Maximum-Achievable Building Energy Targets Subject of ASHRAE Research

Maximum-Achievable Building Energy Targets Subject of ASHRAE Research

How energy-efficient commercial and multifamily buildings can become in the near future if first cost is not considered was explored in ASHRAE 1651-RP.

Application of 30 specific energy-saving measures across all building types and climate zones resulted in a nearly 50-percent reduction in energy use, research funded by ASHRAE reveals.

The national weighted change is 47.8 percent more energy-efficient than ANSI/ASHRAE/IES Standard 90.1-2013, Energy Standard for Buildings Except Low-Rise Residential Buildings, based on site energy and 47.8 percent more energy-efficient than ANSI/ASHRAE/IES Standard 90.1-2013 based on source energy.

The question of how energy-efficient commercial and multifamily buildings can become in the near future if first cost is not considered was explored in ASHRAE 1651-RP, “Development of Maximum Technically Achievable Energy Targets for Commercial Buildings: Ultra-Low Energy Use Building Set.”

“The value of establishing such ultralow-energy targets for buildings is twofold,” Jason Glazer, principal engineer for GARD Analytics, who oversaw the project, said. “These targets will indicate to building design professionals what may be achieved if first cost is not considered and challenge the creativity of those professionals to achieve similar results in actual designs with the real-world constraints of first costs. They also will help advance design guides, standards, and codes by providing an ultimate goal.”

For the project, researchers assembled a list of energy-efficiency measures that can be included in the design of non-residential buildings. The list included both commonly used and cutting-edge energy-efficiency measures, according to Glazer.

From the list of nearly 400 measures, 30 were chosen for analysis. Sixteen prototype buildings that were consistent with ANSI/ASHRAE/IES Standard 90.1-2013 across 17 climate zones were used as baseline models. The 30 measures then were individually modeled. Each of the 30 measures, often with many options, were applied to each building and climate combination. In general, the measures were applied in the following order:

  1.  Reduce internal loads.
  2.  Reduce building-envelope loads.
  3.  Reduce HVAC distribution-system losses.
  4.  Decrease HVAC-equipment energy consumption.
  5.  Major HVAC reconfigurations.

“It is useful to understand how far energy-efficiency measures can go to reduce the use of energy in the built environment,” Glazer said. “It is also important to understand that many of the measures used in the project are widely available today.”

Each measure was applied to each of the 272 building and climate combinations. If energy consumption was reduced, a measure remained in the model. After all 30 measures were applied, the projected U.S. national weighted energy consumption for new buildings was cut nearly in half compared with ANSI/ASHRAE/IES Standard 90.1-2013.

The 30 energy-efficiency measures modeled were:

  • LED exterior lighting.
  • Highest-efficiency office equipment.
  • High-performance lighting.
  • Shift from general to task illumination.
  • Optimal daylighting control.
  • Optimal roof-insulation level.
  • Optimal choice of vertical fenestration.
  • External light shelves.
  • Daylighting control by fixture.
  • High-performance fans.
  • High-performance ducts to reduce static pressure.
  • Demand-controlled ventilation/carbon-dioxide controls.
  • Multiple-zone variable-air-volume-system ventilation optimization.
  • Optimal water/air cooling coils.
  • Occupant sensors for air-handling equipment.
  • Energy-recovery ventilators.
  • Indirect evaporative cooling.
  • High-efficiency/variable-speed packaged direct-expansion cooling.
  • High-efficiency heat pumps.
  • Ground-source heat pump.
  • High-efficiency variable-speed chillers.
  • Heat recovery from chillers.
  • High-efficiency boilers.
  • High-efficiency building transformers.
  • Chilled/cooled beam.
  • Dedicated outside-air system (DOAS) with heat recovery.
  • Underfloor air distribution.
  • Hybrid/mixed-mode ventilation.
  • Radiant heating and cooling and DOAS.
  • Variable-refrigerant-flow air conditioning.

ASHRAE 1651-RP, Development of Maximum Technically Achievable Energy Targets for Commercial Buildings: Ultra-Low Energy Use Building Set, is available for free to ASHRAE members at www.ashrae.org/freeresources. Members must log in via their member account to access the report for free. The report also is available in the ASHRAE Bookstore for $30 at www.ashrae.org/bookstore.

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