Home > Eco Architecture, Eco Energy > Net-zero energy buildings may reduce high energy consumption of U.S. buildings, homes – report

Net-zero energy buildings may reduce high energy consumption of U.S. buildings, homes – report

08/04/2011
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Pushing for the construction of more net-zero energy buildings and homes may be the key to greatly reducing the United States’ overall energy consumption.

The Zero and Net-Zero Energy Buildings + Homes report by Building Design+Construction, published by Illinois-based SGC Horizon L.L.C., suggests that further developing current net-zero energy building designs and harnessing support from concerned government agencies will help address the country’s overall energy consumption.

Almost 40 percent of the United States total energy consumption is guzzled up by buildings and houses. Commercial buildings take up 19 percent from the figure, while homes account for 20 percent.

Energy efficiency and conservation

A net-zero energy building is a building with greatly reduced operational energy needs. It is highly energy efficient with no adverse energy or environmental impact. A net-zero energy building must be capable of producing at least as much energy from renewable sources within a year to compensate for what it draws from the grid.

The renewable energy generation used for the buildings’ needs may be on-site or off-site. A building may also achieve net-zero energy status by purchasing renewable energy to offset its emissions.

The report notes that energy issues may drive architectural plans for net-zero energy building construction.

Planned from the beginning

According to William Maclay of Vermont-based Maclay Architects, which has developed several net-zero energy buildings, metrics must be set for energy conservation levels right from the beginning of construction.

The largest completed net-zero energy building in the United States, the Research Support Facility at the National Renewable Energy Laboratory in Golden, Colorado, applied energy conservation level-setting.

The plans for the $64-million project laid out from the beginning its goal for a platinum certification under the Leadership in Energy and Environmental Design. Energy-modeling dictated how deep the floor plates were set, how much glazing was applied on the facade and how much glass should be used.

Sun, heat and wind

As per definition, net-zero energy buildings incorporate the use of renewable energy into the project from the start. Solar harvesting, geothermal energy, and wind power were cited by the report as the three on-site power generation methods most used by net-zero energy buildings.

Building mounted solar panel systems, particularly rooftop arrays, are the simplest to install and the least expensive. However, builders must be updated with the latest developments in solar efficiency to purchase the most appropriate system for their construction.

Going back to the example of the Research Support Facility, during the building’s first phase development, specified solar panels to be used had only 13 percent efficiency. Upon construction of the second phase, systems with 19 percent efficiency were already available, and were thus considered.

The location of the construction can also be a factor in incorporating renewable energy use into a net-zero energy building. The best type of renewable energy to be used is often whatever resource happens to be easily available.

An example of location determining what renewable energy is incorporated in the building’s design is the case of the Dockside-Green mixed housing project in British Columbia, where waste wood biomass is an option due to the site’s proximity in a heavily forested area.

Location can also be a factor when a planned building is thinking of using geothermal or wind power.

While geothermal is a popular choice for net-zero energy buildings, providing buildings with free heating and cooling, the buildings must be located where drilling at depths of 100 to 300 feet for vertical loops is feasible and permitted.

As for wind power, there may be complaints on noise caused by the turbines. As such, industrial wind farming was cited as the most successful net-zero energy building application.

Favorable Policy

The report identifies the passage of the Energy Independence and Security Act of 2007 as a key driver in the administration’s setting of net-zero energy building construction goals.

The bill sets a goal for net-zero energy use for all commercial buildings by 2030. Furthermore, the bill specifies a net-zero energy target of 50 percent of commercial buildings by 2040 and a net-zero standard of 100 percent for new and existing commercial buildings by 2050.

An additional executive order issued in 2009 directs federal agencies beginning in 2020 to have net-zero energy use in new constructions and renovations by 2030.

President Barack Obama has also proposed for a “better buildings initiative” which aims to make all commercial buildings 20 percent more efficient by the end of the decade.

So far, the United States has a good record in planning and constructing some “firsts” in terms of net-zero energy buildings. The Oregon Sustainability Center is the world’s first urban high-rise net-zero living building, while the 31 Tannery Project in New Jersey is the country’s first net-zero electric building. www.ecoseed.org

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