New Commercial HVAC Standards Promote Part-Load Efficiency for Split, Package & Rooftop Systems

Commercial HVAC Applications: Navigating Through a Period of Change

Significant changes are coming to ANSI/ASHRAE/IES Standard 90.1-2010, which is the energy standard that covers most commercial buildings.  Contractors and facility managers should be aware of the impact of these higher requirements and of the many ways to reduce building energy use and costs.  The 2013 standard will be 40-50 percent more stringent than the 2004 standard.

The energy cost goals for the 2013 standard are:

  • Regulated Loads only – 50 percent reduction
  • Whole building – 40 percent reduction, which includes all energy end uses

The ASHRAE 90.1 standard offers specific recommendations for reducing building energy costs and defines several concepts that equipment manufacturers will work toward.  One of these is IEER, or Integrated Energy Efficiency Ratio.  IEER is a measure that expresses cooling part-load EER efficiency for commercial air-conditioning and heat pump equipment on the basis of weighted operation at various load capacities.  IEER essentially replaces the metric Integrated Part Load Value (IPLV) as the part load energy efficiency descriptor for all commercial unitary products rated above 65,000 Btu/h.

In conjunction with the new standard and energy metrics, the Department of Energy joined industry partners in the Better Buildings Alliance to release a design specification for 10-ton capacity commercial air conditioners, also known as rooftop units (RTUs). The specification was a part of the High Performance Rooftop Unit Challenge initiative, to urge U.S. manufacturers to build and deliver innovative, competitively-priced, energy-saving rooftop units that meet the Commercial Building Energy Alliance-driven requirements for high-performance specification.

Units built according to the High Performance Rooftop Unit Specification are expected to reduce energy use by as much as 50 percent compared to the current ASHRAE 90.1 standard, depending on location and facility type. According to the Department of Energy, nearly half of the cooling-conditioned commercial floor space in the U.S. features rooftop units. Businesses nationwide would save roughly $1 billion each year collectively in energy costs if they replaced their 10- to20-ton commercial units with units that meet this specification.

One of the industry leading OEMs 10-ton unit exceeds the parameters of the RTU Challenge, providing an Integrated Energy Efficiency Ratio of 20.8 – more than 15 percent more efficient than the required minimum of 18.0 IEER.

For more information on the new ANSI/ASHRAE/IES Standard 90.1-2013, visit


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