While materials choice undoubtedly needs careful thought, it is important to also consider the bigger picture. Materials are just one piece of the sustainability puzzle and need to be balanced with many other issues such as energy performance, water use, and social and ecological impacts.
Making the 'right' material choice is no longer based purely on structural efficiency but a balance across a number of different factors, including:
By designing and specifying materials efficiently, the demand for material will be minimised and thus equate to a lower environmental impact.
Fitness for purpose
In addition to meeting the necessary structural performance criteria (eg strength and deflection), materials selection should consider materials that require minimal maintenance, and which can accommodate future adaptation, which can significantly reduce its environmental impact during its lifetime.
Environmental impact/ recycled content
Use of lifecycle analysis and environmental product declarations enable us to assess the likely cradle to grave impact of a building material. This will include issues such as consumption of raw resources, embodied carbon, water consumption, pollution impacts, etc.
Thought should be given to specification of materials that are appropriate given the environmental conditions and skills of the local labour force. This is particularly important in remote areas and developing countries where construction with, and maintenance of, new or unfamiliar materials could be problematic.
As well as selecting the most appropriate material it is important to consider the chain of custody of the material and the environmental credentials of the product supplier. This includes certification of timber to ensure that it has come from a legal source and responsibly managed forests. For other materials environmental certification such as ISO 14001, EMAS, BES 6001 etc. can be sought.
Consideration should be given to how the structure will be constructed to ensure that construction waste is minimised eg through use of pre-fabrication and standard material units.
End of life/ deconstruction
This is an aspect of the design process which is often overlooked or considered an afterthought, but the end of life management of materials can have a significant effect on the overall impact of a structure.
Consideration should first be given to whether materials could be reused in their original form, repurposed or, where this is not possible, how they can be recycled in a manner that limits waste going to landfill to an absolute minimum.
The use of BIM should also be considered within the context of end of life, demolition and disposal (eg Deconstruction Information Modelling).