Keeping the Heat In: A Practical Guide for Homeowners

Natural Resources Canada’s Office of Energy Efficiency created the Keeping the Heat In guide to help homeowners understand the fundamentals of building science and make informed decisions when upgrading their homes. At DOMTOR Energy Services, we see firsthand how proper insulation, air sealing, and system maintenance can transform comfort levels and reduce monthly energy costs. The following overview highlights key concepts from the guide to help you plan your next home improvement project with confidence.

Understanding How Your Home Works

Before beginning any retrofit project, it’s important to recognize how heat, air, and moisture move throughout your home. These elements work together, and changes in one area often affect another. When you understand how your home is built—and how it naturally behaves—you’re in a better position to avoid unintended issues during renovations.

Heating and cooling systems also play a major role in maintaining comfort and managing energy use. When paired with proper insulation and air sealing, they support a more efficient and durable home while helping reduce greenhouse gas emissions.

Choosing the Right Materials

Selecting proper materials is essential, whether you’re upgrading your attic, basement, or main living areas. The guide outlines several options:

• Insulation types and where they perform best

• Air barriers and vapour barriers that help manage airflow and moisture

• Weatherstripping for windows and doors to reduce drafts

Using the right combination of materials—and installing them correctly—ensures your project performs the way you expect.

Comprehensive Air Leakage Control

Air leakage control is one of the most impactful retrofit activities you can undertake. Even well-insulated homes lose heat through gaps around windows, doors, trim, electrical boxes, attic openings, and more. Sealing these areas with caulking, gaskets, tapes, and weatherstripping helps prevent warm indoor air from escaping and keeps unwanted moisture out of the building envelope.

Because air leakage affects both comfort and durability, this step should be prioritized before or alongside insulation upgrades.

Roofs and Attics

Although attics are often the first place homeowners insulate, many other areas lose more heat. Still, the attic offers a valuable opportunity for improvement—especially through air sealing.

Common attic leak points include:

• Chimneys

• Vents

• Plumbing penetrations

• Electrical boxes

Unaddressed leaks contribute to heat loss and can lead to moisture issues over time. Even if your attic already has insulation, enhancing air sealing and ensuring proper ventilation can increase overall efficiency.

Basement Insulation

Basements can contribute roughly 20% of a home’s heat loss because of their large, often uninsulated surface area. Contrary to what many assume, the surrounding earth provides very little insulating value.

Heat loss typically occurs through:

• Uninsulated walls

• Cracks around basement windows

• Penetrations and the sill plate area

Insulating your basement not only boosts efficiency but can also be coordinated with other important work such as radon mitigation, waterproofing, or finishing the space.

Insulating Walls

Like basements, walls account for about 20% of heat loss in many homes. Beyond conductive heat loss through the wall assembly, uncontrolled air leakage through cracks and openings can further impact comfort and efficiency.

If you're planning interior or exterior renovations, this is an ideal time to improve wall insulation and air sealing. Understanding the different wall types in your home helps you choose the right approach and maximize results.

Upgrading Windows and Doors

Windows and doors can represent up to a quarter of total heat loss. While repairs such as caulking or weatherstripping may be enough in some cases, older or damaged units often benefit from full replacement with higher-efficiency models.

Energy-efficient windows and doors:

• Reduce drafts

• Maintain more stable indoor temperatures

• Improve long-term durability

Proper installation is just as important as product selection, ensuring that your investment performs as intended.

Operating Your Home Efficiently

Even the best upgrades can fall short without proper operation and maintenance. Managing your heating, cooling, and ventilation systems efficiently helps maintain the benefits of your retrofit work and ensures the home remains comfortable year-round.

A well-maintained HVAC system can lower your annual energy bills and contribute to better indoor air quality. Simple steps such as routine filter changes, thermostat adjustments, and equipment inspections help keep everything running smoothly.

For homeowners looking for deeper guidance, NRCan provides a full, detailed version of the Keeping the Heat In manual.

You can read or download it here:

Read the full Keeping the Heat In document