By: Jesse Zanavich, Architectural Historian
Delaware State Historic Preservation Office

With the cold weather here and utility bills on the rise, many historic homeowners may be wondering what they can do to cost-effectively weatherize their homes. But before spending big money to replace your older windows (see Figure 1), first consider a home energy audit.

An energy audit will help you to identify your home’s specific problem areas, recommend improvements and, overall, help you to make an informed decision on which projects offer the best investment. To learn more about the audit process, begin by reviewing guidance from the Department of Energy (DOE), and, for those in Delaware, the Delaware Energy Office and Energize Delaware; they’re the authorities on this subject.

To learn what incentives might be available, you should also check with DSIRE (Database for State Incentives for Renewables & Energy Efficiency). Your utility companies might have their own incentive programs as well.

You can either do the energy audit yourself, or, for a more comprehensive report, a professional can be hired. While a do-it-yourself audit can be a great first step, it’s difficult to match the training and specialized equipment that a qualified energy auditor can provide. If you do choose to hire someone, however, here are a few things to keep in mind:

Figures 2 & 3. Energy auditors use tools such as infrared scanning (above)
and calibrated blower doors (below) to spot problem areas.
(Images courtesy of the Department of Energy)

Look for
Building Performance Institute (BPI) or RESNET’s Home Energy Rating System (HERS) Certification

These certifications provide a good minimum threshold to assess auditors’ qualifications. Please note that certain incentive programs may require utilizing a contractor with one specific certification, so check appropriate guidelines.

Check the Auditor’s Performance History
It’s always best to contact customer references and check with the Better Business Bureau.

Be Wary of Auditors Who Are Also Vendors of  Specific Products
An audit should be a standalone service, and auditors should disclose of any financial interests they may have in the energy audit report.

Ensure the Auditor Uses Up-To-Date Equipment
At a minimum, the DOE recommends that auditors use modern equipment such as thermal imaging and a calibrated blower door (calibration allows for more accurate measurement) to identify sources of air infiltration (see Figures 2& 3). Although not yet widely available, PFT Air Infiltration Measurement is another widely recommended technique.

Consider an Audit  in the Late Fall, Winter, or Early Spring
Audits tend to work best with greater interior/exterior temperature differences.

Energy Audit Resources

Considerations for Historic Homeowners

As a historic homeowner, it’s important to avoid the unnecessary replacement, alteration or destruction of significant character defining features – the qualities that essentially define your home (for guidance on identifying these features, see Preservation Brief 17: Architectural Character: Identifying the Visual Aspects of Historic Buildings as an Aid to Preserving their Character).

When it comes to weatherization projects, this inappropriate work usually means replacing your historic windows. Keep in mind that a single-pane window fitted with a storm window can provide thermal efficiency comparable to a low-e vinyl replacement ­– often at a much lower cost. Air infiltration can be further reduced by caulking and weatherstripping, low-cost measures that provide a great return on investment.

Fortunately for historic homeowners, the National Park Service and National Trust for Historic Preservation both offer great preservation-minded weatherization resources to help you stay warm this winter:

Have you had an energy audit on your historic home? What has been the impact? Please share your experiences with us!