Revised ASHRAE Standard Helps to Compare Building Energy Performance

ATLANTA—When it comes to the how-to of measuring a building’s energy use, there is much to take into consideration. Are the measurements of a building’s area—used in the equation to derive energy use per square foot—to be taken from the exterior dimensions or to the centerline of the wall? Since they are normally unoccupied, are storage spaces to be included or not?

The newly revised ANSI/ASHRAE Standard 105-2014, Standard Methods of Determining, Expressing, and Comparing Building Energy Performance and Greenhouse Gas Emissions, supports commonality in reporting the energy performance of existing or proposed buildings to provide a consistent method of measuring, expressing and comparing the energy performance of buildings.

“A standard method of measurement is needed in order to be able to compare one building's energy use to another,” Keith Emerson chair of the Standard 105 committee, said. “For instance, comparing one building's summer energy use to another building's winter use would be comparing apples and oranges.”

According to Emerson, the new edition of Standard 105 now includes procedures for going beyond site energy to calculate the impact of building energy use on primary (source) energy and greenhouse gasses.

It also provides a common basis for reporting building energy use in terms of delivered energy forms and expressions of energy performance; for comparing design options; and for comparing energy performance in terms of energy resources used and greenhouse gas emissions created, both across buildings and for energy efficiency measures within buildings.

“To keep the standard flexible, a number of decisions are left to those who adopt it, including what should be calculated beyond site energy and the multipliers for those additional calculations,” Emerson said.

[an error occurred while processing this directive]Primary energy and greenhouse gas equivalence conversion factors have been left to the discretion of the adopting agencies and authorities, which are available from a number of sources, including an informative appendix in the standard. The standard has also been upgraded to code enforceable language.

The cost of Standard 105-2014, Standard Methods of Determining, Expressing, and Comparing Building Energy Performance and Greenhouse Gas Emissions, is $58 ($48 ASHRAE members). To order, contact ASHRAE Customer Contact Center at 1-800-527-4723 (United States and Canada) or 404-636-8400 (worldwide), fax 678-539-2129, or visit www.ashrae.org/bookstore.

ASHRAE, founded in 1894, is a building technology society with more than 50,000 members worldwide. The Society and its members focus on building systems, energy efficiency, indoor air quality, refrigeration and sustainability. Through research, standards writing, publishing, certification and continuing education, ASHRAE shapes tomorrow’s built environment today.