NightSolar® systems can be configured to offer solar energy generation and conventional energy displacement up to 24 hours a day, all year long. This has been made possible because the SolarWall collector surface can be used for both cooling (in the warmer months) and also heating (in colder months). The end result to the building owner is substantial energy savings that occurs from reducing on-site cooling and heating costs by up to 50%.
NightSolar® systems remove energy from the air to cool buildings without the use of compressors or refrigeration systems. This solar cooling technology is based on the scientific principle of nocturnal radiation cooling, which can cool a roof by as much as 10°C (18°F) below ambient temperature on a clear night. As warm night air touches the cooler surface of the NightSolar® panel, heat is transferred to the surface, which cools the air by radiating the heat to the cold night sky. The chilled air is then drawn in through perforations in the collector and enters the HVAC unit via an economizer cycle. This cooling has the ability to reduce or even displace conventional air conditioning from sunset to sunrise. During the daytime, the NightSolar® system keeps the roof in the dark and thereby reduces daytime heat gains normally transmitted through the roof.
Recent field monitored NightSolar® installations are reporting as much as a 50% overall cooling savings on buildings using existing fans and economizers. And the technology can also be used to still generate daytime heating.
NightSolar® systems utilize a ventilated roof design (also known as above-sheathing ventilation) that is highly desirable for all buildings with metal roofs. This reduces daytime cooling by shading & ventilating the roof, meaning that unwanted solar heat is naturally vented while drying any condensation that may have occurred on the roof.
Oak Ridge National Laboratory states “we serendipitously discovered the second major advance in roofs for our century: We found that elevating the roof cover from the roof deck to induce above-sheathing ventilation is as important as increasing solar reflectance and may be the stronger player in reducing heat gain into the attic. The two combined can reduce heat gain through the roof by 50% compared to nailed asphalt shingle roofs.“