Reflective cool roofing is becoming more and more popular every year, due in part to building owners wanting to capture its energy-efficient qualities for their buildings, but also due to municipalities and states adopting cool roofing codes, standards, and programs.
“There are a lot more cool roofing options today than there were even 5 years ago because of its growing popularity,” says Jay Thomas, director of marketing for Sika Sarnafil, a roofing and waterproofing system provider. “You can now get virtually any roofing system as a cool roof, although some roofs require more components than others. For example, a thermoplastic roof might be white, whereas with a built-up roof you would have to apply and maintain a coating to get the same cool roof benefits.”
With the growing prevalence of cool reflective roofs, the roofing industry is making great strides to keep up and produce innovative solutions for reflective roofing – including advancing the relationship between roofing and solar panel systems.
Teaming with Solar
“One of the things that’s receiving a lot of interest and a lot of work today is the continuing integration with solar,” Thomas explains. “Reflective roofs can help increase the efficiency of solar panels by reflecting the sunlight from the roof to the panels. So I think the industry at large – both the solar industry learning about installing on flat or low-slope roofs and the roofing industry about the implications of installing solar panels on rooftops – is learning from the experience.”
A new, white reflective roofing system can reflect up to approximately 80% of the light that hits it – sending the light back into the atmosphere and away from your building, allowing it to stay cooler and your energy costs to go down. But what if you could capture some of this reflected light and use it to increase the energy produced by your solar panels?
Sanyo, a major electronics company that also produces solar technology, figured out how to do just that by combining its HIT (heterojunction with intrinsic thin-layer) double bifacial PV modules with DuROCK’s TIOCOAT reflective roof membrane, which were installed at DuROCK Alfacing International Ltd.’s headquarters in Woodbridge, Ontario.
Sanyo's unique solar panels generate power from both sides – capturing the light that shines directly onto the front of the panels and the light that passes through the panels after it is reflected off the roof and bounces back – resulting in up to 30% higher energy output than standard single-sided PV modules. The result of the combination of these technologies includes an improved performance and increased energy production of the PV modules because of the high reflectivity of the roof membrane.
“The merging of these two technologies is a great example of the potential that exists within this industry,” says Sandro Costa, president of AVACOS Solar, the Canadian solar installation and project integration company that installed the system. “Maximizing the power generation possible from the sun is not only a win-win situation for the client, but for the environment and society as a whole.”
Other reflective coatings and PV modules – such as Solyndra’s rooftop-mounted panels, made of cylindrical modules that capture sunlight across a 360-degree photovoltaic surface – work in much the same way, capturing sunlight that shines directly on the panels along with a portion of the light that is reflected by the roof.
In addition, the lighter color roofing keeps the temperature of the roof lower than a darker roof, keeping the solar panels closer to their optimum temperature range and allowing for maximum performance.
While cutting-edge reflective roofing products may be of great interest, you’ll also want to ensure that the products have been thoroughly tested and will hold up to long-term applications.
“Certainly there are a lot of new technologies in cool roofing,” Thomas says. “So be careful. Just like any other roofing decision or product you’re considering for the building, it is important to make sure the manufacturer has the track record to support the products so they last as long as they should.”
Kylie Wroblaski ([email protected]) is associate editor of BUILDINGS.