ANSI/ASHRAE/IES Standard 90.1-2013, Energy Standard for Buildings Except Low-Rise Residential Buildings, incorporates 110 addenda. These reflect changes made through the public review process by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE).
The standard was last revised in 2010, and the new version represents a standard 40 to 50 percent more stringent than the 2004 version.
Major changes to requirements for building envelope, lighting, mechanical and the energy cost budget are included.
Meeting the lighting goals was most problematic because of concerns expressed about maintaining quality of lighting installations for occupant satisfaction and comfort while achieving energy savings. The focus in the 2013 standard is to find ways to achieve savings by adding more controls and daylighting requirements as well as including lighting limits for exterior applications based on jurisdictional zoning.
The most significant changes are:
- Building Envelope: Opaque elements and fenestration requirements have been revised to increase stringency while maintaining a reasonable level of cost-effectiveness.
- Lighting. Changes include improvements to daylighting and daylighting controls, space-by-space lighting power density limits, thresholds for toplighting and revised controls requirements and format.
- Mechanical: Equipment efficiencies are increased for heat pumps, packaged terminal air conditioners, single package vertical heat pumps and air conditioner evaporative condensers. Also, fan efficiency requirements are introduced for the first time. Additional provisions address commercial refrigeration equipment, improved controls on heat rejection and boiler equipment, requirements for expanded use of energy recovery, small motor efficiencies and fan power control and credits. Control revision requirements have been added to the standard such as direct digital controls in many applications.
- Energy Cost Budget (ECB) & Modeling: Improvements were made to the ECB and Appendix G provisions to clarify the use of the prescriptive provisions when performing building energy use modeling.
Standard 90 was first published in 1975.