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Energy Manager Q&A

March 21, 2015

Updated ASHRAE standard raises the bar for efficiency in existing buildings.

BUILDINGS editor Chris Olson talks with Rick Hermans about the 2015 update of ASHRAE/ANSI/IES Standard 100, Energy Efficiency in Existing Buildings. Hermans is former chairman of the ASHRAE standards project committee that guided the update.

It has been nine years since the original publication of Standard 100. What factors drove the 2015 update?
The original standard was not widely recognized or adopted. It addressed buildings generally but did not have details for particular building types. The project committee decided that it would be more relevant if the standard used performance metrics, an approach that makes the standard different from other ASHRAE standards like 90.1-2013, Energy Standard for Buildings Except Low-Rise Residential Buildings, which only address new construction and are mostly prescriptive.

The updated standard has established tables with energy use intensity [EUI] targets for 48 nonresidential building types and 5 residential types across 17 climate zones.

How were the EUI targets developed?
We got some help from the DOE and the EIA (Energy Information Administration) by using data from the Commercial Buildings Energy Consumption Survey (CBECS) and Residential Energy Consumption Survey (RECS). Oak Ridge National Laboratory helped produce the EUI tables. Essentially, the top quartile of scores from the survey were used to set the EUI targets. ENERGY STAR ratings have a similar scope; the difference is that those are converted to a scale of 0 to 100. The updated standard sets specific EUIs, which are total energy in BTUs consumed per square foot.

What other key changes are there in the revamped standard?
For buildings larger than 5,000 square feet, it requires a qualified person to be designated as the energy manager who is responsible for energy use in the building. That person must develop and maintain an energy management plan.

The plan covers energy accounting, which includes annual updates of energy use and audit reports. It outlines ongoing commissioning efforts and documents the number of occupants and weekly operating hours. It also explains how the benefits of efficiency are communicated to occupants and contains an operations and maintenance program.

The standard identifies an extensive list of potential energy efficiency measures that building owners can use to improve the energy efficiency of their buildings based upon ROI or lifecycle cost.

As the standard moved forward through the public review process, were there changes or additions made?
To keep it simple, the committee initially restricted the standard to building site energy use that could easily be established from utility bills and compared against the target numbers, recognizing that the CBECS and RECS data is site based. There were concerns raised during the public review about excluding source energy and the impact of generating and transporting energy to a building. As a result, we added an option for adopting authorities to revise the EUI tables based on the source of energy.

The committee is continuing to address the source energy issues as well as other issues such as how to address combined heat and power systems or district energy.

For building owners and facility managers, what would you say are key general principles that the standard promotes?
Being knowledgeable about your consumption is No. 1. As a building owner and manager, you need to know how much you’re using and where it’s being used. Keep records and read your own meter. Don’t only depend on the utility to read your meter for you. More states and municipalities are mandating energy disclosure, which is something that you can prepare for by becoming knowledgeable about your consumption.

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