The Environmental Challenge in the Building Sector

Building construction, renovation and operation consume more of the earth’s resources than any other human activity.

Each year, at least 40% of the raw materials and energy produced in the world are used in the building sector. This generates millions of tonnes of:

No other sector has a greater impact on the global environment or faces a greater obligation to improve its environmental performance.

With so much of the world’s resources consumed in the building sector, learning how to build with the environment in mind is a necessary step that will have a tremendous positive impact.

Can we reduce the environmental impact of buildings?

Yes we can.

By designing and building with the environment in mind, and wisely combining products made of wood, steel, concrete, plastic and other substances, we can have buildings that are energy-efficient, healthier for occupants and environmentally sustainable. But there is a lot we need to know first; for example–

Finding the answers

At the Athena Institute, we believe that life cycle assessment (LCA) is key to answering questions such as these–and we are not alone. LCA is widely accepted within the environmental research community as one of the best ways to compare the environmental impacts of alternative materials, components and services. As a result, we’re also working hard to make LCA more accessible by increasing the range of tools available and facilitating its integration into green building rating and assessment systems such as LEED and Green Globes.

What is LCA?

LCA is a methodology for assessing the environmental performance of materials, assemblies and even whole structures over the course of their entire lives, from extraction through manufacturing, transportation, installation, use, maintenance and disposal or recycling. Impacts are measured in terms of a wide range of potential effects, such as :

All of these measures are indicators of the environmental loadings that can result from the manufacture, use and disposal of building products. The indicators do not directly address the ultimate human or ecosystem health effects–a much more difficult and uncertain task–but they do provide good measures of environmental performance, given that reducing any of these effects is a step in the right direction.

In LCA terminology, the effects associated with making, transporting, using and disposing of products are referred to as ‘embodied effects’, where the word embodied refers to attribution or allocation in an accounting sense as opposed to true physical embodiment. In the building community, the tendency is to refer primarily to ‘embodied energy’, but there is a wide range of embodied effects, as implied by the list of indicators. All of the extractions from and releases to nature are embodied effects, and there are also embodied effects associated with the production and transportation of energy itself (known as pre-combustion effects).

In the case of buildings, the energy required to operate a building over its life greatly overshadows the energy attributed to the products used in its construction. However, for other embodied effects such as toxic releases to water, effects during the resource extraction and manufacturing stages greatly outweigh any releases associated with building operations.

The point is to beware of the common tendency to focus only on embodied energy. The essence of LCA is to cast the net wide and capture all of the relevant effects associated with a product or process over its full life cycle.

In that vein, it is also important to note that the LCA of a given product should take into account the production and use of other products required for cleaning or maintenance during its use phase. For example, we should take into account the paints required to maintain some types of wood cladding, and the cleaning products required to maintain various kinds of flooring.

We must similarly take account of the repair and replacement of products throughout their life cycle in a building application.

The final point to note about LCA is that it is not the same as life cycle costing (LCC). The two methodologies are complementary, but LCC focuses on the dollar costs of building and maintaining a structure over its life cycle, while LCA focuses on environmental performance. Performance is measured in the units appropriate to each emission type or effect category.

For example, global warming gases are characterized in terms of their heat trapping effects compared to the effects of CO₂, and global warming potential is measured in equivalent tonnes of CO₂.