First alternative compliance path in ASHRAE 90.1-2013

The American Society for Heating Refrigerating and Air Conditioning Engineers and the Illuminating Engineering Society have issued ASHRAE/IES Standard 90.1-2013, their new Energy Standard for Buildings Except Low-Rise Residential Buildings.

The standard includes 110 addenda made since the 2010 version. It aims at being 40-50% more stringent than the 2004 standard.

While the standard has lowered lighting power densities, Rita Harrold, director of technology for IES, noted that because of concerns about lighting quality and occupant comfort they had also looked for ways to save energy by adding controls and more daylighting requirements, and limiting exterior lighting.

An important change for the 2013 standard is the first alternate compliance path. (Section 6.6 was added to the 2010 edition to provide a location for alternate methods of compliance.) This first 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

In the mechanical equipment area, the standard increases efficiencies for heat pumps, packaged terminal air conditioners, single package vertical heat pumps and air conditioners evaporative condensers.

Requirements for fan efficiency have been introduced, and there are new provisions for commercial refrigeration equipment, improved controls on heat rejection and boiler equipment, and requirements for expanded use of energy recovery.

Changes were also made to Energy Cost Budget (ECB) and Appendix G to clarify the use of the prescriptive provisions for building energy use modeling. In addition, these sections were revised to enhance capturing daylighting when doing the modeling calculations.

The standard now requires escalators and moving walkways to operate at minimum speed per ASME A17.1 when they are not conveying passengers.

And for the building envelope, there are revisions to fenestration requiring a 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. Also, skylight criteria have been simplified.

To obtain the standard, click here.