The code has multiple compliance paths – from the simple, prescriptive compliance approach (checklist) to complex building energy simulations (performance-based compliance). When the prescriptive levels change (efficiency levels are increased) a new bar is also established for those seeking to use the more complicated energy simulation tools. The changes are climate zone and building type specific.
The ASHRAE 90.1 Standard addresses building envelope and system requirements for commercial buildings, residential buildings higher than three stories, and semi-conditioned buildings (warehouses, etc.). It is the nation’s model standard for establishing the energy performance requirements of these building types.
Many states still recognize and use ASHRAE Standard 90.1-2004 which has been the energy code referenced in the International Building Code (IBC) and the International Energy Conservation Code (IECC). As such, this standard defines code minimums for the classes of constructions covered.
In 2007, for the first time in over 19 years, ASHRAE (The American Society of Heating, Refrigerating and Air-Conditioning Engineers) increased the minimum required prescriptive R-value (resistance to heat flow) for roof and wall insulation levels in Standard 90.1– the national model energy code for commercial buildings.
The above-deck roof insulation requirements - previously at R-15 - went to R-20, an increase of 33%, in every climate zone in the U.S. Similar increases were approved for walls. The increased roof and wall insulation values apply to all commercial and high-rise residential buildings covered by Standard 90.1. These changes now become a part of the newest edition of the Standard – 90.1-2007.
The International Energy Conservation Code (IECC) is being adopted rapidly by state and local code jurisdictions across the United States. The IECC incorporates the ASHRAE 90.1-2007 standard, offering both prescriptive and performance-based approaches.
The newly approved ASHRAE Standard 189.1 - 2009 became the first Standard for the Design of High-Performance Green Buildings Except Low-Rise Residential Buildings, providing minimum requirements for the design of sustainable buildings to balance environmental responsibility, resource efficiency, occupant comfort and well-being, and community sensitivity. ASHRAE Standard 189 uses the U.S. Green Building Council’s LEED Green Building Rating System as a key resource offering a baseline that will drive green building into mainstream building practices.
The next standard of code compliance will be ASHRAE 90.1 - 2010. The requirements for commercial roofs with polyiso insulation are expected to range from R-20 in the southeast to R-35 in the far north. ASHRAE has set aggressive goals for improved energy conservation in the nation’s energy performance standard for commercial buildings – targeting a 30% improvement in efficiency for the 2010 version of the standard.