Australians are becoming increasingly concerned about global warming and other environmental issues.
Sustainable building design is becoming less of an option and more of an imperative.
Windows and doors are among the architectural elements that have the greatest impact on the overall energy footprint of a building. During all phases of the project lifecycle, architects, designers, and builders should be considering how they can use windows and doors to reduce energy usage.
The main options for window and glass door frames are timber, aluminium, steel and PVC. In addition, some manufacturers will use a combination of aluminium and PVC.
For trees to grow, they only need soil, air, water, sunlight and time. If the process is well managed, trees can be grown, harvested and regrown on a continuous basis to provide a renewable resource. This is in stark contrast to other building materials made from finite and non-renewable resources (wadic.org.au)
To reduce environmental impact timber is chosen because it is a renewable material that is predominantly carbon neutral and preferably from a sustainably managed and certified source (wadic.org.au)
Timber is also recyclable - wooden structures can be deconstructed and the wood reused in other buildings or products at the end of their life
In fact, 11% of global greenhouse gas emissions come from building materials and construction. When it comes to windows and doors, by way of comparison, the fossil fuel energy required to manufacture rough sawn timber is 1.5 MJ/kg, while the manufacture of steel requires 35 MJ/kg of fossil fuel energy and aluminium requires a whopping 435 MJ/kg!
Timber is a natural thermal insulator thanks to the air pockets within its cellular structure. Compared to other properties it is 15 times better than masonry, 400 times better than steel and 1,770 times better than aluminium. As timber is a natural insulator then less energy is required (good for the environment) within a building which in turn reduces costs.
When procuring timber for windows or doors, it’s important to make sure the timber is sourced sustainably from a well-managed forest, and that no excessive carbon emissions were created in its transport from forest to manufacturer.
Certain international organisations like the Forest Stewardship Council offer certifications that make it easy to identify timber that meets their standards. In addition, the Australian Government has adopted sustainable forest management standards, which are recognised as some of the best in the world.
Generally speaking, buildings with predominantly north-facing windows will be more energy efficient than buildings with most of their windows in the direct path of the sun.
However, when making decisions about window orientation, the architect should consider the project’s specific location and surroundings. In some cases, neighbouring structures can be used to limit solar heat gain on east, west, or south-facing windows.
When drafting, designing, and building a structure for minimal environmental impact, windows and doors should be top-of-mind. Few other architectural elements play as big of a role in determining the long-term energy footprint of a building.
By thoughtfully positioning windows and doors, selecting sustainable materials, and taking care in construction, architects, designers, and builders can create beautiful, comfortable, environmentally friendly spaces.