ATLANTA - Heat transfer interactions that occur inside and outside conditioned buildings are highly complex and involve thousands of variables. This creates a challenge not only for designers but also for code officials and other entities when trying to assure the proper care was used in determining the load.

To address this need, a new standard is being developed and may soon be available from the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) and the Air Conditioning Contractors of America (ACCA).

Selected portions of ASHRAE/ACCA Standard 183P, Peak Cooling and Heating Load Calculations in Buildings except Low-Rise Residential Buildings, are open for public comment until Oct. 22. To read those sections or to comment, visit

If the current public review is successful, the standard could be published in early 2007, according to Chris Wilkins, chair of the committee writing the standard.

The proposed standard would establish minimum requirements for both the methods used in peak cooling and heating load calculations and the execution of these methods as they apply to commercial, industrial, and high-rise residential buildings.

"We plan to establish a minimum level that is as inclusive of as many methods as possible while still being restrictive enough to mandate an appropriate level of care and accuracy," Wilkins said.

Guidance on load calculations can be found in the ASHRAE Handbook as well as ACCA's Manual N, which currently are being referenced as the calculation "standards" since no true standard exists, according to Wilkins.

"The Handbook and Manual N are useful but are not written to serve as standards so there was a void," he said. "With publication of this standard, code bodies and other organization will have a true standard to reference that embodies what ASHRAE and ACCA believe is an appropriate level of care in performing load calculations."

Publication date: 10/16/2006