A new standard for the design of high performance green buildings is set to revolutionize the building industry. Published by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), in conjunction with the Illuminating Engineering Society of North America (IES) and the U.S. Green Building Council (USGBC), Standard 189.1, Standard for the Design of High Performance, Green Buildings Except Low-Rise Residential Buildings, is the first code intended commercial green building standard in the country.
The new standard was developed over 3.5 years using the ASHRAE consensus process. Many federal agencies, state agencies, and local jurisdictions prefer to adopt consensus standards—those developed using ANSI procedures. (Leadership in Energy and Environmental Design, also known as LEED, is not an ANSI consensus standard.)
Another difference between LEED and 189.1 is that 189.1 is not a point system. Instead, it provides minimum requirements that must be met.
A frequent approach to meeting point systems is to garner as many of the least expensive points as possible. For standard 189.1, all of the mandatory requirements must be met, and then either the prescriptive or performance requirements must be met.
The prescriptive requirements specify a relatively simple method for showing compliance that generally involves little or no calculations. The performance path specifies an alternate method for showing compliance that is typically more complex than the prescriptive path.
Unlike a point system, where certain points can be avoided, standard 189.1 requires that criteria in all areas be met. The standard allows some choices and flexibility in the form of alternative paths or exceptions.