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HVAC Efficiency and the 75F Health Check

Aug 4, 2017 4:58:04 PM

Commercial new-builds, renovations and building additions in the U.S. must comply with ASHRAE Standard 90.1-2016, which achieves about 8.2% energy cost savings on average, nationally, according to the U.S. Department of Energy (DOE). That's the minimum standard for new construction! We can do better.

Also according to DOE, U.S. commercial building owners could save an average of 38% on heating and cooling costs with energy efficient HVAC control systems. HVAC-related savings potential ranges from 22% to 56%, depending on building size, building use, regional climate and local utility costs. The country's commercial buildings need a health check!

HVAC System Efficiency in Commercial Buildings

According to the most recent Commercial Building Energy Consumption Survey (CBECS) completed by the U.S. Energy Information Administration (EIA) in 2012, the efficiency of space heating in U.S. commercial buildings has improved significantly since the last CBECS in 2003. However, energy use for ventilation and cooling has risen significantly as compared to 2003.

U.S. Energy Iinformation Administration CBECS space heating energy use comparison between 2003 and 2012

Clearly, progress is possible, but more work must be done in the HVAC industry, and building owners must invest in smarter building controls to achieve greater efficiency. The good news is that investment in truly proactive and smart building controls can be paid off in three years or less, in many cases. From then on, the energy cost savings and extended equipment life from greater efficiency will be icing on the cake, adding to ROI.

Space heating, ventilation and cooling (essentially, HVAC) energy use comprises over 40% of U.S. commercial building energy use, according to the EIA survey. Thus, the 30% to 50% reduction in HVAC, lighting and major appliance energy use achievable with a 75F building automation system (BAS) can reduce annual average building energy consumption between 15% and 30%, depending on building size, building use, regional climate and local utility costs.

U.S. Energy Information Administration 2012 CBECS space heating compared to overall building energy use

On July 25, 2017, the DOE determined commercial buildings in compliance with ASHRAE Standard 90.1-2016 nationally would achieve, on average:

  • 8.2% energy cost savings
  • 7.9% source energy savings
  • 6.7% site energy savings

ASHRAE Standard 90.1-2016 is the minimum standard for new construction, renovation and building additions. It addresses building systems such as building envelope, lighting (exterior and interior), HVAC equipment and system efficiency, service water heating, and system controls. It also sets minimum energy efficiency and system design requirements.

Most HVAC systems in the U.S. use rooftop units (RTUs), heat pumps, furnaces, boilers and chilling towers that are 20% to 25% oversized. This is to be prepared for the 1% of time each year that the HVAC system must run at full capacity due to maximum building occupancy or weather conditions. However, a significant amount of energy can be saved by "right-sizing" HVAC equipment (installing equipment that operates more efficiently and less costly).

According to the Whole Building Design Guide, a program of the National Institute of Building Sciences, most HVAC systems regularly operate at 50% or less of capacity. Therefore, right-sizing combined with smart HVAC controls that optimize systems for free cooling, indoor air quality and comfort can achieve efficiency gains that far exceed those estimated by the DOE's final determination of ASHRAE Standard 90.1-2016.

Stay tuned for Part 2 of our discussion on HVAC efficiency and cost savings to learn about the capabilities of the 75F Health Check.

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