BUILDING WASTE

The UK construction industry accounts for 90 million tonnes of waste each year, three times more than all the households in the UK combined. It is estimated that 13 million tonnes of this waste is material that is delivered to a site but never used (over ordered, off cuts etc.).

This has a huge impact on the environment filling up land fills and using new resources unnecessarily.

When designing a building as well as during construction attention should be paid to the amount of materials required for a given build. Over ordering can account for as much as 10% of a construction site's waste so a viable ordering strategy should be set out from the start of a build.

Over ordering can be avoided through many methods. The first is to use a Just In Time (JIT) ordering system. JIT systems mean that materials arrive as they are to be used having been ordered with the minimum amount of time before hand. This means that the materials are not left lying around the site where they will be vulnerable to weather damage or theft. Using standard sizing while designing a building will also cut down on waste.

For example using door and window frames of a readily available size will cut down on them needing to be produced or modified on site creating offcuts.

Construction sites are just as susceptible to creating waste through thrown away packaging as any other industry. Often materials will be delivered in a packaging that can be recycled such as cardboard boxes, expanded polystyrene, wooden crates etc. Reducing the amount of packaging sent to the land fill from a construction site would allow major ecological benefits.

For example for every tonne of paper not sent to a land fill and recycled will save nearly 1500kg of CO2 emissions each year. Other materials produce higher gains with aluminium saving nearly 11000KG of CO2 emissions per tonne recycled! There are also economic benefits to recycling, by creating separate bins on site for different types of packaging (skips for plaster based, cardboard, wood, plastic film etc.) means that waste services may take these away for a subsidised price or even free depending on the local area's recycling policy.

Sites should be chosen where minimal landscaping is required to cut down on waste earth generated. Where this is not possible the earth should be put to an efficient use. For example, creating a rammed earth wall using dug up soil and concrete rubble from a previous building will create a solid, low environmental impact, wall thus saving the material from being sent to the landfill and reducing the amount of new bricks required. Excess soil can also be mixed with organic waste produced on site (having a separate bin for food rubbish only) to create compost for use around the finished site.

Parts bins can be set up to allow unused screws, nails, handles etc. to be stored instead of binned, further saving useful items from being thrown away or over ordered.

When designing new structures it is a good practice to build with waste reduction in mind for the future. Designing a building so it can be easily deconstructed will save waste when the building reaches the end of its life cycle. Designing structures that have minimal use of adhesives or nails (as these tend to damage materials), have easy access to interior systems (such as pipework to aid removal), and use mechanical, easily accessible fixing methods such as bolts, will all speed up and increase the amount of material reused from a deconstructed building.

Low impact and simpler materials are also easier to de-construct and as such are a benefit to the green builder when designing for deconstruction, earth walls can simply be knocked down and reused, wood can be recycled etc.

Different methods of building can be employed to cut down on the waste produced at the time of construction. Off site construction allows various units to be transported in from factories and assembled on site. As these units are produced in a controlled factory environment the amount of materials required is reduced to the bare amount necessary with little margin of error. Using off site construction can save between 50 - 90% of waste from a site. Although units will need to be transported in, the carbon generated by transport is offset by the amount saved in waste materials. Off site construction will also allow buildings to be constructed more quickly reducing labour costs and time a project requires.

Alternative methods of construction will also cut back on waste. Cob construction can take earth from around the site, insulating concrete framework will require very little extra material commonly used such as mortar and all wooden projects will tend to only leave smaller offcuts of recyclable wood.

Design changes can also effect the amount of waste generated with an estimate of 1-5% of waste (according to the Waste Resource and Action Project) being due to changes. Changing designs after start will often result in materials either not being used, and then disposed of, or materials that will require wasteful modification.

Deciding on a well thought-out design and sticking to it will not only increase efficiency but also reduce waste.

The current situation of construction waste disposal in the UK is not sustainable.

The Government is aiming to achieve waste neutral construction in its buildings by 2020 and has introduced a land fill tax based on each tonne of material deposited. Land fills are gradually running out of space and with the UK only having limited space, so these costs are only likely to rise. Ideally some form of energy generation can be built into waste sites, and might be essential given the forthcoming energy shortages. By building in an attitude of reduce, reuse and recycle into construction projects huge savings can be gained both environmentally and financially.