Construction accounts for 24 per cent of global raw materials removed from the earth. In addition, the extraction, processing, transport and installation of materials associated with construction consume large quantities of energy and water. Wood is a fundamental part of construction. It is a versatile construction material because it can be found everywhere. Looking around, you can argue that the most commonly used building materials in construction today consists of concrete and steel. Unlike wood however, concrete is made through unsustainable practices. Wood can be torn down to be reused, but concrete cannot be salvaged and it is left where it is demolished. Steel is the newest of the three materials. Steel became a popular building material during the industrial revolution due to its durability. During this time, most people began switching from building with wood to steel. With society’s current knowledge, we know that wood is the best option in terms of sustainability. The progression of concrete and steel may not lead down the most sustainable path. Buildings account for 39 percent of carbon dioxide (CO2) emissions CO2 is a greenhouse gas that greatly contributes to negative global climate change. Scientists predict that left unchecked, emissions of CO2 and other greenhouse gases from human activities will raise global temperatures by 2.5 F to 10 F this century. This could produce rising sea levels, more frequent floods and droughts, and increased spread of infectious diseases. A building's carbon footprint is the amount of CO2 it produces during its operations and activities.Managing and reducing carbon footprints as part of a low carbon strategy, with its inherent cost benefits and revenue opportunities, is increasingly important in building design. Building green is one of the best strategies to temper negative climate change because the technology to make substantial reductions in energy and CO2 emissions already exists.Reducing a building's carbon footprint reduces its running costs, improves employee morale, raises property values and improves LEED scores. Buildings become environmentally responsible, profitable and healthier places to live and work in. The following tips can help reduce a building's footprint.

How to reduce?

1. making roof tiles out of concrete is a better option than using either ceramic or fibre cement roof materials:

2. For bricks, local clays and renewable constituents, such as straw, had lower environmental impacts compared with conventional bricks.

3. Replacing synthetic insulation materials, such as polyurethane rigid foam and EPS (expanded polystyrene), with natural insulation materials, such as cork, wood fibre and sheep’s wool, also appeared to reduce environmental impact. For example, production of polyurethane places high demands on primary energy and water consumption, whilst sheep’s wool could emit 98 per cent less CO2, if the wool is incinerated at end-of-life.

4. Switching to renewable sources of energy and improving technologies by making better use of the waste heat from the furnace or reducing the furnace temperature, for example, could halve the emissions of CO2 from cement manufacture by 2050.

5. Constructing buildings with wooden structures would also lower the primary energy demand and could be almost carbon neutral, or even carbon negative if the wood was recycled and reused at the end-of-life.

6. Other construction materials, such as steel, aluminium, copper, glass and PVC should be reused and recycled where possible to reduce the primary production of these materials. For example, producing secondary steel (e.g. using scrap steel) could reduce emissions by 74 per cent, compared with producing the same amount of primary steel.

7. Companies should be encouraged to construct buildings that can be disassembled rather than demolished at end-oflife, to make it easier to separate materials for reuse and recycling

Thank you for the immediate and helpful response

This is a very good question.

You may make this assumption. However, personally I do not think it is a valid one. Take cementituous materials for example (such as concrete). The environment footprint of the recycled materials will still not be negligible even after recycling. I think this is a very good area of areas to carry out with the aim of evaluating and establishing a robust method for measuring such footprint.

Best wishes.

I agree with the answer of Baboo

Thank you for answering Dr Saidani.Infact zero environmental footprint is only theoretical if we consider that the only processes that is actually omitted as far as enviromental impact is concerned is the first stage of producing the raw materials.