Recently, Ryan Miller and Green Roofing Technology help
construct a roof for the NY Parks and Recreation Department. The goal of the green roofing system was to
provide solar energy for building use.
Other portions of the project included a rainwater collection system and
vegetation on the roof. One aspect of
the project that complicated things was the fact that they could not pierce the
underlying membrane and instead had to rely on a ballasted system. In 2012 Hurricane Sandy hit the area and the
original build crew went out to assess the effectiveness of the green roofing
system.
Many
Components to the System
In order to prevent piercing of the underlying membrane the
team has to ballast the roof, which means it was essentially perfectly
balanced. The sheer weight of the
roofing system keeps everything in place.
Vegetation was also located on the roof, fed naturally by sunlight and
rainfall. Excess rain was captured by a
water collection system and used to regularly irrigate roof vegetation. Finally, photo voltaic panels were installed
to generate usable energy for the building during the day and lights for the
roofing system during the evening.
The entire system was well configured to be an effective use
of evapotranspiration to keep the building cool. In this process water was stored through the
water collection system, located under the upper roof where vegetation and
solar panels were located. The water was
warmed by the internal heat of the building.
As the water evaporated from the system it released the building’s heat,
in a similar mechanism as sweating.
The water collection system also extended the operating life
of the photo voltaic cells by lowering the overall operating temperature on the
surface of each panel. By providing a
cooling effect, the system was able to generate more power, on average, than
bigger solar system.
Power
Generation
Considering the roofing system was built in the northeast
and not College Station, TX, the power generation results was outstanding. The total square footage of the roof was
divided between pedestrian space, vegetation space, lights, and solar
panels. When compared to a solar roofing
system that is completely solar panels, the combined green roofing system
produced 8.3% more power.
What about
the Costs?
The total cost of the combined roofing system was equal to
the cost of a traditional solar power roofing system. The space saved by fewer solar panels and
better operating efficiency, allowed costs to be saved from less required
mounting equipment. That space was converted in living space for plant life.
By the year 2021 the building will have saved over $359,431
in savings at a rate of $.20 kWh.
Additionally, the federal government offers many tax incentives that make
these roofing systems financially attractive.
One program in particular, called the Business Energy Investment Tax
Credit can allow up to a 30% tax concession on the roofing system. Savvy building owners can also tax advantage
of carbon credits, which can be sold with the aid of investment firms and
brokers.
Combined green roofing systems have found a special place in
the roofing industry. Future
ramifications of this system could prove to be a consistent source of revenue
after the system has paid for itself. In
this particular study, the system generated full ROI within 5 years.
Schulte Roofing is a professional Houston roofing repair company with over
100 years of combined experience. As
Home of the Bulletproof Roof™ Guarantee, Schulte Roofing can help design and
build the green roof you require. To
learn more about combined green roofing systems, contact your
local roofer.
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