At the heart of all building projects are the materials, the stuff, the bricks and sticks, the elements that are assembled to build a building. Different materials have different impacts on the Earth. Some require extensive resources for their manufacture. Steel and other metals need to be refined from ore and processed into their final forms, often several operations, all taking great amounts of energy. The choices that go into selecting building materials have long range ramifications in a number of ways.
The materials we use in our buildings have an enormous impact on the Earth. Choosing materials with a lower impact can be an important criterion, but the matter needs to be looked at with proper long-term perspective. Careful use of materials with a long useful life (rather than materials which merely stick around for a long time after they have reached the end of their useful life, like vinyl siding) can result in a building that serves generations. Densities of use found in modern cities are only realistically possible when using higher impact materials such as steel. However, the offsetting benefits coming from the use of those materials helps to make this a more reasonable choice.
Because buildings last for such a long time, renovation and remodeling are important factors to consider. In the same way that the greenest purchase is often the one you don’t make, the greenest building can likewise be one that isn’t built. By re-using existing buildings, maintaining and improving them, and adding on to them as needs expand, rather than building new buildings.
This is not to say that no new construction is needed, or that all construction should be stopped. The economic facts are such that, at times, it makes more sense to build new, rather than re-use an existing building. But a well-built, well-designed building that can adapt to new patterns of use and sit on a site for 1000 years uses far fewer materials than a succession of 100 year buildings. Too often, in the US, 100 years old is a ‘historic’ building, and many buildings do not last that long.
Some characteristics to consider in building material choices:
- Longer life means lower cost, less labor needed (and subsequently wasted), less waste of materials, and less impact from the materials that were used in the construction.
- Local production is beneficial in reducing transportation energy, as well as supporting local economies and in working with appropriate materials for the region.
- Low production energy means that it is less resource intensive to collect, harvest, manufacture and deliver the materials. Adobe and wood are low production energy materials. Aluminum is a very high production energy material (leading to it sometimes being nicknamed “frozen electricity”).
- Relatively small differences made at the outset of a building project can pay back in larger dividends over the life of a building. There is very little additional material and almost no difference in labor between building with 2×6 stud walls rather than 2x4s. But, with the increase in insulation available with the deeper cavity, a thicker walled home will have lower energy use which will pay back in lower energy bills over many years.
image source: Alno – via Wikimedia Commons