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Roof Reflection
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Area roofers
offer energy efficient roofing, which can cut utility bills in half.
By Peter Downs
With energy costs going through the roof, more and more businesses
are looking at their roofs to cut costs.
“Clients are definitely expressing interest in energy efficiency,”
says Eric Kirberg, vice president of Kirberg Roofing, and the right
roofing choices can definitely save a business money. According
to the U.S. Environmental Protection Agency (EPA) and the Department
of Energy (DOE), building owners spend approximately $40 billion
each year to air condition their facilities. Energy efficient roofing
products can reduce the amount of air conditioning needed in buildings
so much that they cut energy bills by up to 50 percent.
Energy efficiency starts with insulation, says Douglas Jones, president
of South Side Roofing and Sheet Metal Company. Architects used to
specify a certain thickness of insulation, but now they’re more
aware that it is the R-value that is important, he says. R-value
is a measure of the effectiveness of the insulating material. The
higher the R-value, the better an insulator it is.
For example, South Side is bidding on replacing a roof at the Ford
Hazelwood plant, and the architect specified not only the number
of inches of insulation, but also an R-value of 5.7 per inch.
Even if you are not replacing your roof, however, you still can
make it more energy efficient. A dark roof absorbs heat and transfers
it to the interior of the building. In hot climates, that increases
the cost of cooling a building. In cold climates, however, it cuts
the cost of heating. St. Louis, however, has both hot summer days
and cold winter ones, so what should building owners specify?
“It’s harder to cool a building than it is to heat it,” Kirberg
says, so in St. Louis, “it’s still better to have a reflective roof.”
There are several products available to convert a roof into a heat
reflector from a heat absorber. There are reflective coatings that
can be sprayed onto some roofs to give them a white or shiny aluminum
surface, and if you are recovering your roof, there are white, single-ply
rubber membranes you can use.
Of those, the white products usually reflect the most heat, and
maintain the most reflectivity as they age, Kirberg says.
The EPA and the DOE have a joint program for evaluating products
that can reduce building energy use, and thereby save owners money.
Products that pass certain standards get to use an Energy Star label.
They also have a web site, www.energystar.gov, that describes the
program and lists approved products.
Above:
Steve Gereau, journey roofer with Kirberg Roofing Inc., operates
a seam welder atop Steris Corporation.
The roofing standard for receiving an Energy Star label is that
the product must initially reflect a quarter of the sun’s radiation,
and after three years it has to reflect one-sixth of the radiation.
Some products, however, perform much better. They can reflect two-thirds
of the sun’s radiation.
According to the two government agencies, Energy Star roofing products
can reduce the surface temperature of a roof by up to 100 degrees
Fahrenheit on a sunny day, and that can cut the amount of work an
air conditioning system has to do by 15 percent.
The advantages of an Energy Star roof purportedly go well beyond
the daily electric bill.
In new construction, installing an Energy Star roof to reduce peak
cooling demand means the owner can install a smaller, less expensive
air conditioning system.
An Energy Star roof can last longer than a conventional roof. Roofs
expand as they heat up during the day and contract as they cool
at night. Reducing the amount of heating and subsequent cooling
by reflecting the sun’s heat away from the roof reduces that expansion
and contraction, and the roof degradation that results from it.
Many built-up roofing systems will not last for 20 years, Kirberg
says, but a white, single-ply membrane will. There are other roofing
systems that will last that long, but they are more expensive. Built-up
roofs, made with asphalt, have been used in St. Louis for more than
100 years. They remain the industry standard.
An Energy Star roof decreases pollution. It does this in two ways.
One, by reducing the demand for electricity for cooling, which reduces
the need to burn fossil fuels to produce electricity. Burning fossil
fuels generates 90 percent of the energy in the United States, which
creates the air pollution associated with smog, acid rain and global
climate change. The Department of Energy estimates that 83 percent
of greenhouse gases produced in the U.S., for example, are produced
by electric power plants. Two, by reducing the heat island effect,
which is a phenomenon in which cities can be 2 to 8 degrees Fahrenheit
warmer than the surrounding countryside. Many buildings and paved
surfaces are designed with dark materials that absorb heat from
the sun. Once those surfaces heat up, they warm the air that passes
over them. This not only elevates the temperature during the day,
but also causes the air temperature to remain high at night. When
temperatures are higher, people use their air conditioners more,
whether in buildings or cars. Vehicle air conditioning burns more
gas, which can increase the severity of smog.
Energy Star roofs improve public health. By reducing the heat island
effect and smog, these roofs cut heat- and smog-related health problems,
such as the numbers of severe asthma attacks.
The biggest impact will be on those buildings that have a large
roof surface compared to their overall size, in other words, long,
wide, short buildings as opposed to tall ones.
Kirberg says the Energy Star rating is starting to have a real impact
on the roofing business. “Property managers and corporations are
really becoming aware of it,” he says.
Peter Downs is a free-lance writer and editor of Construction
News & Review.
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