Highly Energy Efficient Buildings and Rooftop Solar Equipment

Cool roofs may add only marginal energy savings to buildings that are already highly energy efficient. Highly efficient buildings are often well insulated to minimize the flow of heat through the walls and roof. This helps the occupied space stay cool in summer and warm in winter, regardless of the roof’s surface temperature. However, dark roofs on well- insulated buildings can become very hot, so cool roofs help achieve the environmental benefits associated with lower roof temperatures. Keeping a roof cool may also extend its lifetime.

Solar energy systems, such as photovoltaic (PV) panels and solar thermal collectors, absorb solar energy and can become hot in the sun. Solar equipment mounted flush with the roof’s surface can act like a dark roof, transmitting heat to the building and increasing air conditioning demand. Physical gaps between the solar equipment and roof can reduce this effect, since airflow through the gap can remove some of the heat that would otherwise flow into the roof. On permanently shaded portions of the roof, the roof’s solar reflectance does not affect air conditioning demand. This includes regions of the roof that are completely shaded by solar panels xx.

Some newer thin- film PV modules can be integrated directly with roofing materials. They may meet current cool roof requirements for steep sloped roofs9 but do not satisfy the more stringent standards for low sloped roofs.

Congratulations, you have completed the knowledge section of the course.

You may now complete the course by successfully passing the course quiz.