Sustainable Materials

Considerations when choosing materials

• How long is the garden to last for?

• Is the style something that will be still appropriate into the future?

• What is the embodied energy of the material?

• What is the ongoing maintenance of the material?

• What is the opportunity cost of the material?

• Can the space be made smaller?

Interpreting embodied energy of materials

Commonly embodied energy is calculated in MJ/Kg. This does not necessarily give you a good comparison of materials as they can be used in different ways to create the same object. To make a screen wall, two different materials we could use are timber and concrete. To build a concrete wall we need to we need to build a solid wall of perhaps around 150mm in thickness and provide a strip footing across the length of the wall of concrete. However, to build a timber screen we might place posts at around 2.4 metres apart with only a footing around the post. We would then run rails between the posts and then clad the rails. The amount of material needed is significantly higher in the concrete wall. On top of that the weight per cubic metre of the material is significantly higher as well. A heavy timber might be around 1 tonne per cubic meter, while a cubic meter of concrete might be more like 2.4 tonnes per cubic metre. So even though both materials have an embodied energy of approximately 2Mj/Kg, the embodied energy of the concrete wall will be significantly higher.

Embodied Energy of materials

Statistics taken from: Your Home - Australian Government

Lesson Outline

• What is embodied energy?

• How does it effect material Choice

Presentations

Definitions