The Act requires all states to certify that they have state energy codes in place that are at least as stringent as 90.1-2004, or justify why they cannot comply.
"The quantitative analysis of the energy consumption of buildings built to Standard 90.1-2004, as compared with buildings built to Standard 90.1-1999, indicates national source energy savings of approximately 13.9 percent of commercial building energy consumption. Site energy savings are estimated to be approximately 11.9 percent," says the ruling published by the Federal Register on Dec. 30, 2008.
The DOE noted that the newer version of the standard contained 13 positive impacts on energy efficiency. These impacts included changes made through the public review process in which users of the standard comment and offer guidance on proposed requirements to the standard. The positive impacts include:
- Removed explicit allowance for supply air into non-occupied isolation areas.
- Limitations of the use of dampers in closed-circuit cooling towers in place of water bypass valves and piping.
- Additions of insulation requirements for buried ductwork.
- Mapping of envelope requirements to new climate zones, which led to greater geographic expansion of economizer requirements.
- Addition of requirements for ventilation fan controls.
- Lowered size range for part-load fan power limitation.
- Addition of requirements for heat pump pool heaters.
- Complete replacement of interior lighting power density allowances.
- Revised exterior lighting power density allowances.
- Addition of occupancy sensor requirements for classrooms, meeting, and lunch rooms.
- Lower retail sales lighting power allowance.
- New exit sign wattage requirement.
In addition, AHRAE is working on providing more stringent energy guidance in a proposed standard for high-performance buildings. Being developed in partnership with IESNA and the U.S. Green Building Council, Standard 189.1, Standard for Design of High-Performance Green Buildings Except Low-Rise Residential Buildings, will provide minimum requirements for the design of high-performance new commercial buildings and major renovation projects, addressing energy efficiency, a building's impact on the atmosphere, sustainable sites, water use efficiency, materials and resources, and indoor environmental quality.