New Air-Conditioning Design Standard Could Help Cool Green Buildings

July 7, 2009

Building occupants, who may soon feel cooler from increased air movement, can thank a committee of building science specialists. The committee in charge of ANSI/ASHRAE Standard 55 - Thermal Environmental Conditions for Human Occupancy (after months of study and discussion) has voted recently to allow increased air speed as an option for cooling building interiors (increased air speed is the equivalent of turning up the fan).

The new ruling promises greater flexibility for designers and retrofitters of green buildings, who now may be able to increase the use of fan cooling and reduce energy-intensive air-conditioning.

Standard 55 is one of several important industry standards that influence building mechanical codes and criteria for independent green building rating systems, such as USGBC’s Leadership in Energy and Environmental Design (LEED). Standard 55 sets the range of temperature and other thermal environmental conditions that are intended to satisfy building occupants. 

As chair of the Standard 55 committee, Constructive Technology Group’s (CTG) Stephen Turner was instrumental in helping make these important changes to the standard. As a fellow committee member, CTG’s Sahar Abbaszadeh also helped the committee develop and adopt the update. The Center for the Built Environment (CBE) at UC Berkeley; its director, Dr. Edward Arens; and researcher Hui Zhang led key research efforts and were major contributors to the changes to the standard. 

Turner and Abbaszadeh, and their industry colleagues, analyzed research studies that conclude that elevated air speeds in warm and slightly warm conditions can provide the same level of comfort as cooler conditions without air movement. The practical implication of these findings is that air movement through the use of ceiling fans, stack effect (natural airflow), or operable windows can be used to reduce the need (and/or the running time) for energy-intensive cooling systems. 

According to Turner, “The changes to Standard 55 are a huge step toward enabling high-performance building design. Architects and engineers now have fewer barriers to design and deliver sustainable buildings that achieve maximum occupant comfort as well as increased energy efficiency.”

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