The United States Department of Energy officially defines a zero energy building (ZEB) as “an energy-efficient building where, on a source-energy basis, the actual annual delivered energy is less than or equal to the on-site renewable exported energy.” In layman’s terms, a zero energy building or net-zero home produces enough renewable energy to meet or exceed its own annual energy consumption requirements.
As evidenced by the growing number of solar panels gracing the roofs of single-family homes here in the Lowcountry, more and more homeowners are moving in the right direction as far as energy consumption goes. Traditional buildings are significant contributors of greenhouse gases, consuming about 40% of the total fossil fuel energy in the U.S. and the European Union. In order to reduce carbon emissions and dependence on fossil fuels as well as save money on energy bills, builders and consumers are beginning to look toward net-zero homes.
How Does It Work?
Zero-energy homes are built from the ground up with energy efficiency in mind. Beginning with the most basic of construction and design elements, the focus is on reducing energy requirements for systems that usually account for the most energy usage in a home. The goal is to reduce the amount of energy needed while also increasing the home’s energy-generating capacity.
Typically, energy is harvested onsite via energy-producing technologies like solar and wind power. That self-sustaining power source is combined with technologies like highly efficient HVAC and lighting, spray-foam insulation, triple-glazed windows, skylights to reduce lighting needs, energy-savvy appliances, smart thermostats, and other energy-efficient features. Keep in mind, however, that an energy-efficient home is only truly efficient if the people who live in it practice good energy-saving habits. Net-zero homes and energy-saving features aren’t going to work if you leave the lights on all day long, run the air conditioner on full blast, and take long, luxuriating showers every day.
What Are Some Advantages?
There are many advantages to owning a net-zero home, including:
- Isolation from future energy price increases
- Reduced total cost of ownership thanks to improved energy efficiency
- Reduction of monthly bills
- Reduced risk of power outages due to grid blackouts
- Improved reliability after natural disaster or other weather problems
- Higher resale value than a comparable traditional home
- Contribution to the greater benefits of society
- Reduced carbon footprint
What Are Some Disadvantages?
As with anything in life, there are cons to go along with the pros of net-zero housing. These include:
- Cost of building or retrofit can be higher
- Few builders or designers have the skills and experience needed to build ZEBs
- Current subsidies will be phased out as solar-photovoltaic mass production lowers future prices
- Solar energy only works in locations that are unobstructed from the sun
- Without other energy-efficient features and energy-saving habits, a net-zero home won’t be worth the initial cost.
Is This Actually Attainable for the Average Homeowner?
As you might have already assumed, building a net-zero home does cost more than building a same-size traditional home with the same features. The increase in price can be anywhere from 20 to 60 percent. But once you begin to consider factors like federal and state energy-efficiency rebates and major savings on energy bills, that upfront price increase starts to look more attractive. Those savings can add up, eventually leading the home to pay for itself. “Zero-energy homes are actually affordable,” says Jacob Corvidae, principat at the Rocky Mountain Institute, a research nonprofit focusing on clean energy. He stresses that it’s important to make this widely known, as the perception that net-zero building is expensive and unattainable would make consumers, builders, and policymakers reluctant to encourage it. The Rocky Mountain Institute took a look at how long it takes for the savings on a 2,200-square-foot net-zero home to cover the initial building costs in the 30 largest cities in the U.S. They found that it would take 7.8 years in San Francisco, CA; 11 years in Los Angeles, CA; 10.9 years in Jacksonville, FL; 12.5 years in Dallas, TX; and 11 years in Washington, DC, for example. Realtor Magazine states that “the biggest savings tend to be in locales with high electricity rates and older building codes.”