by Brianna Crandall — February 21, 2014—A new federal analysis has demonstrated that the requirements of the 2013 revision of the industry-leading energy standard recently published by building technology society ASHRAE (formerly the American Society of Heating, Refrigerating and Air Conditioning Engineers) and the Illuminating Engineering Society (IES) will result in buildings that could achieve six to eight percent more efficiency than buildings built to the 2010 standard.
Published in October 2013, the updated ANSI/ASHRAE/IES Standard 90.1-2013, Energy Standard for Buildings Except Low-Rise Residential Buildings, provides minimum requirements for the energy-efficient design of buildings except low-rise residential buildings. In support of the U.S. Department of Energy’s Building Energy Codes Program, the federal lab Pacific Northwest National Laboratories (PNNL) conducted the energy savings analysis on 110 addenda included in the standard.
PNNL’s analysis shows that the site and energy cost savings are 37.7% and 37.8%, respectively, by using the 2004 standard as baseline for the regulated loads only. For the whole building energy consumptions, national aggregated site energy savings are 29.5% and energy cost savings are 29.0%. On a nationally aggregated level, building-type energy savings range from 19.3% to 51.9% and energy-cost savings from 18.6 to 50.6%. These figures include energy use and cost from the whole building energy consumptions including plug and process loads.
For PNNL’s extensive analysis, 16 different building prototypes were modeled in 17 different climate locations for a total of 272 building types and climate zone combinations. The energy reduction was achieved through 33 addenda related to major changes to requirements regarding building envelope, lighting, mechanical, and the energy cost budget. The most significant changes are:
- Building Envelope: Opaque elements and fenestration requirements were 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 were 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: These 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. 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.
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 was developed for computer room/data center systems using the Power Usage Effectiveness (PUE) metric established by the datacom industry. ASHRAE notes that this alternate compliance path could be used as a framework to provide alternate paths for other energy-using facets of buildings not easily covered in the prescriptive provisions of the standard.
The standard is written in mandatory code language and offers regulatory code bodies the opportunity to make a significant improvement in the energy efficiency of new buildings, additions and major renovations, concludes ASHRAE.
