The opportunities to use materials efficiently can be very specific to the site or project. Consequently, some of the following solutions are best practice principles, rather than technical advice.
Efficient use of materials
Construction materials are chosen for a number of reasons, including:
- cost
- availability
- performance
- aesthetic quality
Increasingly, projects are including environmental performance as a specification consideration. The environmental performance of materials can be assessed in a number of ways, these are described in the table provided.
| Material | Example |
|---|
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Reclaimed/Reused
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Reuse of a brick as a brick
Reuse of reclaimed slate tiles on roofs
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Recycled
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Reuse of a crushed brick as aggregate
Reuse of timber beams as street furniture
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Materials with recycled content
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Plasterboard that is made with 85% recycled gypsum
Blockwork that is made with 50% recycled aggregate
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Environmentally labelled
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BRE Green Guide A+ rated materials – the Green Guide provides a simple online guide to the environmental impacts of building materials.
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Low embodied energy
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Use of plywood boards instead of chipboard
Use of glasswool insulation instead of polystyrene
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Locally produced materials
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Sand and gravel from available sources in Hertfordshire
Use of UK sources for all other materials
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Natural materials
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Using natural slate rather than artificial slate
Using thermafleece (sheep wool) or mineral wool rather than foam insulation
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Materials with good whole life performance
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Use of aluminium faced timber windows rather than PVC windows
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Reclaimed/Reused/Recycled materials
Substitution of primary/virgin materials for reclaimed or recycled materials improves the sustainability of buildings by:
- reducing the reliance on primary materials
- reducing construction and demolition generated waste, (or waste from other industries if the materials are sourced externally)
- reducing the environmental impact from processing primary materials
A number of material types lend themselves well to reclamation, notably those that have a high economic value or particular aesthetic quality such as:
- hardwood flooring
- timber structural joists and steel beams
- stone (e.g. York stone, limestone)
- high value cladding (e.g. granite or marble)
- brickwork
Construction clients, developers, public bodies and planning authorities are increasingly setting requirements for reused and recycled content on their projects. Commonly, a target of 10-15% recycled content is being set for new buildings although actual performance is frequently higher.
Examples of products that inherently have a high recycled content are listed below. The products listed do not incur additional cost or impact upon other project considerations such as programme, aesthetic quality or functionality.
However, in some instances, products with a higher recycled content raise technical issues. For example the use of cement replacements (e.g. pulverised fuel ash) increases concrete curing time.
| Product | Typical recycled content | Best practice recycled content |
|---|
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Plasterboard
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36%
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84%
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Blockwork
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0%
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90%
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Concrete
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1) 20% of course aggregate 2) 50% of cement replaced by GGBS*
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1) 100% of course aggregate 2) 70% of cement replaced by GGBS (ground granulated blast furnace slag)
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Vinyl floor finish
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12%
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100%
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Roof concrete tiles
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0%
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22%
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Mineral/rock wool insulation
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25%
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50%
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Environmental labelling
The Green Guide to Specification contains environmental information on more than 2000 specifications used in buildings (e.g. for external walls, roofs). It summarises their relative environmental impacts using an A+ to E ranking system, where A+ represents the best environmental performance (least environmental impact), and E the worst environmental performance (most environmental impact).
The Green Guide is an integral part of BREEAM (the BRE Environmental Assessment Method) as the Green Guide.
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Building type
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Category/Element
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Domestic
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Roof Construction
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Pitched roof timber construction
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Structurally insulated timber panel system with OSB/3 each side, roofing underlay, counter battens, battens and concrete interlocking tiles
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Retail
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Insulation
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Insulation
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Cavity blown glass wool insulation - density 17kg/m3
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Building type
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Category
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Sub category
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Element
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Industrial
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External wall construction
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Brick, stone and block work, cavity wall.
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Brick or stone block work, cavity wall.
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Brick on outer leaf, insulation, aircrete, block work, inner leaf, cement mortar, plaster, paint.
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Many standard elemental specifications are A rated.
Material
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Brick outer leaf, insulation, dense blockwork inner leaf, plasterboard.
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Aluminium insulated composite cladding, galvanised steel rails, dense blockwork, plasterboard.
Internal walls
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Steel/timber stud, plasterboard, wool insulation, paint.
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Aerated block, plasterboard, paint.
Roofing
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Flat roof, inverted deck: Galvanised steel deck, asphalt, insulation, paving slabs.
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Pitched roof: concrete tiles, battens, sarking felt, on timber roof structure with insulation between rafters.
Floor finish
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Hardboard sheathing, linoleum.
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Wool/nylon carpet, natural.
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Fibre underlay.
Timber certification
The timber industry has developed a number of sustainable certification schemes for individual forests and plantations. These provide independently certificated guarantees that these were managed in a sustainable way (i.e. as per widely recognised sustainable forest management criteria, such as biodiversity, recognition of local community and indigenous right, and so on). The sustainable certification schemes (with a valid Chain of Custody for the product purchased and the appropriate supplier) that are recognised by BREEAM are listed below.
Low embodied energy materials
Embodied energy is the energy used to extract, process and transport a material (from cradle to factory gate). For example, the embodied energy of a brick is the energy consumed by all the processes associated with a brick, from the acquisition of natural resources to product delivery.
Generally, higher mass materials are subjected to intensive manufacturing processes and require extensive transportation energy (e.g. HGV diesel); and therefore have higher embodied energy.
However, embodied energy can be offset by using materials with a higher recycled content or materials sourced locally.
The following tables denote comparison examples of different options by material type (insulation) and by function (structure).
Local materials
The use of local materials presents three notable benefits:
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Support for the local/UK economy and skilled tradesmen.
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Reduced environmental impact associated with road haulage.
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Aesthetic qualities that complement local character distinctions - Hertfordshire is known for its weatherboard cladded houses and chiltern brick.
Natural materials
Natural materials typically have a lower environmental impact than synthetic alternatives; however, some can cost more and some have shorter lifespans. Example products and associated impacts/benefits are set out in the table below.
| Standard product | Impacts and benefits | Natural alternative | Impacts and benefits |
|---|
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Chemical based paint
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Production includes complex chemical processes and can be toxic during manufacture and application
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Low VOC paint – water and vegetable oil based paints
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Has low embodied energy and mostly non-toxic
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Foam insulation
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Good thermal performance and less thickness is needed, but produces toxic substances in combustion
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Wool insulation
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Can be 100% natural (sheep wool) and provide good thermal performance
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Chipboard
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Has high chemical and adhesive content, but contains recycled timber chippings. Difficult to recycle.
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Compressed timber composite (plywood, softwood)
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Has no chemical content and provides a good base for finishes
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Reconstituted slate
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Has high chemical content and high embodied energy but low cost and easy to install and maintain
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Natural slate
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100% natural material with no chemical content. It is non-combustible, resistant to acids and highly durable
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Whole life performance
The whole life performance of a material is the performance of a material (or building) over a defined period of time. Typically building performance is measured over 60 years. Whole life performance takes into account the following issues:
- Capital costs
- Maintenance, replacement and repair costs
- Facilities management costs
- Disposal costs
Whole life costing analysis measures the economic impact of a built asset over its life, taking into consideration design, construction, installation and operation of building systems; rather than focusing solely on initial capital costs.in some cases the costs of final disposal are also considered.
Whole life considerations also impact upon the selection of materials with low environmental impact. For example, high mass external wall cladding options such as brick have a higher direct environmental impact than light weight timber and steel systems. However, they typically have lower maintenance requirements and a longer life, therefore their whole life costs are lower.
Often, whole life costing analysis demonstrates that investing a little more initially can present very favourable lifecycle savings.
IMPACT allows construction professionals to measure the embodied environmental impact and life cycle cost performance of buildings.
Whole life costing analysis is a mandatory requirement in publicly procured projects.
Major lifecycle significant items
Major lifecycle significant items in order of impact are as follows:
- internal finishes consisting of:
- flooring (carpet, vinyl etc)
- walls
- ceilings
- doors (internal and external)
- emergency lights which include their own batteries
- fixtures fittings and furniture
- automatic building control systems
- closed circuit TV systems
- heating systems
- light fittings
- external windows
- rainwater goods
- external walls
In some instances, it may be appropriate to select lower grade materials where the building or its fit out is expected to be short term (e.g. retail environments).
Items or rooms requiring high levels of maintenance should always be designed so that they are easy to access.
maintenance should always be designed so that they are easy to access.
Off-site construction
Off-site construction reduces waste as materials can be more accurately calculated and left over materials can be reused.
Off-site construction also has benefits relating to reduced time on site and disruption and improved safety.