The Many Benefits of White Roofs

April 3rd, 2011 | Posted by tjones in Green Building | Green Homes | Green Products | Living Green

Lots of folks seem to be familiar with green roof systems – a layer of impermeable membrane covered by a growing medium and lots of flora, grasses, trees, or otherwise.  The installation of green roofs over the last few years has expanded extensively, and the benefits of green roofs are substantial: they lower the heating and cooling costs for a building, they mitigate storm water runoff, and they provide essential islands of biodiversity and animal habitat in the urban environment.

One of the drawbacks of green roofs, however, is the initial cost of installation.  For larger projects, green roofs can require literally tons of growing medium, and even structural reinforcement of a building for heavier flora like trees.  The cost of this averages out to about 15 to 20 dollars per square foot, excluding the waterproof layers.  The savings average out over time, but initial cost can be a real deterrent to some folks.

WHITE ROOFS

White roofs have significant energy-saving advantages and even contribute to the mitigation of climate change, at significantly more affordable prices than green roofs.

Living in a large city means living with the effects of an urban heat island: the stone-like concrete and asphalt environment absorbs significantly more sunlight, and heat, than a natural ecosystem; concrete also releases heat at a slower rate, meaning that temperatures in the city are often noticeably higher than in surrounding areas.

Dark-colored surfaces also absorb solar radiation instead of reflecting it back out into space.  This is actually a contributing factor to climate change: when solar energy is absorbed by a dark surface, it is reflected back at a lower wavelength, which cannot pass through greenhouse gases and gets caught in the atmosphere, contributing to global warming.

White roofing can address both of these issues.  By reflecting sunlight at a high frequency back into space, it not only reduces the trapping effects of the urban heat island, but also reduces the amount of energy trapped in the atmosphere by greenhouse gases.

And, perhaps most significantly for the homeowner, installing a white roof can reduce the costs of cooling a home in the summer, leading to much lower utility bills.  And according to wikipedia, if white roofs were installed in the Greater Toronto metropolitan area in conjunction with street trees, the area could save more than $11 million on annual energy costs.

GREEN DEPOT SOLUTIONS

Bulldog/Durex TC101 is an elastomeric, single component, high-performance waterborne roofing topcoat formulated with 100% acrylic resins. It creates a seamless, monolithic coating when cured. The coating provides superior durability, weatherability and elongation. When applied in the white pigmented formulation that is Energy Star® rated, it will reflect heat from the roof surface: lowering cooling costs, and extending the life of roof membranes and surfaces.

When installed over a properly prepared substrate and dry insulated roof, it’s also a lower-cost option than roof tearoff and replacement. This coating can be used over a wide variety of surfaces, and can add aesthetic value in the form of one of the many color options available.

[This post was updated on July 9, 2012]

For green building materials, like eco insulation, as well as many other green products for a sustainable lifestyle, visit http://www.greendepot.com.

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