Tag Archives: faq-myth

Are cool roofs more expensive than normal roofs?

It depends. On low-sloped roofs (typically found on commercial or high-rise residential buildings), installing a white roof is often a matter of simply choosing the right color coating. If the building needs a new roof anyway, there is no additional cost. If the roof is retrofitted ahead of schedule in order to install a cool roof, there will be some incremental cost. Depending on the kinds of materials used, the incremental cost of choosing a cool roof over a more traditional dark roof for a commercial building is approximately US$0 to US$2.20 per square meter (US$0 to US$0.20 per square foot). When factoring energy savings into the equation, the incremental cost can be fully recovered in many applications over a period of zero to six years.

On steep-sloped roofs (typically found on residential buildings), changing the reflectivity of the roof is usually not as simple. Because most people do not like the aesthetics of a white roof (which would be visible thanks to the sloped nature of the roof), increased reflectivity is best gained through highly reflective shingles that can come in any color. Currently, these roofing materials do cost more than standard materials, but as the market grows, the price is likely to come down.

There are also important non-cost factors to consider:

    Comfort: In unconditioned buildings, cool roofs can maintain cool indoor temperatures.
    Durability: Cool roofs may degrade slower and last longer than similar non-cool roofs, but more research is needed to prove this.

I live in a cold climate and use more energy heating my building in the winter than cooling it in the summer. Are cool roofs still a good idea?

One of the primary values of cool roofs is their ability to lessen the cooling demands of a building thanks to their higher reflectivity. In climate zones where the energy required to cool the building in the summer is greater than that required to warm the building in the winter, white roofs are valuable both to residents and to utilities.

Many people believe that the converse effect is also true; that white roofs increase the heating requirements for buildings in northern climates, the so-called “winter penalty.” There is sound evidence that the winter penalty is non-existent or minimal, since the sun is at a low angle in the winter months and heating loads are more pronounced in the evenings, especially in residential buildings. White roofs will still provide a higher albedo surface in these areas, creating a climatic benefit, even if the cost savings to the building inhabitants are minimal.

Visit the US Department of Energy’s Roof Savings Calculator to estimate what your energy and cost savings would be if you installed a cool roof.