Buildings

as noise pollution, chemical pollution and hazardous waste issues such as asbestos and lead content in paint (UNEP SBCI 2010b).

Avoiding waste, in addition to minimising energy and water consumption over a building’s life-cycle, is crucial to the sustainable performance of buildings. Life-cycle management brings a cradle-to-cradle perspective, covering a building value chain that includes the manufacturing of material supplies, the construction process, building operation and maintenance as well as the disposal, recycling, or reuse of building, operations, construction, and demolition waste.

Buildings consume great quantities of materials, energy and other resources, the root of which start with planning and design and reach all the way to eventual demolition. The consumption of these resources can have significant environmental impacts

at global and local levels.

Ensuring that undesirable impacts are minimised, architects and design professionals play a major role in energy conservation and responsible resource usage. Research into the energy consumption of buildings today is directed towards analysis of operational energy (during use phase) as well as the energy embodied within the fabric of the building, energy needed to extract and process raw material into finished building components, as well as energy used in the construction of the building. As operational energy consumption is improved, embodied energy becomes proportionally more significant. The embodied energy of a building’s materials is one measure of its ecological impact and use of ecosystem services, which raises questions about the acquisition of raw and processed materials.

Measuring the embodied energy of building material components, or the building as a whole, presents an enormous challenge unless information is systematically collected from the design stage to the completing of construction and is made available by all manufacturers involved.

In order to reduce the building impact and fulfill a complete life-cycle of building and material construction analysis, it is necessary to establish low-impact criteria during the design process; construction, operation/ maintenance and disposal/recycling. The following criteria can be considered: raw material availability; land and water availability; minimal environmental impact; embodied energy efficiency (production and process energy requirements); transportation; product lifespan; ease of maintenance; potential for product re-use; and material durability and recyclability. In order to analyzse the environmental impact of the materials according to their entire life-cycle, building materials are divided in three groups: organic, ceramic and metallic. Organic building materials include

timber. Ceramic building materials are the inorganic, non-metallic ones, primarily consisting of concrete and masonry products as well as glass. The metallic building materials include steel, aluminum, copper and lead. These are all natural resources. Issues also arise from the increasing use of synthetic materials such as plastics, which tend to be complex materials that pose difficult problems for recycling and reuse. Reducing the number of material components in products as well as separating natural from synthetic material allows higher rates of recyclability and reuse (McDonough and Braungart 2002).

Comparative analysis of materials using the above- listed criteria (Lawson 1996) shows that, by example, sustainably-sourced wood is one of the best options for ensuring low embodied energy and a minimal environmental impact. While metallic materials have the highest embodied energy, they also perform well in terms of their lifespan, maintenance, reuse and recyclability. Lawson’s study, carried out in Australia, reported that 95 per cent of embodied energy that would otherwise go to waste can be saved by the reuse of building materials. Savings range from 95 per cent for aluminium to only 20 per cent for glass.

The recycling of building materials is a relatively new concept and has only been assessed in a few studies. In a study carried out in Sweden, two cases were compared: (a) a building with a large proportion of re-used materials and components, and (b) the same

Box 4: Water savings in a 4-person single house

Water use in a standard 4-person single-family detached house can be reduced by 57 per cent (from 500 litres to 218 litres per day) by installing more efficient devices in place of conventional toilets,

showerheads, taps, dishwashers,

washing machines etc. (van Wyk 2009). Water- efficient appliances such as rainwater harvesting systems and systems for re-using grey water require additional investment costs, but most cost-saving effects relate to saved potable water. These are determined by the average cost of potable water. In the case of a 4-person single- family household, setting a high price for water (US$ 1.91 per m3

(as in Canada)

the saving will be about US$ 42 per year . UNESCO (2001)

, as in Germany) will result in a

saving of about US$ 202 per year, whereas with a lower price of US$ 0.40 per m3

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