No building owner will naturally ventilate his building if outside air temperature or humidity levels are unacceptable for indoor comfort conditions.
Thus, a rare few climates allow for a purely naturally ventilated building.
For all US buildings, space cooling and ventilation consume 16% of building energy use.
However, in cooling-dominated climates, this percentage is significantly higher.
This limitation in NV has lead to hybrid ventilation (HV) – a mix of NV and more traditional mechanical heating, ventilation, and air conditioning (HVAC) methods.
While HV systems predictably require a larger capital investment than either a NV or mechanical HVAC system, the cost savings of an HV system over its lifetime could conceivably more than pay back the initial investment. Thus, each student admitted to the program is expected to take part in a research project.A major contribution to the student's education in this program comes from the experience gained carrying out research and design on the fundamentals of new technologies and their application to buildings.A major gap currently exists in our ability to predict the performance of an HV system – thus its energy and cost savings – when buoyancy-driven flow is present.Airflow network tools exist that predict airflow driven both by wind and buoyancy effects, however the assumptions used to model buoyancy-driven flow are often unrealistic.A recently completed program tested and analyzed both of these benefits, with the goal of quantifying energy savings and providing to building owners, control manufacturers and electric utilities the information needed to make informed decisions about investing in new technologies.The performance of ventilation systems was monitored in several buildings and models were developed to correlate fan power with airflow and pressure.My goal is being able to predict the strength of air stratification in a room, and the effect that this density gradient has on the temperature of the room's occupied zone and the air flow in and out of each zone.Student: Stephen Ray, Ph D student in Department of Mechanical Engineering Advisor: Leon Glicksman In the United States and most developed countries buildings consume roughly 40% of the nation’s primary energy, a number that is steadily growing.Such assumptions include a uniform temperature distribution in the ventilation duct, when actually the distribution is highly stratified especially near the duct entrance, or unidirectional flow in the duct, when bidirectional flow is likely due to the presence of large eddies in the flow.The aim of this research is to deepen the understanding of NV to allow for better modeling in airflow network tools used in building energy modeling software to more confidently predict the energy and cost savings of a hybrid ventilation system. Spindler (Mechanical Engineering)Advisor: Les Norford The majority of commercial buildings today are designed to be mechanically cooled.