Prefab sustainability eliminates construction waste almost entirely.
The construction industry accounts for over half of all deposits in UK landfills and 32% of total waste in the EU. To understand prefab sustainability, we should consider that projects incur a large part of this figure before materials even arrive on site.
Alterations, mistakes and overordering during the design phase are major sources of waste. Designers often encounter unforeseen circumstances when materials are manufactured and procured, leading to last-minute changes and errors. The two most wasted materials — timber (up to 25% of the total) and plasterboard (up to 36%) — are frequently ruined because of weather and improper storage. Up to 10% of each material is rendered unusable at the building site.
Prefab sustainability involves early decisions and manufacturing in controlled environments. Since components are made in-factory, design changes are much less costly, and the factory recycles discarded materials. Weather is not as problematic because buildings are assembled almost immediately after arriving at the site.
One study, which looked at four different projects, found that prefabrication reduces timber waste by 74–87%. A recent Waste & Resources Action Program study put the total possible reduction of waste from prefabrication at 90%.
At the build site, off-cuttings and error rectification cause crews to send significant excess materials to landfills. Shoddy workmanship and rushed construction are the overwhelming causes of structural defects, which not only compromise safety but are major environmental problems since builders have to demolish components and scrap materials.
“Because [systems-built homes] are built in a factory and much of the lumber is pre-cut, there is less scrap and waste; the cut-off pieces are often ground up and recycled; the central location of a factory means no wasted transportation to get workers to an isolated job site, so there’s savings in fuel and energy,” said Steven Winter, chairman of the U.S. Green Building Council’s LEED program. “So, in a whole array of material savings, time savings, and energy savings attributes, systems built homes go a long way toward achieving green objectives.”
Victoria State in Australia made a checklist for reducing construction and demolition waste. Its suggestions include:
– Procurement and purchasing policies that support waste avoidance,
– Building for deconstruction,
– Building to standard sizes, and
– Practices & contract specifications that support material salvage & re-use where appropriate.
While there are many more items on the list, prefab sustainability can reduce waste by up to 90% because it checks off the most crucial.