What materials are sustainable when it comes to building? How do we choose materials from both a cost, quality, aesthetic criteria, but also materials that maintain a healthy non-toxic space for our family and that look after the environment? True sustainability is not just trying to reduce the negative effects of construction on the planet, but actually looking at whether the way we design and build can have a positive impact instead!
There are often complex ways of assessing the lifecycle costs from cradle to grave of a material, including its extraction, processing, transport and also treatment to maintain its longevity. But there are some simple points that you can consider, regarding the environmental footprint of a materials, that help to build your home in a way that respects the planet.
In a similar way to choosing organic food produce, you can consider building materials from the following perspective:
- Ideally materials should be Locally sourced from near your site (in order to limit transportation pollution), and be produced in your own country.
- They should be Renewable and harvested sustainably (e.g. sustainably managed forests, bamboo, FSC certified timbers, wool, cork)
- It could be Biodegradable and return naturally to the earth over time without negative effects to the land or our bodies (e.g. using natural oils to coat timber)
- It could also be Naturally durable (such as cedar, rubber) without toxic treatments required to improve its longevity.
- Also they may be Raw materials (that do not require a high amount of energy or pollutants to create or form, eg. straw, rammed earth, timber). Questions to ask would be - Does it require high CO2 emissions through the manufacturing process, or is it likely to release VOCs into the air inside the home through the addition of solvents, glues or coatings.
The fact of the matter is that often the common (and cheaper) materials readily available and acceptable by the building code, do not meet all these criteria. Most products have both positive and negative environmental aspects. So the next selection process would be taking into account how these effects can be mitigated in some way:
- Can this material be Recycled easily (e.g. Metal, Aluminum) while some materials can be high in energy and resource extraction to produce, could it be reused for different purposes in the future. Synthetic materials are often very difficult to recycle as well as creating pollutants in their manufacture.
- Is the material’s longevity or Durability for a specific site an asset that means replacement is not required for generations, and reduces the future use of pollutant treatments to maintain it (e.g. masonry, brick, stone, tile, terracotta tiles)
- Can the building actually include Recycled materials or include recycled components (e.g. Fly ash, slag, or recycled glass as the aggregate for concrete or paving, recycled timber doors or recycled timber interior linings or flooring.)
- Has the extraction of a mined material of a non-renewable resource (metals, earth, fibre-cement) been Managed by Regeneration of any mined areas, and the health of the local environment and waterways managed (both here and overseas).
- Are there other options for Reducing VOCs if we need a certain performance or durability criteria (e.g. Low VOC paints, formaldehyde free plywood, natural textiles)
Finally, the actual design of the house and the method of using a specific material can impact on other environmental effects:
- Can it Minimize Waste – eg. the use of Sips panels (prefabricated insulated panels) give an have a high insulation performance, but also are efficient in material use and can substantially reduce the amount of waste that goes to landfill.
- Is the material going to substantially Reduce the Energy consumption of the building over its life-time? While concrete, block and brick use a lot of energy to produce, their use in the design may mean they are offset by reducing the energy consumption and CO2 emissions to heat or cool a space.
- Is this building going to stand the test of Time. Are the quality and integrity of the materials selected compatible with a timeless design to enable this building to last for many years ahead. Will it weather well, gaining value and beauty as it ages.
Going through this list is something we do as we work through a design concept with you, we can discuss the options for your unique site and design. For more specific manufacturers product information you can check out Envirospec and Declare which describes which products meet Living Building Challenge, (full lifecycle sustainability) or Green Star & HomeStar (resource and energy efficiency) environmental criteria. For a little further information on NZ timbers you can check out our previous blog post here.
Have a great week!