The building envelope is the shell that keeps the interior of your building at a comfortable temperature. An efficient building envelope will drastically reduce your energy consumption (by as much as 50% in some cases) which helps you to save money and reduces the carbon footprint of your home or business. Whether you are planning to retrofit an existing building, or are embarking on a new build, establishing an effective building envelope is the key to green building success and energy savings.
For a building envelope to work efficiently, careful planning and faultless execution are required. A green building consultant can assess your building’s needs and recommend suitable building materials and insulation that will help you achieve your energy saving goals. No matter how carefully you plan, shoddy workmanship that leaves gaps and holes will render even the most dedicated planning ineffectual.
Site selection and orientation
Aside from the obvious ecological impact of building placement, orienting your building correctly can make a significant impact on energy consumption. Orient your building to get the most sunshine in colder climes while using passive heating techniques to absorb solar energy into the home. The effects of solar heating can be mitigated in the warmer months by planting deciduous trees to provide shade. Take advantage of the prevailing winds for natural ventilation.
Selecting the best materials
Consider building with insulating building materials such as ICFs. ICF’s not only provide some of the most comprehensive insulation on the market, they also act as a thermal mass which absorbs solar heat during the day and radiates it back into the building at night. During warmer months, ICF’s are able to provide a tight building envelope which keeps warmer air out and cooler air in. Building with ICF’s can reduce your energy consumption by 30%.
A growing trend is to retrofit insulated basements with ICFs. Up to 40% of heat can be lost through basements which are inadequately insulated.
Older homes and buildings have insufficient insulation to ensure a comprehensive building envelope. You can effectively insulate attics with small spaces with spray foam insulation or use raised-heel trusses to create a larger attic space. This will enable you to increase the amount of insulation you can use in the attic and enables you to utilize cheaper insulation materials like loose fill cellulose or fiberglass batts.
Now that the walls and roof are helping to save energy, it’s the turn of your window panes to improve insulation. Advances in window technology mean that designers no longer have to make the choice between natural lighting and energy efficiency. Energy efficient windows are graded with a U-factor. A lower U-factor value indicates a high insulation value. Refer to the Energy Star® chart for the ideal rating for your area. As a general guideline, buildings in warmer areas of southern and western Canada can use windows with a U-factor rating of 1.80 to 1.60. Colder areas and the north need windows with U-factors of 1.40 to 1.20. Adding energy efficient windows can save you 7 to 12 percent on your current energy costs.
Good news! You’re being audited
Energy audits are the most important step in ensuring build envelope efficiency. A blower door test will reveal leaks and gaps in the building envelope where precious energy is escaping. These tests are augmented by thermograms; pictures of your home or business that reveals the gaps and leaks. Thermograms are created by thermal imaging and infrared cameras.
While materials that improve the efficiency of your building envelope will cost a little more initially, green building materials offer an excellent ROI and you can look forward to a lifetime of energy savings.