Drafts, condensation, cold floors... If heat is escaping from your home, you need to use more energy to make up for the loss. Did you know that, in Québec, heating accounts for 50% of the energy used in a typical household?

If you are planning major home renovations, consider including work to minimize air leaks and heat loss through your home’s thermal envelope. By keeping heat inside your home in the winter, you’ll lower your energy use and your electricity bill!

Did you know?

About 75% of the heat in a home is lost through its thermal envelope (roofs, walls, ground-bearing floors, windows, etc.). Air leaks and ventilation account for the remaining 25%.

Do you know how heat is escaping from your home?

If you plan to take advantage of your renovations to improve your home’s insulation, your first step will be to find out where you are losing heat. Energy efficiency advisors can guide you through any major project involving insulating your home or eliminating air leaks. They can help you assess the relevance of an insulation project in great detail, particularly if your home was built before 1980 and has never been renovated.

The two main points to consider are heat loss through your home’s thermal envelope and heat loss caused by air leaks. Do you know the difference?

Dessin de maison avec flèches indiquant où se trouve les pertes de chaleur

Heat loss through the thermal envelope is any loss that occurs “through” your home’s surfaces. It tends to be greater if your home has large surfaces, if the difference between the indoor temperature and outdoor temperature is significant, and if the thermal insulation (also known as thermal resistance) of the surfaces is low.

The level of thermal insulation depends on the materials used to insulate your home’s external walls, roofs, exposed floors (on piles) and floors against the ground. A high level of thermal insulation limits the transfer of heat from inside the house to outside.

Heat loss caused by air leaks is any loss occurring from unintentional exchanges between indoor air and outdoor air, known as either air infiltration or exfiltration. There are many places in a home where these exchanges take place: the seals around doors and windows, chimneys, etc.

Maximize your renovations

How to maximize your renovations with the Rénoclimat program

Carried out by certified advisors, the evaluation available under the program checks your home for air leaks and evaluates its overall energy efficiency. The insulation level recommended for your home is then presented to you, along with details on the energy you will save by implementing the changes suggested (kWh/year).

Once you know this information and the cost of the recommended changes, you’ll be better equipped to analyze the situation and make an informed decision about which improvements you wish to make.

Find out more about the Rénoclimat program

When the exterior siding on your home or your inside walls need to be replaced, it’s often cost-effective to improve the thermal resistance of the walls. Similarly, projects that require access to your home’s foundations or to the inside of walls or roofs are a great opportunity to make improvements that will minimize air leaks and heat loss through your home’s thermal envelope. Some examples of these projects include:

Major basement renovations
Replacement of exterior siding
Major interior renovations
Replacement of the shingles on a flat or cathedral roof

If you need to upgrade your home’s thermal insulation, we recommend you take the opportunity to add insulating material and check if your walls, roofs and entire thermal envelope are properly protected against winds and extreme moisture.

Keep in mind that you don’t necessarily need to remove the exterior cladding or interior finishing on your walls to improve your home’s thermal resistance. For example, if you have an accessible attic space, you can add insulating material, a vapor barrier, ventilation and a draft-proofing system, all without any major renovations.

Insulating your thermal envelope: improving thermal resistance

Insulating materials are essential for improving your home’s thermal resistance.

Here are the most common types of insulation

Materials:

Fiberglass
Mineral fiber

Uses:

Inserted into the cavities of walls, roofs and framed floors.

Recommandations:

An air barrier and vapor barrier are required when using this type of insulation in walls and roofs. In floors, the rim joists need to be sealed using an air barrier, and the insulation must be covered with a vapor barrier on its interior surface.
The insulation must not come into direct contact with a concrete wall or a concrete floor against the ground: a humidity barrier is required.
Batt, blanket and loose-fill insulation is generally less costly per R value than rigid board or spray foam insulation.

Thermal resistance

The thermal resistance value (RSI), or R in imperial units, is a measure of a material’s capacity to limit the transfer of heat through conduction. The higher the resistance value, the lower the heat loss.

Materials	Approximate range RSI/25.4mm (R/po)	Indicative RSI/25.4mm (R/po)
Fiberglass	0.55-0.76 (3.1-4.3)	0.62 (3.5)
Mineral fiber	0.53- 0.70 (3.0-4.0)	0.62 (3.5)

Materials:

Blown cellulose fiber
Blown glass fiber
Blown mineral fiber

Uses:

Blown into the cavities of roof frames.

Recommandations:

Requires air and vapor barriers: the effectiveness of the air barrier in roofs must be ensured and the insulation must be covered with a vapor barrier on its interior surface.
If the insulation is applied in spaces other than the cavities of roof frames (in wall frames, for example), specific installation techniques must be used to limit the gaps caused by the settling of this material.
Blowing requires specialized equipment and workers.
Batt, blanket and loose-fill insulation is generally less costly per R value than rigid board or spray foam insulation.

Thermal resistance

Materials	Approximate range RSI/25.4mm (R/po)	Indicative RSI/25.4mm (R/po)
Blown cellulose fiber	0.53-0.67 (3.0-3.8)	0.62 (3.5)
Blown glass fiber	0.48-0.63 (2.7-3.6)	0.53 (3.0)
Blown mineral fiber	0.53-0.67 (3.0-3.8)	0.53 (3.0)

Materials:

Expanded polystyrene (“bead” board)
Extruded polystyrene
Polyisocyanurate and polyurethane (covered with aluminum on both sides)

Uses:

Installed continuously across walls, floors and roofs.

Recommandations:

Extruded polystyrene boards have a low permeability. They do not absorb moisture or let it through easily.
- These boards can be used for concrete walls and floors in contact with the ground. Certain high-density expanded polystyrene boards have been specifically designed for this purpose.
- Be cautious and mindful when using these boards in anything other than frames with isolated cavities (minimum R value proportional to that of the cavity) in the same way one would with other boards, such as those covered with a low permeability material.
Extruded polystyrene boards and boards covered with an appropriate material can act as an air barrier if joints are sealed. At a certain thickness, they can also act as a vapor barrier.
The materials used on interior surfaces must be covered with a fire-resistant material.
These boards can be used for certain types of roofs (no-cavity or low roofs that are not accessible and do not allow for easy ventilation with outdoor air).
Rigid board and spray foam insulation are generally more costly per R value than batt, blanket and loose-fill insulation.

Thermal resistance

Materials	Approximate range RSI/25.4mm (R/po)	Indicative RSI/25.4mm (R/po)
Expanded polystyrene (“bead” board)	0.67-0.77 (3.8-4.4)	0.70 (4.0)
Extruded polystyrene	0.88 (5.0)	0.88 (5.0)
Polyisocyanurate and polyurethane (covered with aluminum on both sides)	0.88-1.23 (5.0-7.0)	1.06 (6.0)

Materials:

Polyurethane

Uses:

Sprayed continuously across the surface of walls (closed-cell structure, high density).

Recommandations:

Closed-cell polyurethane foam sprayed continuously may be used for:
- insulating the interior surface of concrete walls in contact with the ground;
- creating an air barrier and, past a certain thickness (about 2 in), a vapor barrier.
Polyurethane sprayed on an interior surface must be covered with a fire-resistant material.
Spraying should always be done by specialized and experienced workers using specialized equipment.
Allow a 24-hour off-gassing period before occupancy can resume.
Rigid board or spray foam insulation is generally more costly per R value than batt, blanket and loose-fill insulation.
Though not commonly used, low density open-cell polyurethane foam can be sprayed non-continuously into cavities. It can act as an air barrier but not a vapor barrier.

Thermal resistance

Materials	Approximate range RSI/25.4mm (R/po)	Indicative RSI/25.4mm (R/po)
polyurethane	0.88-1.15 (5.0-6.5)	1.06 (6.0)

If you do decide to improve the thermal resistance of your home, we recommend aiming for the thermal insulation levels required for new buildings.

Summary of the main regulatory requirements related to thermal resistance