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How to Conduct a Home Energy Assessment

Home technology expert Ross Trethewey shows a homeowner where her energy consumption is going and how to save some money moving forward.

Home technology expert Ross Trethewey goes on a house call to help a homeowner figure out her energy loss. After discussing her energy consumption concerns, Ross suggests a home energy assessment and gets to work.

Understanding where a home is losing or consuming that majority of its energy is the first step toward lowering energy bills. Using some measurements and calculations, a home energy assessment can turn a home’s energy usage or loss into a computer model. This can help a homeowner make informed decisions about their home’s insulation, appliances, windows, and more.

Steps for Conducting a Home Energy Assessment

Note: This assessment requires specialized equipment and is probably outside the realm of a DIYer, but the following steps will explain the process.

1. Start on the Outside

A good home energy assessment starts outside. The assessor will be looking at the siding, windows, roof, foundation, chimney, gutters, and any penetration for vents, wires, and piping. They’ll be looking for gaps or damage, as well as proper drainage to ensure the home is as enveloped as possible from the outside.

2. Measure the Rooms

For a home energy assessment to be as accurate as possible, grab a measurement from every single room. Measure the width and length of the room as well as the height to calculate the room’s cubic footage or volume. These volumes will come into play during computer modeling.

3. Assess the Insulation

The home’s insulation plays a major role in its energy efficiency, so it’s necessary to assess its condition (or existence, in many cases). Give this a shot by removing the cover plates around outlets in exterior walls. Use a flashlight to peek around either side of the outlet and look for insulation of any sort. Continue this in every room. Be sure to check the attic and rim joist in the basement for insulation as well.

4. Check the Appliances and Systems

Every major appliance and system has a rating plate that describes the serial and model number. These devices include the boiler, furnace, washer, dryer, oven, refrigerator, and other appliances. Take pictures of these plates as they’ll be used for the computer model.

5. Evaluate the Windows

A home assessment involves evaluating the windows as well. Measure each window, as well as the glass panes that they consist of. Also, check for double-pane glass as well as storm windows. Each of these features or measurements will affect the home’s energy efficiency.

6. Use a Blower Door to Check for Leaks

Shut off all the combustion appliances, close all wall openings, vents, or flues, and set up a blower door in one of the exterior doorways. Set this blower door to roughly 50 Pascals and allow the fan to get up to speed. Use a thermal imaging camera and a small smoke machine to find cold air penetrating through walls, windows, the basement rim joists, vents, and other areas.

7. Input the Data into the Computer Model

Input all of the data compiled during the assessment into the computer model. Following the above formula, the model will determine where the majority of energy loss is, whether it’s the windows, walls, roofs, or other areas. Use this information to make decisions about future upgrades.


Resources

Ross conducts a full home energy assessment. He recommends starting by walking the exterior of a home to visually inspect the siding, windows, and roof.

  • Siding: What is the condition of the siding? Are there any gaps in the siding?
  • Windows: What kind of shape are the windows in?
  • Roof: What is the condition of the roof? Are any shingles missing? Is the attic vented or not?
  • Water: Is there any obvious water damage? Are there any signs of puddling? Are gutters/downspouts conveying water away from the building? When it comes to the exterior, you want to make sure there aren’t ways for water to get into the house.

For the interior walkthrough, Ross says to evaluate all major devices and systems. He also recommends checking for insulation and taking measurements (like the length, width, and ceiling height of rooms).

To identify where air leakage is occurring, Ross conducts a blower door test. A blower door is a machine used to measure the airtightness of buildings. It can also be used to measure airflow between building zones, test ductwork airtightness, and help physically locate air leakage sites in the building envelope.