What is a "Net-Zero" Energy Building?

Some of you may have heard the term "Net-Zero Energy" building. But just what is a Net Zero Energy building? Simply defined, a Net-Zero Energy building is a structure that produces as much, or more energy than it consumes - as calculated and averaged over a 12-month period [1]

As you might expect, the monthly utility bill savings for such a facility can be significant. Preposterous you say? It's more than just a theory. Net-Zero energy buildings are a reality - though admittedly, still somewhat of a challenge to design. Currently there are only 21 recognized Net-Zero Energy buildings in the US, though several more with the potential of achieving this rare distinction [2].

Net Zero Energy San Luis National Wildlife Refuge
In one sense, designing a Net-Zero Energy building could simply be a matter of loading up an otherwise conventionally energy-inefficient building with power-producing photovoltaic panels. If the energy produced by those panels over a year is greater than the net amount of energy consumed by the building over the same year, then voila, you've got yourself a Net-Zero Energy building. Fortunately, that's almost never done, as the cost of installing the photovoltaics needed to offset such careless, high-energy use would be prohibitively expensive.

In most cases, Net-Zero Energy buildings are designed to consume as absolutely little energy as practicable from the start. All possible no-cost 'passive' strategies for energy-savings are explored first. Concepts such as optimized building orientation; properly placed, sized, and specified windows; natural daylight and ventilation opportunities; the incorporation of thermal mass, etc. are all low-to-no cost green buildings concepts. Once these low-cost ideas have been incorporated, then more sophisticated strategies can be considered. Energy-saving options such as higher-performing insulation products, better quality double (or even triple) glazed window systems, heat and electricity-saving lighting components, high-performance heating and cooling systems, as well as light shelves and other architecturally-based solar management strategies can all be evaluated for their life-cycle cost/benefit applicability.Finally, when all of these energy-saving options have been incorporated (or rejected) into the building's design, then and only then is the total net energy load for the building modeled and calculated, and a corresponding renewable energy system (typically solar photovoltaics) engineered to meet the remaining net electrical and power load requirements of the building. My company, Catalyst Architecture, is proud to have designed what we expect will be the 22nd Net-Zero Energy facility in the US - the 17,000-square-foot San Luis National Wildlife Refuge Visitor Center [3] located in the central valley of California. Despite the oppressively hot climate of the central valley, we were able to design this facility as Net-Zero Energy structure utilizing a 55 kW photovoltaic array. Not too bad for a building of its size. This building is also expected to achieve a LEED-Platinum rating - the highest rating possible from the US Green Building Council. It is already recognized as the highest-performing facility in the US Fish and Wildlife Service.

With news stories of climate change, superstorms, and rising sea-levels appearing in the news almost daily, it only makes sense - environmentally and financially - to press our design, development and construction industry professionals to strive for Net-Zero Energy facility design whenever possible for our future building needs.

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