A net-zero home produces renewable energy equal to or greater than the energy the home consumes from public utilities.
Net-zero homes are part of the broader category of “green homes”(though non net-zero homes may still be considered “green” if they incorporate recycled building materials or other green technologies).
Net-zero homes are not the same as “carbon neutral” homes. Carbon neutrality can be attained for any home by purchasing carbon credits (often from geographically distant renewable energy sources) to offset the carbon emissions the home produces. Net-zero homes actually generate renewable energy on-site.
In regions of the world where homes must be heated or cooled for parts of the year, the design of a net-zero home is crucial. Net-zero homes minimize energy consumption by:
- Taking advantage of natural elements such as sunlight, prevailing breezes, topography (for earth-sheltered building and geothermal systems), and vegetation.
- Incorporating appropriate weatherization, insulation, and ventilation
- Using “daylighting” such as skylights and solar tubes, high-efficiency light fixtures and bulbs, high-efficiency appliances
- Reducing “phantom loads” of electrical power caused by electrical equipment on standby
- Reclaiming and reusing energy whenever possible instead of venting it outside as in conventional homes; for example, in some net-zero homes refrigerator exhaust is used to heat water.
Net-zero homes also produce their own renewable power using solar, wind, hydro, and/or geothermal “microgeneration” systems. The type of power generated will depend on climate and topography. Some net-zero homes are autonomous or “energy-autarkic” (i.e. “off-the-grid”) while others are connected to the grid and feed power back to the grid when it is not being used in the home.
While true net-zero homes generally must be specifically designed as such, it is possible to move toward net-zero energy usage for a conventional or existing home.
- Make the “envelope” of your home as efficient as possible with appropriate insulation, weatherization, energy-efficient windows, passive solar, and ventilation.
- Reduce energy demand by upgrading to high-efficiency furnaces (or heat pumps), air conditioning, lighting, and plumbing. Also, reduce “ghost load” from appliances on standby.
- Add micro-generation capacity. For most North American homes, solar is the most appropriate choice, though residential wind turbines are also gaining in popularity. Some local utilities even offer assistance and rebates for installing solar.
- If you are building a home, keep it as small as you can while still meeting your space needs.
And, the most important part of making your home as close to net-zero as possible: be disciplined about your daily energy use habits!