Materials Impacts in Construction

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Materials are critical in determining the environmental profile or impact of buildings. The embodied energy of construction, for example, is equivalent to:

  • 10 - 15 years operational energy for houses
  • 4 - 40 years operation energy for commercial buildings

Add to this that new research is indicating that the embodied energy of commercial building fitouts may approach or be equal to the operational energy of commercial buildings, and it becomes apparent that materials are very important.

Of course embodied energy is not the only measure of sustainability. The discussion below overviews this and other critical issues.

Overview

According to research by the Federal Government, buildings are responsible for significant environmental impacts (30 % of the raw materials used, 42% of the energy, 25% of water used, 12% of land use, 40% of atmospheric emissions, 20% of water effluents, 25% of solid waste and 13% of other releases) (Australian Federal Department of Industry Science and Tourism 1998).

If we look at the broader infrastructure including bridges, roads and so forth, materials account for upwards of 70% of our total materials flows globally. The figure is believed to be similar in Australia. Much of our total building activity, including associated infrastructure, is associated with residential development.

Materials used in house construction impact on almost every aspect of sustainability including:

  • Raw-resource extraction impacts on the physical environment for example cutting down tropical forests for window or flooring timbers, or chemical spills from poorly managed mines for metal, paint or ceramic products
  • Non- renewable resource depletion, including oil, and resource quality degradation, such as pollution of water
  • Greenhouse gas emissions from energy production in all stages of material manufacture and use
  • Waste leading to land fill burdens, some of them toxic.

According to Australian research if we look at one indicator of environmental impact, energy consumption, it takes as much energy to make a standard brick veneer house as it does to run one for fifteen years (Commonwealth of Australia 2002).

As well as environmental impacts, which are often hard to locate or quantify precisely, there can be significant human health impacts. These range from emissions from products polluting indoor air over many years, to short term high-level emissions in construction (such as painting) through to long-term health issues such as ground-water contamination from leachates from landfill.

Building materials were one of the important factors identified in a 2002 report that identified "indoor air quality is a most significant environmental issue that has not been seriously addressed in this country. Unhealthy indoor air is costing the Australian community an estimated $12 billion a year. Australia is failing its responsibilities of a 'duty of care' to protect the community in the environment where we spend most of their time" (Clean Air Society of Australia and New Zealand 2002).

Materials in Commercial Buildings

BRE 'Green Guide' Findings

A useful life-cycle study for looking at the impacts of commercial/institutional buildings is the UK Building Research Establishment's 'Green Guide to Specification' by Jane Anderson and David Shiers. Now in its 3rd edition, the Guide looks at 3, 8 and 20 storey buildings and looks at:

  • The relative importance of different building elements (walls, floors etc) into the overall building
  • The relative performance on a life cycle basis of generic element products over a 60 year cycle rated in 'Ecopoints'. For example for 'Upper Floors' the Guide looks at hollow precast slab, profiled steel permanent steel shuttering etc and gives each an 'ecopoints' rating.

The ecopoints rating is not product specific (and we know from Australian research that the differences between apparently similar products can be very large) and there are many detail differences between UK practices and Australia - for example we don't tend to use a great deal of PVC-u weatherboards. However there are many similarities and the Guide is well worth a look to Australian specifiers.

Among the key findings of the BRE Guide is where the highest environmental impacts in the building occur.

Element

Approximate percentage of total impact depending on building size (3, 20 storey)

Floor finishes

35 - 40%

Upper Floors (particularly in taller buildings)

12 - 25% (3, 20)

Footings

12%

Floor surfaces (e.g. raised floors)

12%

External walls, high mass types

5-10% (3, 20)

Roof

3 - 12% (20, 3)

Ground Floor

4%

Windows & curtain walling

2 - 5% (3, 20)

Superstructure

1%

Internal Walls & Partitioning

1 - 2%

Suspended ceiling & ceiling finishes

1 - 2%

While the BRE study takes a life-cycle analysis approach, the LCA includes UK data on energy and other assumptions including details of materials and fabrication.

Australian 'BuildLCA' Findings

Another useful data source for Australian commercial buildings is the BuildLCA study completed in 2002 by a consortium of researchers including the Centre for Design and Deakin University.

The study included a detailed embodied energy analysis of a number of buildings including a medium sized office building, 15 storeys, 3 basement levels, GFA of 50000m2.

Embodied energy is a useful 'proxy' or indicator of a range of environmental impacts, as the production of energy, particularly in Australia which is highly coal-dependent, is very pollution intensive.

The study found that for this office building the following areas constituted the highest impacts (base building only, excludes fitout).

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Looking at a detailed material breakdown the research showed the following materials were responsible for the majority of the impacts:

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