Changes to help make buildings and systems more sustainable are part of the newly published version of the high performance green building standard from ASHRAE, the U.S. Green Building Council (USGBC), and the Illuminating Engineering Society (IES).
ANSI/ASHRAE/USGBC/IES Standard 189.1-2011, Standard for the Design of High-Performance, Green Buildings Except Low-Rise Residential Buildings, provides a foundation for those seeking to design, build, and operate high performance buildings. It covers key topic areas of site sustainability, water use efficiency, energy efficiency, indoor environmental quality, and the building’s impact on the atmosphere, materials, and resources. When first introduced in 2009, the standard was the first code intended commercial green building standard in the United States.
“Since Standard 189.1 was first published, we have received much input from the industry offering suggestions on how to strengthen it in all areas,” chair Dennis Stanke said. “This 2011 version incorporates much of that input. More importantly, the 2011 version incorporates updated connections to its referenced standards—primarily ANSI/ASHRAE/IES 90.1-2010 and ANSI/ASHRAE 62.1-2010. Compliance with these updated provisions will result in further improvements to indoor environmental quality, while further reducing energy use and environmental impact through high-performance building design, construction, and operation.”
New Energy Requirements
The most significant change in energy related provisions results from new requirements in ANSI/ASHRAE/IES Standard 90.1-2010, Energy Standard for Buildings Except Low-Rise Residential Buildings, adding to and superseding requirements in the 2007 version. In October 2011, the U.S. Department of Energy found that the 2010 version of Standard 90.1 contains significant energy savings over the 2007 standard. The energy savings in the Standard 90.1-2010 provisions also result in energy savings for building projects complying with Standard 189.1, according to Stanke.
In addition, mandatory and prescriptive renewable energy requirements were clarified to reduce confusion and simplify calculations; now both mandatory provisions to prepare for on-site renewable energy and provisions to produce prescribed levels of renewable energy must be met. Additionally, buildings that meet the prescriptive requirement for renewable energy production are now deemed to comply with the mandatory requirement for renewable energy site preparation.
The standard also updates the performance option for energy efficiency (Appendix D) so that it refers to Appendix G of Standard 90.1-2010, which is now a normative appendix. Appendix G of 90.1 applies to projects seeking to reduce annual energy cost more than would be possible by merely meeting the requirements of that standard. Appendix D in Standard 189.1, on the other hand, provides a performance option for compliance as an alternative to the less complex prescriptive option; it must show that the project design results in annual energy cost equal to or less than would be possible by meeting the mandatory plus prescriptive requirements of the standard, according to Stanke.
Additional changes to the 2011 standard include:
- More stringent Lighting Power Density allowances due to the change in reference to Standard 90.1-2010. Both interior and exterior values are now set as a percentage of the Standard 90.1 allowances, based on building, space or area type.
- Automatic controls are now required for lighted signs visible during daytime hours; controls must reduce the lighting power to 35% of full power. For other outdoor signs, automatic controls must now turn off lighting during daytime hours and reduce the lighting power to 70% of full power after midnight.
- Open-graded (uniformed size) aggregate and porous pavers (e.g., open-grid pavers) qualify as a hardscape surface for heat island mitigation with no further testing. Permeable pavement and permeable pavers must meet a minimum percolation rate rather than a minimum solar reflectance index (SRI).
Standard 189.1 is currently a jurisdictional compliance option in the International Green Construction Code developed by the International Code Council, ASTM International, and the American Institute of Architects.
The cost of ANSI/ASHRAE/USGBC/IES Standard 189.1-2011, Standard for the Design of High-Performance, Green Buildings Except Low-Rise Residential Buildings, $119 ($99 ASHRAE members).