CH-24-C005 - Evaluating the Field Performance of a Solar Air Heating System for Preheating Building Ventilation Air

Data, key findings, and best practices are presented from field demonstrations of a Solar Air Heating System (SAHS) used to preheat ventilation air at a Department of Defense facility. A SAHS is an addition to an exterior wall that incorporates an air cavity and dark, perforated cladding to transport thermally-warmed air into an existing forced ventilation intake or directly into a building’s space. The primary components of a basic SAHS include dark colored exterior panels made of perforated aluminum with a cavity behind that easily absorb radiant solar energy . These panels are typically installed vertically with a southern exposure, coupled with an intake fan that draws the pre-heated air through the panel into the building ventilation system. The use of an automated outside air damper, which opens and closes depending on SAHS operation, can provide solar pre-heated ventilation air to the space, improving indoor air quality (IAQ). Under winter design conditions, supplemental heating may be required through the existing building ventilation system. Overall, the SAHS system is primarily a passive heating technology that requires the use of an intake fan to supply heat to the space. Despite utilizing free solar energy and pre-heating ventilation air, the application of this technology is dependent on geographic variables like solar insolation, and space heating demand. Similar to other solar heating technologies, favored climate zones like ASHRAE zones 5, 6, and 7 where a combination of higher solar insolation and heating demand are optimized, are preferred and preclude a wider market adoption. By appropriately selecting installation sites in the best possible geographic regions, energy savings can be optimized.

As countries around the world seek technologies to reduce their greenhouse gas emissions, many have sought technologies to reduce heating and cooling loads. A primary source of renewable energy is solar energy, which is captured by photovoltaic cells and converted to electricity. SAHS is a much simpler technology and does not require additional roof space. At their current state, despite the target for low-cost operational space heating, minimal maintenance and operating costs at commercial and industrial sites, expensive upfront installation costs have precluded larger market implementation. As part of the continued effort to combat global climate change and improve indoor air quality in a post-pandemic environment, SAHS’s can be a promising technology to decrease greenhouse gas emissions while maintaining minimally acceptable indoor air quality. This paper focuses on characterizing the seasonal performance, as well as discussing the energy savings, lessons learned and economics of a SAHS installation at a Department of Defense facility.