In some climate zones (see ASHRAE Table 6.5.6.1), energy recovery may be required for air-handling systems with as little as 30% outside air, reducing the size of a unit that triggers the requirement. Additionally, individual variable air volume (VAV) fans with motors greater than or equal to 10 hp need a variable speed drive (VSD), or another means of reducing fan power consumption. This can be achieved through lower static pressure duct systems, which translates to fewer bends, wider ducts, and shorter runs-all of which impact architectural space planning. Calling for more efficient fans, ASHRAE 90.1-2010 will reduce the amount of fan power allowed to be used in a building. HVAC systems saw the greatest change in ASHRAE 90.1-2010, including alterations to the minimum equipment efficiency ratings, fan power limitations, energy recovery, reheat limitation, economizers, and duct sealing and leakage. Though more significant changes are expected in the 2013 edition, the minimum insulation values for opaque assembles have also increased, depending on the climate. While most new buildings employ this technology as a “sustainable element,” 90.1-2010 made it standard. Automatic daylight controls are required in any space adjacent to a window 250 sq ft or larger.
The air barrier and all the joints on the façade need to be detailed. Assemblies, such as curtainwalls, must be rated to limit air leakage to 0.04 cfm/sq ft. This will further reduce cooling loads and take advantage of southern solar gains when the sun is low in the sky during the winter months, while being able to more effectively shade the high summer sun. While ASHRAE 90.1 previously had no orientation requirements, the 2010 version now requires that buildings be oriented so that more of the glass is distributed across the south façade, minimizing glazing on the east and west walls. And, while the energy cost budget method allows for more flexibility and trade-offs between building systems, it’s likely that the floor-to-ceiling glass tower built just five years ago won’t be able to be replicated, as it’s very difficult to get enough performance out of a floor-to-ceiling glazed curtainwall. Per the prescriptive path, no more than 40% of any surface façade can be fenestration unless the façade can perform as well as a wall that is 40% window or less. Additionally, the early integration of architecture and mechanical, electrical, plumbing (MEP), and fire protection engineering will be inevitable to achieve compliance and optimal envelope performance. Cool roofs are now required in climate zones 1 through 3, while building orientation will play a larger role as well. More insulation and better glass will be required of tomorrow’s building envelope. Here’s a quick look at what’s new and how, where, and when it all applies.
Calling for a 30% energy improvement over the 2004 standard, the law of diminishing returns will begin to come into play as the code authoring committees and designers continue to increase the performance requirements for each new building, squeezing every last kilowatt hour out of the sponge. Today, however, ASHRAE 90.1, with its newest 2010 version, and scheduled for a new release in 2013, stands at a key inflection point. Green Building Council’s LEED also references 90.1, making it one of the most successful and widely adapted energy codes to date. Additionally, the International Energy Conservation Code registers compliance with 90.1 as an alternative way of meeting that code, while the U.S. of Energy to review each new version of Standard 90.1, while requiring all states to adopt energy codes that are substantially equal to the standard as well. In 1992, the Energy Policy Act required the Dept. As ANSI/ASHRAE/IESNA Standard 90.1, Energy Standard for Buildings Except Low-Rise Residential Buildings, has evolved and expanded over time, so has its impact on the industry.