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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Home Energy Audits

Professional energy assessments generally go into great detail to assess your home’s energy use. The energy auditor will do a room-by-room examination of the residence, as well as a thorough examination of past utility bills. Many professional energy assessments will include a blower door test. Most will also include a thermographic scan. There’s also another type of test — the PFT air infiltration measurement technique — but it is rarely offered. Check out the Energy Saver 101 home energy audit infographic to get an idea of what energy auditors look for and the special tools they use to determine where a home is wasting energy.

Preparing for an Energy Assessment

Before the energy auditor visits your house, make a list of any existing problems such as condensation and uncomfortable or drafty rooms. Have copies or a summary of the home’s yearly energy bills. (Your utility can get these for you.) Auditors use this information to establish what to look for during the audit. The auditor first examines the outside of the home to determine the size of the house and its features (i.e., wall area, number and size of windows). The auditor then will analyze the residents’ behavior:

  • Is anyone home during working hours?
  • What is the average thermostat setting for summer and winter?
  • How many people live here?
  • Is every room in use?

Your answers may help uncover some simple ways to reduce your household’s energy consumption. Walk through your home with the auditors as they work, and ask questions. They may use equipment to detect sources of energy loss, such as blower doors, infrared cameras, furnace efficiency meters, and surface thermometers.

Finding and Selecting an Energy Auditor

There are several places where you can locate professional energy assessment or auditing services.

  • Your state or local government energy or weatherization office may help you identify a local company or organization that performs audits.
  • Your electric or gas utility may conduct residential energy assessments or recommend local auditors.
  • Your telephone directory under headings beginning with the word “Energy” may list companies that perform residential energy assessments.
  • The Residential Energy Services Network provides a directory of certified energy raters and auditors near you.

Before contracting with an energy auditing company, you should take the following steps:

  • Get several references, and contact them all. Ask if they were satisfied with the work.
  • Call the Better Business Bureau and ask about any complaints against the company.
  • Make sure the energy auditor uses a calibrated blower door.
  • Make sure they do thermographic inspections or contract another company to conduct one.

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