As part of the RoofPoint rating program for sustainable roofing systems, the Center has developed a unique approach to the selection of energy-efficient roof surfaces. First, RoofPoint starts with the different energy-related outcomes a roofing designer may seek to achieve. In almost all cases, net energy savings will be important; and in many areas of the country the type of roof surface can make a big contribution in reducing total heating and cooling costs. In other areas, peak energy usage is also important, especially in localities with peak demand charges for the electricity needed to power air conditioning systems. Finally, reducing heat island effects may also be important, especially in dense urban areas.
In addition to recognizing different energy outcomes, RoofPoint also identifies a broad array of roof surface types to address these energy factors. In many parts of North America, especially in warm, sunny climates, highly reflective roofs may offer significant benefit in all three energy categories, saving both net and peak energy as well as reducing heat island effects. In cooler areas of North America, roofs with slightly less reflectivity may offer a workable trade-off between reducing solar heat gain in summer and minimizing solar heat loss in winter. And in climates with extremely cold winters and cool summers, low-reflective roofs may offer the best overall energy solution. In addition, RoofPoint also recognizes non-reflective surface options such as vegetative and ballasted roofs, which offer viable energy solutions in a wide variety of climates.