Net-Zero Homes for a Zero Emission Future

In 2020, residential homes in the US accounted for 11.5% of total energy consumption. Only 7% of energy consumed by homes came directly from renewable sources. This is a huge problem if the US wants to meet the national energy goal of a zero emission energy grid by 2035. Since 42% of energy use options are decided at home, with the right energy infrastructure, the nation could shift towards net-zero energy homes. 

According to the National Institute of Standards and Technology (NIST), a net-zero energy home is simply a home that produces as much energy as it consumes. These homes utilize technologies like solar panels, to produce energy on site, and then dispense it into the energy grid. They also maximize energy efficiency through construction of well insulated roofs, walls, windows, and foundations, and the additions of high-quality windows, LED lighting, low-flow water fixtures, heat-reflecting roof tiles and energy-efficient appliances, all of which drastically cut back on the amount of energy the home uses. If the home dispenses an amount equal to its consumption (or more) then it is a net-zero energy home!  

In my state of Maryland for example, "furnaces, water heaters, dryers, and stoves account for at least 95% of residential building emissions, but are replaced just once every 10-25 years" according to Rewired America, a nonprofit working to electrify American homes. If homeowners do not replace their inefficient home appliances, with clean energy efficient ones then their homes will continue to need dirty infrastructure and will never reach to zero emissions. A clean grid is one piece of the puzzle, it is crucial for homes to actually have appliances running on electricity that can utilize the clean grid. 

Rewired America estimated that in 2035, even if the US meets its goal of creating a clean electrical grid, if most homes still do not use this clean electricity to power their appliances, still relying on gas or other fossil fuels, then national residential emissions will plateau at 200 million metric tons. However, if on top of the clean electrical grid, homes are also fitted with appliances that use clean electricity, then emissions would drop to 100 million metric tons in 2035, and get down to almost zero by 2045.

In 2012, NIST created the Net-Zero Energy Residential Test Facility (NZERTF) in Maryland. The structure was fitted with existing renewable energy and energy efficient technologies which included, an air-to-air heat pump system, solar panels, a solar thermal hot water system, and a heat recovery ventilation system (HRV). According to NIST's data, the solar panel system exceeded the home's annual energy needs and the solar thermal hot water system provided 54% of the energy required to meet the hot water load. Overall, the project demonstrated that a net-zero energy home home could meet the needs of a four person family.

Even though the NZERTF shows that net-zero homes are viable in the US, the number of real net-zero homes is surprisingly low. According to the Net-Zero Energy Coalition, as of 2019 in the US, there are only a combined total of 5,000 and 7,000 net-zero energy single family and multifamily homes, respectively. In July of 2021, the Zero Emissions Home Act was introduced in the US Senate. The bill aims to, "provide rebates for the purchase and installation of electric appliances and equipment in single-family homes and multifamily buildings, with additional support for low- and moderate- income households." 

As of now, the government's Energy STAR initiative is helping homeowners increase energy efficiency in their homes. Proponents of the Zero Emissions Home Act cite that electric appliances for heating, cooling, and cooking, oftentimes outperform the fossil fuel powered ones. For example, energy star certified electric clothes washers use about 25% less energy than regular washers. According to Energy STAR, 800,000 of its certified products were sold every day in 2019, and a total of 300 million of their certified energy efficient lightbulbs were sold that year. These items' sales along with other partnerships, has prevented the emission of "nearly 390 million metric tons of greenhouse gases, roughly equivalent to 5% of U.S. total greenhouse gas emissions." This is great progress, but clearly 5% is not close enough to the US's ambitious target. What initiatives like this showcase, is that the technology to reduce residential sector emissions exists, but we just need to utilize this technology to its full potential through establishing more net-zero energy homes. The most critical step in this is to incentivize people to adopt to these new technologies, and this legislation, if passed, could greatly benefit this effort.

Works Cited
Bringing Infrastructure Home: A 50-state Report on U.S. Home Electrification. Rewiring America, content.rewiringamerica.org/fact-sheets/bringing-infrastructure-home/bringing-infrastructure-home-50-state-report-on-us-home-electrification.pdf. Accessed 14 Nov. 2021.
"ENERGY STAR Overview." ENERGY STAR, www.energystar.gov/about?s=footer. Accessed 14 Nov. 2021.
Fanney, A. , Payne, W. , Ullah, T. , Ng, L. , Boyd, M. , Omar, F. , Davis, M. , Skye, H. , Dougherty, B. , Polidoro, B. , Healy, W. , Kneifel, J. and Pettit, B. (2015), Net-Zero and Beyond! Design and Performance of NIST’s Net-Zero Energy Residential Test Facility, Energy and Buildings, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=916099 (Accessed November 14, 2021)
"Heinrich Leads 11 Senate Democrats in Introducing Zero-Emission Homes Act to Establish New Rebate Program for Home Electric Appliances, Equipment." 15 July 2021, www.heinrich.senate.gov/press-releases/heinrich-leads-11-senate-democrats-in-introducing-zero-emission-homes-act-to-establish-new-rebate-program-for-home-electric-appliances-equipment. Accessed 14 Nov. 2021.
Higgins-Dunn, Noah. "Net Zero-energy Homes Have Arrived and Are Shaking up the U.S. Market." CNBC, 14 Feb. 2019, www.cnbc.com/2019/02/14/homes-that-produce-their-own-energy-might-be-the-future-and-california-is-inching-closer.html. Accessed 14 Nov. 2021.
"How Much Energy Is Consumed in U.S. Buildings?" U.S. Energy Information Administration, 3 May 2021, www.eia.gov/tools/faqs/faq.php?id=86&t=1. Accessed 14 Nov. 2021.