Can Net Zero Buildings Help the Clean Power Plan?

Net Zero buildings are also known as Zero Energy Buildings, Zero Net Energy Buildings or Net Zero Energy Buildings.

The definition of a Net Zero building, according to the New Buildings Institute is:

“...a building that uses no more energy over the course of the year than it produces from on-site renewable sources”.

Drury “Dru” Crawley defines a Net Zero building in the paper 'Getting to Net Zero' as:

"...a building where the use of on-site renewable options over off-site options minimizes the building’s overall environmental impact by reducing energy transportation, transmission and conversion losses."

Conceptually, a Net Zero building is one that has no adverse energy or environmental impact associated with its operation. Net Zero buildings can achieve this by generating as much energy as they use through renewable sources, such as solar, wind and geothermal.

Important considerations in Net Zero energy buildings include site, source, cost and emissions. From the Whole Building Design Guide (WBDG), "site energy" refers to the energy consumed and generated at a site, for example at a building, regardless of where or how that energy originated.

In Net Zero site energy buildings, for every unit of energy the building consumes over a year, it must generate 1 unit of energy.

Source energy refers to the primary energy needed to extract and deliver energy to a site, including the energy that may be lost or wasted in the process of generation, transmission and distribution (also known as "transmission losses"). The U.S. EIA reports that electrical transmission and distribution losses in the USA were estimated at 6.6% in 1997 and 6.5% in 2007. By using underground DC transmission, these losses can be cut in half.

A coal burning power plant may generate 1 joule of electricity for every 3 joules of energy in the coal consumed. If natural gases are used at a site, for every 20 joules consumed, 1 joule may be needed to extract and distribute the gas to the site. Metrics for Net Zero source energy buildings account for those factors, those metrics may vary depending on site and utility factors.

Net Zero Energy Cost

Net Zero energy cost is perhaps the simplest metric to use.

Net Zero energy cost means that a Net Zero building has an energy utility bill of $0 over the course of the year. In some cases, building owners or operators may take advantage of selling renewable energy credits or RECs, from on-site renewable generation.

While many conventional energy sources result in emissions of carbon dioxide, nitrogen oxide, sulfur dioxide, a Net Zero energy emissions building uses either no energy that could result in emissions, or offsets any emissions by exporting emissions-free energy, typically from on-site renewable energy systems, such as solar photovoltaics.

It's important to note that ASHRAE, the American Institute of Architects (AIA), the U.S. Green Building Council (USGBC) and the Illuminating Engineering Society of North America (IESNA) have all agreed to use site energy measurements as their definition for Net Zero energy buildings.

Most Net Zero energy buildings are still connected to the electric grid, allowing for electricity produced from traditional energy sources, such as natural gas or coal, to be used when renewable energy generation cannot meet the building's energy load.

Conversely, when on-site energy generation exceeds the building's energy requirements, the surplus energy may be exported back to the utility grid where allowed by law. This is known as “Net Metering”. The excess energy production offsets later periods of excess demand, resulting in an energy consumption of 0.

Why Are Net Zero Buildings Important for Climate Change?

Buildings also account for approximately 40% of total US greenhouse gas emissions. And nearly all of the greenhouse gas emissions from the residential and commercial building sectors can be attributed to energy use.

As Climate Change tools, Net Zero buildings can help achieve both environmental and socio-economic goals.

Environmental goals include reduction in fossil fuel energy usage and reduction in greenhouse gas emissions. Socio-economic goals include reduction in total building energy cost to building occupants, as well as increased energy independence and security of U.S. citizens.

In the paper 'Zero Energy Buildings – A Critical Look at the Definition', Torcellini observes that commercial and residential buildings use almost 40% of the primary energy and approximately 70% of the electricity in the United States.

The energy used by the building sector continues to increase, primarily because new buildings are constructed faster than old ones are retired and electricity consumption in the commercial building sector doubled between 1980 and 2000 and is expected to increase another 50% by the year 2025.

The total energy used by U.S. buildings in 2005 topped $369 billion, and energy consumption in the commercial building sector is expected to continue to increase until buildings can be designed to produce enough energy to offset the growing energy demand of these buildings.

Most, if not all the money building owners spend on energy can be saved by constructing or renovating buildings to be Net Zero energy.

Challenges to Create Net Zero Buildings

To improve the potential performance of residential buildings in the U.S. and abroad, organizations such as the Living Futures Institute and the U.S. Department of Energy encourage builders to adopt net zero designs.

The U.S. Department of Energy (DoE) conducts an annual Solar Decathlon that challenges collegiate teams comprised of educational institutions from all over the world to design, build, and operate solar-powered houses that are cost-effective, energy-efficient, and attractive.

Student participants in the Solar Decathlon learn that buildings can reduce emissions through their choice of energy supply, or by reducing energy consumption through improved building design, increased energy efficiency and conservation and other mechanisms that reduce energy demand in buildings.

Over the next 25 years, CO2 emissions from buildings are projected to grow faster than any other sector... With emissions from commercial buildings projected to grow the fastest: 1.8% a year through the year 2030.

Most energy consumed in the US is from the combustion of coal which powers most buildings and contributes to smog, acid rain and other negative health impacts. In addition, coal mining, especially surface mining and mountaintop removal is destroying some of the world's most biologically important ecosystems, not to mention the health of the coal miners themselves.

The Earth’s atmosphere is currently at a carbon dioxide concentration of 400 ppm and is increasing by approximately 2 ppm annually. Scientists warn that irreversible climate change will occur if 400 ppm is sustained for very long, and that the safe long-term level of atmospheric greenhouse gases is 350 ppm.

Climate change is an energy problem, specifically the burning of fossil fuels and there are two sides of the energy issue: supply and demand.

In order to effectively address climate change and global warming, we must reduce the demand for electricity from fossil fuel burning power plants. Fossil fuels will not last forever, however, by using renewable sources of energy to heat, cool and light our buildings, we can achieve a bit of energy security and independence for ourselves.

The Energy Independence and Security Act of 2007, or EISA 2007 calls for a 100% reduction in fossil fuel energy use relative to 2003 levels for new Federal buildings and major renovations by 2030. To effect this change, EISA 2007 directed the US Department of Energy to form the Net Zero energy commercial building initiative, a public/private collaboration designed to develop and disseminate technologies, practices and policies to promote and facilitate the transition to Net Zero energy commercial buildings.

EISA 2007 calls for all newly constructed commercial buildings to be Zero Net energy consumers by 2030 and 50% of commercial buildings stock in the US by 2040 and all US commercial buildings to be zero net energy consumers by the year 2050.

Net Zero and the Clean Power Plan

On August 3, 2015, President Obama and EPA announced the Clean Power Plan – a historic and important step in reducing carbon pollution from power plants that takes real action on climate change.

Net Zero buildings can contribute to reaching the goals of the Clean Power Plan by reducing the demand for fossil fuel energies, encouraging the consumption of renewable sources of energy and spurring the nascent green jobs market in the U.S.

Success with Net Zero and/or the Clean Power Plan would reinforce to the world that the United States is committed to leading global efforts to address climate change.