Reducing environmental impacts

Reducing environmental impacts

Reuse and recyclability
The construction industry generates a great deal of waste, and it is estimated that up to half the waste going to landfill is from construction. Promoting recycling in the construction industry should be a priority, as the Government is committed to meeting the EU Waste Directive, which requires Britain to substantially increase the proportion of waste which is recycled. This section considers the use of reclaimed and recycled materials in construction and design for future recycling.
The reuse of buildings
All new building is going to be damaging to some extent in strictly environmental terms, and so you should only build new when all possibilities of refurbishing and reusing existing buildings have been exhausted. Prefabricated timber buildings are routinely taken down and reused in North America.
Only build new when all possibilities of refurbishing and reusing existing buildings have been exhausted, and elsewhere, and there have been examples in Britain. One example is the Segal Method of timber construction, based on the use of standard building products used in their standard sizes within a modular framework, and one or two Segal Method buildings from http://roadmapsroutefinder.com/ have been taken down and the materials reused to build new buildings.
Reuse of materials in new buildings
When designing new buildings:
• Consider the potential for using second-hand materials in the construction
• Give preference to new materials which can be easily recycled and which have a high recycled content
• Design in a way that permits the reuse or recycling of materials at the end of the building’s useful life.
Limits on the use of reclaimed materials
There are a number of issues which act as disincentives to the growth in the use of reclaimed materials (materials which can be reused with little or no processing — second-hand bricks, for example):
• The market for second-hand materials is underdeveloped in Britain. There is a small market for architectural salvage — high-quality items, but at a high cost. There is an established market in certain materials in certain areas (bricks in and around London, for example, whereas this market does not exist to any great extent in the North of England)
• The development of a market in general materials is restrained by the common perception that second-hand materials are inferior. In practice, the reverse is often the case. Reclaimed timber is generally well-seasoned timber cut from mature trees with close, straight grain and few knots. Second-hand bricks and tiles are often handmade with a depth of character and texture which a machine-made article can never attain
• The market is limited by the general reliance on standards, quality assurance, guarantees and so on in the construction industry. It is often difficult to give such guarantees on second-hand materials — although as we have said, they may often be of superior quality
• Information on the availability of reclaimed materials is also very limited.
Transporting reclaimed materials long distances
increases their environmental impact, yet it is
surprising how far you can carry a material for it still to be environmentally better than a new material. The maximum distances you can carry reclaimed materials before they will have a greater environmental impact than new materials produced locally are quoted from the BRE Green Guide to Housing Specification below:
Reclaimed tiles 100 miles
Reclaimed aggregates 150 miles
Reclaimed bricks 250 miles
Reclaimed slates 300 miles
Reclaimed timber 1,000 miles
Reclaimed timber is always worthwhile.
Pre-consumer recycled materials
Once you have considered reclaimed materials you should look at recycled materials which require reprocessing before reuse. Many materials routinely contain a proportion of recycled waste generated during production processes (so-called preconsumer waste); an example is chipboard, made with a high proportion of timber waste from converting trees into sawn or planed lumber. Recycling post-consumer waste, that is waste produced after something has been used, after a building has been demolished for example, generally has a greater environmental benefit.
Post-consumer recycled materials
A number of post-consumer recycled materials are routinely used in construction: granular fill used as a sub-base for roads and pavements, and hardcore is generally crushed brick or concrete. Up to 20% recycled aggregates can also be used in concrete, which will still retain its technical specification. A number of plastic products are made from recycled plastic, which include timber substitute, street furniture and cladding boards. It is also possible to recycle components such as boilers, lift motors and electrical equipment.
The Green Guide to Housing Specification
This gives information on a number of measures relating to recycling:
• Recycled input: the quantity of recycled or waste material contained within a product
• Recyclability: the percentage of the material which can be recycled or reused at the end of the life of the product
• Currently recycled: the proportion of the product currently recycled or reused
• Energy saved by recycling: comparison of the energy required to recycle and/or reuse the product compared with the energy required to produce a similar product from primary resources.
This information is presented as an A, В or C rating, A being the best.
Design for recycling
Design for recycling starts with specifying materials
which are easy to reuse or recycle as outlined above. The way that they are combined is critical. A number of common-sense measures apply:
• Avoid composite materials (bonding aluminium onto plywood, for example)
• Reduce the amount of Portland cement used in mortars and renders — or better, use lime-based mortars and renders so that bricks can be reused
• Use mechanical fixings in preference to adhesives; bolt steel rather than weld it
• Adopt dry construction techniques wherever possible (e.g. use neoprene gaskets to seal glazing rather than mastic).
Costs and benefits
Using recycled or reused materials will reduce environmental impacts and waste. Some secondhand materials may cost more but many will be substantially less than new materials.
Summary: using recycled or reused materials
When designing new buildings:
• Consider the potential for using second-hand materials in the construction.
• Give preference to new materials which can be easily recycled and which have a high recycled content.
• Design in a way that permits the reuse or recycling of materials at the end of the buildings useful life.
The Green Guide to Housing Specification gives useful information on the recycled content.

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