Three years of hard work, characterized by widespread building industry collaboration, has resulted in the first comprehensive U.S. commercial green building standard accredited by the American National Standard Institute (ANSI) and intended for adoption into local codes. The Standard may also be used by utility programs and green building rating systems prior to code adoption.

On January 22, 2010, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), with the Illuminating Engineering Society of North America (IES) and the U.S. Green Building Council (USGBC), published Standard 189.1, Standard for the Design of High-Performance, Green Buildings Except Low-Rise Residential Buildings, a compilation of criteria that must be met in order to be considered a “green” building. These criteria include the same topic areas found in most green building rating systems: site, water use, energy, indoor environment, and building impact on atmosphere, materials, and resources.

As a standard, minimum performance levels, for all criteria, must be achieved. Standard 189.1 includes an energy efficiency goal to achieve a minimum 30 percent reduction in energy cost over that in ANSI/ASHRAE/ANSI Standard 90.1-2007 (the current version). Energy Efficiency, Section 7 of Standard 189.1, addresses seven major categories: envelope requirements, on-site renewable energy systems, mechanical equipment efficiencies, ventilation, energy consumption data collection, peak load control, and lighting.

• Envelope requirements are built upon those in 90.1-2007, with fenestration orientation requirements to reduce solar gain from the east and west in specific climate zones, and with an added requirement for a continuous air barrier to reduce air leakage.
• The standard requires building design to facilitate future installation of onsite renewable energy systems. A prescriptive path option requires renewable system installation at the time of construction. (Both of these options provide an exception if the building is in a location with poor incident solar radiation).
• Minimum mechanical equipment efficiencies are set assuming integration with on-site renewable energy production. If mechanical equipment efficiencies are increased to meet ENERGY STAR or other more stringent requirements, then renewable energy requirements are reduced.
• Demand control ventilation is required for densely occupied spaces and fan power is limited to 10 percent below the limitations specified in Standard 90.1.
• Daily energy consumption data, including hourly use profiles, must be collected and retained for at least three years. Depending upon project energy use, there are additional thresholds that require data collection and storage for various energy subsystems.
• Demand limiting or load shifting capabilities are required to reduce peak electric demand by at least 10 percent.

Complete information on the standard, including a readable on-line copy, may be found at www.ashrae.org/greenstandard.