MBI and BD+C Modular Advantage | Winter 2011
 

Using Off-Site Construction to 
Eliminate Waste in Design Phase




The environmental consequences of construction and demolition waste in the U.S. are staggering. With more than 135 million tons of debris to landfills every year, it’s the single largest waste source. [1]  Reducing the amount of waste in a project is an important part of sustainable building and begins with the design process. Choosing alternative methods of construction such as prefabrication, modularization, and off-site construction techniques is an effective way to design out waste reducing the overall construction waste during construction vs. managing and diverting it after the fact.
 

AIA/CES
Learning Objectives
 

To earn one AIA/CES learning unit, read this article and the test questions, then submit your answers by clicking the Submit Test Answers link at the bottom of this page.

1. Understand that construction and demolition waste can be lessened even before on-site work begins, when designing out waste in early stages of construction. 
 
2. Learn how alternative methods of construction like modularization, prefabrication, and offsite technologies are particularly effective ways to manage waste.
 
3. Recognize that designing whole buildings for reuse at the same or different locations is a more sustainable concept than abandoning or demolishing buildings.
 
4. Learn how using controlled environments to construct buildings can help projects be healthier, safer, and more environmentally-friendly.
Green building efforts for site-built construction focus on reuse, recycling or diversion of waste that is generated on site. With off-site construction, however, the materials can be managed prior to leaving the factory, offering a much more efficient process to reduce the amount of waste sent to landfills.
 
(Left) Waste hierarchy showing that the target for any waste reduction strategy is to first design out waste, and then focus on recycling and reusing any remaining waste material. Data courtesy the U.K. Waste & Resources Action Programme (WRAP). [2]

Due to the factory-controlled process, modular construction is by nature material and resource-efficient. One of the great economies of modular construction is the ability to assemble repetitive units in controlled conditions. Another is to minimize material waste associated with conventional construction due to weather intrusion and construction site theft. Whole modular units – largely finished prior to arriving at the construction site – can significantly limit construction waste generated at the site and contribute directly to construction site waste management.

Modular construction capitalizes on the ability to move product in controlled manufacturing conditions, and on tight inventory control and project schedules. It is inherently waste conscious and can have minimum site impact if delivered carefully and strategically with respect to site constraints. In addition, since modular builders work in a factory controlled environment, they can have many construction projects underway simultaneously in one location, so they are better able to re-inventory materials that may have been allocated to one project, for use in another. With site built construction, a general contractor would send any overage to the recycle bin or to the dump. [3]

A 2007 report published by WRAP supports the fact that off-site manufacturing processes can help the construction industry reduce waste. Offsite manufacturing already offers the construction industry benefits in terms of time and cost predictability, health and safety, and skills. However, this work shows there is the potential to make a significant difference to the amount of waste the industry produces. The WRAP report shows up to a 90% reduction can be achieved by reducing wastes such as wood pallets, shrink wrap, cardboard, plasterboard, timber, concrete, bricks and cement by increasing the use of off-site manufacture and modular construction. [4]

A recent Environmental Protection Agency (EPA) report states that the industry average of C&D waste for non-residential projects is approximately 4.34 lb/sq. ft. A LEED® Gold certified modular project by NRB Inc. generated 2.86 lb/sq. ft. of waste material, much less than the industry average. [5] Find more information on the project here.




WRAP has developed an excellent resource, “Designing out Waste: A design team guide for buildings” to help owners and contractors. [6] The report names key principles that design teams can use during the design process to reduce waste, one of which is design for off-site fabrication. The report states that modular construction helps the industry reduce waste by improving the workmanship quality and reducing on site errors and re-work, which themselves cause considerable on site waste, delay and disruption. In addition, other benefits of off-site construction are reduced construction related transport movements, improved health and safety on site through avoidance of accidents, and reduced construction timescales and improved programs.

The report also names design for reuse and deconstruction as another key design principle to use to reduce waste. The modular construction industry has for many years been practitioners of flexible design and reuse. Whole buildings can be reused by reversing the process in which the building was installed. The building can come apart in pieces in the same way they were created. The complete reuse of the buildings is a much more sustainable concept than abandoning or demolishing the building.

Following is a case study where deconstruction and complete reuse were applied to a modular building.

Marriott Grande Lakes Sales Center



The sales center was initially manufactured in 2003 as a 10-unit custom office located in Myrtle Beach, SC. After 6 years of use, the building was disassembled including a complete site-built roof / portico element, and sent to storage. In 2009, a new development in Florida required an upgrade sales center. It was determined that 6 of the original 10 units could be relocated and used with complete renovation, with the addition of 4 new units added to the center to serve as the primary entry vestibule.



The renovated building features 10 ft. tray ceilings, custom millwork, granite c-tops, and a portico entry with a four-plane clay tile roof system. This architectural detail conceals the roof mount HVAC units and extends the building height to 18 ft. above grade. The exterior wall finish is synthetic stucco with corbel elements below soffits, architectural banding, leader pipes, columns and indirect architectural lighting. Find more information here.



Summary

Site-built construction focuses on recovery, reuse, recycling or diversion of waste post-construction, rather than reducing waste on the front end, through better management, procurement, and construction practices. Designing out waste at the earliest stages of the construction process, however, offers the greatest opportunities for waste minimization. Design for renovated reuse and deconstruction also has an important role in streamlining the construction process to reduce waste. Once effective waste reduction measures are in place, it is then appropriate to consider how to reuse, recycle, or dispose of the remaining waste.

Modular construction, combined with the use of BIM, provides an effective technique to reduce overall waste on a project, providing a more environmentally sustainable building solution and creating a healthier and safer environment.

_________________________________________________________________________

Notes:

[1] EPA Report Estimating 2003 Building Related Construction and Demolition Materials Amounts:   http://www.epa.gov/osw/conserve/rrr/imr/cdm/pubs/cd-meas.pdf

[2]  WRAP Report Designing out Waste: A design team guide for buildings: 
http://www.wrap.org.uk/downloads/19279-02_Design_Guide_online_pdf_version.c663251c.7167.pdf

[3] MBI White Paper Modular Building and the USGBC’s LEED Version 3.0 2009 Building Rating System:
http://modular.org/marketing/documents/Modular_09V3LEED.pdf

[4] WRAP Report Current Practices and Future Potential in Modern Methods of Construction:
http://www.wrap.org.uk/downloads/Modern_Methods_of_Construction_-_Summmary.a268f69e.3663.pdf

[5] EPA Report Estimating 2003 Building Related Construction and Demolition Materials Amounts:   http://www.epa.gov/osw/conserve/rrr/imr/cdm/pubs/cd-meas.pdf

[6]  WRAP Report Designing out Waste: A design team guide for buildings: 
http://www.wrap.org.uk/downloads/19279-02_Design_Guide_online_pdf_version.c663251c.7167.pdf

Photo Captions:

Off-site construction image courtesy PTI Group, Inc.

On-site construction waste image courtesy WRAP
 

 

AIA Continuing Education Test

1. Construction and demolition waste in the U.S. is the single    
     largest source in the waste stream

a. True
b. False

2. Alternative methods of construction that help design out 
    waste include:

a. Prefabrication
b. Modularization
c. Off-site construction
d. All of the above

3. With off-site construction, materials can be managed prior to 
    leaving the factory, offering a much more efficient process to 
    reduce the amount of waste sent to landfills. 

a. True
b. False

4. Modular construction provides an effective way to reduce 
    waste on a project due to:

a. Its factory controlled process
b. Its site-built construction method
c. The amount of recycling done on site

5. The waste hierarchy chart by WRAP demonstrates that the 
    target for any waste reduction strategy must be to first 
     design out waste, and then focus on recycling and reusing 
     any remaining waste material.

a. True
b. False

6. Modular builders can have many construction projects 
    underway simultaneously in one location, so they are better 
    able to re-inventory materials that may have been allocated 
    to one project, for use in another.

a. True
b. False

7. WRAP’s “Designing out Waste: A design team guide for 
    buildings” states that modular construction helps the industry 
    reduce waste by improving the workmanship quality and 
    reducing on site errors and re-work because:

a. It prevents considerable on site waste, delay and disruption
b. Eliminates the need to use cranes
c. Requires more material deliveries
d. All of the above
e. None of the above
 
8.  The same WRAP report names which of the following as 
     additional benefits of off-site construction:

a. Reduced construction related transport movements
b. Improved health and safety on site through avoidance of accidents
c. Reduced construction timescales and improved programs
d. All of the above
e. None of the above

9. The WRAP report also named what other key design principle 
    to reduce waste besides design for off-site construction?

a. Design for demolition
b. Design for deconstruction and reuse
c. Design for reliability

10. NRB Inc.’s recent LEED® Gold certified modular project 
       generated more waste material than the average for the 
       non-residential construction industry

a. True
b. False


Evaluation:
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