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Numbers to know: A look at the costs of commercial ZEBs

By Joe Salimando

Released this past March, “Getting To Zero 2012 Status Update: A First Look at the Costs and Features of Zero Energy Commercial Buildings” is a report from New Buildings Institute (NBI), available online at no cost.

If NBI rings a bell, it was its study of LEED buildings in 2008 that revealed some were energy hogs. The study was used both by USGBC on its website and by LEED opponents.

Background

Zero-energy buildings are part of California’s and the U.S. government’s official plans. That’s why this report may be said to be an “early warning” indicator for electrical distributors.

Zero-energy types have their own terminology. Three of the 47 pages in the report offer a glossary. Among other terms:

  • Zero-energy buildings (ZEB). You’ll also find NZEB with the “N” standing for net.
  • Zero-energy-capable buildings (ZEC)
  • Energy use intensity (EUI)—expressed as thousands of Btus used by a given building, per square foot, per year. (See graphic below). Note that, while it’s not in the report’s caption, the numbers below are in kBtu per square-food per year.

Lighting is the star

While you hear a lot about HVAC systems and building envelope stuff in ZEB conversations, the report can be said to put the electrical industry front-and-center.

Above: A graphic, “Technologies used in ZEB and zero-energy-capable buildings.” HE stands for high efficiency.

As shown, on the projects studied, the use of daylighting (which requires sophisticated lighting controls, at the very least) and HE lighting are the ones NBI found most prevalent. The least prevalent is UFAD, or, under floor air distribution.

Key findings

Among other things:

  • Most ZEBs identified in the NBI study are “small or very-small buildings.”
  • Solar PV panels provide the energy input to all building studied.
  • What happens when someone tries to use the ZEB approach to a larger office building? According to NBI, “Minimizing plug load and other miscellaneous or ‘unregulated’ loads is a priority.” Does this mean fewer receptacles installed in a commercial building? It’s not clear.
  • NBI seems to retain its realistic approach. Two examples from the report:
    • 29 buildings were found “that claimed to be possible ZEB or ZEC.” But the facts could not be verified. Data from these buildings were not included in the study.
    • Do higher costs for ZEB design seem likely? NBI said, “the few reported ZEBs appear to show lower overall incremental costs than the modeled estimates, possibly due to trade-offs with other features in the design and construction process.” Costs for ZEB design (the premium) run, NBI said, from 0% to 10%.

Footnote

A ZEB is not necessarily a building that never draws on the local electric utility. It is, instead, one which—over a year’s time—feeds as much power into the grid as it uses. According to NBI, “The ZEB concept provides…a pathway that moves commercial buildings from current standard design practice to deep energy efficiency.”

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