Understanding your home’s building envelope: how to stop heat from escaping

When you think about making your home more energy efficient, you might picture a new heat pump, smart thermostat or solar panels.

But before upgrading your equipment, there’s another part of your home worth paying attention to: the building envelope.

Your home’s envelope is the boundary between your indoor living space and the outdoors. It includes your walls, roof, windows, doors, foundation, insulation and air sealing—all working together to keep drafty weather outside and your heated or cooled air inside.

A well-performing envelope can make your home more comfortable and help your heating and cooling equipment work more efficiently.

What does the building envelope actually do?

Think of your home like a winter jacket.

The insulation is like the jacket’s warmth-retaining layer, while air sealing is like closing the zipper and making sure there aren’t gaps where cold air can get in.

If your home has insufficient insulation or air leaks, your heating system may need to work harder to maintain a comfortable temperature.

Common places for heat loss and air leakage include:

• Attics and roofs
• Exterior walls
• Basement walls and foundation areas
• Windows and doors
• Areas around pipes, wires and other penetrations
• Gaps around the foundation or other parts of the building envelope

Insulation and air sealing aren’t the same thing

They’re often talked about together, but they solve different problems.

Insulation slows heat transfer.
It helps prevent heat from moving through your home’s walls, ceilings and floors.

Air sealing reduces drafts.
It helps prevent heated indoor air from escaping through cracks and gaps — and outdoor air from sneaking in.

You can have lots of insulation and still have a drafty home if there are significant air leaks.

That’s why a comprehensive approach can make sense when improving your home’s envelope.

How do you know where your home is losing energy?

One of the best places to start is with a home energy assessment.

An energy advisor can evaluate your home and identify opportunities to improve its energy performance. Depending on your home, recommendations may include additional insulation, air sealing, window and door upgrades or other improvements.

This can help you prioritize the upgrades that are likely to make the biggest difference — rather than guessing where your money is best spent.

Why does this matter before upgrading your heating system?

If you’re considering a heat pump, improving the building envelope may be worth considering as part of the same renovation plan.

A more efficient envelope can reduce the amount of heating and cooling your home needs. That can improve comfort and may also affect the size and operation of heating and cooling equipment needed for the home.

In other words, don’t just ask how efficient your new equipment is. Ask how efficiently your home uses the energy that equipment provides.

What upgrades should you consider?

Depending on your home’s needs, improvements could include:

Attic insulation

Heat rises, making the attic an important area to assess. Adding insulation can help reduce heat transfer between your living space and the attic.

Exterior wall insulation

Older homes may have less insulation than newer construction. Improving wall insulation can help reduce heat loss through exterior walls.

Basement, garage and foundation insulation

Basement walls and other foundation areas can be another source of heat loss, particularly in older homes.

Air sealing

Sealing gaps and cracks around areas such as windows, doors, pipes and wiring can help reduce drafts and unwanted air movement.

Windows and doors

Older or poorly performing windows and doors can contribute to heat loss and drafts. Depending on their condition, upgrading them may be part of a broader energy-efficiency renovation.

Could you save money?

Improving your home’s envelope can reduce the amount of energy needed to maintain comfortable indoor temperatures. Exactly how much you could save depends on your home’s current condition, the upgrades you make and how you heat and cool your home.

There can also be an important comfort benefit.

A drafty room, cold floor or uneven temperature can make a home feel uncomfortable even when the thermostat says the temperature is right. Addressing the underlying source of heat loss can help create a more consistent indoor environment.

There are rebates available, too

The Home Renovation Savings program offers incentives for several home-envelope improvements, including insulation and air sealing. Current program offerings include up to $7,700 for eligible insulation upgrades and up to $250 for eligible air sealing, with eligibility requirements applying.

Some upgrades require a home energy assessment and the program currently offers a rebate toward the cost of eligible initial and final assessments.

Before starting work, check the program requirements to understand which upgrades qualify and what steps need to happen before you begin.

Start with the home you already have

You don’t necessarily need to undertake a major renovation to make your home more energy efficient.

Start by understanding where your home is losing energy. From there, you can prioritize improvements that make sense for your home, your comfort and your budget.

And if you’re planning a bigger upgrade — such as a heat pump, solar panels or battery storage — improving the home’s envelope can be an important part of the bigger picture.

A more efficient home starts with keeping the energy you already use from going to waste.

Explore home energy upgrades and rebates through the Home Renovation Savings program.