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.