Center for the Built Environment

Is there a place for improving passive performance in existing buildings?  Even in naturally ventilated buildings, it is relatively common during a retrofit to add new cooling and ventilation equipment to address increased internal gains, indoor environmental quality concerns, and in some cases occupant expectations. Mixed-mode strategies, which combine natural ventilation and mechanical cooling to meet peak loads, offer the possibility of using existing building features to enhance passive performance, as demonstrated by a growing number of retrofit projects. Whether air conditioning is being reduced or minimized, these designs often involve a compromise between the need for new systems, a desire to retain original operable windows, and the goal of being “green.” As more attention is directed towards deep energy reductions in existing commercial buildings, understanding how designers have made decisions to integrate operable windows with new systems offers insights into the opportunities and risks associated with this type of project.