Energy Efficient Renovations

Retrofitting existing homes to net zero or getting them on the path to zero is as important as building new zero energy homes. This TED Talk explains why. More and more builders are showing that it is feasible to retrofit an older home to zero or close to zero. Retrofits provide the construction industry with business during economic downturns, improve the indoor health and comfort of your customers, increase the value of their homes, create jobs by employing a wide range of workers, and help reduce carbon emissions.

Cost-Effective Steps to Zero Energy Retrofits

With a few important variations, zero energy retrofits have a lot in common with building a new zero energy home. The following steps create a framework that can be applied to any retrofit.

Energy Audit

Conduct an energy audit of the existing home including a blower door test, thermal imaging with an infrared camera, and assessments of current insulation levels, window and door quality, water heater and HVAC systems, a year’s worth of utility bills, and the efficiency of existing lights and appliances.

Energy Modeling

Use energy modeling to develop a zero energy retrofit plan that includes the degree of airtightness to be achieved, the R-value of insulation to be installed, the U-value, of the windows, and the energy efficiency of the appliances, ventilation system, heating and cooling system, and lighting required. The model should also include the cost of each proposed measure, so that the most cost-effective combination can be selected.


Add blown-in ceiling insulation, which often is an easy and inexpensive measure. Install floor insulation or basement wall insulation. Install insulation in the existing walls by blowing it into the walls, or by removing the siding and adding rigid foam insulation to the outside of the wall before re-siding.


Replace all the light bulbs with energy-efficient CFL or LED light bulbs. LED bulbs are preferable because they are more energy efficient, last much longer and contain no mercury. Consider adding motion detectors in areas where homeowners may tend to leave lights on.

Hot Water Conservation

Install low flow showerheads and faucets to reduce hot water use. Consider replacing an inefficient water heater with a more energy efficient model, such as a heat pump water heater. If relocating the water heater, place it as close to the kitchen and bathrooms as possible.

Heating and Cooling

If you are sticking with an existing central heating system, be sure that the ducts are well sealed and insulated. If you are upgrading the heating and cooling system, consider a ductless mini-split heat pump, which is very energy efficient and easy to install as part of a retrofit.

Energy Efficient Appliances

Replace any existing energy inefficient appliances with the most energy efficient models. Consider installing a heat pump drier.

Plug Loads

Install switches that will turn off electric outlets in home offices, family rooms and TV rooms, so that homeowners can easily turn off the plug loads on electronics, which otherwise would continue to use energy, even when they are “shut off.”


Replace leaky, energy efficient windows with windows with a U-Value close to 0.2 or install low-e storm windows, internal or external, which can save up to 20% of the heat lost through the windows.

Ventilation System

Install an Energy Recovery Ventilation System or Heat Recovery Ventilation System to provide a continual supply of fresh, filtered air in the home if the Air Changes per Hour is near or below 4.0. The Panasonic Whisper Comfort Spot ERV is an inexpensive ventilation system that may be appropriate for smaller homes.

Renewable Energy

Install or lease a solar PV system that produces sufficient kWh of electricity to power the remaining energy needs of the home.

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