New requirements regarding air speeds, analysis, and documentation are included in the newly published American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) thermal-comfort standard, ANSI/ASHRAE Standard 55-2010, Thermal Environmental Conditions for Human Occupancy.
“The standard continues to focus on defining the range of indoor thermal environmental conditions acceptable to a majority of occupants, while also accommodating an ever increasing variety of design solutions intended to provide comfort and to respect today’s imperative for sustainable buildings,” Stephen Turner, Standard 55 Committee member, said.
The standard specifies the combinations of indoor thermal environmental factors and personal factors that will produce thermal environmental conditions acceptable to a majority of occupants within a space.
Standard 55 incorporates recent research innovations, such as the use of elevated air speeds, to widen the acceptable range of thermal conditions. The standard previously allowed modest increases in operative temperature beyond the predicted mean vote/percentage of persons dissatisfied (PMV/PPD) limits as a function of air speed and turbulence intensity.
The standard also includes a new method for determining the cooling effect of air movement above 30 fpm. This allows ceiling fans, or other means of elevating air speed, to provide comfort at higher summer temperatures than were permissible previously. New provisions based on field-study research allow elevated air speed to broadly offset the need to cool air in warm conditions, replacing requirements that originated primarily from climate chamber studies.
Another revision makes clearer the mandatory minimum requirements for analysis and documentation of a design to show that it meets the standard’s requirements. Additionally, a compliance form for documentation of design is included in an appendix. The compliance template mirrors the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) template for the thermal-comfort design credit in LEED New Constuction-2009.
The cost of Standard 55 is $69 ($59, ASHRAE members). To order, contact ASHRAE Customer Service at 1-800-527-4723 (United States and Canada) or 404-636-8400 (worldwide), fax 404-321-5478, or visit www.ashrae.org/bookstore.