and analyze major building epidemiology studies
and meta-studies of their results
Establish norms for design Review and analyze major building indoor environmental
factors characterization studies
Test hypotheses using intervention studies Study effect of changing hypothesized critical variable
on outcome of interest
Using the first approach -- characterization of factors believed important to indoor air
quality -- if elevated volatile organic compounds (VOC), are often associated with elevated
SBS symptoms, then VOCs can be controlled by design. The first approach involves
reviewing studies of occupant responses that determine their associations with the different
environmental conditions. These may be building investigations, studies, or surveys.
Then the second method -- establishing norms -- can be done for important volatile
organic compounds and their relevant concentrations by reviewing data from
comprehensive surveys that characterize VOCs most commonly found in buildings. . The
third approach (not discussed here) uses intervention studies to test hypotheses developed
using the first two approaches.
The second and third methods are relevant to determining control strategies --
evaluation of the common VOC control strategies including source control and ventilation.
Normative values can be based on what has been observed in studies and surveys. The
norms can be used as a basis for design or for evaluation of existing conditions. The
methods and outputs of the first two approaches are very different, but both are valuable
sources of data that can be used to assist designers determine values and criteria for their
work. The results of the use of the first two approaches is discussed below.
Analysis of Large Building Survey Results
The largest and most important SBS studies have been reviewed extensively by
several authorities including Lindvall (1992), Mendell (1993), Norback (1990), Seppänen
(1994), Stenberg (1994), and Sundell (1994). Their reviews and “meta-analyses” identify
risk factors for occupant SBS symptoms. A logical analysis of SBS risk factors was
performed and causation hypotheses formulated in a review of the highest risk factors in
the Danish Town Hall Study (Skov, 1987) by Levin (1989). Potential synergisms among
the factors were hypothesized. Finally, control measures were identified to minimize SBS
risks (Levin, 1989b).
Later, a set of modified risk factors that can be addressed by building design and
material selection decisions were presented based on the risk factors identified in the meta-
analyses (Levin, 1994). The most frequent and logically-consistent building environment
determinants of occupant responses should be the targets for building design and material
selection decisions. Selected risk factors found frequently in the major studies,
investigations and meta-analyses are shown in Table 3.
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Table 3. SBS risk factors identified in major studies and reviews. (Levin, 1994)
—————————————————————————————————————————
BUILDING FACTORS
Low ventilation rates (< 10 L/s p) (L, M, Se, Su)
Ventilation operations (<10 h/d) (Su)
Insufficient materials control (L, N)
Fleecy materials (N, Sk)
Carpets (M, N)
Air-conditioning (M)
BUILDING ENVIRONMENTAL FACTORS
High temperature (M, Sk)
High humidity (L)
Low relative humidity (M)
Volatile hydrocarbons (N)
Microbial VOC (L)
Dust (N)
BUILDING USE / OCCUPANCY FACTORS
High occupant density (M)
VDT use (M, St, Su)
Photocopiers present (St, Su)
OCCUPANT FACTORS
Perception of “dry air” (St, Su)
—————————————————————————————————————————
Notes: Initials of lead authors of articles listed in the Reference section.
L= Lindvall M= Mendell N= Norback Sk=Skov
Se= Seppanen Su=Sundell St= Stenberg
Prioritizing design concern for IAQ
Addressing those building factors that are primary or root factors from among the risk
factors in Table 3 presumably will have the greatest impact on SBS symptom prevalence
rates. “Root factors” are primary or basic; they can be controlled directly, and their
outcomes can be secondary or indirect risk factors. Elevated temperature is a primary risk
factor because it increases the rate of microbial growth and of VOC emissions from
materials. It also affects occupant perception of air quality. Low relative humidity is a
secondary factor relative to elevated temperature and air conditioning. VOCs (including
formaldehyde) concentrations result from one or more factors including poor material
selection, inadequate ventilation (low ventilation rate or insufficient operation) and
elevated temperature. But elevated temperature may also be an outcome of other risk
factors such as inadequate ventilation if outside air temperatures are lower than indoor air
temperatures.
Table 4 shows an elaborated set of risk factors categorized as primary and secondary.
In addition to the risk factors listed in Tables 3 and 4, certain factors logically pose
important risks. These are the presence of carcinogens or other genotoxic substances,
strong or noxious odorants, irritants, infectious agents, or allergens; extreme temperature
or humidity; and, sources of micro-organisms and their amplification and dissemination.
A design philosophy of “prudent avoidance” dictates that designers implement practical
control measures that can reduce or eliminate these a prior risk factors. Designer and
client judgment as well as regulatory authorities will determine the extent of such control
efforts.
Because the etiology of many (if not most) indoor air related health and comfort
problems is “multi-factorial;” it is necessary to understand the linkages among contributing
factors. Designers must assess theselinkages, analyze their design implications, and
determine their importance for building design and materials selection. Analysis of the
linkages among contributing factors can direct designs to address primary factors rather
than their secondary outcomes. Outside air ventilation rate, temperature, moisture
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intrusion, and strong sources of contaminants are root factors. Elevated airborne
concentrations of contaminants result from some one or more of the above root factors.
Table 4. Primary and Secondary Risk Factors for SBS and Their Potential role in
SBS or BRI Etiology (Levin, 1994)
——————————————————————————————————————————
Primary Risk Factors Secondary Risk Factors Exposure or Role in SBS/BRI
Etiology
———————————— ——————————— ———————————————
LOW VENTILATION
Air exchange rate
Operational hours
Air distribution
Reduced dilution of
contaminants Increased exposures to chemical,
physical, and biological contaminant
STRONG SOURCES
Building materials VOC emissions Increased exposures to odorants,
irritants, toxins
Furnishings
Occupant activities
Consumer/office products
Housekeeping materials
Maintenance materials
Outside air or soil gas
TEMPERATURE
(elevated) Microorganism amplification Increased exposure to fungi, bacteria,
viruses
Occupant discomfort
Perceived stuffy or stale air Increased exposure to airborne VOC
MOISTURE INTRUSION OR
ACCUMULATION Material moistening - high
water activity on surfaces Microorganism growth, Increased
occupant exposure to spores, MVOC
Leaky building exterior
Condensation on surfaces
Standing water
High indoor relative
humidity
Odor from MVOC
Material deterioration and VOC,
particle emissions
Increased VOC emissions and
exposures
———————————————————————————————————————————
To illustrate, the intrusion of moisture into exterior building walls does not itself cause
health or comfort problems. But moisture intrusion results in mold growth and, most
likely elevated air levels of VOCs including microbial VOCs (MVOC). Designers can
specify mold resistant materials (e.g., mineral-based products such as stone or brick) or use
fungicide-treated materials, but the root problem is the moisture penetration. High water
activity at material surfaces supports fungal growth and competes with VOCs for
adsorption sites. Preventing or controlling the moisture intrusion will control fungal
growth, reduce airborne concentrations of VOCs, reduce indoor air relative humidity, and
prolong the life of the building materials and contents. Many comfort and health problems
and costly remediation measures can be avoided by directly controlling moisture intrusion.
Some key factors will have both direct and indirect effects on the building
environment and the occupants. Many of these key factors appear more often in research
on associations between occupant symptoms and environmental factors. A key primary
factor is high indoor air temperature. Occupants are less comfortable at temperatures near
the upper end of the thermal comfort envelope, and they are more likely to perceive the
indoor air as stuffy or stale (Berglund and Cain, 1989; ASHRAE, 1993). Furthermore,
increasing temperature will increase VOC emissions from building materials, furnishings,
and other surfaces due to increased vapor pressures. This will increase occupant exposures
to VOCs, and microbial growth and occupant exposure to bioaerosols and microbial VOCs
will also increase.
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Trade-offs, Alternative Solutions
Ultimately, the designer and building owner or occupant determine which preventive
or mitigation measures to employ in a newly designed or renovated building; Their
decisions are based not only on the perceived importance of the measure to reduce the risks
of health and comfort problems but also on the feasibility, practicality, and cost of
implementing the measures. In most cases, trade-offs are made to achieve the desired
outcome. For example, to reduce the concentration of a contaminant emitted from a
particular material the decision may be 1) to select low-emitting products, 2) to condition
or treat the product before installation in the building, or 3) to ventilate the building after
installation prior to occupancy.
Characterize Environmental Parameters
While the analysis presented above can provide guidance to the most important
problems, designers need more specific guidelines for design. Following are excerpts from
a review of several surveys of selected indoor environmental parameters intended to
illustrate that guideline values or norms can be established on the basis of carefully
selected data (Levin, 1995b). A valuable source of information is the collection of studies
that have reported data based on a consistent measurement protocol. While only a small
number of these exist, they are likely far more reliable than comparisons of results from
studies based on different methods or studies of very diverse buildings. Among the most
interesting of these surveys are those done at large scale using reasonably standardized
measurement methods, at least within a single study. The most useful of these studies are
several U.S. and European surveys, mostly reporting measurements of VOCs,
formaldehyde, and, in some cases, ventilation rates.
VOC Concentrations and Emissions Data
The concentrations found in occupied non-industrial buildings are often reported as
total VOC (TVOC). Virtually every measurement method, even when used correctly,
likely underestimates the true TVOC concentration due to method-specific limits on the
compounds that can be collected and analyzed (Wallace, 1991). Compounds with very
low or very high volatility are not measured by most of the methods in common use.
Many authors reporting TVOC concentrations in fact are reporting the sum of the
individual VOCs that they have identified and quantified. Therefore, these values are
referred to here as the sum of the VOCs (SumVOC) rather than TVOC.
Values of SumVOC in indoor air reported using the various common methods tend to
fall in a range from less than 0.1 milligrams per cubic meter (mg/m3 ) to 1.0 mg/m3. A few
buildings have been reported to have concentrations above 1.0 mg/m3, and even fewer
above 2.0 or 3.0 mg/m3. Occasionally a building is reported with 10.0 to 20.0 mg/m3, and
even more rarely, with concentrations of 20 to 100 mg/m3. The higher concentrations are
typically attributable to easily identified strong sources - either processes or products.
Telephone Administrative Building Survey. Shields reported long-term (~30-day)
samples collected passively on charcoal at ten telephone company administrative offices
throughout the United States (Shields, 1993). The results are shown in Figure 1. None of
these offices was new at the time of the study, although minor construction activity was
reported in some. Most buildings measured had SumVOC concentrations ranging from
about 0.15 to 0.3 mg/m3. None of the ten buildings had VOC concentrations that exceeded
1.0 mg/m3. However, the reported limitations of the measurement method included loss of
certain compounds and an inability to identify certain others. The high concentrations
found in one building were associated with construction activity
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
ABCDEFGH I J
Building identifier
SumVOC (mg/m3)
Figure 1. SumVOC concentrations from 10 telephone administrative offices.
EPA Public Buildings Study. Sheldon et al (1988) reported results from the two
separate studies conducted for the EPA over a period of several years. The buildings
included offices, nursing homes, elderly homes, and schools. In most of the buildings, the
age of the building was reported. In some buildings, measurements were made on separate
occasions several weeks or even months apart, thus allowing observation of the trend
toward decaying emissions as building materials and furnishings age. The SumVOC
values reported above 1.0 mg/m3 were collected in buildings just 1 week after completion
of construction.
0
0.4
0.8
1.2
1.6
0.1 10 1000
Building age in weeks
Mean SumVOC (mg/m3)
Figure 2. SumVOC from EPA Public Buildings Study by age of building
There is a clear overall trend in the data suggesting that the older a building may be,
the lower the VOC concentrations. However, in one building, a hospital, the
concentrations rose dramatically from the early to the later measurements. The specific
compounds responsible for this increase were ingredients of common cleaning and
maintenance materials.
Preliminary European Audit Project Data. Preliminary data were presented in
posters by each participant country in the European Audit Project at Healthy Buildings ‘94
in Budapest. Data on VOCs in 38 buildings from six of the nine countries participating in
the European Audit Project are shown in Figure 3. The data presented here were obtained
by interpolation of bar charts presented at Healthy Buildings ‘94 and may not coincide
exactly with the values obtained by the researchers. The six countries shown are France
(F), United Kingdom (UK), Denmark (DK), Greece (GR), Switzerland (CH), and Finland
(FI).
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Figure 3 shows SumVOC concentrations by country for each building measured. The
measurements were made using standardized sampling and analytical methods based on
sample collection on Tenax, and analysis by GC/MS. (Note that these are preliminary
data; Final data may differ and are expected to be reported by the overall project team in
late 1995.)
The buildings were of various ages and were served by a variety of ventilation types.
Many of the buildings were ventilated with mechanical systems. Smoking was permitted
in some and not in others. There was a degree of variety in the buildings in each country
but no strict mix formula appears to have been applied for building selection. Therefore, it
may not be meaningful to plot the results together on a single chart. Similarly, even within
each of the participating countries, the mix of buildings makes comparison of results
among buildings difficult to interpret.
The data plotted in Figure 3 indicate that with only one exception, SumVOC
concentrations in buildings were <1 mg/m3, and, in most cases, they were <0.5 mg/m3.
There were significant variations among buildings in most of the countries reported here.
Ventilation rates ranged from 0.4 air changes per hour (ach) to 10.5 ach. Country averages
for air exchange rates were from a low of 0.9 ach (GB) to a high of 3.6 ach (GR). Studies
reporting contaminant concentrations that also include ventilation rate measurements are
particularly useful because they allow calculation of the source strengths associated with
the concentrations.
0.0
0.2
0.4
0.6
0.8
1.0
Building by country
SumVOC-(mg m-3)
F GB DK GR CH FI
1.8
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
Building by country
SumVOC source strength (mg m-2 h-1)
8.5
5.8
F GB DK GR CH FI
Figure 3. SumVOC for European Audit Project
Preliminary Data Figure 4. SumVOC source strengths calculated
from European Audit Project preliminary data
Source strengths can be determined from measurements of concentrations and
ventilation rates. For most buildings where these measurements have been made together,
building-wide average source strengths tend to range from about 0.5 milligrams VOC per
square meter per hour (mg m-2 h-1) to around 1.5 mg VOC m-2 h-1. In very low-VOC
buildings, source strengths have been reported well below 0.5 mg VOC m-2 h-1, and in
strong source buildings, source strengths of 2.0 to 10.0 mg m-2 h-1 have been found (Levin,
1995b).
Figure 4 shows average SumVOC source strengths by building for each country
calculated from reported TVOC concentrations and ventilation rates. Note that the source
strengths in Figure 4 are not consistent with those reported on the Healthy Buildings ‘94
posters. The source strengths reported on the posters appear implausible relative to the
VOC and ventilation rate data. This may be due to lack of clarity in the project manual
regarding calculation, measurment limitations, or some other cause. The final report may
explain reasons for the discrepancies.
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Design Guidance for IAQ
It is clear that an analytical process can result in more systematic prioritization of
design concerns to address IAQ problems. Existing data can be used to provide
considerable guidance to designers considering IAQ issues. Further research will continue
to clarify some of the issues, but existing research provides a considerable base of
information for designing healthy buildings with respect to indoor air quality.
GENERAL ENVIRONMENTAL IMPACT
Avoiding adverse building impacts on the larger environment may be more difficult
than avoiding adverse affects on occupants. The purpose of buildings is to protect people
and their possessions from the hazards and unfriendly forces of the natural environment.
But to do this, the natural environment must be altered. Resources must be extracted and
transformed to create and operate buildings. Water, land, living organisms, and mineral
resources are used. Pollutants are emitted to the air, land, and water, and waste is produced
that must be disposed if not re-used or recycled.
The major impacts of a building on the general environment are related to the
materials and energy used for building construction, maintenance, and operation.
Approximately 20% to 40% of all such resource consumption in the United States is
related to buildings (Levin, 1995a). The impacts occur during the entire life cycle of the
building as well as during the production of the building materials and products used to
construct it. Life cycle analysis (LCA) methodologies are now being applied to evaluate
the environmental impacts of buildings and advise designers regarding appropriate choices
(AIA, 1995). These efforts are only now beginning, and much research and data gathering
is necessary to fully evaluate building design decisions.
A recent trend toward increased concern about the impacts of buildings on the larger
environment has led many building design professionals to design so-called “sustainable
architecture” or “green buildings.” Their efforts are intended to reduce harmful
environmental impacts of buildings. “Sustainable design” is usually defined as avoidance
of environmental damage that will decrease the livability of the planet for future human
generations. Some suggest also minimizing impacts on other living species. These are
quite strongly interdependent, so treating them independently is dangerous. Regardless of
which view one adopts, sustainable design remains an abstract goal not currently achieved
by efforts in industrialized societies. The best that is being done now is to reduce the
magnitude of the harmful environmental impacts imposed by most building activities.
Efforts to provide advice to designers abound. Among the most prominent are the
BSRIA (1994), BEPAC (1993), and AIA Environmental Resource Guide (ERG) (1995).
Each of these has been published - the AIA’s ERG being the most elaborate weighing in at
more than 5 kg. But each of these publications and a rapidly growing number of others
providing advice on “sustainable design” generally fail to provide any direction for
prioritizing the various environmentally-conscious actions they recommend. Inevitably,
designers must prioritize various design alternatives and recommend favored ones to their
clients from among them. Design is always a matter of trade-offs, No building is likely to
be completely harmless to the environment. The real question is how to boost efficiency in
terms of energy and other resource use and in terms of reducing pollution while learning to
build more sustainably.
The United States in particular must consider how to reduce significantly its
consumption of resources and emission of pollutants by more closely balancing its
environmental resource inflows and pollution outflows with the earth’s carrying capacity.
Currently comprising only 4.6 percent of the global population, the U.S. accounts for about
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25% of the worlds energy consumption, a little over 20% of its CO2 emissions, and equally
disproportionate shares of other other resource consumption and pollution emissions.
In California, more energy is used by the typical office worker commuting to work
than is used in the offices where they work. Transportation and planning are critical
factors. In Europe and elsewhere, efficient, convenient mass transport exists, and
urbanization is generally far denser than in the United States, In most U.S. cities, and in
some other parts of the world, most workers ride to work in automobiles, often one only
occupant per car. The infrastructure does not exist for efficient commuting, and affordable
and desirable neighborhoods are not always available close to one’s workplace. The
transportation sector accounts for more than one-quarter of all energy use in the United
States, the industrial sector accounts for more than one-third, and commercial and
residential building sectors account for more than one-third. Energy required to construct
and operate buildings is estimated by various sources between 40 and 45% of all energy
use in the United States (Darnay, 1994).
Life Cycle Analysis
The :LCA process widely cited for building design has evolved from LCA methods
used for consumer products. It has been codified by the Society for Environmental
Toxicology and Chemistry (SETAC, 1991; 1993). It has also formed the basis for
industrial ecology used to improve industrial processes and plant operations (Graedel and
Allenby, 1995). The traditional use of LCA has been to evaluate consumer products.
However, these evaluations have focused on inventory and impacts related to the
production and disposal of consumer goods while largely ignoring the product’s use phase.
Building designers, operators and users must emphasize the use phase when they design,
so a more meaningful “modified LCA process” includes the use phase. A building design-
oriented adaptation of the LCA process is shown diagramatically below.
Inventory ⇒ Impact ⇒ Valuation/Ranking ⇒ Design ⇒ Implementation ⇒ Feedback
Determining What’s Important to Guide Design
To guide design to reduce buildings’ environmental impacts, it is important to
prioritize efforts according to the most critical environmental problems. For example, is
global warming a more important problem than ozone depletion or biodiversity loss?
Should design efforts to minimize one of these or other problems dominant or be
submerged relative to other design alternatives? The problem of deciding what to do
during design is unmanageable due to the large number and the inter-relatedness of the
various environmental concerns. The necessary prioritization can be done by examining
the total impact of buildings on the environment and by ranking the most important
environmental problems. This will allow a hierarchy of design features related to
environmental protection.
To assess buildings’ contributions to LCA inventory flows and environmental
impacts, estimates of building-related contributions were prepared from U.S. national data
(Levin et al, 1995a). Building-related raw materials uses average about 40% of U.S. raw
material consumption. For some materials such as PVC, timber, sand, and clay, it is
>50%. Building operational energy use is >35% with an additional 5% or more of U.S.
energy use embodied in building materials. Water use, including industrial and power
plant operations attributable to building construction and operation, is ca. 20%. Building-
related atmospheric emissions of CO2 for building-related energy use and for producing
building-related materials are >30% of U.S. totals. Between 25% and 35% of solid waste
produced in the U.S. is building-related -- either direct (e.g., from construction,
demolition) or indirect (e.g., mining resources for building materials and products).
12
Building-related “other releases” or emissions (including noise, thermal pollution,
radiation, electromagnetic fields) represent significant fractions of such releases (Darnay,
1994; Brown, 1995).
These data indicate that building-related contributions to total inventory flows and
environmental impacts normally assessed in LCAs are large and, therefore, important. The
detailed analyses for these estimates are being used to scope ongoing modeling and to
prioritize data gathering efforts aimed at developing guidance for building designers,
product manufacturers, and others trying to create “sustainable” buildings or “green”
building products.
By examining building-related environmental impacts, it is possible to identify those
of greatest concern. By assessing inventories in relation to prioritized impacts of concern,
design, manufacturing, construction and building operation activities can be focused on
those most likely to produce buildings that are least harmful to environmental end points of
concern. Work in progress is improving the reliability of the inventory estimates. Work is
also being undertaken to articulate the network or chain of impacts in order to categorize
the end-points of concern and identify inventory-impact vectors of greatest significance.
Identifying the most important problems
To identify the most important environmental problems, it is necessary to apply
consistent criteria. The Science Advisory Board (SAB) of the U.S. EPA developed a set of
criteria for their report, “Reducing Risks” (EPA, 1992) Table 5 shows the four criteria
used by the EPA’s SAB plus two more appropriate for building design considerations.
Table 5. Criteria for priority ranking of building-related environmental problems
⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯
1. THE SPATIAL SCALE OF THE IMPACT
Global, regional, local (large scale being worse than small)
2. THE SEVERITY OF THE HAZARD
More toxic substances being of more concern than less toxic substances
Irreversible changes - e.g., death or species extinction -- is more severe than reversible damage
3. THE DEGREE OF EXPOSURE
Well-sequestered substances being of less concern than readily mobilized substances
4. THE PENALTY FOR BEING WRONG
Longer remediation times being of more concern than shorter times
5. THE STATUS OF THE AFFECTED SINKS
An already overburdened sink is more critical than a less-burdened-one
(Sinks = receptors, environmental compartments)
6. THE RELATIVE CONTRIBUTION OF BUILDINGS
Large share of building-related in- or out-flows being worse than a small share
⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯
Using these criteria, environmental problems are classified or ranked. The U. S. EPA
Science Advisory Board (SAB) used the first four criteria shown in Table 5 and ranked
risks as top, medium, or low priority. The two additional criteria added to the SAB list are
intended to improve the applicability of the criteria for application to building problems
and design. The resulting rankings are shown in Table 6.
13
Table 6 . Priority ranking of environmental problems; (source: EPA Science Advisory Board,
1990).
⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯
Relatively High Risk Ecological Problems:
• Habitat alteration and destruction
• Species extinction and overall loss of biological diversity
• Stratospheric ozone depletion
• Global climate change
Relatively Medium-Risk Ecological Problems:
• Herbicides/pesticides
• Toxics, nutrients, biochemical oxygen demand, and turbidity in surface waters
• Acid deposition
• Airborne toxics, including smog related constituents
Relatively Low-Risk Ecological Problems:
• Oil spills
• Groundwater pollution
• Radionuclides
• Acid runoff to surface waters
• Thermal pollution
⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯
A separate list of health problems was also prepared, although not with any ranking.
These appear in Table 7.
Table 7. High risk health problems (source: EPA Science Advisory Board, 1990).
⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯
High Risk Health Problems:
• Indoor Air Pollution
• Outdoor Air Pollution
• Worker exposure to industrial or farm chemicals
• Pollutants in drinking water
• Pesticide residues in food
• Toxic chemicals in consumer products
⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯
Using the lists in Tables 6 and 7 to prioritize actions intended to avoid or minimize
environmental damage focuses design efforts on the most critical problems. Thus,
solution of the problems listed as high risk should not be compromised substantially to
address problems ranked lower. A difficulty occurs when attempting to make trade-offs
between ecological risks and health risks. Nevertheless, this ranking allows prioritization
of the various “environmentally conscious” design activities and actions related to the
highest risk environmental problems. Table 8 shows an example of several environmental
problems and the design issues related to them. By focusing on the highest priority
problems, designers can be more confident that their solutions have appropriately
addressed environmental issues of greatest importance. An example is shown in Table 8
using five ecological and health risks prioritized according to the criteria in Table 5 as top,
medium, or low, priority. In the right hand column, building design issues are identified
related to the ecological or health problem in the left hand column.
14
Table 8. Example of five environmental (ecological and health) impacts listed by priority
with their main contributors in buildings.
Ecological or health problem Priority
group Contributors in buildings (that can be influenced during
design or by changing the building)
TOP PRIORITY
Ozone depletion TP
Refrigerants
Foams for insulation
Excess energy consumption requiring refrigeration
MEDIUM PRIORITY
Acid deposition HP1 Electricity use (coal/oil generated) for lighting, heating
Some building related industries
Groundwater resource depletion HP2 Water used for washing/bathing, toilet flushing
Water used for cooling in power plants
Water used when making building materials
LOW PRIORITY
Indoor air pollution --
non-radon
MP 1 Building materials, ventilation systems
Operation and maintenance
Operations malfunction
Finish renewal, renovation
Chemicals in the workplace MP2 Copper in electrical wires
Roofing materials
Plastics in pipes/on roofs, etc.
Aluminum window frames, etc.
A more sophisticated approach requires estimation of the resources consumed and
environmental emissions of each alternative. Then the emission or resource consumption
must be related to the environmental problem of concern and the magnitude of the
environmental impact estimated for each environmental problem. Next, the emissions
must be multiplied by a weighting factor representing the seriousness of the problem as
ranked by criteria shown in Table 5. One difficulty in assigning a weighting factor is
determining the economic and other basis for valuing various environmental and health
risks. Different people will value them differently according to their viewpoint and
interestss. Many useful approaches to valuation have been described that can incorporate
the value of natural resources such as significant views, resources, species, or other
elements of the natural world that are not necessarily valued by traditional economic
analyses (Pearce, 1993).
The ranking or score or other information can be derived to guide design decisions
will ultimately be limited by data availability, scientific knowledge of environmental
impacts, and projections of future population, resource limitations, and environmental
consequences. Nevertheless, a score or ranking system can call attention to critical
problems and produce more informed design decisions. It can also help prioritize the
actions of building products manufacturers, of researchers, and of policy-makers. Finally,
it can call attention to data and research needs to improve the process of determining
critical environmental factors.
DECIDING WHAT’S IMPORTANT IN DESIGN
A simple illustration of the application of criteria that might be developed for healthy
material selection considering the indoor air quality, indoor environment, and the general
environment is shown in Table 9. The importance of each factor for each environment is
indicated by the number of marks in the matrix. This exercise shows that there is
considerable overlap among the criteria for different environmental compartments.
15
Table 9. Sample Matrix of Criteria for Healthy Materials Selection
⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯
Material Selcetion Criteria IAQ Indoor General
Env’t Env’t
⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯
Resource conservation X XXX
Durability XX X XXX
Low emissions/pollution production XXX
Low emissions/pollution finished XXX XX
Maintenance chemical requirements XXX X XX
Replacement frequency XX X XXX
Hard surface (IAQ vs. acoustics) XX XXX
Smooth surface XXX XX X
Energy consumption X XX XXX
⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯
Design Guidance
Following is preliminary design guidance that attempts to integrate both indoor and
general environmental considerations.
Resource conservation. Selecting building materials and products that are extremely
durable and can be expected to perform well over an extended useful life will generally
result in a better environmental choice than one that must be replaced twice or even ten
times during the same time period. This is evident from the approximately ten-fold greater
relative additional resource extraction/consumption, manufacturing, transport, installation,
and disposal. A roof used in many European applications may last between one and three
hundred years while in the United States typical roofs last ten to thirty years. It is obvious
that the environmental impacts of U.S. roofs are roughly ten times that of the European
roofs regarding the extraction and disposal of materials. Long-lived products are an
inherently preferred solution for resource conservation and environmental protection.
Re-using materials and products that have reached the end of their useful lives is the
next most effective way to avoid withdrawal of additional resources and creation of
environmental pollution associated with the extraction, transport, processing,
manufacturing. and installation. A longer-lasting material is inherently more desirable
(Goldbeck and Goldbeck, 1995).
Durable materials tend to have low emissions. Therefore, the tend to be better for
indoor air quality than less durable ones. They may also require less frequent application
of maintenance and surface renewal chemicals and use of less harmful chemicals. There is
a sort of multiplier effect from the use of durable materials..
Designs that assume frequent changes in interior partitions should provide for re-
mounting durable ones rather than demolition/disposal and new construction.
Pollutant source control. Controlling pollution at the source is generally four times
as cost effective as removing pollution from air, water, or soil. This applies both to indoor
air as well as ambient air. It also applies to both surface and groundwater water. It is
widely accepted that the most effective strategies for indoor air quality involve reducing
indoor air pollutant sources and their source strengths or toxicities by one of the following
measures: elimination, reduction, substitution, or source isolation. Important
considerations for material selection and indoor environmental quality include functional
requirements, surface characteristics, total mass, chemical composition and emissions,
durability - longevity, and cleaning, maintenance and renovation requirements. Selecting
low-emitting materials, especially for those products that will be present in large quantities
by mass or exposed surface area, is also important to reduce emissions to the general
16
environment. Typically, low-emitting products will have resulted from production
processes involving lower exposures of the manufacturing workers.
Design for effective moisture protection is important to prevent intrusion of water
from outdoors through cracks, openings, or semi-permeable membranes and eliminate
potential for standing water or condensate inside the building from chilled water systems.
This will prevent the growth of microorganisms. This will also prolong the life of the
building and its components resulting in resource conservation.
Energy conservation. The first step toward reducing energy consumption is
conservation. This includes effective building envelope insulation, tightly-sealed
openings, and control of air movement and thermal transport mechanisms between the
building and the outside and, in some cases between spaces within the building. This does
not mean minimal ventilation; it mean reducing the requirements for conditioning
ventilation air by avoiding unintentional thermal losses. Energy conservation will produce
more comfortable indoor environments. Energy conservation is extremely important in
reducing potential emissions of greenhouse gases at power plants, and acid-forming gases
that cause acid deposition. This will also reduce the need for refrigeration involving
ozone-depleting compounds.
Energy efficiency. Where energy-consuming devices are required (such as fans,
pumps, motors, appliances, etc.) it is essential to select efficient appliances. The ratio
between the best and worst in a class of products may easily be 2-to-1 or even 3-to-1, so it
does make a great deal of difference which product is selected.
Ventilation. Ensure adequate ventilation to control pollutants that reach the indoor air
by reducing and removing them through dilution, exhaust (local, general), filtration, and
air cleaning. Occupant-controlled ventilation can produce energy savings while reducing
occupant stress and building sickness symptoms.
Overall design. Design for the whole person: The human body and mind integrate all
the factors in the physical, chemical, biological, and psychosocial environment. Full
integration of environmental considerations in design will include not only indoor air
quality but also thermal comfort, lighting, acoustics, and spatial relationships. Such
designs will be inherently healthier. A building that meets the needs of its users
(occupants, operators, others) will endure longer and not require demolition, replacement,
or other resource- and pollution-intensive actions. The more satisfied building users are,
the longer the building will remain in service, avoiding the need for additional
construction.
Building design and indoor environmental quality issues must be considered
throughout the process of planning, design, construction, use, and disposal/re-use/recycling
buildings. The major design phases include site selection, project feasibility, budgeting,
building configuration, building envelope, environmental control scheme, energy
considerations, and environmental impact analysis.
DISCUSSION and CONCLUSION
This paper has emphasized a “building ecology” view of buildings as dynamic,
interdependent systems (Levin, 1981). This view argues for planning during the design
phase for varying cycles of building performance and use or requirements during the
building’s lifetime. The more specific the analysis, the more relevant its application to any
17
given building design. Generic analyses are helpful but suffer from the potential to miss
important characteristics of a particular situation.
Examining sample decisions, it becomes apparent that in many instances, the design
alternative best for indoor environmental quality is also best for general environmental
quality. For example, durable materials will be less likely to emit contaminants into the
indoor air, will require lower quantities and less toxic chemicals for the maintenance and
refurbishing, and, by definition, will be longer lasting. Service life is an extremely
important determinant of overall impact on the general environment since each
replacement cycle requires the use of additional resources with the concomitant pollutant
emissions.
Designers must be aware of the impacts of the building on the larger environment.
These will include impacts on biodiversity, global warming, ozone depletion, on the soil,
air, and water, on resource depletion, on waste generation, and on energy consumption,.
Some of these will ultimately, although perhaps imperceptibly, affect the building itself
and its users. Therefore, each building must be planned and designed as though it were
being replicated a million times over so that we take seriously the consequences of its
impacts on the global environment and, in a very real sense, its own environment.
ACKNOWLEDGMENTS
The preparation of this paper was based in part on work prepared by Atze Boerstra, Shela Ray,
and Eugena Bendy.
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