Homeowners are becoming increasingly interested in improving the energy efficiency of their house to reduce costs, improve comfort and help protect the environment. Many older Canadian houses are relatively drafty and lightly insulated, and this can result in higher heat losses and energy bills — even in those built more recently, between the 1950s and the 1980s. These houses likely use at least 25 per cent more space heating energy than houses built after 2010, because increased insulation and airtightness levels have been included in more recent building codes.

In Canada, space heating accounts for over 60 per cent of residential energy use and, therefore, makes up a good proportion of your overall energy bill. Fortunately, there are several options that you, as a homeowner, can consider for reducing heat loss, including adding, or retrofitting, insulation to your house. A well-insulated and well-sealed house needs less heating in the winter (and less cooling in the summer), protects you from increasing energy prices, uses resources more efficiently, has less environmental impact, and is more comfortable to live in.

Before planning an energy retrofit for your house, Canada Mortgage and Housing Corporation (CMHC) recommends that you hire a qualified residential energy service provider to undertake an EnerGuide audit. During the audit, the energy service provider will measure the existing airtightness of your house, identify air leaks that should be sealed, provide specific options for upgrading insulation, recommend door and window improvements, and suggest upgrades to your space heating system. Fenestra Group has the necessary equipment and a qualified staff to conduct repair works after an assessment by a professional in energy evaluation. Thanks to this equipment, we can confirm and repair the flaws stated by the inspector..

Improve Airtightness

Reducing unintentional air leakage (that is, air sealing) through the walls, ceilings and foundations of the house is one of the most cost-effective ways to improve its energy performance and comfort. This should be the first priority in any building envelope retrofit because air leakage can reduce the effectiveness of some types of insulation, and allows warm, conditioned air to escape to the outdoors or lets cold outdoor air infiltrate to the interior, causing the heating system to work harder. If left uncorrected for too long, air leaks can also cause moisture and indoor air quality problems. First, you have to find the leaks. While some leaks are easily detected, most leaks are found during a “blower door” test. This test is done as part of the EnerGuide audit, or can be done independently by a contractor. The blower door depressurizes your house causing outside air to leak in through cracks and openings, and the operator uses tools such as smoke pencils or thermographic equipment to locate these leaks. Common air leakage points include:

  • ceiling pot light fixtures recessed into attic spaces;
  • electrical boxes penetrating ceilings below attic spaces;
  • wiring, plumbing and duct penetrations into the attic;
  • exhaust fans located above bathroom ceilings in the attic space;
  • window-wall joints (behind the finishing casings);
  • operable windows;
  • door weatherstripping;
  • electrical boxes on exterior walls;
  • floor-wall joints;
  • first- and second-floor rim joist areas;
  • foundation rim joist area; and
  • foundation wall and floor electrical, plumbing and duct penetrations.

You may use many different approaches to sealing the various parts of the house. For instance, you may air seal leaky windows and doors with new gaskets and weatherstripping. You can seal small gaps around wiring with caulking, and larger gaps with spray foam. You can also install airtight gaskets under the cover plates on electrical switch and outlet boxes, and airtight boxes constructed of polystyrene board insulation over exhaust fans in attic spaces. You should consult an air leakage control specialist for the most effective methods.

Common Situations

Many homeowners experience houses that are cold, drafty or have high heating bills, especially on windy days during the heating season. The process of improving the energy efficiency of the entire building envelope can seem like an overwhelming task. An understanding of the principle that the house functions as a system (see the House as a System section) is critical for anyone undertaking a building envelope retrofit. Prioritizing the different aspects of the work and learning about viable retrofit techniques can help you to work through the many decisions that must be made.

To help you recognize problems and to plan an energy- efficiency building envelope retrofit, consider these important areas :

  • Structural problems : There may be structural problems. Any existing problems and damage must be repaired as part of the retrofit project otherwise your renovation, and all of your invested time and money, will be at risk.
  • Moisture : VThere may be moisture problems in the existing house that must be identified and remedied to protect your renovation investment. Be aware that building envelope retrofit work may increase humidity levels in the building and you might have to install mechanical ventilation to compensate.
  • Heating and ventilation : Inadequate and inefficient heating and ventilation may be symptoms of a poorly performing building envelope. Additionally, by adding insulation to, and increasing the airtightness of, the building envelope, the heating system may become over-sized. It may be advisable to consult with a heating contractor on the post-renovation heating needs of the house.
  • Finishes : Finishes may be damaged from moisture problems associated with poor building envelopes.

Summary

Remember that improving airtightness is the most cost-effective measure and is necessary to maximize the benefits of adding insulation; you should insulate and air seal as much as possible given your circumstances. Even a modest improvement to a drafty, poorly insulated building is better than no improvement at all.

Retrofitting the building envelope for space heating energy savings can provide significant savings on energy bills and a more comfortable house to live in.

The Air Barrier System

To know where, and how, to seal your house, you have to understand what makes up the “air barrier system.” An air barrier system is composed of one or more materials that resist the movement of air through the walls, roof and foundation of your house. Most air barrier systems are made up of a combination of air-impervious materials such as polyethylene, spun-bonded polyolefin, polystyrene, oriented strand board and gypsum board, and — in the case of windows — glass. Ideally, the individual components are sealed together by gaskets, weatherstripping and sealants to form a continuous, draft-proof wrap around the house. However, in reality, there are often many unsealed joints in, and penetrations through, the air barrier systems in most houses, representing both a problem and an energy efficiency retrofit opportunity.

First, you have to find the leaks. While some leaks are easily detected, most leaks are found during a “blower door” test. This test is done as part of the EnerGuide audit, or can be done independently by a contractor. The blower door depressurizes your house causing outside air to leak in through cracks and openings, and the operator uses tools such as smoke pencils or thermographic equipment to locate these leaks.

You may use many different approaches to sealing the various parts of the house. For instance, you may air seal leaky windows and doors with new gaskets and weatherstripping. You can seal small gaps around wiring with caulking, and larger gaps with spray foam. You can also install airtight gaskets under the cover plates on electrical switch and outlet boxes, and airtight boxes constructed of polystyrene board insulation over exhaust fans in attic spaces. You should consult an air leakage control specialist for the most effective methods.

Ventilation

A highly energy-efficient building envelope retrofit will provide a more airtight house, which is important for reducing energy consumption. However, this will also result in less incidental ventilation, which would otherwise be provided by a leaky enclosure. This can cause the air in the retrofitted house to seem stale, and could also lead to moisture problems. Odours from previously unnoticed sources (such as pets or stored items) may become more apparent and more objectionable. Therefore, energy-efficient mechanical ventilation should also be included in any house energy retrofit strategy. This can be accomplished by adding a heat recovery ventilator (HRV) or an energy recovery ventilator (ERV). This ventilation should improve occupant health and comfort. Consult a qualified mechanical ventilation contractor and your EnerGuide service provider for more information.

Building Envelope Durability

Installing additional insulation can increase the risk of moisture to the building envelope if inside and outside sources of moisture are not controlled.

Pre-Existing Problems

Pre-existing problems should be corrected prior to undertaking an energy efficiency building envelope retrofit so that the problems do not worsen. Pre-existing problems include:

  • moisture problems (high humidity, water leaks, dampness, mold, etc.) in the roof, walls, floors or foundation;
  • indoor air quality problems (stale air, lingering odours, soil gas, pollutant emissions from household products, etc.);
  • radon or other soil gases;
  • structural sags, cracks and deflections; and
  • the presence of hazardous materials such as asbestos, lead paint and rodent/bird waste.

A Word of Caution

Building envelope energy efficiency retrofits can have unintended consequences if consideration is not given to assessing the condition of the house for pre-existing problems and anticipating the possible effects of the retrofit work on indoor air quality, building envelope durability, heating appliance performance or other possible performance issues.

Links

CMHC: Energy Efficiency Building Envelope Retrofits

Source: cmhc-schl.gc.ca/

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