With the increased awareness of green construction practices, there is a growing acceptance of the environmental advantages of the modular construction process.

Think of modular construction as more of a process than a facility type. The same materials are used in modular construction as in conventional projects—wood, concrete, and steel.

Modular facilities are also built to the same codes and specifications as conventional construction—just built off-site in a quality-controlled environment. Due to this process, several “green” advantages result. Here are a few:

• Reduced environmental impact on the site
• Less materials waste in landfills
• Labor and resource efficiency

Reduced Environmental Impact – Because of the unique off site construction process, modular construction workers report to work at the same manufacturing facility rather than commuting to and from various construction sites.  Once a project is completed in the factory, the building components are then transported to the site for installation.  This process greatly minimizes the traffic from workers, equipment, and perhaps most importantly, suppliers.  Rather than making multiple deliveries to the site, modular manufacturers buy in bulk with fewer deliveries.

A recent research project led by the University of Virginia (UVa) and Yale University seems to confirm this position.  The report states that the researcher team’s aim was to evaluate two methods of building construction in the United States, conventional construction and modular/off-site construction and attempt to determine which is more environmentally preferred. The analysis showed that impacts from off-site construction were generally lower than those from on-site construction.  For global warming potential, average on-site construction impacts were about 23 percent higher than off-site. This research is still in its preliminary stages with results expected in fall 2010.

Another research project by the National Institute of Standards and Technology (NIST) titled “Advancing the Competitiveness and Efficiency of the U.S. Construction Industry” found that the U.S. construction industry could improve its productivity and efficiency with a greater use of prefabrication techniques.  In particular, the study noted that one advantage relating to environmental impacts of off-site construction was:

“Fewer job-site environmental impacts because of reductions in material waste, air and water pollution, dust and noise, and overall energy costs”

Less Materials Waste in Landfills – Because modular manufacturers buy in bulk and can be working on multiple projects simultaneously at the same “site” there is a much greater efficiency in terms of materials usage.  Again, manufacturers tend to buy material in bulk and save excess materials for the next project.  Virtually no waste is shipped to the site, and thus ends up in landfills.

From the same UVa research, one commercial company reports almost zero material sent to the landfill, and relatively small numbers of recycled materials.   Many manufacturers reuse any ‘waste’ within the factory, and keep their procurement policies very tight.  The strategy of ordering 5 percent or 10 percent extra material – common for on-site construction – is very uncommon in off-site facilities. On-site builders often have limited storage space at their construction sites, and do not always have an exact accounting of all necessary materials at the start of construction, leading to less efficient procurement.

A report published by the United Kingdom group Waste & Resources Action Programme (WRAP) concurs, finding that off–site manufacturing processes can help the construction industry reduce waste by up to 90 percent!

The U.S. Green Building Council (USGBC) also recognizes the inherent materials advantages with using prefabrication and off-site construction techniques. In its Leadership in Energy and Environmental Design (LEED) for Homes rating system, the USGBC awards points under its materials and resources section for “projects with a precut framing package (e.g. modular homes, kit homes).” Additionally, LEED for Homes includes a credit specifically for off-site fabrication.

Materials Resource Credit # 1.5 – Off Site Fabrication “the credit should only be awarded if the walls, roof, and floors are fabricated off-site.”  The Modular Building Institute (MBI) recently produced a whitepaper to demonstrate how all this process dovetails into the LEED rating system.

Labor and Resource Efficient –Because construction of the building can occur simultaneously with the site work (or even before the site work), the traditional construction schedule is significantly compressed using modular.

This allows for most projects to be completed 30 percent to 50 percent sooner.  The coordination of trades that occurs at the factory also improves efficiency.  No longer do electricians and plumbers have to wait until the entire building is framed in to begin work.  No longer does the first floor need to be completed before beginning on the second.  This streamlined and efficient work process results in few labor hours needed per project and thus fewer trips to the site per project.

Case study examples
A look at a few projects further highlights the green advantages made possible through modular construction.

MBI annually hosts the Awards of Distinction, the premiere awards contest for the commercial modular construction industry.  Included in the contest is a category for best “renovated reuse” of an existing building.  Renovated reuse is defined as a reconfiguration of an existing factory-built commercial structure to meet the needs of an application that is different from its original design.  MBI also hosts a category for best green building design.

The 2007 winner in the renovated reuse category was the Brookfield Homes Sales Office in Kona, HI.  The original unit was a standard double wide with metal siding, VCT flooring, wood paneling, and modulux lighting.  Due to the technical simplicity of the modular unit, the architect was able to freely design and accomplish all of the requirements by the owner.  The modular provided a solid foundation to work from.  The architect was surprised at the rigidity and quality of the framing and insulation. The a/c duct work and the electrical wiring was a cost that he could take out his estimate due to the extent of the modular’s pre-finished condition.  The layout was designed to create the atmosphere and to showcase the quality of the homes being offered.   The interior included Italian marble, ceramic tiles from Spain, exotic Hawaiian woods such as koa and milo, and the finest furniture was also installed.

Brookfield Homes Sales Office by Hawaii Modular Space

The 2009 winner in the green building design category was High Tech High in Chula Vista, CA.  The school is LEED® Gold certified with the USGBC.  In addition, the school was submitted to the Collaborative for High Performance Schools program, a national initiative to improve student performance and the overall education experience by building the best possible school.  The project includes 59 modular units totaling 32,807 square feet.

Various green materials were used to enhance classroom acoustics, day-lighting and energy efficiencies. The modular units feature various high-performance products including: dual pane windows with low-E coatings, acrylic skylights, light fixtures with motion controlled sensors and low volatile organic compound (VOC) paint. The project also incorporated renewable and recycled materials such as sealed lightweight concrete floors, Homasote 440 Sound Barriers, which are high-density fiberboards made from recycled newsprint that help to control acoustics in walls, and a sprayed polyurethane roof. All the materials, with the exception of the interior casework, were available locally further reducing the carbon footprint of the project.

 High Tech High by Williams Scotsman

In summary, utilizing modular construction can result in a much more efficient process that yields less material waste.  To capitalize on these advantages, it is not necessary for the entire project to be completed by a modular manufacturer.  Architects, general contractors and owners would be well advised to have conversations with modular manufacturers prior to a project to determine if certain components of the project lend themselves to off -site prefabrication and realize efficiencies immediately.

There is a great deal of inefficiency and waste in the current construction environment.  We believe that the modular construction process can  improve some of these areas and encourage the architect/engineer/contractor/owner community to find out more through our website.

About the Author
Tom Hardiman is the Executive Director of the Modular Building Institute (MBI).  MBI is the international non-profit trade association representing commercial modular contractors.   For more information, visit www.modular.org.