Gaze upon the Helliers' half-built
house in Bristol, Vermont, and you might think you're
looking at an ordinary home construction project. Table saws,
building materials, and piles of earth lie around the newly
framed dwelling, while a crew of carpenters mills around the
site, dressed for warmth in the chilly fall air. But look
closer, and some unique features emerge. The exterior frame is
wrapped in an outer layer of heat-trapping insulation. Sunshine
streams in through large, south-facing windows, flooding the
interior living spaces with light. Once the house is completed,
solar panels will supply the family's hot water and much
of its electrical power. And indoor finishes, paints, rugs, and
fabrics will be nontoxic.
In short, the Helliers' house
is being built to be green. And that puts it in good company;
new
green homes jumped in number by 30% between 2005 and 2006 and
could include up to 5% of the entire U.S. housing market within
five years, predicts McGraw-Hill Construction, an industry
information provider, in its June 2006 Residential Green Building SmartMarket Report. That makes green homes bright spots in an
otherwise dismal housing market facing its worst slump in
decades.
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The Hellier home in Bristol, Vermont, is
going up green. Among
other features, a south-facing orientation (top left and right)
capitalizes on natural light and thermal energy, while
insulated panels (bottom left) and wrapped framing (bottom
right) seal the home. This home also enjoys the advantage of
know-how: with experience, builders generally can trim much of
the "green premium" from such projects.
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images: Charles W. Schmidt |
To everyone's benefit, green homes
link sustainable materials and practices with better human and
environmental health. "You're really looking at a
tripod of components," says David Johnston, president of
green building consultancy What's Working and author of Green from the Ground Up,
a forthcoming book on sustainable residential design. "First, energy efficiency has to be above minimal
code requirements for your climate. The second component has to
do with improved water and resource efficiency, and the third
concerns indoor air quality. If your design doesn't
address all three of these issues, then you don't have
a green home."
According to the U.S. Environmental
Protection Agency (EPA) Office of Air and Radiation, indoor air
is typically 2–5 times more polluted than outdoor air,
owing to the presence of asthma-inducing agents such as mold
and toxic chemicals in carpets, paints, and other synthetic
materials. In fact, the EPA ranks indoor air as one of the top
five human health risks, says agency spokesperson Dave Ryan.
By
requiring nontoxic materials, green designs limit indoor
exposure to carcinogens such as formaldehyde in manufactured
wood products including sheathing and particleboard, and to
volatile organic compounds (VOCs) in finishes.
Home energy uses also contribute to global
warming. The Energy Information Administration (EIA) in
Washington, DC, estimates that domestic power demands account
for 21% of all the greenhouse gases emitted in the United
States. The construction industry as a whole accounts for 48%
of U.S. greenhouse gas emissions, according to advocacy group
Architecture 2030. And by optimizing insulation, green designs
save on oil and gas bills, which are (quite literally in poorly
insulated homes) going through the roof.
But even as green
homes gain in popularity, they're also dogged by a sticky association
with the rich, seen by many as too pricey for ordinary buyers.
Indeed, McGraw-Hill Construction identified cost perceptions as
a top obstacle to green building among homeowners and builders
alike. Fueling that preoccupation with cost is a media
obsession with "eco-mansions," laments Charles
Lockwood, a green building consultant in Los Angeles and New
York. "Most of what you see in the press would leave you
thinking you'd have to live in Malibu or Aspen to afford
one of these places," he says. To wit: the Maine Sunday Telegram in
Portland ran a feature on 4 November 2007 titled "Unaffordably
Green?" about a $1 million ultra-green home in nearby
Freeport that was unsold after a year on the market.
Christopher Briley,
an architect with Green Design Studio in Yarmouth, Maine, concedes
that most
people who build their own houses have above-average incomes
(McGraw-Hill Construction's SmartMarket
Report shows that nearly
two-thirds of those who buy green homes make more than $50,000
a year). And buyers with more money to spend, Briley says, are
apt to mix green design elements in with a host of other more
expensive features—radiant floors and granite
countertops, for instance—that skew costs higher.
"A lot of these houses are going to be expensive
anyway," he says. "But that doesn't mean you
can't have an affordable green house. It's all
about where you decide to spend your money."
A Growing Trend
National standards for green homes are
just now emerging. Energy Star, a joint program by the EPA and
the Department of Energy (DOE), has been setting energy
sustainability targets for lighting, appliances, and home
electronics since the early 1990s. But being limited to energy,
the program addresses only one component of green design.
The newest and farthest-reaching
national standards have come from the U.S. Green Building Council
(USGBC). Since 2000, the USGBC's Leadership in Energy and
Environmental Design (LEED) system has set the bar for
sustainability in commercial settings. Today, roughly 5% of
public buildings in the United States are LEED-certified. Now,
with the organization's LEED for Homes program, which was
launched officially in November 2007 after a two-year pilot
project, the council is poised to issue comprehensive national
guidelines for residential green design. The system requires
third-party verification by inspectors who qualify homes as
basic-, silver-, gold-, or platinum-certified, depending on how
many green features they have. As this article was going to
press, 381 homes nationwide had achieved some type of LEED
status, and 10,000 more were in the pipeline, according to
USGBC spokesperson Ashley Katz.
The National Association of Home Builders
(NAHB) in Washington, DC, also offers guidance to builders who
are going green. The association released its Model Green Home Building Guidelines in
2006 and is set to launch a Green Professional certification
program in 2008. Certification will
be awarded after 24 hours of course work and requires builders
to maintain regular additional continuing education credits.
The NAHB has also initiated a process, along with the
International Code Council, to develop a voluntary standard for
green home building construction practices to be compliant with
the American National Standards Institute. The standard is
expected to be in place by the end of 2008.
Banking on Low-Hanging Fruit
For the USGBC and
others in the green building community, changing cost perceptions
has become a top
priority. Steve Konstantino, who runs Maine Green Building
Supply in Portland, says a wealth of cost-effective options are
available to consumers. For instance, he says, PaperStone™ countertops
made with recycled paper and water-based resins cost roughly
the same as petroleum-based Corian®.
Bamboo hardwoods can be sustainably cultivated, but the plants
aren't locally grown in the United States outside of
California. In fact, most of the bamboo sold worldwide comes
from Asia. The best option, Konstantino advises, is to go with
local hardwoods from sustainably harvested forests. Costs begin
to climb when buyers ask for reclaimed woods harvested from old
barns and industrial buildings. These materials figure
prominently in many green home standards, but they also cost
upwards of $7 per square foot and typically more, compared with
other options such as pine, which generally costs $5 per square
foot or less.
To get the most bang for
the buck, cash outlays in green building should target low-hanging
fruit that
can deliver the bulk of a home's sustainability for the
lowest price, Briley says. Merely siting a house so that the
longest walls and largest windows face south (in the Northern
Hemisphere) is the single most important thing a builder can do
to keep homes naturally warm in colder climates, he adds.
South-facing orientations optimize solar exposure as the sun
travels across the sky. According to calculations by the Rocky
Mountain Institute, an environmental think tank in Boulder,
Colorado, pointing a house in the right direction can shave 30%
off monthly utility bills. "That's free light and
heat," Briley says. "I'm amazed at how many
homes are oriented toward the road without giving a single
thought to the sun." In warmer climates, of course, such
a strategy would drastically increase cooling needs during the
summer; appropriate siting strategies would therefore include
the use of increased natural shading.
The next bunch of low-hanging
fruit is home sealing and insulation. Most homes built after
World War
II—when many assumed that heating oil would stay cheap
forever—were barely insulated at all. After the oil
shocks of the 1970s, builders began adding more insulation, but
green designs go a step further; they aim to make living spaces
virtually airtight. If done correctly, interiors are so tightly
sealed that, with doors and windows closed, mechanical
ventilators must be used for air exchange with the outdoors.
The insulating process starts in the frame—liberal
amounts of caulk seal interior spaces between stacked wall
studs, while hard-drying urethane foam gets squeezed into every
nook and cranny that could produce a draft.
A Few Ways to Make a House Green . . . |
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Most conventional homes
limit insulation to the inside of the frame; green homes also
wrap the
frame's exterior to create what's called a
"thermal break." That's a critical step,
Briley asserts. "If you insulate only between wall studs
that you cover with [wallboard], that means you haven't
insulated any of the points where the studs meet the exterior
wall. The consequence is that up to twenty percent of the house
isn't really insulated at all. Providing a thermal break,
or insulating around your studs, will maximize your
coverage."
Custom woodworker Skimmer
Hellier, who owns and designed the green home described earlier,
cautions
that with an airtight interior, it's important to avoid
toxic materials indoors. "If you're building a
super-insulated house and you put in some type of synthetic
wall-to-wall carpeting, you could be dealing with some
troublesome air quality issues," he says.
"You've got to avoid formaldehyde or VOCs in
paints—offgassing is something you've got to pay
attention to." But ultimately, airtight homes are
healthier for their inhabitants, Hellier adds, in part because
they block drafts where moist air gets into the wall cavity and
condenses at dew points inside the wall—a chief cause of
mold growth behind wallboard. (It's important to note
that other steps, for instance, tight roofing and overhangs to
prevent water intrusion, in addition to appropriately placed
vapor barriers in wall structures, can also block mold growth.)
Briley adds that passive solar design can
be augmented by incorporating thermal mass inside the house,
using heavy, dense materials such as concrete slabs under
floorboards or masonry fireplaces in sunny rooms. These
structures stabilize interior temperatures and take the spikes
out of heating and cooling, he says.
Thinking about Cost
By creating an airtight
building envelope, homeowners can lower heating and cooling costs
by 50% or more.
The up-front expense of doing so can be minimal, adds Greg
Kats, managing director of Good Energies, a venture capital
firm that invests in sustainable technology. Kats's
investigations have revealed the average "green
premium" for sustainable design totals no more than
$3–5 per square foot, generally to cover added
insulation, double- or triple-glazed windows, high-efficiency
appliances, and in some cases, a builder's learning
curve.
But the premium dwindles
as builders gain experience and professional contacts in the
field, Johnston
says. "We've found that the first time builders
build green, the houses run about ten percent higher," he
explains. "But then they get their materials and
subcontractors figured out, so that the second house costs
three percent more and by the time they get to the third house,
costs aren't any more than one percent higher."
The main thing to consider
with green design is positive monthly cash flow, Johnston emphasizes. "If savings from energy conservation are greater than the
increase in the monthly cost of the mortgage or construction
loan, then the homeowner is literally making money month after
month," he says. "Energy conservation is not a
cost, it's an investment that only gets more valuable
over time. That holds true no matter the income bracket of the
homeowner." Although payback over time is a certainty,
the length of time it will take is almost impossible to predict
because of uncertainty about future energy prices, says
Johnston. The question is how much buyers will invest up front
for savings down the line.
Passive solar technologies,
sufficient insulation, high-efficiency fixtures and appliances,
and
sustainable building materials yield the most bang for the buck
by far, says Hellier. Compact fluorescent lamps (CFLs), for
example, cost 3–4 times more than incandescent bulbs, but
they use a fraction of the energy and can last ten times
longer. After that, systems become far more expensive with
diminishing returns. Solar power is a case in point: Solar hot
water units, which cost from $4,000 to $9,000 installed
depending on size requirements (in contrast to $700 or less for
a conventional unit), have a typical payback of five years or
less, making them somewhat affordable. But solar photovoltaic
(PV) panels, which supply a home's electricity, can run
$6,000 per kilowatt or more installed (most U.S. homes need
between 2 and 5 kilowatts of capacity to accommodate all their
electrical needs throughout the year). Similarly, the cost of
wind energy—best for rural properties with at least an
acre of land—runs between $3,000 and $5,000 per kilowatt
installed.
Fortunately, a host of
rebate programs can offset some of this expense. By tapping a
mix of these
programs, the Helliers cut costs for their own 3.5-kilowatt PV
installation—and their solar hot water heater—by
about a third. And after that initial investment, solar and
wind energy are free. Ideally, excess renewable power generated
by those systems during sunny (or windy) days can be dumped
back into the local electrical grid if the home is connected to
it. Then, if utilities use "net metering," the
retail value of that electricity can be deducted from what
homeowners pay for power on wind-free or cloudy days. [For more
on incentive programs, see "Room to Grow: Incentives
Boost Energy-Efficient Homebuilding," p. A32 this issue.]
Yet even with those savings,
the payback on sun or wind power can take many years, even decades,
putting
them out of reach of most consumers. One of the main factors
driving the expense of solar and wind technology is limited
manufacturing, says Cécile Warner, a principal engineer
at the DOE's National Renewable Energy Laboratory in
Golden, Colorado. Therefore, as more of these units are sold,
prices are expected to fall. So in a sense, those who do buy
into these systems are performing a kind of civic duty.
Perhaps the simplest
way to build an inexpensive green home is to build a smaller
home—a
strategy emphasized by LEED for Homes. "Given the
inflated sizes of many new U.S. homes, this strategy is a
no-brainer," says Tristan Korthals Altes, managing editor
for Environmental Building News. In 2006 the average new
U.S. single-family home measured 2,459 square feet, according
to Gopal Ahluwalia, vice
president for research at the NAHB, speaking at that
group's 2007 International Builders' Show. In 1973,
new homes averaged about 1,500 square feet.
Even as green housing embraces
affordability, others are trying to bring green principles to
affordable housing for low-income populations, including the
elderly. A top organization working in this area is Enterprise
Community Partners, a Columbia, Maryland–based provider
of capital and expertise for developing affordable housing.
Through its Green Communities Initiative launched in 2004, the
organization has already spent $450 million to build 11,000
green homes within 245 multifamily housing developments in
approximately 25 states.
Dana Bourland, who heads
the Green Communities Initiative, says Enterprise developed standards
through its own "green communities criteria," which
were based on input from several expert organizations in
health, planning, and architecture. The standards closely
mirror those found in the LEED for Homes program, she adds.
"Low-income families in some ways have the most to gain
from healthier homes," she says. "Too many of them
live in substandard housing that heightens risks for asthma and
other respiratory illnesses. We've got anecdotal evidence
of immediate health improvements from moving to green
residential settings. And what's more, green homes allow
low-income residents to save three to four hundred dollars a
year on energy and water bills. So, Enterprise has committed
itself to make all its projects green from here on out."
Looking to the Future
Moving forward, green homes
stand to become far more innovative than they are now. Today,
the race
is on to make houses that generate all their power from
renewable sources affordable to ordinary consumers. Energy
regulators in California recently pledged that all new homes
built there after 2020 would produce as much energy as they
consume, a feature known as "net-zero" energy
consumption. The entire country of England plans to make a
similar policy mandatory by 2016 in a bid to reduce that
nation's carbon dioxide releases by 60% over 1990 levels
by 2050. The first such British home was unveiled in June 2007;
it features solar panels, a biomass boiler that burns
woodchips, and the capacity to harvest and use rainwater. The
architects who designed the house assume the carbon dioxide
given off by the boiler is offset by the amounts absorbed when
the crop fuel was grown. The home's cost comes in at
roughly 40% more than a conventional house of the same size,
concedes its designer, Alan Shingler of Sheppard Robson
architects in London. But those costs should fall as more
similar homes are built, he adds.
According to Warner, the
DOE hopes to make the cost of solar power competitive with grid
electricity by
2015 as part of its Building America program, which aims to
reduce whole-house energy use in new homes by 50% by 2015 and
by 90% by 2020. "That's an aggressive path
we've taken hand-in-hand with industry," she says.
Doing that won't be easy: PV panels—made from
crystalline silica—are made using the same painstaking
processes used to make semiconductors for the computer chip
industry. PV costs, Warner explains, correlate directly with
panel size. Therefore, the best way to reduce price is by
modifying materials to make them thinner and more efficient in
terms of converting light to power. Once that's achieved,
it is conceivable that solar panels, currently limited mostly
to rooftops and backyard installations, could wind up in
unexpected places such as window shades, awnings—anywhere
the sun shines.
Driven by net zero goals,
green home research has become striking in its complexity. For
instance,
NREL principal engineer Craig Christensen works with a software
tool called "BEopt" that looks for optimal
combinations of 300 different measures pertaining to a
building's outer shell, its interior envelope, equipment,
appliances, and more. The software runs hour-by-hour
simulations combined with a year's worth of hourly
weather data, looking to compare energy costs versus energy
savings. "It helps us set realistic targets," Christensen
explains, referring to goals set by the DOE Building America
program.
These are ambitious goals
for a country of builders trying to adapt to the green mindset.
Some are
resistant to change—particularly if they've been
building a certain way for a long time—and resent the
intrusion. Others have already been building green for years,
but just haven't called it that. Still others are
starting their careers as certified green builders. "All
we need is more people to transform the market place and
educate the public," Briley says. "It will just
serve to make us and our buildings better."
Green Building Resources |
Building America
http://www.eere.energy.gov/buildings/building_america/
Building America is a public–private
partnership sponsored by the U.S. Department of Energy that
assembles segments of the building industry that traditionally
work independently of one another. The program focuses on
developing energy-efficient solutions for new and existing
housing that can be implemented on a production basis.
Database of State Incentives for
Renewables and Efficiency
http://www.dsireusa.org/
The Interstate Renewable Energy Council
and the North Carolina Solar Center have teamed up to develop
the Database of State Incentives for Renewables and Efficiency.
This website features clickable maps that allow visitors to
access a wide variety of resources on federal and state
programs that support purchasing energy from renewable sources.
Energy Star
http://www.energystar.gov/
Since the early 1990s the federal Energy
Star program has helped consumers identify energy-efficient
goods and building products. Today, entire buildings can
qualify for the Energy Star label. The Energy Star website
helps individuals and businesses find products to help them
make their homes and workplaces greener.
Rocky Mountain Institute
http://www.rmi.org/
The Rocky Mountain Institute
aims to help everyone from governments to individuals reduce
their
environmental impact in the most cost-effective manner. The
Buildings section on its website offers practical tips on
saving energy and money in households and presents a look at
the institute's Built Environment Team, which provides
consulting services to developers, architects, and other real
estate professionals to help them incorporate cutting-edge
efficiency processes in their projects.
U.S. Green Building Council
http://www.usgbc.org/
The U.S. Green Building Council (USGBC)
oversees the Leadership in Energy and Environmental Design
program, which rates buildings according to the incorporation
of sustainable practices. In addition to information on this
program, the USGBC website also provides a state-by-state list
of green architects and builders as well as a wealth of
educational information on green design, construction, and
operations.
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Charles W. Schmidt