Sidebar: Embodied Energy--Just What Is It and Why Do We Care?
What Embodied Energy Doesn’t Tell Us
Embodied energy values can play an important role in assessing the overall environmental impact of a material, but they cannot give the whole picture. Among the other important factors to consider are:
- The environmental impacts of energy use vary significantly with the type of fuel and how it is consumed. Knowing the quantity of energy used in producing a material is a good first step. Identifying the fuels used and their associated pollution profiles is the next. Natural gas produces much less pollution per Btu than coal, for example, and solar energy doesn’t produce any.
- The resource extraction and manufacture of building materials have environmental impacts other than energy use. Wood products, for example, tend to have low embodied energy values because they require relatively little energy-intensive processing. The damage done to a forest by careless harvesting, however, also needs to be considered. The use of recycled-content materials reduces the problems associated with resource use and damage from mining or harvesting.
- How a material performs after installation in a building is important as well. Factors such as longevity/durability, impact on operating energy consumption, maintenance requirements, and eventual disposal or reusability can either offset or reinforce conclusions based on embodied energy assessments and the other criteria listed above.
