As part of President Obama's stimulus package, nearly $5 billion has
been distributed nationwide since March 12 to promote home weatherization, the
process of reducing energy bills by upgrading the insulating capability of
houses. Michigan has received about $243 million to benefit low-income families
by improving the energy efficiency of their homes, a huge increase from the
$15 million Michigan usually receives each year to weatherize homes. The
plan vows not only to make Michigan more energy friendly, but also to lower
energy costs for low-income families, create jobs and improve the resale value
of houses. In general, homes with occupant incomes below 200 percent of the
federal poverty level or 60 percent of state median income (whichever is
greater) are eligible to receive weatherization subsidies. Both homeowners and
renters are eligible for weatherization services, and a total of 33,000 homes
are expected to be weatherized, with a maximum of $6,500 spent per house.
be accomplished by insulating ceilings and walls; replacing water heaters and
furnaces; or replacing windows and sealing air leaks.
weatherization research took off in the 1980s at the Princeton Center for
Energy and Environmental Studies. During a project looking at low-income
housing, researchers measuring the heat transfer from living spaces into the
attic found that heat losses were three to five times larger than what was
predicted by the routine calculations. The reason was that the materials used
in walls and ceilings were full of holes and cracks, which allowed air to move
through the insulation. Insulation is measured by its resistance (R), which can
be degraded by as much as 70 percent, so that R19 insulation may end up only
providing an R6 effect, depending on the house in which it is installed. Since
R value in itself was not a sufficient measure, the researchers at Princeton
developed what is knownas the "blower door," a diagnostic tool that is used to blow air into a building and measure its
airtightness and locate leaks, determining where insulation should be put. In
the original article on the research featured in National Geographic, Kenneth
Gadsby and Gautam Dutt estimated that by fitting all of the nation's residences
with adequate insulation, the U.S. could save the equivalent of two-thirds of
its foreign oil imports.
One of the people who worked with the
Princeton team was Don Nelson, now president of D.R. Nelson andAssociates. His
company pioneered the application of so-called building science innovations in
America in theearly 1980s, and has delivered solutions to more than 100,000
"The rate of air
leakage," Nelson told MichiganScience, "affects how everything else in the
house performs, such as insulation. In building science, we take a look at how
the house performs as a system and how all the elements go together, and air
leakage is the key element."
Nelson, however, calls the nation's focus on weatherization
a "cookie-cutter approach," with its primary focus on windows and insulation of
ceilings, even though those are the least cost-effective changes in a state
like Michigan, where winters are harsh and summers are mild.
"It's as if they didn't learn anything from the
'80s," he said. "After President Carter, there was a fair amount of federal
money aimed at low-income people to try and do weatherization programs. The
problem was that money was simply put at windows or ceiling insulation."
Nelson points to Washtenaw County, which is set to
receive $4.2 million to be used for weatheriation over the next three years and
talks about blower doors in a 2009 proposal, but does not outline aims for
performance testing or goals for how airtight structures must be.
In Michigan, the administration of the weatherization
money is being carried out by the Michigan Community Action Agency Association.
Jim Crisp, executive director, says the 30 member organizations of MCAAA can
sometimes spend as much as $25,000 weatherizing a house, including money from
the Department of Energy and the Michigan State Housing Development Authority.
"We can do sidewall insulation or attic insulation,
or we insulate basements," Crisp told MichiganScience. "The savings-investment
ratio has been re-evaluated from 2:1 to 1:1, meaning that for each dollar
spent, there has to be $1 in energy savings. We find that our usual investment
in the project is usually around $2 back for every dollar spent."
But as Nelson
explained, fixing windows and ceilings are the least effective ways of spending
money on weatherization. Using software developed under contract from the U.S.
Department of Energy and the Environmental Protection Agency, he has analyzed
how energy efficient a house can be with different forms of weatherization.
Take for example a typical 1,000-square-foot ranch built in the 1950s with
low-grade insulation. Nelson can predict how much money and energy it would
take to heat and cool the house.
a direct correlation between energy consumption and carbon exhaust that can be
measured as well. Nelson's calculations are shown in the chart.
"Perhaps it's not wise to spend $6,500 on every
house," he said.
Iain Walker, a researcher at Lawrence Berkeley
National Laboratory and a specialist in thermal distribution systems and
ventilation, says windows are the last thing that should be done to improve a
home's energy efficiency.
"Windows should only be replaced for energy
conserving reasons if you have already done everything else," Walker explains,
"although there are other excellent reasons for window replacements which
override energy conservation efforts, such as condensation resistance or if the
old windows are rotted out."
He emphasizes how important it is to have aims for
performance testing and goals for how airtight a structure should be, for
example when performing blower door tests.
"We don't know much
about houses, but we do know that if you don't measure things like
airtightness, you have no idea how much you improved a home," Walker said.
According to Stacie
Gibson of the Michigan Department of Human Services, which administers the
weatherization funds, a pre-inspection done by contractors on the local level
determines which methods meet the savings-investment ratio and are most cost-effective.
"It can be attic, floor and foundation insulation, air
sealing, electric baseload measures or appropriate ventilation," she told
MichiganScience. "The primary focus is on achieving the maximum energy savings
possible in the home with the dollars available."