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Poor insulation can result in major heat losses, besides reducing the comfort of your home. Improving the insulation and airtightness of your home are among the most effective ways to substantially reduce energy bills and your environmental footprint. The energy savings often end up paying for the cost of the renovation work over the short, medium or long term. And of course when you improve the energy efficiency of your home, you are also helping to reduce the production of greenhouse gases (GHGs). Insulation is often an issue that has to be treated on a case-by-case basis. It’s a good idea to call in a specialist to assess the different factors that can optimize the insulation effectiveness of a home. The insulation chart below summarizes the features of the most common insulation products and can help you make the right choice for your needs.
The insulating capacity of any material is expressed in terms of thermal resistance – in other words, its capacity to block heat transfer. This resistance is expressed as the R factor in the imperial system (insulating value per inch of thickness) or as the RSI value in the international system (insulating value per metre of thickness). The scales for the two systems are different, but in both cases, the higher the number, the higher the insulation value.
|Measurement unit||Insulating value expressed:||Minimum and maximum values for common types of insulation|
Per inch of thickness
3.0 to 6.0
Per metre of thickness
21 to 42
There are many different types of insulation on the market. Here are some variables to consider to help you choose the most appropriate type:
Technical feasibility: The thickness of the walls, the presence of thermal bridges (part of the inside structure in contact with the outside) and the accessibility of the location to be insulated are the first criteria to consider. For example, in spaces that are hard to access, it’s best to hire professionals to blow or spray in insulation.
Thermal capacity of the material: A well-insulated home generates a much weaker impact on the environment because it uses less energy. Energy is usually a major source of greenhouse gases. That’s why thermal capacity is such an important factor to consider. If you are hesitating between two materials, the one with the higher R (or RSI) factor is generally the best choice.
Air and vapour-tightness: Depending on how the walls and roof are built, some types of insulation, such as spray polyurethane foam, can serve as both air and vapour barrier for the building envelope.
Safety factors at the insulation site: The importance of resistance to high temperatures, fire, humidity or air circulation varies depending on where the insulation will be installed. For example, fibreglass and cellulose should not be installed where water may be present or where it’s impossible to install a vapour barrier.
Insulation saves energy and reduces GHG emissions. If you’re choosing among products with similar insulation values (R or RSI), you can reduce resource waste by opting for products that contain recycled materials. A high percentage of recycled content encourages waste recovery and helps close the loop of materials use.
Cellulose insulation products may contain up to 80% recycled materials, and fibreglass is often made of 70% recycled glass. Mineral wool can be made of 99.5% mineral by-products that are abundant in the environment (diabase, basalt and lime), but it contains little recycled material.
Recycled content is now incorporated in some kinds of insulation that also provide airtightness. For example, spray polyurethane foam may contain over 40% of recycled plastic.
Insulation saves energy and reduces GHG emissions, but to be effective and reduce health impacts, it is especially important to reduce heat loss and prevent water infiltration at the foundation.
Before pouring a foundation slab, install a polyethylene membrane and rigid insulation, such as polystyrene panels. This will reduce the humidity and insulate the floor. You should also ensure that the gravel you use is certified to be pyrite-free, as otherwise it could oxidize and deform your foundation.
Spray polyurethane foam is very energy efficient if you are certain there is no water infiltration and no traces of humidity on the foundation walls. One of the most effective and economical techniques is to install polystyrene panels sealed with adhesive tape and covered with a vapour barrier on the warm side of the insulation.
Buildings represent over 30% of national energy consumption in Canada. (NRC Institute for Research in Construction)
Insulation saves energy and reduces GHG emissions, but to be effective, it is especially important to reduce air leaks and heat loss by installing the right insulation in the right place. No matter where it is being installed, you should always choose the insulation with the highest R or RSI value.
Technical feasibility is the first thing to consider in your choice of insulation: the type of construction, the thickness of the walls, the presence of thermal bridges and the accessibility of the location may make it impossible to use some kinds of insulation, while others provide the perfect solution to reduce air leaks or heat loss.
To insulate closed or hard-to-access spots, like attics, a good choice is loose-fill cellulose, a product that can be laid or blown in, but not compacted.
To insulate exterior walls, there are different techniques and many products available. Batt or roll insulation includes mineral wool and fibreglass, which are designed to be inserted between wall studs and ceiling joists. There are also several types of rigid and semi-rigid panels, made of polystyrene or polyurethane, designed for special purposes: basement walls, exterior walls above foundations, exterior walls that are partly underground, etc.
To insulate potentially damp places like basements and foundations, it is best to install mould-resistant products like polystyrene or polyurethane. But these products are often highly flammable and it is prohibited to leave them uncovered, in the unfinished part of the basement, for example. Under cement slabs, polystyrene panels are the best choice, because they are so resistant to compression.
To insulate a house with air leakage problems, one highly effective option is to use spray polyurethane foam, installed from the inside or the outside, depending on the wall structure and covering.
To insulate spaces around windows and doors and the building framework, use polyurethane foam in a pressurized container. Be careful, though, because once applied, the foam expands and hardens quickly. Your best bet is a low-expanding product.
There are also other types of durable insulation made with rapidly renewable resources, such as hemp or straw, but their use requires a particular type of construction and special expertise to guarantee safety and reduce resource waste.
Many people today are hypersensitive to their living environment, and that means that a problem like poor indoor air quality can easily cause health problems for them. Precautions should be taken to limit the impact on their health, besides reducing the impact on resources.
Many kinds of insulation contain volatile components that may be diffused throughout the house. These products may be irritating for people sensitive to their living environment and may cause respiratory problems. The best option is to always choose the least toxic products possible, in order to maintain good indoor air quality and safeguard human health. If inhaling cellulose or mineral wool dust will cause a problem during handling, choose urethane foam, but make sure it is CFC- and HCFC-free, to reduce GHGs. You should also bear in mind that non-biodegradable flame-retardants are often added to insulation to make them more fire resistant. Polystyrene panels, for example, must be covered for safety reasons: they release toxic compounds when exposed to flame.
The vermiculite produced between 1920 and 1990 may contain amphibole asbestos, which has been linked to lung cancer and cancer of the chest cavity. Vermiculite installed in wall cavities and attics poses little health risk if it is not disturbed. If you must handle vermiculite during insulation work, first read the Health Canada safety sheet.
Avoid compressing insulation during installation: this reduces its thermal capacity, which is dependent on its thickness.
Pay careful attention not to leave uninsulated spaces where air can infiltrate, such as around doors and windows, in crawl spaces, around openings for pipes and wires, and around thermal bridges such as concrete balconies or steel beams.
Many kinds of insulation can be irritating to the skin, eyes and respiratory tract during handling. Make sure you follow the manufacturer’s recommendations and installation instructions and protect yourself adequately.
Some kinds of insulation, such as spray or blown-in insulation, require a lot of expertise to be applied safely and properly. Call on specialized contractors.
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