LBNL Report Number
Whole-house ventilation systems are becoming commonplace in new construction, remodeling/renovation, and weatherization projects, driven by combinations of specific requirements for indoor air quality (IAQ), health, and compliance with standards, such as ASHRAE 62.2. At the same time we wish to reduce the energy use in homes and therefore minimize the energy used to provide ventilation. This study examined several approaches to reducing the energy requirements of providing acceptable IAQ in residential buildings. Two approaches were taken. The first used RIVEC – the Residential Integrated VEntilation Controller – a prototype ventilation controller that aims to deliver whole-house ventilation rates that comply with ventilation standards, for the minimum use of energy. The second used passive and hybrid ventilation systems, rather than mechanical systems, to provide whole-house ventilation.
Computer simulations were performed for four typical whole-house ventilation systems, both with and without RIVEC, so that the energy and IAQ impacts of RIVEC could be compared. Three passive ventilation strategies were also simulated to assess their energy and IAQ potential to provide whole- house ventilation. The above simulations were carried out for 16 California climate zones, three envelope leakage levels, and three house designs.
The results showed that RIVEC could typically reduce the energy penalty from adding whole-house ventilation (including fan energy and the space-conditioning energy used to temper the ventilation air) by more than 40%, without compromising long-term chronic or short-term acute exposures. Critical and average peak power loads were reduced as a consequence of using RIVEC. The passive systems could also meet chronic and acute standards, but uncontrolled over-ventilation during extreme weather resulted in excess energy use. This study also demonstrated that controls for passive systems could ameliorate some of this excess energy use. However, more work needs to be done to optimize and demonstrate passive system controls.