What is a net-zero home?
All the technical terms, ratings, and systems associated with net-zero energy homes can often be confusing and even overwhelming for first-time buyers. But don’t worry — we’ve compiled the fundamentals of green home ratings and incentive programs to guide you in your search for a greener home.
Net-zero energy homes create as much renewable energy as they consume over a year, making your energy consumption essentially zero. Owning a net-zero energy home has many cost and health benefits, such as cleaner indoor air, no energy bills, and year-round comfort. As a growing real estate segment in cities like Phoenix and Chicago, net-zero energy homes are proving to be a durable and health-conscious option for homebuyers across the country.
Net Zero Rating Systems
To maintain industry standards, there are several rating systems for net-zero homes. We broke down the basics of the most common energy rating systems below.
The Home Energy Rating System (HERS) Index
Developed by RESNET in 2006, the Home Energy Rating System (HERS) Index is a nationally recognized system that inspects and measures a home’s energy performance, including the effectiveness of the building envelope, HVAC systems, insulation, and other building qualities. HERS gives you the big picture when it comes to the home’s level of energy efficiency.
To calculate the HERS Index Score, diagnostic data is compared to a reference home, which is a home of the same size and shape. If you are interested in cutting energy costs with a net-zero home, keep your eye out for a HERS score of zero, or at least very close to zero.
Energy Performance Scores (EPS)
The Energy Performance Score (EPS), developed by the Energy Trust of Oregon, estimates the building’s actual energy use. Scores range from zero to more than 200 — the closer the score is to zero, the more efficient the home.
Compared to the HERS rating, EPS estimates actual energy consumption. This means that the rating takes actual house size into consideration, allows for home-to-home comparisons, and estimates total carbon emissions. Look for a home with a low EPS if you want to save on money and energy.
Net Zero Certification Programs
Several organizations offer formal net-zero energy certification programs. If you’re looking to purchase a zero-energy home, you can check for one of these certifications to ensure the house is truly energy efficient.
Earth Advantage provides Zero Energy and Zero Ready Home Certifications. In order to be certified, buildings must achieve all five pillars of sustainability: efficient use of space, high-performance shell, right-sized mechanical systems, high-efficiency appliances and lighting, and renewable systems.
The International Living Future Institute’s Living Building Challenge offers nationwide Net Zero Energy Building Certification. To qualify for certification, projects must have 100 percent of their energy needs supplied by on-site renewable energy. The NZEB designation verifies that a building meets the challenge’s five main requirements: limits of growth, net-zero energy, rights to nature, beauty and spirit, and inspiration and education.
The U.S. Department of Energy's (DOE) Zero Energy Ready Home program has resulted in more than 14,000 energy-efficient homes and millions of dollars in energy savings. To become a DOE Zero Energy Ready Home, the house must meet rigorous standards and requirements in energy savings, comfort, health, and durability. A Zero Energy Ready Home must be approved by the HERS Standards and abide by all applicable building codes.
The Passive House Institute US (PHIUS) provides nationwide Passive House Certification. PHIUS+ certified buildings fall in the “sweet spot” where efficient energy reduction overlaps with cost-effectiveness. All PHIUS+ certified projects qualify for the U.S. DOE Zero Energy Home program and also meet industry-leading standards for healthy indoor air quality.
Net-zero energy buildings not only save energy, they also save money. Many locations offer rebates or subsidies for buildings powered by renewable energy. Here are a few states that offer energy incentive programs:
- Arizona: Arizona Smarter Greener Better Distributed Generation Program
- California: Pacific Gas & Electric Zero Net Energy Pilot Program
- Illinois: Clean Energy Community Foundation
- Maryland: EmPOWER Maryland Program
- New Jersey: New Jersey Clean Energy Program