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

“The value of establishing such ultra-low-energy targets for buildings is two-fold,” said Jason Glazer, principal engineer for GARD Analytics who oversaw the project. “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 resulting list of almost 400 measures, 30 were chosen for additional analysis.  Sixteen prototype buildings that were consistent with Standard 90.1-2013, Energy Efficiency Standard for Buildings Except Low-Rise Residential, 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:

•  Reduce internal loads

•  Reduce building envelope loads

•  Reduce HVAC distribution system losses

•  Decrease HVAC equipment energy consumption

•  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.”

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

The 30 energy efficiency measures modeled were:

• LED exterior lighting

• Highest efficiency office equipment

• High performance lighting (LED)

• 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/CO₂ controls

• Multiple-zone VAV 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 DX cooling

• High efficiency heat pumps

• Ground source heat pump

• High efficiency and variable speed chillers

• Heat recovery from chillers

• High efficiency boilers

• High efficiency building transformers

• Chilled/cooled beam

• Dedicated outside air system with heat recovery

• Underfloor air distribution

• Hybrid/mixed mode ventilation

• Radiant heating and cooling and DOAS

• Variable refrigerant flow air conditioning

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