Sustainable Building Materials

How sustainable building materials can be used for different applications

What is meant by sustainable building material?

Constructing with sustainable materials is not only good for the planet and common sense, it can save the client money, help preserve our heritage, respond to planning policies and help get credits in BREEAM, LEED, and other environmental assessment tools.

Sustainable material is one that:

• Do not deplete non-renewable (natural) resources.
• Has no adverse impact on the environment when used.

In practice, both these objectives are impossible to achieve, but they do show us the direction we should aim.

We can preserve natural resources in many ways:

• Avoid using scarce (non-renewable) materials, such as peat and weathered limestone.
• Creating less waste.
• Using less; by not over-specifying performance requirements, by designing minimum weight structures, and by matching demand to supply (such as supply balancing cut & fill).
• Using reclaimed, rather than new materials.
• Using renewable materials (crops).

We can reduce the impact on the environment of using construction materials by:

• Using materials with low(er) embodied energy.
• Reducing transport of materials and associated fuel, emissions, and road congestion.
• Preventing waste from going to landfills.
• Designing and constructing for ease of reuse and recycling at end-of-life (design for deconstruction).

Different types of sustainable building materials

Sustainable building materials, their sources, and applications

Tools and techniques for selecting construction materials that are less damaging to the environment

Detailed analysis of the impacts of materials using these techniques can then be reduced to relatively straightforward guidance for the designer or specifier, for example:

• ‘Environmental preference’ methods use star-ratings to substitute ‘normal’ materials and components with more ‘environmental’ alternatives.
• Methods that calculate a single numerical score, such as an EcoPoint, for the impact of each material (per kilogram) and aggregates these according to the quantities in different types of construction for a given building. This approach underpins the Green Guide to Specification developed by the UK Building Research Establishment.
• Methods that use embodied energy or carbon dioxide emissions as the single measure of impact, are then processed using ‘carbon accounting’.

Another approach is to tackle the use of materials by adopting a strategic and hierarchical approach to decisions – beginning with the ‘best’ from an environmental point of view, then the next best, and so on.

For example:

Choose materials and construction techniques that progress from:

• A linear approach to using materials: extract, process, manufacture, use, demolish, throw away.
• ‘Closed-loop’ thinking or a ‘zero-waste’ society: extract, process, manufacture, use, reuse (as many times as possible), dismantle or disassemble, recycle (as many times as possible), then finally, only when no further use remains, throw away.

Re-use materials or components in situ:

• Reuse a whole building, upgrading it as necessary.
• Reuse part of a building such as the structural frame, masonry façade, or foundations.
• Build upon the existing ground floor slab of a previous building.
• Reuse an existing retaining wall or embankment.

Use reclaimed materials or components with little processing:

• Steel beams and columns from a dismantled building.
• Demolition arising (such as crushed aggregate) can be used for landscaping or backfilling excavations.
• Crushed glass can be used as a bedding material for paved or block surfaces.
• Reclaimed paving stones or slabs.
• Railway sleepers or telegraph poles.
• Steel tubes from the oil industry can be used as piles.
• Recycled black-top.

Use manufactured materials or components with significant and known recycled content:

• The Recycled Content (RC) of entire construction works can easily be more than 20% (this was achieved at the London Olympics site) and this can gain LEED or BREEAM credits.
• Concrete made with Recycled Crushed Aggregate (RCA – typically up to 40%, depending on the source). For example, using demolition arising or ‘waste’ from quarries.
• Concrete using cement replacement materials such as Pulverised Fuel Ash (PFA) or Ground Granulated Blast-furnace Slag (GGBS – 5-15% RC).
• ‘Recycled Roads’.
• Precast concrete blocks, paviours, kerbs, etc., made using RCA (more than 60% RC).
• Concrete pipes, drains, etc. made using RCA (more than 60% RC).
• Plastic street furniture (bollards, barriers, etc.) is made from 100% RC plastic.
• Decking, furniture, etc. made from 100% RC ‘plastic lumber that looks like timber.
• Plastic drain or soil pipes made using recycled plastic (50-100% RC).
• Cast-iron drain pipes are made using recycled cast iron (up to 96% RC).
• Tarmac with crushed glass fill, up to 30% RC.
• Geo-textiles are made from 100% RC plastic.
• Any ‘forest product’ using ‘waste’ timber, such as chipboard, blackboard, and some glulam.

Use natural materials that have low embodied energy and/or environmental impact:

• Timber (in preference to steel).
• Concrete reinforced with timber, bamboo, or natural fibers.
• Geo-textiles and other products are made from crops.
• Straw bales.
• Materials that are accredited as being responsibly sourced (such as FSC timber).

Conclusion

Sustainable building materials are those which are produced or sourced locally. These materials are containing recycled & industrial waste materials and by-products. Sustainable materials have a lower impact on the environment & are thermally efficient. The production of these building materials requires considerably less amount of energy in production when compared to modern or traditional construction materials.

The advantages in the selection of sustainable building materials lie in the fact that they are not only economically viable but also reduce toxic emissions thereby reducing overall environmental impact. Sustainable building materials & technology should be utilized appropriately & contextually in each neighborhood development. The use of sustainable material & technology not only reduces transport & production costs, carbon emissions but also provides avenues for employment & skill development for community members.

References

1. 10 Sustainable Materials Every Architect Must Know
2. Sustainable materials for construction
3. Green Building Materials
4. Sustainable Construction Materials & Technology in Context with Sustainable Development