If you’ve found your way to our blog, you may already know what a net-zero energy home is: a house that produces as much renewable energy than it consumes over the course of a year. You pay nothing for your home’s energy usage, and you reduce the net operating emissions for your home to about zero.
What’s not to love? But why stop there?
What if your home could produce more clean, solar energy than it consumes. Would there be any point to it? Is a net positive house even possible? That’s what I’m going to explore in this post. Read on!
What is a net positive house?
First, let’s look at definitions. In simple terms, a net positive home can be defined as one that not only produces enough renewable energy on an annualized basis to meet its own demands but produces a surplus. Most net-zero homes produce a little extra power over the course of a year, so are they all net positive? Technically, yes, but I think a more useful working definition of net positive homes would be ones that produce a significant excess–enough to do something useful, like recharge the homeowner’s electric car, which seems to be the most common use case, although there are others, as we will see.
No energy bills
Just as with a net-zero house, the bills for y0ur energy use will zero out over the course of a year. Your utility may still charge you a connection fee or base service charge, but your kilowatt hours will be covered.
Power your electric car
The average American family spends about $5,000 per year on gas. Skipping the pump altogether and charging an electric car with free electrons generated on your own roof has tremendous appeal. It also greatly reduces your personal carbon footprint.
Reduced dependance on fossil fuels
The U.S. Energy Information Administration reports that in 2022, the residential sector accounted for about 22% of total U.S. energy consumption, when you factor in electrical transmission losses. The U.S. Department of Energy found that the transportation sector accounted for a whopping 28% of total U.S. energy usage in 2021. In other words, if the net-positive concept were fully embraced, we could shave off about half of our country’s energy use, increasing energy security at the same time.
Drawbacks and challenges
While there are many benefits of going net positive, there are a few challenges as well.
The main hurdle for most homeowners and people contemplating a net-positive home is the added cost of the large PV system. While adding extra solar panels certainly does add expense, the price per watt of solar has been coming down for years, and the marginal cost of adding panels may be less than you would expect.
See also: What Does a Net Zero House Cost?
Expenses aside, you will need a large expanse of unshaded south-facing roof area to achieve the net positive goal. This may be a challenge for certain lots and certain home designs, but it can usually be overcome with proper planning. For instance, all of our designs at Powerhouse are net-positive ready and are capable of generating enough electricity to charge at least one, if not two EVs.
Net metering is a must
Just like a net-zero home, a net-positive home requires a net metering agreement with your local utility. It is a good idea to research if and how you would be compensated for more energy produced beyond what you use. It is rare for utilities to pay you for any excess renewable energy you produce, and some states zero out or reduce any excess production “credits” you might have left at the end of the year. I recommend trying to size your PV system to produce enough to cover the amount you plan to use (for your home, car, and other applications) but not more energy than that.
Designing and building a net positive home
The approach is similar to designing and building net zero homes. Here’s a quick recap of what you’ll need to keep in mind:
Ultra efficient design
Achieving the net positive goal requires strategic architectural choices, such as optimizing site orientation for solar exposure, incorporating well-placed windows for natural light and ventilation, utilizing shading elements to mitigate heat gain in the summer, and integrating materials with high thermal mass.
Careful attention to building materials and construction details
It’s also essential to maximize energy efficiency throughout the entire building envelope and systems. The goal is to minimize energy waste and reduce the overall energy demands of the home by paying close attention to details, such as insulation, air sealing, and windows.
More solar panels than required for net zero home
To go beyond the net-zero goal, it’s essential to install an increased number of solar panels to generate more electricity than the home’s total energy demands. The specific kW size of the PV system will depend on factors like the energy requirements of the household, the efficiency of the home, and the desired surplus energy generation. PV systems can often range from 10 kW to 20 kW or larger. The limiting factor for solar systems in many home designs is the south-facing roof area available for solar panels. We prefer to design asymmetrical gabled roofs or clerestory roofs rather than shed-style roofs, which require extra engineering and materials.
Examples of net positive homes
Through our sister company, TC Legend Homes, we have built many net positive homes in the greater Seattle and Bellingham, Washington, areas. Here are a few examples.
Bellingham Power House
Nicknamed the PowerHouse, this pioneering home in Whatcom County operates in harmony with the electrical grid, producing more energy than it uses over the course of a year. Despite common assumptions, the Pacific Northwest proves to be an ideal location for solar energy. With its airtight shell, structural insulated panel (SIP) construction, strategically positioned south-facing windows, passive solar design, efficient heat pump, solar hot water system, and locally produced ITEK solar PV array, this exceptional house not only eliminates electricity bills (except for the grid-tied system’s monthly service charge) but also requires no expenses for heating. It functions entirely without the use of oil, natural gas, or any other conventional fuels. And, bonus, it charges the owners electric cars! View U.S. Department of Energy case study
This 2,540 square-foot net-zero certified house in western Washington showcases the possibilities of sustainable living. Designed with a passive-solar window layout and cutting-edge HVAC systems, it optimizes energy efficiency. The integration of a 19.2 kW solar array enables the house to produce excess energy, which the owners put to novel use. “Our usage is vastly higher than average,” says the homeowner John Trax Jr. “We are wired for 2 electric cars though we currently have only one. We also operate three computer servers 24/7 for the company we work for. And, third, we operate a full production wood shop as a side business.” While they haven’t crossed the net-zero threshold yet due to all these extra loads, as John notes, “Just eliminating [the servers] would put us net positive.” Learn more
Bellingham Affordable Net Positive Home
Net-positive doesn’t have to be expensive, complicated, or large. The TC Legend Homes/Powerhouse Designs team has created a modest (yet mighty) net positive home that exemplifies sustainable living. Through meticulous design and construction, the Bellingham Affordable Net Positive Home achieves remarkable energy performance. With only an 8.1kW photovoltaic system, it generates more energy than it needs to power the home, with enough left over to charge an electric car. Incorporating features like Neopor R29 SIPs, Energy Star appliances, a heat recovery ventilator, and stormwater infiltration, this home sets a high standard for efficiency and sustainability. Recognized with certifications including Energy Star, EPA Indoor airPLUS, and 5-Star Built Green, it shows that net positive living is achievable on a tight budget. Learn more about this home
Whatcom County Net Positive Home
This net positive Built Green Five Star home stands out as a Department of Energy 2019 Housing Innovation Award Winner. The house maximizes solar exposure with asymmetrical roofs and ample south-facing glazing for passive solar harvesting during winter. Appropriately shaded windows and regionally suitable eaves and porches prevent summertime overheating and further reducing energy consumption. The rectangular footprint prioritizes space for PV, while smaller east and west walls reduce heat gain in summer. The exposed slab-on-grade floor provides a cooling underfoot mass and houses in-floor hydronic heating for winter comfort. With an open floor plan, efficient use of space, triple-pane windows, air-to-water heat pump, heat recovery ventilator, electric car-charging capability, and sustainable materials throughout, this 2707-square-foot home showcases the perfect balance of efficiency, sustainability, and exquisite craftsmanship, including locally sourced wood details milled on-site. Learn more
Sneak Preview: Lynden Power House
Currently under construction, the Lynden Power House is a net positive home project that aims to generate a significant amount of power. This project is designed to one day incorporates a community power-station concept to charge neighborhood cars with the excess energy produced by the home. Contrary to the assumption that net positive homes are more expensive due to the cost of solar panels, this project demonstrates that working with a builder experienced in net-positive design and construction can make a net positive home cost-effective compared to a code minimum home. Even with its abundance of solar panels and 30kWh of batteries to store excess energy, the Lynden Power House is expected to cost around $300/square foot, a significant savings over the approximately $400/square foot average for code-minimum homes in the area. “We couldn’t afford NOT to build net-positive,” says homeowner Bob Edmiston. He and his wife also appreciate the flat year-round energy costs of their new net-positive home as compared to their current Seattle home, which has peaks in the summer and winter.
Can an existing home be converted to net positive?
Yes, it is possible to convert an existing home into a net positive home, but the feasibility and cost-effectiveness depend on the current energy efficiency of the home, available space for solar panels, and the extent of renovations required. Upgrading a net-zero home to net-positive may be as simple as adding more solar panels, if you have the roof space, while bringing a 1800s home up to the standard might never be financially or practically feasible. A thorough energy assessment and consultation with a qualified professional can help determine the viability of transforming your existing home into a net positive one.
Can a net positive home be affordable?
While the upfront costs of building a net positive home may be higher compared to conventional homes, the long-term savings on energy bills and potential incentives and rebates can make it a wise long-term investment. The overall affordability also depends on factors like the size of the home, desired features and technologies, and the local availability of resources. Working with experienced designers, builders, and exploring financing options can help make a net positive home more financially feasible. See our Cost To Build Calculator.
I want one! How do I get started?
To get started on building a net positive home, research and educate yourself on sustainable technologies and design. Set your energy and sustainability goals, consult professionals experienced in net positive design projects, and collaborate on an energy-efficient and sustainable home design.
We’re here to help
Building a net positive home is a complex process that requires expertise and careful planning. Not only do we sell predesigned net-positive home plans, but we also offer custom design services and consultation. We are here for you every step of the journey. We love helping folks realize their vision of a sustainable, energy-efficient, and net positive home. Feel free to contact us to learn more.