How To Get a Net-Zero Home (or Close)
With new heating technology and lower-cost renewable energy systems, any home can get to net zero — that’s a balance between the power a home needs and the renewable energy it can generate to meet the need.
The best first step is to schedule an energy assessment — a Home Energy Solutions (HES) Energy Audit and HERS Model performed by a rater, someone certified by the RESNET (Residential Energy Services Network) HERS (Home Energy Rating System).
An energy audit of your home will include an analysis of your existing utility bills, as well as several tests inside your home. They include a blower door test to determine how airtight the home is, thermal imaging with an infrared camera, and assessments of insulation, window and door quality, water heater and systems for heating, ventilation and air conditioning (HVAC).
The Energy Model will be used to develop a zero-energy retrofit plan that includes air sealing, various forms of insulation, whether there is a recommendation to replace windows, and the energy efficiency of the lighting, appliances, and HVAC systems. The model should also include the cost of each energy recommendation.
Recommendations toward a net-zero home could include:
• Insulation blown into the ceilings, beneath the floors, behind walls, in and around basement walls, or by removing the home’s exterior siding to add rigid foam insulation before re-siding, which eliminates heat loss through the studs.
• Replacing all the light bulbs with energy-efficient LED light bulbs.
• Installing low-flow showerheads, faucets and toilets.
• Installing a hybrid heat pump water heater.
• Insulating and sealing ducts.
• Installing an air-sourced heat pump HVAC System or mini splits.
• Replacing any energy inefficient appliances with EnergyStar appliances.
• Installing switches that turn off electric outlets in home offices, family rooms and TV rooms, so that homeowners can easily turn off electronics that might draw energy otherwise.
• Replacing leaky, energy inefficient windows or installing storm windows.
• Installing an energy-recovery or heat-recovery ventilation system to provide a continual supply of fresh, filtered air if the measured air changes per hour is near or below 3.
• Installing or leasing a solar panel system that produces enough kilowatt hours of electricity to power the remaining energy needs of the home.
Even if a homeowner cannot achieve a net zero house, they can reduce their energy needs by 50 to 90 percent with such energy audits and actions.
Super insulating and air sealing a home can significantly improve the energy performance of an old house. These deep energy retrofits achieve household energy up to 90% by addressing all (or nearly all) energy loads — space conditioning, hot water, lighting, appliances, and plug loads.
Andy Mayshar is a member of the North Haven Clean Energy Task Force, which offers monthly articles on ways to save money and energy.