The use of mechanical means of heating, ventilation, and air conditioning (HVAC) came about because of the combined ability and desire to control the interior building environment in extreme climates. The price of this ability to control the indoor climate is beginning to surface in the form of air and water pollution from energy use, sick building syndrome (SBS) from factors such as build-up of molds in air conditioning fluids, and loss of individual control of one’s thermal environment. All of these factors provide motivation to re-incorporate natural ventilation as a hybrid strategy, taking the lead from history as well as from advanced design, construction, and analysis techniques, to take advantage of natural winds to reduce energy consumption and provide greater human health and comfort while maintaining the flexibilities offered with conventional HVAC systems.
This case study assesses a hybrid natural ventilation strategy against a traditional mechanical HVAC system. Tables 1 and 2 above provide a summary of the primary environmental, health & safety (wellness), and cultural benefits of hybrid natural ventilation systems over conventional mechanical HVAC systems for the East Campus Project, per the methodology described earlier. Each major benefit is then described and discussed, including an estimate of potential energy and emissions reductions and a life cycle analysis (LCA) of the emissions from the manufacture of air-conditioning equipment. Throughout this case study, the term “natural ventilation (NV)” will refer to a hybrid ventilation strategy that also makes use of a mechanical HVAC system when exterior climatic conditions are not suitable for natural ventilation, as it is unlikely that a pure natural ventilation system could meet the needs of the Boston climate. A hybrid system thus includes the relative advantages of a mechanical system, such as reliability of performance and ability to filter air when needed.