ASHRAE Standard 105 provides a method of energy performance determination, expression, and comparison in mandatory language that can be applied to any building. It is intended to provide 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. The standard provides a great deal of flexibility for adopting agencies and authorities.

The 2014 edition of Standard 105 supplements site energy measurements with methods of determining primary energy and greenhouse gas emissions at the option of the adopting authority. Primary energy and greenhouse gas equivalence conversion factors have been left to the discretion of the adopting authority.

Standard 105 is accompanied by downloadable supplemental files that include the forms shown in Normative Appendices A, B, C, D, E, and F.