Standard could complicate heating and cooling calculations for small buildings, according to the ACCA.

ARLINGTON, Va. - The Air Conditioning Contractors of America has announced its opposition to a proposed ASHRAE standard on commercial-load calculations.

The American Society of Heating, Refrigerating and Air-Conditioning Engineers' proposed standard, "Procedures for Performing Peak Heating and Cooling Calculations in Buildings Except Low-Rise Residential Buildings," contains significant flaws in its approach to small commercial buildings, according to the ACCA. The association said it believes that procedures that may be acceptable for large buildings are not fully appropriate or practical for small buildings.

"Rather than satisfying a real industry need, the proposed standard significantly increases liability exposure of HVAC contractors, engineers, and other professionals who undertake small building load calculations," said Greg Leisgang, chairman of the ACCA board of directors. "Additionally, ASHRAE's proposal effectively precludes the use of many of today's calculation procedures that are widely accepted and practiced by design professionals in the light commercial sector."

According to Chris Wilkins, chairman of the committee writing the ASHRAE standard, it would establish minimum requirements for the methods used to determine peak heating and cooling loads.

"The biggest challenge is allowing for enough flexibility that an engineer can choose the appropriate tool for calculating the load while at the same time being strict enough that an appropriate level of accuracy is attained for all methods," he said.

The ASHRAE standard primarily addresses methods for determining the peak-cooling load, both manual and otherwise. It requires that calculations for cooling loads be performed in appropriate months and times of the day and sets criteria for the use of weather data, external heat gains from fenestration, opaque building enclosures and infiltration and internal heat gains.

The proposed ASHRAE standard requires numerous calculations, according to the ACCA. The association said it believes that for large commercial buildings, some of the guidelines in the standard are appropriate. However, for small buildings, the ACCA said it is necessary that the procedures be simplified.