Investigation of hybrid ventilation potential of commercial buildings in US

Abstract

As one of the largest energy consumers in our society, commercial buildings take up approximately 20% of total energy consumption based on the data from Department of Energy (DOE). Among this energy consumption, nearly half of it is consumed by air conditioning systems for maintaining a comfortable thermal environment for building occupants. Despite this high energy consumption, complains of thermal comfort and health problems still commonly exist in air-conditioned buildings. The mean building satisfaction rate was only reported as 59% based on a large survey of building occupants, which is far below the minimum thermal comfort requirement in ASHRAE standard 55. Meanwhile, there also exist health problems in air-conditioned buildings, which include both building related diseases (typically caused by specific exposure to infectious indoor source) and sick building syndrome, which describes a group of general symptoms including eye or throat irritation, shortness of breath, visual disturbance etc. Thus, in these years, coupling natural ventilation with mechanical ventilation, hybrid ventilated buildings have attracted more attention from both academia and industry with increasing awareness of building sustainability. Hybrid ventilated buildings have the potential to minimize the energy bills for owners without compromising the thermal comfort of building occupants. Compared to the mechanical ventilated building, the hybrid ventilation system allows opening the window when the outdoor environment is favorable, which provides occupants with amenity to nature and saves energy in the building operation. Compared to the natural ventilation building, the hybrid ventilation building could protect the building occupants from the unfavorable outdoor environment with air conditioners on. As the first step to further popularize the hybrid ventilation building, this dissertation will provide a thorough investigation of the hybrid ventilation potential across different US climates with accounting for comprehensive and influential aspects related to the usage of natural ventilation, including different levels of uncertainties a hybrid ventilation building could experience, the influence of building intelligence and the impact of outdoor air quality. How to better assess the thermal comfort risks and utilize simulation to design this type of building will also be presented.