AC/DC: Let There Be Hybrid Cooling

• Main Author: Podes, Christopher
• Format: Others
• Published: Scholar Commons 2010
• Subjects: Subtropical Architecture; Passive Cooling; Thermal Comfort; Garden Classroom; Educational Building; American Studies; Architecture; Arts and Humanities; Urban Studies and Planning
• Online Access: http://scholarcommons.usf.edu/etd/3434; http://scholarcommons.usf.edu/cgi/viewcontent.cgi?article=4629&context=etd

In today’s increasingly energy conscious society, the methods of providing thermal comfort to humans are constantly under scrutiny. Depending on the climate, and the comfort requirements of the occupants, buildings can be designed to heat and cool occupants with passive methods, as well as mechanical methods. In the subtropics, where buildings often need to be heated in the winter and cooled in the summer, a synthesis of these two methods would be ideal. However, there is a disconnect between the integration of passive cooling and mechanical air conditioning, in subtropical architecture. A study of user attitudes, based out of Australia, found that, “Central control of temperatures has been used to cut demand by preventing users from altering thermostats and other parts of the building for microclimate control. In particular, windows are sealed to prevent tampering.”1 Reliance on air conditioning has the everyday person convinced that if we save energy in the right places, we can use air conditioning as much as we like. The same study goes on to state, “Air-conditioning has been assumed to replace the need for climate design features in buildings creating poor thermal design and high energy use.”2 This can be most clearly seen in our public buildings. Fully conditioned buildings pump cool air into sealed envelopes, adjusting the thermostat to regulate thermal comfort year-round, often in a climate in which mechanical air conditioning is needed only four months of the year, and during the warmest hours of the day. Inversely, ventilated buildings provide passive cooling in a climate in which the temperature and humidity are often too high for thermal comfort during the same four months of the year. In his book Natural Ventilation in Buildings, Francis Allard points out that the global energy efficiency movement, begun in the early 1990s, has now emerged as a concept that incorporates active air conditioning and sitespecific climate design of buildings into one holistic approach.3 However, these buildings exist in more dry and temperate climates, and do not fully apply to the subtropics as cooling models. A model is needed for subtropical architecture allowing a building to reach both ends of the spectrum; from natural ventilation, through mechanical ventilation, to mechanical air conditioning. The goal of this thesis is to design a hybrid model for subtropical architecture which maximizes the use of natural and mechanical ventilation, and minimizes the use of mechanical air conditioning. The vehicle for this explanation is the design of an educational facility. Research of thermal comfort needs for occupants in the subtropics was accompanied with observation studies. This research was compared with case study, site and program analysis. The analysis was supplemented by a handbook of passive and mechanical cooling which was compiled to aid in establishing cooling strategies for the design process. The implementation of the research and analysis was brought to a conclusion that successfully achieved the goals of this thesis. By using passive methods to lower the temperature of the air surrounding the classroom buildings, the incoming air used to cool the occupants reached temperatures low enough to be considered comfortable inside the classrooms.