Download Climate Change, Density and Development

National Association of Home Builders
Climate Change,
Density and Development
Better Understanding
the Effects of Our Choices
We find ourselves in the middle
of a sometimes contentious debate
over the future of the built environment.
It is the future of the way we build our homes
and organize our lives spatially.
It is the future of the way we live.
In recent years, global climate change has emerged as a highly charged and
potentially polarizing issue. Federal, state and local governments, as well as
private interest groups, are exploring ways to combat its presumed effects.
Early efforts focused primarily on improving energy efficiency through the
adoption of green building ordinances, more stringent code requirements,
and increasing sources of renewable energy through planning and
incentives. The emphasis now is on reducing the emissions impacts
stemming from automobile use by dictating patterns of development that
will presumably decrease the number of vehicle miles traveled.
The Way We Live
The emerging paradigm rests on the assumption that society can reduce
climate change effects by requiring higher density development, increasing
transit usage and reducing vehicle miles traveled (VMTs). This paradigm also
argues that higher density development gives people better access to jobs,
improves quality of life by reducing commute times, and enhances
affordability and health by enabling people to give up their cars and walk
and bike more.
We know from experience, however, that it is not so simple.
Our communities reflect a diverse range of people, needs, and ideals. Their
design and shape are dictated by powerful market forces and realities that
reflect the choices consumers make about where they live, work, and play.
As communities age, evolve and grow, community leaders must balance
often competing needs, including:
•
A wide range of neighborhood and housing options;
•
Housing that meets the needs of families across the economic and
demographic spectrum;
•
Reasonable proximity to jobs, commerce, and recreation;
•
Safe neighborhoods and a healthy environment;
•
Open space and access to natural resources;
•
A variety of transportation options.
Many in the policy community now are promoting higher density
development with little regard for these diverse needs. In many cases,
rather than basing new policy decisions on demonstrable facts, new
policies are based instead on assumptions and theories about how
residential density and community design affect people’s transportation
choices and how those choices are believed to affect greenhouse gas
emissions.
As some in the policy community attempt to impose their vision of higher
density development on the local planning process, they instigate a spirited
debate not only over human impact on climate change and the planet, but
also over the future of building technology, land use patterns and the way
our lives are organized spatially.
It is a debate over the
future of the way we live.
In an effort to better understand the effects of housing and residential
construction on greenhouse gas (GHG) emissions, and to better inform
evolving policies, NAHB conducted extensive research on a range of issues
using data from the U.S. Department of Energy, the Bureau of the Census
and other government agencies. Topics explored included home energy
usage, differences in energy usage between building types, and the
concept of embodied energy – the amount of energy used in manufacturing, transporting and installing the materials that go into a home.
NAHB also sought to learn more about the relationship between density
and climate change and asked two highly regarded, impartial research
organizations to review the state of knowledge and understanding on these
complex issues. Abt Associates, a science and public-policy research firm
based in Cambridge, Mass., and ECONorthwest, an economic consulting
firm based in Eugene, Ore., conducted extensive reviews of existing
research on density, land-use patterns, vehicle usage and GHG emissions
and returned two separate reports.
It is clear from this research that caution must be exercised as choices are
made about the future of our homes and communities. Solutions that seem
simple to some are instead complex and fraught with tradeoffs that make
them far from ideal. A proposal that may solve one problem may generate
new problems. Decision makers also must be mindful of potential
unintended consequences as they assess this complex web of issues.
Finally, policy makers at all levels of government must seek to balance the
full range of policy goals and cannot address climate change to the
exclusion of other crucial concerns.
This publication provides a fact-based look at the existing research on
these issues.
photo by Doug Johnson
Below are key findings from research conducted by Abt
Associates and ECONorthwest, as well as the U.S.
Department of Energy, the Bureau of the Census and other
government agencies. These findings make it clear that the
relationship between the built environment and greenhouse
gas emissions is complex, and that higher density
development will not necessarily deliver the benefits that
many in the policy community ascribe to it.
Key Findings
At-A-Glance
•
The amount of GHG emitted from a residential
structure during a typical year is primarily a function of
how much energy it consumes.
•
Residential buildings account for 18 percent of total energy use in the
United States and emit 18 percent of total GHGs.
•
Homes built after 1991 are significantly more energy efficient than older
homes.
•
Household behavior, such as how long lights are left on, has a significant
impact on residential electricity consumption.
•
The energy required to manufacture, transport and install materials used
in construction and the resulting emissions (embodied energy and
embodied emissions) must be factored into the equation when
considering the long-term efficiency of different development patterns,
construction materials and technologies.
•
Brick and concrete have the most embodied energy of any materials
used in a home, while wood products have the least embodied energy.
•
The existing body of research demonstrates no clear link between
residential land use and GHG emissions and leaves tremendous
uncertainty as to the interplay of these factors.
•
The assumption of a causal connection between density and GHG
emissions is based on prevailing beliefs within the planning community
and not on verifiable scientific research or analysis.
•
After controlling for socioeconomic factors, density directly influences
vehicle miles traveled (VMT) and transportation choice. However, the
weight of the evidence suggests that the effect of density on travel
behavior is modest. In fact, doubling density results in about a 5 percent
decrease in vehicle trips and VMT.
•
The independent effect of residential land-use patterns on travel activity
appears to be weak. The density and layout of communities have only a
modest impact on peoples’ transportation choices and travel behavior.
New Urbanism-type street patterns have little or no impact on auto
usage. They have a more pronounced impact on walking and bicycling.
•
Density at the destination – the place of employment – is more important
than residential density in shaping commuters’ decisions to use public
transit.
•
While much of the vast volume of research on the topic shows a link
between higher density communities and the number of VMTs, it is an
oversimplification to believe that higher density equals lower GHG
emissions. In truth, complex interactions between density and many
other factors dictate the number of VMTs. These include:
•
The continuing trend toward decentralization of employment away
from city centers;
•
The growing importance of non-work trips, which represent the
majority of trips taken, involve multiple destinations and are thus
less suited to public transit;
•
The increasing number of households with two workers who often
commute to different locations;
•
The availability and efficiency of public transit options.
•
Minimizing commutes is not the primary consideration for households
when selecting their residential location.
•
Most studies do not account for differences in household or
demographic characteristics or quantify how those differences
contribute to differences in residential land use or in GHG emissions.
•
Existing research tends to understate the importance of self-selection.
This is significant because household decisions about residential
location are made in conjunction with decisions about transportation.
For example, people who dislike driving may self-select to live in
walkable neighborhoods with convenient access to transit, while
people who like driving may be more likely to select neighborhoods
with good auto accessibility. Studies that ignore the impact of selfselection are likely to overestimate the impact of the built environment
on travel behavior.
•
Changes in policies that affect the cost of car ownership, such as
increases in gas taxes or the price or availability of parking, are more
effective in changing travel behavior than any other policies, if that is
the core objective.
As concern over global climate change grows, lawmakers and
regulators at the federal, state, and even local level are beginning
to establish policies aimed at minimizing the production of
greenhouse gas emissions from everyday activities.
Although initial efforts focused on green building
and energy efficiency, over time they have expanded
to include the possible connection between
land use patterns and climate change.
The Obama Administration’s Livability Principles and
its Sustainable Communities Initiative – which seek to create
better communities by integrating transportation, land use, and housing –
are examples of this new policy emphasis. Announced in 2009, these efforts
focus on pushing development toward existing communities and
infrastructure and boosting density and transit-oriented development.
The Evolution of
GHG and Climate
Change Policies
California’s Sustainable Communities and Climate Protection Act, passed in
2008, is the nation’s first law that seeks to control GHG emissions by curbing
sprawl. It specifically directs local governments, developers, and other
stakeholders to work together to reduce GHG emissions by better aligning
their transportation, housing, and regional land-use plans. Other states,
recognizing the climate change impacts stemming from transportation, have
considered policies intended to reduce the number of vehicle miles driven by
citizens. In 2008, the State of Washington adopted broad statewide goals to
reduce annual per capita vehicle miles traveled by 50 percent by 2050. In
2009, Maryland considered a proposed bill to reduce VMTs by 35 percent by
2036, but it was withdrawn after receiving an unfavorable report.
Many local governments have adopted green building requirements and
incorporated energy efficiency requirements into their local codes. Some
have gone further. King County, Wash. (Seattle) requires proponents of
“significant” new development projects to assess the impacts of their project
on climate change prior to project approval. The Sacramento Area Council of
Governments (SACOG) has calculated that implementation of its regional
2050 Blueprint smart growth land use plan would result in CO2 emissions
reductions of 14 percent as compared to those expected following businessas-usual trends, and the city of Boulder, Colo. imposes a Climate Action Plan
tax on its residents to directly combat global warming. The City of Chicago
has taken a completely different tack and operates the Employee Commutes
Options (ECO) Program, which reduces overall VMTs by promoting ridesharing.
Clearly, governments at all levels have begun to incorporate measures to
address global warming into their regulatory and planning efforts. The number
of entities adopting such measures has reached the point where the trend is
undeniable. While some jurisdictions have yet to act, political pressure to
demonstrate commitment to sustainability will compel many forward.
These efforts, combined with market response to demand for sustainable
development and green building, are going to bring significant changes in the
way we build our homes and communities.
Did You Know?
Homes, communities, transportation, green building, energy use and density are all interrelated.
A quick look at the facts shows that the relationship between community design, housing, vehicle
usage, and greenhouse gas (GHG) emissions is complex. More research is needed to provide
accurate information about the effects of various choices and tradeoffs as we seek the best path
forward.
Greenhouse Gas Emissions
did you
Greenhouse gases (GHGs) are chemicals that, when released into the atmosphere,
have the potential to cause global warming. GHGs include carbon dioxide (CO2),
methane, nitrous oxide, various hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride. CO2
makes up the lion’s share. GHGs are emitted by natural sources as well as by human activities. The
largest components of GHGs generated by human activity are from energy production and use.
know?
What does it mean?
Humans are responsible for creating GHG emissions every time they turn on a light bulb or drive a
car. To the extent that there is a desire to reduce the overall climate change impact associated with
human activity, steps must be taken to become more energy efficient. One key step would be
educating consumers about the effects of their choices and behaviors.
GHG Emissions from Residential Versus Other Use Sectors
did you
America’s housing sector accounts for just 18 percent of total GHG emissions
measured in CO2 equivalents, according to the Energy Information Administration
(EIA), the Department of Energy’s statistical agency. Industrial use and all transportation use together
account for 60 percent.
know?
More than half of total residential energy “consumption” is actually due to losses that occur in
generating electric power – that is, energy lost in producing and transmitting electricity, rather than
energy actually used in residential structures.
What does it mean?
Housing represents only about one-fifth of energy consumption and GHG emissions, and half of that
comes from inefficiencies in generating and transmitting electric power. To the extent that fossil-fuel
burning electric power plants can be replaced by sources of renewable energy, such as solar and
wind power, GHG emissions attributed to housing can be dramatically reduced. The use of new
energy technologies that can be built into a home, such as photovoltaic cells, passive solar (such as
solar water heaters) and even small wind turbines, can further reduce energy use and GHG emissions
from homes.
GHG Emissions from New Versus Older Existing Homes
did you
Single-family detached homes built between 1990 and 2001 on average use about
43,000 Btu of energy per year per square foot of heated area, in contrast to 71,410
Btu for homes built between 1940 and 1949. Newer technologies, such as thicker insulation, building
wraps that seal the home, doubled-paned sealed windows, and high-efficiency heating and air
conditioning systems make the newest homes the most energy efficient homes ever.
know?
For a primer on Btu and standardized methods of assessing energy use, visit
www.nahb.org/climatechange.
What does it mean?
As home builders produce new homes to meet the needs of a growing population, and as older
housing stock is replaced by new homes, housing becomes increasingly more energy efficient. New
home building and energy production technologies have dramatically reduced energy consumption
and GHG emissions from the housing sector.
The Influence of Household Behavior on GHG Emissions
did you
The choices consumers make regarding appliances and amenities and their usage
habits have a significant impact on the energy use and GHG emissions of homes.
For example, adding a hot tub increases typical annual household use of electricity by 7.3 million Btu.
know?
What does it mean?
Because consumption patterns that are solely attributable to household behavior (such as leaving
lights on or the frequency of dishwasher use) have such a strong impact on total electricity use,
anyone who is seriously concerned about energy usage and GHGs, must take deliberate action to
reduce energy use. Likewise, a policy to reduce residential greenhouse emissions is likely to be more
effective if it focuses on consumer education and encouraging conservation practices among home
owners.
Homes can only be built so green—it’s up to consumers to live green in them.
Embodied Emissions in Materials
did you
Embodied emissions are greenhouse (and other) gases generated as part of an
industrial process, such as manufacturing, transporting and installing the products
used in building a home. In new home construction, the overwhelming majority of embodied
emissions are produced during the manufacturing of materials, which accounts for almost 50 metric
tons of carbon dioxide (CO2) or its equivalent in a typical home.
know?
Brick and concrete were found to have the most embodied energy of any materials used in a home,
and wood products the least. For example, wood siding materials (such as cedar or pine), typically
emit 1.5 metric tons of CO2 less than vinyl siding. Stucco has roughly the same impact as vinyl siding.
Brick, on the other hand, adds more than 20 metric tons of CO2 or its equivalent to a baseline home.
Construction and transportation have relatively little effect on the total emissions. Roughly four
percent of the total GHGs are generated during the construction process. Transporting building
materials to the construction site accounts for less than one-half of one percent.
What does it mean?
In order to assess a home’s potential impact on GHG emissions, the materials that go into the house
and the energy required to manufacture, transport and install those materials must be considered.
Clearly, there are tradeoffs to be had when determining which materials to use in constructing homes
and communities. Steel and concrete may last longer than wood or other materials, but it takes
significantly more energy to produce them. This has an impact on the types of communities we build.
High-density communities may better support mass transit, but high-density development – and
mass transit itself – use materials that represent significantly more embodied emissions.
For more information about embodied emissions, including definitions of the “typical home,” and
information about CO2 equivalents, go to www.nahb.org/climatechange.
GHG Emissions and Transportation
did you
According to the Energy Information Administration, about 33 percent of total U.S.
GHG emissions are generated by the transportation sector. The overall emissions
are the result of gasoline consumption, which is determined by a combination of total vehicle miles
traveled, efficiency of vehicles, and the speed at which they are driven. Due to the complexity of any
such equation and absent a well-established, verifiable method for estimating CO2 emissions from
the transportation sector, vehicle miles traveled are often used as a proxy for determining the
associated GHG emissions. In short, VMTs are the total number of miles driven by all vehicles within
a set period of time. In theory, if VMTs are reduced, GHG emissions will similarly be lowered.
know?
What does it mean?
The number of VMTs in any given geographic area is determined by a complex set of interactions
among a range of factors. Density and land use characteristics are only part of the story. The
socioeconomic characteristics of residents, the availability of public transit, neighborhood
accessibility to jobs and services, the time and costs associated with various forms of transportation,
and many other factors have significant effects on travel behavior.
Job Location and the Configuration of Today’s Cities
did you
Less than a quarter of jobs are now located in a central business district; almost
half are located more than 10 miles from a downtown area. Not surprisingly then,
suburb-to-suburb commutes are twice as common as suburb-to-central city commutes. These
trends, which started more than a half a century ago and have continued unabated, indicate that the
traditional view of the monocentric city – with jobs at the core and housing in the suburbs – is a poor
approximation for the reality of most American cities today.
know?
Likewise, because the number of two-worker households has been increasing over the past several
decades, the business decentralization trends have meant that these two workers are more likely to
commute to different locations.
What does it mean?
The decentralization of jobs lessens the ability of public transit – particularly fixed rail systems – to
meet travel needs, and increases the complexity of household location decisions, reinforcing the
need for auto ownership and neighborhoods that accommodate autos, and increasing VMTs.
Commuting Patterns
did you
Work travel decreased from 32 percent of all trips in 1969 to 22 percent in 2001.
The majority of trips are non-work trips that typically involve multiple destinations.
Data from the 2000 Census provide further insight into commuting patterns. The data show that the
correlation between density and commute time is not linear. In fact, higher density development does
not always lead to less congested commutes.
know?
Demographics also affect travel behavior. Mobility increases with income, so higher income people
take more trips and own more cars. But mobility also decreases with age. In addition, minorities have
longer commutes, use transit more, and are less likely to own a car than non-minorities.
What does it mean?
Divergent location and housing preferences translate into different commuting choices. Married
couples with and without children end up locating further away from jobs and having longer
commutes in terms of time and miles compared to other households.
Fewer than eight percent of households in any category choose a neighborhood because it’s near
public transportation. Married couples are less likely than other types of households to choose a
neighborhood because it’s close to public transportation. Non-work trip chains are less easily served
by transit.
A more detailed analysis of the 2000 Census data and other research information can be found at
www.nahb.org/climatechange.
Household Location Decisions
did you
The 2007 American Housing Survey (AHS) shows that the most common factors
influencing the choice of a neighborhood are convenience to a job, being close to
friends and family, and the looks of the neighborhood. Married couples with children under 18 value
being close to schools as often as they value being close to a job. And, whether or not they have
children, married couples are more often motivated by considerations that have little to do with
location, such as the appearance of the neighborhood, or the desirability of a particular house. Single
parents, on the other hand, value being close to friends and family more than any other factor,
including job location.
know?
What does it mean?
Family size and composition have a big impact on households’ choices regarding the location of their
home, the basic type of housing, and various aspects of commuting behavior.
These differences in preferences suggest that different types of housing and housing locations are
needed to serve different segments of the population. The relatively low use of public transportation
reported by all types of households also suggests that there are limits on how far new public
transportation systems, or new homes located near current public transportation systems, can go
toward reducing traffic on streets and highways. Although it is possible that increased availability of
public transportation may induce more households to use it, the data suggest that the strength of this
effect is likely to vary depending on the type of household.
Transit Availability and Efficiency
did you
Transit availability has a small impact on auto use. The demand for transit depends
in part on its supply—the type, frequency, cost, and quality of service. But the
supply is dictated more by residential or employment density than any other measure of demand.
Transit use is also more closely related to density at the destination of the trip than at the origin. Thus,
densely developed monocentric cities with centralized employment are the best candidates for fixed
rail transit. Yet as noted previously, cities increasingly do not fit this description.
know?
In addition, while bus transit provides better flexibility in connecting jobs and workers, research
consistently finds that it is more difficult to attract riders to buses than to rail transit.
Roughly 30 percent of households live within a quarter mile of a bus or rail stop, but only two percent
of commuters use transit. Despite massive investments in rail transit over the last decades, its use
has been declining since at least 1940. The other primary type of public transit available in the U.S. is
the bus. Bus systems have obvious advantages over rail systems: they do not require large infrastructure investments, they have flexibility to respond to changes in the geographic distribution of
employment, and they are less expensive to operate. The main shortcoming of a bus is that it is not a
train. That is, many people view bus travel as a less desirable option. Generally, the higher a person’s
income, the less likely it is that they will ride a bus. Further, cars are usually faster, more comfortable,
and more flexible than either rail or bus transit.
The efficiency of transit from a climate change perspective depends on the type of transit, the type of
fuel (which varies by region), and the average number of riders, among other factors. Overall, rail
transit is more efficient than auto use, but diesel buses—currently the most common bus fuel—are
less efficient.
What does it mean?
The demand for and supply of transit are interrelated: better transit service – especially more frequent
service – increases demand for transit. Household satisfaction with transit accessibility is more
important than actual proximity to transit in determining auto ownership. For example, research
indicates that the frequency of bus service is more important than the distance to the nearest bus
stop in determining bus use. Given the small impacts of current transit availability on travel behavior,
most researchers conclude that massive investments in rail lines would be required to substantially
increase availability and thus increase rail transit ridership and decrease VMT.
photo by Terry Allen
With Congress and several federal agencies considering sweeping program
reforms and targeted incentives on density, transit and climate change,
NAHB believes it is important to ensure that policy makers understand the
actual research on these issues and the complexities involved. This
information is particularly necessary and timely because American
consumers will continue to need and demand a range of housing types and
neighborhood and transportation options in both urban and rural settings.
Many Factors,
Many Choices,
Many Solutions
Many have suggested that increased density and transit availability should
be the wave of the future. Greater density will allow homes to be closer to
shops, public spaces and jobs, while the transit will provide transportation
options and reduce vehicle miles traveled. But as the research from Abt
Associates and ECONorthwest makes plain, it is not certain that highdensity, transit-oriented development can deliver all the benefits that its
advocates ascribe to it – particularly those associated with climate change.
NAHB supports higher density, mixed-use, walkable and transit-oriented
development and the adoption of local land use policies that make it easier
to create that type of development. But such development is not a panacea.
First, there are many trade-offs that must be made in the density and
climate change equation. For example, because planning is not simply
about managing resources with one objective in mind, but about optimizing
multiple community objectives, focusing on one objective such as density or
climate change alone may not result in success. As stated in the Abt
Associates study, “The decision to encourage or require higher-density
residential development is more complex still, because an effort to reduce
greenhouse gas emissions is only one reason for favoring a particular
development pattern. Other important features of residential development
include the affordability of the homes, their appeal, the cost of production,
the privacy they provide, and the comfort and protection they offer to the
residents of the housing.” Likewise, higher-density and transit-oriented
communities almost always use more concrete and brick products, which
represent significantly more embodied energy than wood and other
products. And finally, not everyone wants to, or is able to, live in a highdensity community, so market factors also play a significant role.
Second, the relationship between density and GHG emissions is highly
complex. Because the relationship between residential development
patterns and climate change is not as simple as “higher-density
development equals lower greenhouse gas emissions,” it is difficult to
identify or quantify the benefits. This is in part because of the complex
interactions between density and the many market and demographic forces
that influence consumer choice and travel behavior.
There is no doubt that planners and regulators are committed to creating
strong and vibrant communities. Any government policies that will broadly
shape the future of our communities should be based on solid research and
sound science and data and allow for choices and flexibility in the market.
The list of vibrant, attractive, mixed use and higher density communities
built over the last 20 years is long and clearly shows that with the
encouragement and cooperation of forward-thinking local governments, the
market can help meet the growing demand for sustainable development.
The National Association of Home Builders (NAHB) continues to raise the
bar for the residential construction industry in the effort to conserve natural
resources and respond to concerns about climate change. NAHB’s green
building and smart growth policies, for example, have provided models for
green building and green development that reduce GHG emissions and
have been adopted and used across the country.
NAHB’s smart growth principles, first articulated in 1999, call for efficient
land use, a comprehensive process for planning growth, fair and balanced
funding of infrastructure, revitalization of older suburban and inner city
communities, and a wide range of housing choices that meet the needs of
families across the economic spectrum.
Reducing
Impacts by
Growing Smart
and Going Green
Builders and developers across the country have applied those principles to
create strong, vibrant communities with a mix of homes, shops, restaurants,
offices and great public spaces – all while reducing impacts on climate
change. Local governments are increasingly revising their zoning ordinances
and land-use regulations to allow more mixed-use, pedestrian-friendly
development that is consistent with the efficiency principles that support
emissions reductions.
Today, builders routinely incorporate more energy efficiency, water and
resource conservation, sustainable or recycled products, attention to indoor
air quality, and green issues related to site and lot development into the
everyday process of home building. This is one reason why today’s homes
are so much more energy efficient than homes constructed in the past.
Long a leader in green building, NAHB took it to another level in 2008 when
it launched the National Green Building Program to help accelerate
voluntary, regionally appropriate market-driven green building by providing
extensive educational and training resources and a third-party green
building verification program.
Under the program, homes and subdivisions are inspected and certified to
the National Green Building Standard, which was approved by the American
National Standards Institute in January 2009 for new single-family and
multifamily residential projects, remodeling and renovation work, and
residential land development projects. As of December 2010, more than
1,300 projects representing over 2,500 homes had been certified.
Among them: an affordable senior housing project outside St. Louis, a
luxury apartment complex built on the site of an old parking lot near the
Johnson Space Center in Houston, and an Indiana development of singlefamily homes near a commuter rail line to Chicago.
The nation’s home builders have led the way in designing and building
green and have demonstrated how following certain smart growth policies
can reduce the overall impact on global climate change. As a result, they
are well-positioned to continue to meet the growing demand for green
homes and green communities and to continue to find solutions to reduce
energy use and the production of GHGs.
Reference Materials:
This publication is a summary of findings from the research reports listed below. All of these
reports can be found online at www.nahb.org/climatechange.
Research on Factors Relating to Density
and Climate Change
Prepared for NAHB by Abt Associates,
June 2010
Household Type, Housing Choice, and
Commuting Behavior
Paul Emrath, PhD and Natalia Siniavskaia, PhD
NAHB, December 2009
The Relationship between Residential
Development and Environmental Quality:
A Literature Review Summary
Terry Moore and Jules Kopel-Bailey
ECONorthwest, August 2008
Greenhouse Gases and Home Building:
Manufacturing, Transportation, and
Installation of Materials
Warren Carnou
NAHB, September 2008
The Relationship between Residential
Development and Greenhouse Gas
Emissions
Eric Fruits
ECONorthwest, August 2008
Vehicle CO2 Emissions and the
Compactness of Residential Development
Helen Fei Liu, PhD
NAHB, December 2007
The Relationship between Residential
Development Patterns and Travel Activity:
A Literature Review
Randall J. Pozdena, PhD
ECONorthwest, August 2008
Residential Greenhouse Gas Emissions
By Paul Emrath, PhD and Helen Fei Liu, PhD
NAHB, April 2007
For More Information:
NAHB STAFF CONTACTS
INTERNET RESOURCES
Land Development
Debbie Bassert
202-266-8443 / [email protected]
www.nahb.org
Environmental Issues
Susan Asmus
202-266-8538 / [email protected]
www.nahb.org/landdevelopment
Housing Policy
Paul Emrath
202-266-8449 / [email protected]
Public Affairs
Robert Pflieger
202-266-8403 / [email protected]
Blake Smith
202-266-8583 / [email protected]
National Association of Home Builders
1201 15th Street NW
Washington, DC 20005
800 368 5242
www.nahb.org/climatechange
www.nahb.org/environment