ASHRAE/IES introduce major changes to energy standard

Major changes to requirements regarding building envelope, lighting, mechanical and the energy cost budget are contained in the newly published energy standard from ASHRAE and IES.

ANSI/ASHRAE/IES Standard 90.1-2013, Energy Standard for Buildings Except Low-Rise Residential Buildings incorporates 110 addenda, reflecting changes made through the public review process. Appendix F gives brief descriptions and publication dates of the addenda to 90.1-2010 reflected in this new edition.

“While many things have changed since the first version of Standard 90 was published in 1975, the need to reduce building energy use and cost has not,” Steve Skalko, chair of the committee that wrote the 2013 standard, said. “This standard represents many advances over the 2010 standard, as we worked toward our goal of making the standard 40 to 50% more stringent than the 2004 standard.”

“Achieving the stringency goals established for the 2013 standard presented a challenge in reducing the requirements for lighting,” Rita Harrold, director of technology for the Illuminating Engineering Society of North America, said. “While interior lighting power densities (LPD) were re-evaluated and most lowered, there continues to be an ongoing concern about maintaining quality of lighting installations for occupant satisfaction and comfort while achieving energy savings. The focus in the 2013 standard, therefore, was not just on lowering LPDs but on finding 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. Opaque and fenestration assemblies in Tables 5.5-1 through 5.5-8 are revised in most climates. These changes include:

• Criteria requiring double glazed fenestration in many climates.
• Minimum visible transmittance/solar heat gain coefficient (VT/SHGC) ratio to enable good daylighting with minimum solar gain, while not restricting triple and quadruple glazing.
• Simplification of the skylighting criteria.

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, air conditioners and evaporative condensers. 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. Finally, the 2013 edition completes the work that was begun on equipment efficiencies for chillers in the 2010 edition.

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 modelling. In addition, these sections were revised to enhance capturing daylighting when doing the modelling calculations.

Another important change for the 2013 standard is the first alternate compliance path in Chapter 6. Section 6.6 was added to the 2010 edition to provide a location for alternate methods of compliance with the standard. The first such alternate path has been developed for computer room systems and was formulated with the assistance of ASHRAE technical committee 9.9, Mission Critical Facilities, Data Centers, Technology Spaces and Electronic Equipment. This path uses the power usage effectiveness (PUE) metric established by the datacom industry. This alternate efficiency path format provides a framework that could be considered for other energy using facets of buildings not easily covered in the prescriptive provisions of the standard.

Also new to the standard are requirements for operating escalators and moving walkways at minimum speed per ASME A17.1 when not conveying passengers.