Group Title: Affordable housing issues
Title: Affordable housing issues ; vol. 15 no. 2
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Title: Affordable housing issues ; vol. 15 no. 2
Series Title: Affordable housing issues
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Language: English
Creator: Shimberg Center for Affordable Housing
Publisher: Shimberg Center for Affordable Housing
Place of Publication: Gainesville, Fla.
Publication Date: February 2005
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M.E. Rinker, Sr., School of Building Construction College of Design, Construction & Planning PO Box 115703,
University of Florida, Gainesville, FL 32611-5703 TEL: (352) 273-1192 SUNCOM: 622-7697 FAX: (352) 392-4364

Volume XV, Number 2

February 2005

Green Building is a process that involves incorporating environmental considerations into every phase
of the home building process. That means that during the design, construction, and operation of a home,
energy and water efficiency, lot development, resource efficient building design and materials, indoor
environmental quality, homeowner maintenance, and the home's overall impact on the environment are
all taken into account. Although Green Building programs are appearing across the country, many
jurisdictions do not have the resources to create a program from scratch. Accordingly, the National
Association of Home Builders (NAHB), with a panel of experts, developed a list of Green Building
Guidelines. The guidelines are summarized in this newsletter. The complete NAHB Model Green
Home Building Guidelines publication is available on the Internet at
file Upload details.aspx?contentTypelD=7&contentID=1994.

Before proceeding, it is important to recog-
nize that the builder must keep in mind that:
1) environmental considerations should be
incorporated into the project from the very
beginning because it is much harder to weave
green home concepts into a project after the
house plans are finished, and 2) the house
should be looked at as a whole as the builder
determines which of the green home guideline
items to put into the house. For example, mak-
ing a home's building envelope tighter through

air sealing and quality building techniques can
affect the way in which the builder designs the
home's ventilation system.
Another important point cited by the NAHB
is that these guidelines should be considered as
a dynamic list. Granted that the guidelines
were developed on the best available scientific
data, there are still many unknowns that may
become better understood as time passes. As
we build more green buildings and as we learn
more about the tradeoffs and interactions, this
list of guidelines may change. There is also the

H 0 U I N G

local priority aspect. For example, a recirculat-
ing hot water system that reduces water con-
sumption may be a desirable option in a region
that suffers from severe water shortages even
though the recirculating system consumes more
energy that other system designs.
Now to answer the question, "Why should
we care about green building?" There are many
compelling reasons for changing the way in
which we build and operate homes. Although
we cannot avoid impacting the environment
when we build a house, green building can
work toward minimizing that environmental
These guidelines were designed with the
mainstream home builder in mind. We recog-
nize that many home building companies
already incorporate some elements of green
building into their current practices. However,
the purpose of these guidelines is to highlight
ways in which a mainstream home builder can
effectively weave environmental concerns
holistically into a new home and to provide a
tool that local associations can use to create a
green home building program.
At the time these guidelines were created,
there were 28 green home building programs in
operation throughout the United States.
These programs have done a great job at
spreading the word about green home building.
However, there are numerous other locales that
are interested in green home building that do
not have the resources but have not had the
resources to create a program from scratch.
These guidelines are intended to serve as a
toolkit for home builder associations to create
new programs, and to help those programs
expand and flourish.

As noted above, during the process of building
a green home, a builder takes numerous
considerations into account simultaneously
and consciously incorporates environmental
issues into all decisions. The attached model
green home building guidelines consist of a

variety of distinct line items that a builder can
choose from in creating a green home. For
organizational purposes, we have grouped the
line items into overarching sections, or guiding
principles. Below are the guiding principles
addressed in green home building:

Guiding Principle Lot design,
preparation, and development
Resource efficient site design and develop-
ment practices help reduce the environmental
impacts and improve the energy performance of
new housing. For instance, site design principles
such as saving trees, constructing onsite storm
water retention/infiltration features, and orient-
ing houses to maximize passive solar heating
and cooling are basic processes used in the
design and construction of green homes.

Guiding Principle Resource efficiency
Most successful green homes started with the
consideration of the environment at the design
phase-the time at which material selection
occurs. Creating resource efficient designs and
using resource efficient materials can maximize
function while optimizing the use of natural
For instance, engineered wood products can
help optimize resources by using materials in
which more than 50% more of the log is con-
verted into structural lumber than conventional
dimensional lumber 1.
Resource efficiency is also about reducing
jobsite waste. Invariably, there are leftover
materials from the construction process. Devel-
oping and implementing a construction waste
management plan helps to reduce the quantity of
landfill material. The average single-family
home in the U.S., at 2,320 ft2 (NAHB, 2003), is
estimated to generate between 6,960 and 12,064
lbs. of construction waste. Thus, by creating an
effective construction waste management plan
and taking advantage of available recycling
facilities and markets for recyclable materials,
construction waste can be reduced by at least two-
thirds, creating potential cost savings for builders

and reducing the burden on landfill space.
Lastly, basing the selection of building mate-
rials on their environmental impact can be
tricky. For instance, a product might be renew-
able, but on the other hand it takes a relatively
great amount of energy to transport the product
to a project's job site. While one way to compare
products is to look at a product's or a home's
life-cycle environmental impacts through a
process called Life Cycle Analysis (LCA). An
LCA of a building product covers its environ-
mental impacts "cradle-to-grave" through six
basic steps: 1) Raw material acquisition, 2)
Product manufacturing process, 3) Home
building process, 4) Home maintenance and
operation, 5) Home demolition, and 6) Product
reuse, recycling, or disposal. There are numer-
ous reasons why building products are not
commonly selected via LCAs. One of the issues
is the availability of data there is a lack of data
to feed into tools that allow for an LCA on a
product or system.
One such tool created by the National Insti-
tute of Standards and Technology (NIST) is the
Building for Environmental and Economic
Sustainability (BEES) software program. BEES
has ten impact categories: Acid rain, Ecological
toxicity, Eutrophication, Global warming,
Human toxicity, Indoor air quality, Ozone
depletion, Resource depletion, Smog, and Solid
waste. Since information is not available to
conduct full LCAs on all available building
products, we have instead included an LCA
mindset in creating the list of line items in the
Resource Efficiency section. Our hope is that in
the future the prescriptive line items in the
guidelines will eventually be replaced with a
full LCA approach for the home as a system and
the components therein.

Guiding Principle Energy efficiency
Energy consumption has far-reaching envi-
ronmental impacts: from the mining of fossil
fuel energy sources to the environmental emis-
sions from burning non-renewable energy
sources. And each home consumes energy year
after year, meaning that the environmental

impacts associated with that use accrue over
time. Therefore, energy efficiency is weighted
heavily in a green building program.
Energy consumption not only occurs during
the operation of a home, but also during the
construction of a home and, indirectly, in the
production of the materials which go into the
Although the energy used to heat and cool a
home over its life far outweighs that to manu-
facture the materials and construct it, the large
number of homes built (currently about 1.85
million per year) renders the energy used
during the construction phase significant. 1
information 14.php
On average, a home built between 1990 and
2001 consumed about 12,800 kWh per year for
space and water heating, cooling, and lights and
appliances. Where natural gas is used, con-
sumption averages 69,000 cubic feet per house-
hold annually. Total energy expenditures
during a year cost these homeowners about
$1,6002. Energy efficiency improvements that
make a home 20% more efficient-a conserva-
tive estimate for many green homes-could
significantly reduce a homeowner's annual
utility bill expenses.
No matter what the climate, energy efficiency
is considered a priority in most existing green
building guidelines/programs. Moreover, as
the cost to heat and cool a home becomes more
unpredictable, it is advantageous to every
homeowner to be "insulated" from inevitable
utility bill increases. As with all aspects of these
guidelines, the greatest improvements result
from a "whole systems" approach. Energy
performance does not end with increased R-
values, the use of renewable energy, and/or
more efficient HVAC equipment. Rather, there
needs to be a balance between these features
and careful window selection, building enve-
lope air sealing, duct sealing, and proper place-
ment of air and vapor barriers from foundation
to attic to create a truly high performance,
energy-efficient home that is less expensive to

operate and more comfortable to live in than a
conventionally-constructed home.

Guiding Principle Water efficiency
The mean per capital indoor daily water use
in today's homes is slightly over 64 gallons.
Implementing water conservation measures can
reduce usage to fewer than 45 gallons. For this
reason, green homes are especially welcomed in
areas affected by long- and short-term drought
The importance of water resources is becom-
ing increasingly recognized, especially in the
western third of the country. Choices between
sending water to growing urban areas versus
making water available for irrigation highlight
the issues surrounding the scarcity of this
valuable resource.
Green homes often conserve water both
indoors and out. More efficient water delivery
systems indoors and native and drought-
resistant landscaping choices outdoors can help
prevent unnecessary waste of valuable water
resources. Communities can obtain additional
benefits when builders effectively use native
species in landscaping. Current research and
practice has shown that natural processes can be
a successful means of filtering and removing
contaminants from storm water and wastewater.

Guiding Principle -Indoor environmental
Healthy indoor environments attract many
people to green building. After energy effi-
ciency, the quality of a home's indoor air is
often cited as the most important feature of
green homes. Pam Sessions, President of
Hedgewood Properties in Atlanta, explained
during the 2002 National Green Building Con-
ference that the majority of people interested in
green homes in the Atlanta market indicated
that indoor air quality was their top issue of
An increase in reported allergies and respira-
tory ailments and the use of chemicals that can
off gas from building materials have contrib-
uted to a heightened awareness of the air we
breathe inside our homes. Even though there is
no authoritative definition of healthy indoor air,

there are measures that can mitigate the effects
of potential contaminants including: controlling
the source, diluting the source, and capturing
the source through filtration.

Guiding Principle Operation,
Maintenance and Homeowner Education
Improper or inadequate maintenance can
defeat the designer's and builders best efforts to
create a resource-efficient home. For example,
homeowners often fail to change air filters
regularly or neglect to operate bath and kitchen
exhaust fans to remove moist air. Many home-
owners are unaware of the indoor environmen-
tal quality impact of using common substances
in and around the house such as pesticides,
fertilizers, and common cleaning agents. By
providing homeowners with a manual that
explains proper operation and maintenance
procedures, offers alternatives to toxic cleaning
substances and lawn and garden chemicals, and
points out watersaving practices, a builder can
help assure that the green home that was so
carefully built will also be operated in an envi-
ronmentally responsible manner.

Guiding Principle Global Impact
There are some issues related to home build-
ing and land development that do not fit nicely
into the context of the aforementioned guiding
principles. For these items that are a by-product
of home construction, we have added a separate
principle global impact. One example of an
issue having global impact is the selection of
paints that contain relatively low or no volatile
organic compounds (VOCs). Although the VOC
content of paint is often considered for indoor
environmental reasons, the vast majority of
VOCs are released by the time the paint is dry.
However, the release of VOCs from wet paint
help form ground-level ozone pollution. There-
fore, the use of low- or no-VOC paints falls
under the global impact principle because the
environmental impact of using paints with
relatively high VOC levels is greater on the
global scale than it is on the indoor environment

Guiding Principle Site planning and
land development
The process of green home building should
not stop at the house. If a builder is also in-
volved in the development of the community,
site planning and land development can be part
of the process. Therefore, information about
low-impact site planning and land development
is included in Appendix A. Considering the
entire community and existing infrastructure in
addition to the individual buildings) can
amplify the benefits of green home building.
For example, by improving a subdivision's
storm water management plan and preserving
natural resources through careful design and
construction practices, a builder can influence
not only the resource efficiency of each particu-
lar house but also the entire subdivision's
overall environmental impact. Low Impact
Development (LID), which uses various land
planning and design practices and technologies
to simultaneously conserve and protect natural
resources and reduce infrastructure costs, is one
way to approach green development.

The previous section highlighted the environ-
mental benefits of green building practices.
However, green building is much more than
just reducing a home's environmental footprint.
Homeowners can also realize direct benefits by
owning a green home. Here are some of the
primary benefits that owners of green homes
have experienced compared to owners of
conventional homes:
Lower operating costs Homeowners
receive less expensive utility bills due to
energy and water efficiency measures.
Increased comfort Green homes have
relatively even temperatures throughout
the home, with fewer drafts and better
humidity control.
Improved environmental quality By
following the attached guidelines, build-
ers pay extra attention to construction

details that control moisture, choose
materials that contain fewer chemicals,
and design air exchange/filtration sys-
tems that can contribute to a healthier
indoor environment.
Enhanced durability and less mainte-
nance Green homes incorporate build-
ing materials and construction details that
strive to increase the useful life of the
individual components and the whole
house. Longer-lived materials not only
require fewer resources for replacement
but also reduce maintenance and the
economic costs of repair. Green homes
have lawns that require less weeding and
watering, building elements that require
less maintenance, and more durable
building components that reduce the time
needed for upkeep. It is important to note
that a builder can only do so much when
it comes to how the home will perform.
Homeowners play a big role in the house
performance and, therefore, should be
instructed on how to operate the green
home as it was intended.

The NAHB Green Home Building Guidelines
was developed through a public process that
included the following major steps:
1. An extensive review of the existing local
green home builder programs primarily
home builder association programs, but
also including several public sector and
non-profit programs. All but three of the
28 existing programs are voluntary and
2. A review of the voluntary energy effi-
ciency programs endorsed by the Na-
tional Association of Home Builders
3. A review of the leading life cycle analysis
(LCA) tools available for use by residen-
tial design and construction professionals
in North America (e.g., BEES, ATHENA).

4. Input through an open process from
numerous individuals on the NAHB
Advisory Group and the Stakeholder
5. Applying certain criteria to each line item
in order to give the line items point
Each line item in the guidelines has a point
value attributed to it. Once the Stakeholder
Group members finalized the list of line items
for inclusion in the guidelines, the NAHB
Research Center team looked at each line item
through three different lenses: 1) Environmental
Impact, 2) Building Science and Best Building
Practices, and 3) Ease of Implementation. The
team used publicly available information,
experiential data, and other data inputs to
assign each line item points via these three
criteria. Each line item's final point total was
calculated by weighting the criteria. Environ-
mental Impact received the greatest weight,
followed by Building Science and Best Building
Practices, with Ease of Implementation receiv-
ing the least weight.

Environmental Impact The main purpose
of these guidelines is to provide a framework
for builders to reduce a home's environmental
impact. We assessed how each line item helped
make a home more energy efficient, improved
indoor environmental quality, and so on. As-
signing a value to each line item is an inexact
science since all of the necessary data is not
available. In addition, some line items had
impacts that spanned multiple principles and,
in some cases, the impact was positive for one
guiding principle while negative for another.
With that as background, the NAHB Research
Center team took into account all of the above
considerations and available data to assess the
environmental impact of implementing each
line item. Using qualitative and quantitative
information, the team assigned value to each
line item based on the positive impact to the

Building Science and Best Building
Practices Certain green building practices
dramatically impact how a house operates. For
example, the sealing of a home's building
envelope has an impact on the home's HVAC
system. In addition, some measures such as
proper flashing details and installation of
weather barriers enhance durability, minimize
the possibility of indoor environmental prob-
lems, and are considered "best building prac-
tices." Line items that help a home perform
effectively as a system for the long-term were
assigned a higher point value. Ease of Imple-
mentation Some line items are easier to
implement than others. The NAHB Research
Center team compared each line item to current
home building practices and estimated how
difficult it would be for a builder to implement
the line item relative to primarily cost and time.
For instance, would it take longer to install a
new technology? Would subcontractors need to
be educated on the use of a new product?
Would a new technology cost more to buy? A
line item will have a positive environmental
impact only if it is implemented. Line items that
were relatively easy to implement (and there-
fore more likely to be implemented) were
assigned a greater point value than the items
that are more difficult to implement.

Green Programs and Homes Differ
Across the Country When assigning points to
the line items, the NAHB Research Center
assumed the home would be built in Baltimore,
MD, which is in Zone 4 of DOE's proposed
climate zone map. The map can be viewed at
the following URL: http://
For associations located outside of Zone 4
that are interested in creating a green building
program, point values can be customized for
some line items most affected by climate condi-
tions. For example, an association in Florida,
you will likely want to increase the point values
attributed to installing an energy efficient air
conditioning system and decrease the point

value associated with installing a high efficiency
heating system. Similarly, in the southwestern
United States associations would likely place
higher value on water efficiency measures. A
thermometer symbol in the User Guide identi-
fies line items that most likely will see point
value changes due to climatic differences across
the country.
Additional factors can lead to the decision to
alter point values for a certain location, such as
the availability of materials, the recycling
marketplace, and the existence of rebate pro-
Determining a line item's point value is
accomplished by way of consensus among the
members of the green home building program's
development committee. This is primarily a
qualitative process and some acknowledgment
of the decision-making process should be
clearly stated in the program.

Homebuilders differ in their relative knowl-
edge and comfort level with green building
Some builders have been building green for
years, while others are being introduced to the
ideas for the first time. Recognizing this broad
range of knowledge, the NAHB Research Center
team established various thresholds to delineate
different levels of green building effort.
The first step was to identify practices that
should be part of any home building project.
The first level of green building, Bronze, in-
cludes additional line items that in the end
show that a builder paid special attention to a
project's environmental impact. The next two
levels of green home building, Silver and Gold,
include additional line items that place increas-
ingly greater emphasis on the home's environ-
mental impact. The "How to Use the Guide-
lines" section of this document outlines how to
score a home to determine if it meets or
exceeds any of the green home building levels
noted above.

It should be noted that although many green
building programs have been in existence for 10
years or more, the concept and practice of green
building is not clearly defined and straightfor-
ward. Many gray areas remain in identifying
and quantifying the precise environmental
impact for each particular line item. For ex-
ample, there is very little publicly available
information regarding manufacturing processes
that document energy consumption, impact on
natural resources, or C02 emissions for each
building material.
In addition, a particular guideline may
contain tradeoffs and carry with it contradictory
characteristics. For example, a recirculating hot
water system can help save conserve water, but
may use a relatively large amount of energy in
its operation. Although the guidelines in their
current form are based on experiential evidence
and the latest independent scientific research
available, they still may leave many questions
unanswered due to the lack of scientific and
quantitative data.
Finally, assigning a particular degree of
importance to different criteria undoubtedly
involves a certain amount of personal or local
value judgment. Life Cycle Assessment (LCA)
tools are beginning to sort out such questions,
but the tools still remain in their infancy. There-
fore, this set of green home building guidelines
should be viewed as a dynamic document that
will change and evolve as new information
becomes available, improvements are made to
existing techniques and technologies, and new
research tools are developed. How to Use the

Job Opportunity

Coordinator, Research Programs and Services Shimberg Center, University of Florida
The Shimberg Center for Affordable Housing at the University of Florida is currently
accepting applications for Coordinator, Research Programs and Services. The position is
located within the Florida Housing Data Clearinghouse, a long-term project of the Shimberg
Center. The primary responsibilities of this position are to develop and manage the Clearing
house assisted housing inventory of federal, state, and locally subsidized housing and to
initiate research proposals and coordinate applied research projects dealing with the assisted
housing market, housing program evaluation, special needs populations and other related
topics. Beginning salary range is $40,000 to 45,000. Master's degree or a bachelor's degree in
an appropriate area of specialization with two years of appropriate experience is required. A
Master's degree or higher is preferred.
For further information on the position and to view application instructions and complete
an online resume, please visit and click on "Job Opportunities." Refer
ence number for this vacancy is REQ # 32006. This is a full-time, time-limited position. If an
accommodation due to a disability is needed to apply for this position, please call (352) 392
4621 or the Florida Relay System at (800) 955-8771 (TDD). An Equal Opportunity Institution.

Affordable Housing ISSUES is prepared bi-monthly by the Shimberg Center for Affordable Housing for the purpose of
discussing contemporary issues facing affordable housing providers. Reproduction of this newsletter is both permitted and
encouraged. Comments or questions regarding the content are welcome and should be addressed to Robert C. Stroh, Director.

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