Building Envelope

Deep Energy Retrofit Steps

  1. Step 1:

    Upgrading your home’s building envelope.

  2. Step 2:

    Updating your home’s mechanical system.

  3. Step 3:

    Adding renewable energy systems to your energy-efficient home.

See Steps Overview

Building Envelope Retrofit Measures

The building envelope is the physical separator between the conditioned and unconditioned environment (essentially the barrier between the outdoors and your interior creature comforts) including the resistance to air, water, heat, light, and noise transfer. In addition to heat loss through your walls, cracks and penetrations may allow uncontrolled air leakage into and out of your home.

The first step to take during a home energy retrofit is to ensure that your home’s air barrier is adequate, and the thermal barrier is deeply upgraded. Making sure that any necessary building envelope retrofit measures are completed in the initial stages will ensure that your retrofit project achieves maximum efficiency.

Illustration of a cross section of a house highlighting building envelope features.

Before you start your home energy retrofit project, get an EnerGuide home energy evaluation to understand how your home uses energy and identify all improvement opportunities. As always, check with your municipality, utility or retailer to see if there are any rebates available.   


In addition to providing security and an emergency exit, energy-efficient doors better prevent air and temperature leaks into and out of the home. Doors come in a variety of materials and methods of construction, some of which reduce heat flow better than others. For example, depending on the style and type of insulation, metal-clad doors can be more efficient than solid wooden doors. No matter what the material, ill-fitting doors can make your home drafty and uncomfortable.

What to Look For 

  • Doors made of materials with high insulating values, such as fibreglass, vinyl, or steel. 
  • Wood, vinyl or thermally broken metal frame. 
  • Low air-leakage rates (for pre-hung door systems). 
  • Maintenance-free framing materials. 
  • A high energy efficiency rating or a minimum of double glazing with a 12 mm (half-inch) or greater air space. 

Things to Consider 

  • Make sure that windows, doors and skylights are ENERGY STAR® certified, and hire a professional installer to ensure they perform their best. 
  • Warranties differ from door supplier and type; compare before you purchase. 

Cost : $400 – $2,000 per door. 


Draftproofing is one of the most affordable and easy ways to improve the energy efficiency of a home. It’s also the single most important step to improve the energy efficiency of your home and should always be the first step of any retrofit project. You can save up to 30% of your energy costs by caulking cracks and plugging gaps on walls, inside and out. 

Older homes typically have more air leaks, around windows and doors, electrical outlets, and cracks in the foundation and walls. You can seal air leaks in your home with weather-stripping and caulking or by applying gaskets and tapes. 

What to Look For 

  • Detect all sources of air-leakage before you undertake your project; assess your ventilation needs to ensure adequate indoor air quality. 
  • Each house will respond to draftproofing in its own way, so monitoring is important. Older homes may require remedial measures—such as mould or asbestos removal—before comprehensive work to seal leaks. 
  • Every time you insulate or upgrade/install the air barrier system, it’s important to ensure that moisture does not enter the insulation or building envelope. 

Types of draftproofing products include: 

  • Caulking, a putty-like substance best applied to non-moveable gaps like baseboards and wood trim 
  • Weather-stripping tapes and plastic forms 
  • Expandable spray foam which can be applied to irregularly shaped air gaps 
  • Shrink-wrap plastics which can be applied to the interior of windows 

Things to Consider 

  • For detailed advice on draftproofing, which is also known as air-sealing, contact a professional installer.  
  • Be sure to check window glazing, thresholds and door/window frames and electrical outlets and switches as potential sources of air-leakage. 
  • Choose premium caulks for durability. Practice running and smoothing beads before you do the actual job. 
  • Check the size and colour of doors and windows before purchasing weather-stripping to ensure you buy the right product. Adhesive-backed foams and tapes can lose their effectiveness over time so you may need to replace it every few years. 

Cost : $200 – $1,500

Attic Insulation 

Air leaks, thermal bridging, and insulation gaps in your attic will result in substantial heat loss and lead to a variety of moisture-related problems in your home through things like the stack effect. For maximizing energy efficiency, attics should be properly: sealed, insulated, and ventilated. 

What to Look For 

  • Insulation is rated by its R-value. “R” stands for resistance and the higher the R-value, the more efficiently it resists the transfer of heat from one area to another. RSI-value is the metric variant, while R-value is based on imperial measurement. 
  • Different types of insulation have different R-values, but you can combine them to achieve a higher overall rating. 
  • The most common types of insulation used in attics are spray foam, loose-fill, and batt/blanket insulation. 

Things to Consider 

  • Ensure your project meets the minimum R-value needed to receive available rebates. 
  • Hire a professional. Improper installation can lower the R-value of the material, and cause complications to health and safety.  

Cost : $1.50 to $3.50/ft2 

Basement Insulation 

A basement can account for about 20% of a home’s total heat loss. Adding insulation to your basement is important, whether it will be finished or not. For optimal energy efficiency, your home should be properly insulated from the roof down to its foundation to create a continuous thermal barrier. 

Much like your attic, basements need to be sealed, insulated, and ventilated. Proper insulation not only reduces heating and cooling costs but also improves comfort. The materials used to insulate your basement will depend on your foundation and whether you’re insulating on the inside or outside of your home. 

What to Look For 

  • Insulation is rated by its R-value. “R” is the resistance and the higher an insulation’s R-value, the more efficiently it resists the transfer of heat from one area to another. RSI-value is the metric variant, while R-value is based on imperial measurement. 
  • The bare minimum the basement should have is R-12, for 100% of the space. 

Things to Consider 

  • Before planning your renovation, assess your basement. Check for water leaks, dampness and determine if you need interior or exterior insulation. 
  • Do not insulate the interior of a basement with water leaks or moisture problems. 
  • Ensure your project meets the minimum R-value needed to receive any available rebates. 

Cost : $6,500 to $18,000

Wall Insulation 

Walls can account for up to 20% of heat loss in your home. Insulation is designed to prevent heat from being transmitted from one area to another, with the added benefit of dampening transmission of sound. It works by using pockets of air which slow the movement of radiation and vibration. The type of insulation you need will depend on the type of walls (i.e., concrete block or wood frame) in your home.  

What to Look For 

  • Insulation is rated by its R-value. “R” is the resistance and the higher an insulation’s R-value, the more efficiently it resists the transfer of heat from one area to another. RSI-value is the metric variant, while R-value is based on imperial measurement. 
  • Different types of insulation have different R-values. You can use more than one type to achieve a higher overall R-value rating. 
  • You can install one or more of the following: blown-in, rigid board, batt/blanket and spray foam insulation. 

Things to Consider 

  • Cold floors and walls in the winter and mould growth are signs of a poorly insulated home. 
  • Ensure your project meets the minimum R-value required to be eligible for rebates, if available. 
  • Hire a professional. Improper installation can lower the R-value of the material, and there are health and safety considerations as well. 

Cost : $150 to $3,000, plus installation. 

Cool Roof 

Cool roofs reflect the sun’s rays and reduce heat build-up through a light coloured or highly reflective roofing product such as a coating, new membrane or shingle. 

Most roofs in Canada are dark in colour and absorb heat from the sun’s rays transferring it into attics and the rooms below. Because cool roofs are better at reflecting the sun’s energy, less heat is transferred to your home. As a result, your heat-pump or air-conditioner may not have to work as hard, saving energy and reducing greenhouse gas emissions. Cool roofs also increase the life expectancy of your roof, because they reflect the heat and UV rays that damage and age roofing materials. 

Dark-coloured roofs in high-density areas also contribute to the urban heat island effect by reradiating absorbed heat back into the air, like the heat radiating off a sunny sidewalk on a hot day. As a result of climate change, Canada is expected to see dramatic increases in the number of days with heat advisories. Installing a cool roof is one way to help offset this and increasing incidences of heat-related illness. 

There are cool roof options for all types of roofs, including steep slope (pitched roofs), low slope (flat roofs). Roofing products are tested for their reflectivity and given a Solar Reflective Index (SRI) value between 0-100. The higher the number, the more reflective it is. 

If you want to convert an existing roof into a cool roof, you have the following options: 

  • Retrofit your existing roof – apply a coating that is waterproof and has reflective properties 
  • Replace your existing roof – install a new cool roof using a reflective roof product. 

What to Look For 

  • Low slope or flat roof – look for cool roof products with an SRI value of 78 or greater. Options include single-ply membranes, stone white calcite gravel, fluid applied membranes or a coating of white reflective paint. 
  • Steep slope or pitched roof – look for cool roof products with an SRI value of 25 or greater. Options include asphalt shingles, metal, tile, shake, among others. 
  • Products with a thermal emittance or emissivity of greater than or equal to 0.9 
  • Products that are asbestos and mercury-free, and emit zero volatile organic compounds (VOCs) and ozone-depleting substances. 
  • You can search for cool roof products using the Cool Roof Rating Council’s directory.  

Things to Consider 

  • Switch to a cool roof when your roof needs replacement, as converting a standard roof that is in good condition to a cool roof isn’t cost-effective. 
  • If your roof is not ready to be fully replaced, consider applying a cool roof coating. 
  • Like all roofs, the condition of your cool roof must be assessed each year and cleaned (if required) to maintain its high reflectivity. 

Cost : $6 to $22/ft2 


Heat gained or lost through inefficient windows can increase the energy used to heat and cool your home by 25-30%. 

Energy-efficient windows have: 

  • special coatings (known as low emissivity coatings, or “low-E glass”) and insulated frames and sashes which will reduce the cold transfer from outside and condensation on the glass. 
  • more glazing (panes of glass) for better exterior noise reduction and even more energy savings. 
  • special inert gases between the glass panes rather than just air for better insulation. 
  • a label on the product to indicate where the model is certified for use in Canada. 

What to Look For 

  • A low U-value. The U-value is a measure of the window’s insulation value. Look for windows in the range of 0.25 to 1.25, with 0.25 being the best. 
  • Buy windows certified for installation in Canada. In Canada, all windows should be at least double-glazed, that is: having two panes of glass. 
  • Windows with more glazing (panes of glass), dense gas fills (like argon), and low-E coatings are the most efficient. 
  • Hinged windows (casements, awnings, hoppers, tilt-turns) are more air-tight than sliders. 

Things to Consider 

  • Purchase certified ENERGY STAR® windows. 
  • Windows that don’t open are more energy-efficient, but floors with bedrooms require at least one window that opens for emergency egress. 
  • The window frame affects a window’s insulation value, strength, maintenance and longevity. Wood and fibreglass frames are the most efficient. 
  • Hire trained installers to ensure your windows and skylights will perform their best. 
  • Window and supplier warranties vary. Compare before you purchase.
  • Consider installing high insulation value windows on the east and north sides of your house to reduce heat loss. 

Cost : $500 to $1,000 per window, plus installation. 

Source: Natural Resources Canada

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Step 2 of a home energy retrofit project

Learn about the measures involved in upgrading the mechanicals in your home.

View Step 2
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Step 3 of a home energy retrofit project

Learn about the upgrades involved in installing renewables at your home.

View Step 3