New air-conditioning design standard allows for increased air speed to cool building interiors

August 11, 2010

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, has voted recently to allow increased air speed as an option for cooling building interiors.  In lay terms, 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 which influence both 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.  ANSI is the American National Standards Institute.  ASHRAE, ANSI’s accredited developer for this and related standards, is the American Society of Heating, Refrigeration, and Air-Conditioning Engineers, which among other activities establishes best practices and national standards for many energy-consuming systems in buildings. 

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, Ph.D, and researcher Hui Zhang, Ph.D. led key research efforts and also were major contributors to the changes to the Standard. 

Turner, Abbaszadeh, and their industry colleagues analyzed research studies which 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 air flow), 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 towards enabling high performance building design.  Architects and engineers now have fewer barriers to design and deliver sustainable buildings which achieve maximum occupant comfort as well as increased energy efficiency.”

With the support of CTG Energetics, Inc., and its parent company Constructive Technologies Group, Inc., Stephen Turner chairs and oversees updates to the ASHRAE Standard 55 Thermal Environmental Conditions for Human Occupancy.  Turner also chairs the ISO technical committee for ISO/TC 205, Building environment design, which has just published a new energy efficiency standard. Turner is a member of the Rhode Island State Building Code Board and chairs their Energy Code Subcommittee.  Turner is a professional engineer licensed in New York state.

About CTG:
Founded in 1997, CTG (www.ctg-net.com) is a group of multi-disciplinary technical consulting firms dedicated to innovative problem-solving in the built environment.  The Energetics group focuses on sustainability and energy efficiency in buildings and communities.  The Forensics group provides expert testimony for the resolution of construction and design-related disputes in the mechanical, electrical, plumbing, cost estimating and scheduling disciplines.

         
 

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