Being cool is a matter of wearing the
Dave Alden applied the fashion axiom to the roof of three
low-rise office buildings he manages in Walnut Creek for financial
services giant Wells Fargo & Co.
The white acrylic coat reflects heat and light instead of
absorbing it. That translates into energy savings, which means
money. ``The reflective coating does a super job,'' said Alden,
regional manager for Northern California administrative buildings
for Wells Fargo & Co.
``It reduces the heat load tremendously,'' he said, estimating
the coating cut the daytime roof temperature an average 42 degrees.
It cost $1.70 per square foot, including a 15-cent state rebate, to
install cool roof coating on the roofs of three low-rise Wells Fargo
& Co., office buildings in Walnut Creek.
A cooler roof means less heat penetrates the building to warm
interior air - air that gets cooled by pricey electric power. The
system appears to work.
Services employee Tang Huynh applies the "cool roof" to
a building in Livermore. Michael Lucia - Staff
``Before, we had to operate three pieces of equipment first thing
in the a.m.,'' Alden said. Now it's ``noonish,'' before a second air
conditioner is turned on, he said.
Cool roofs are one of several initiatives that were lent added
seriousness by the energy crisis of 2000-2001. While probably not
the most exciting or largest energy saver, cool roofs cut
electricity usage when it counts - at peak load, midday hours.
To encourage commercial building owners to switch to white
coatings, the state sweetened the pot with subsidies.
Cool roofs also reduce so-called ``urban heat islands'' -
microclimates caused by heat-absorbing tar roofs and asphalt that
radiate heat, raising temperatures.
Still, the technique is no panacea. Some professionals fear cool
roof materials don't last and may prove uneconomical in the long
run. A cool roof can run anywhere from about $1.50 per square foot
installed for the simplest spray on coating jobs to $5 per square
foot for an entirely new cool roof.
Experts also admit cool roofs won't provide much bang for the
buck on high rises, or on most homes.
There also is a wide variation in products. Roof coatings -
painted on - are cheaper to buy and install, about $1.50 to $2 per
square foot. Membranes - sheets of material rolled out and tacked,
nailed or glued down - tend to last longer but cost between $2.50
and $5 per square foot. There are exceptions to both rules, and
figuring out which system is most cost-effective generally depends
on the type and condition of the existing roof.
What works also depends on who you ask.
``Obviously, the guys who sell membranes want to sell more
membranes, the guys who sell coatings want to sell more coatings,''
said Dan Varvais, a consultant for Placerville-based Applied
As of July, California has installed or has on the books 44
million square feet of cool roofs, according to Rob Schlichting,
spokesman for the California Energy Commission.
``That should save the equivalent of 15 megawatts of electricity,
enough to power 15,000 homes,'' Schlichting said, referring to peak
load capacity on a typical hot summer day.
It doesn't sound like much compared to the 2,301 megawatts
generated by PG&E Co.'s Diablo Canyon nuclear power plant. But
the idea is reducing peak load - those hot days when the multitudes
seek air conditioned relief and draw enough power to threaten
The difference is on top. Roof temperatures can be 82 degrees
higher than air temperatures on an ordinary black gravel roof,
according to a study by the Lawrence Berkeley National Laboratory.
Some cool roofing materials cut that figure to as little as 9
The impact depends on the scale.
Varvais advised the Homebase home improvement chain on roof
repairs for it's 83 stores. A particular roof's condition dictated
what kind of fix he recommended.
``Sometimes it is better to let a roof wear out, and plan on
replacing it in two or three years,'' and sometimes a repair job is
in order, Varvais said.
On top of the $0.15 subsidy per square foot, tax advantages can
guide a decision. Roof repairs can be written off as a one-time
charge against income, while a new roof can be amortized over 40
years, Varvais said.
Varvais is a believer. He said roof temperatures on a Sacramento
elementary school dropped from 172 degrees before installation to
103 degrees after.
``There was a significant reduction in the heat gain going into
the building,'' he said.
Government scientists say cool roofs benefit air quality. Dark,
energy trapping roofs actually help raise temperatures in
surrounding areas. A concentration of dark roofs and asphalt
pavement - typical of urban and suburban landscapes - lift
temperatures, creating so-called ``urban heat islands.''
Scientists say ground-level ozone, a component of smog, more
easily creates smog at warmer temperatures.
Officials from the California Energy Commission estimate the
average energy savings per square foot of cool roof at about 0.4
kilowatt hours a year.
According to PG&E, basic commercial electricity rates range
from 12 to 14 cents per kilowatt hour. The savings works out to
roughly 5 cents per foot per year.
A kilowatt hour is a unit of electricity equal to the amount
needed to light ten 100-watt light bulbs for an hour. Officials said
the rebate is necessary to encourage the new technology.
``The one thing about the roofing industry, people are afraid to
try something new,'' said Virginia Lew, a California Energy
Commission engineer. And the jury is still out on many products.
Some roofers have learned a wait-and-see attitude. They say new
products frequently don't perform or last as promised. ``New
products come out and make a lot of money for the first few years
and when problems come out, (the manufacturers) file for
bankruptcy,'' said Jack Pickerill, president of Livermore-based J.
Pickerill Roofing Inc. Pickerill says a majority of his customers
prefer ``tried and true'' products.
``I like for something to be out a year or more before I get
involved in it. I don't want to be a guinea pig,'' Pickerill said.
One roofer also said products sold in California, meeting state
requirements limiting volatile organic compounds, may not stick as
well, and thus may not last as long.
Patching or replacing a flaw in a new roof would probably wipe
out the economies provided by rebates and energy savings. Experts
said roofs can last from as little as two years up to as long as the
building itself, with proper maintenance. Some materials are damaged
by puddles of water forming on a roof that fails to drain. Other
products lose their efficiency when they get dirty, so cleaning is
Cool roofs for residential homes remain elusive. Because they are
typically sloped instead of flat, most products designed for the
large typically flat-roofed commercial buildings don't work. White
coatings and membranes also face consumer resistance because of the
Another issue is efficiency. Cool roofs deliver their lower
interior temperatures during midday - precisely the time most
homeowners are at work five days a week, making them less likely to
lower the air conditioning control knob when it gets hot.
Homes can qualify for the rebate, but only if they already have
an air conditioner.
Experts said cool roofs combined with evaporative ``swamp''
coolers, ceiling fans, and broad leaf trees can mitigate much of the
need for air conditioning - even in very hot areas. Broad-leaf trees
can shade windows in the summer, keeping out the heat, but drop
leaves in the fall, allowing winter light in.
Still, residential cool roofs are far from ubiquitous. Lisa
Gartland, a consultant at Oakland-based Positive Energy and a cool
roof proponent, said she is having an ordinary roof installed on her
home because she couldn't find a cost-effective cool residential
alternative. Still, the commercial applications are promising.
Alden, the Wells Fargo manager, says he expects the $1.70 per
square foot Wells paid installing the cool roofs will pay for itself
in three to four years. Alden said energy consumption for the three
buildings this July was 20 percent lower than the previous year. The
company also installed energy saving T-8 lighting.
Alden said the company's goal is cost cutting. On some
properties, Wells is replacing old air conditioning units with more
efficient ones. ``Overall we have a 16 percent, 20 percent reduction
in (electricity) consumption in Northern California,'' Alden said.
Marc Albert can be reached at (510) 208-6414 and firstname.lastname@example.org