LEED 2012 is coming to your future project. Material Credits are being re-addressed, just when you thought you understood sustainability in materials and construction as being defined by low VOCs, recycled content, and regional content. You will need to start considering Life Cycle Analysis.
From Green Build, Oct. 5, 2011, there was a program comparing Two Recent Life Cycle Analysis (LCA) Studies for Buildings: On Site Verses Off-Site Construction and Building Material Use.
Presented by Matthew Eckelman, Yale University, Dept. of Chemical & Environmental Engineering and Brad Guy, The Catholic University of America
At first blush you would think building buildings in a modular fashion in a factory setting would save on the buildings environmental impacts.
You can consider the plusses:
- You can order materials cut to size eliminating waste.
- Materials would be stored in a climate controlled space. Modular construction in a factory setting eliminates the need to throw away materials that have gotten wet or frozen.
- Time delays would be minimized due to weather.
- Employee transportation ideally would be minimized. Employees would commute from areas around the factory. They would not need the pervasive pick-up truck because the materials are delivered in bulk to the factory. Employees could also take advantage of carpooling due to a regular location and work schedule.
But then you have to consider the minuses:
- Consider the way the modular needs to be constructed. A module has to have some portion of all 6 sides of the space constructed so it can be transported on the flat bed truck. When put together in the field there is a double wall between the modules which would not be required in conventional construction. This offsets the materials saved during the construction in the factory.
- The factory setting requires the construction of the factory building itself.
- The space is large and is moderately temperature controlled during the construction process. These spaces tend to be energy intensive when compared to conventional construction.
- Transportation of the completed modules is usually a greater distance.
- There is a requirement for larger cranes to set them into place.
- Some employees still need to travel to the set to facilitate utility connections and final finishing.
By the end of the discussion your perception was spun around. Conventional construction appeared to have less environmental impacts over all. Design Teams of course will still need to evaluate their particular project. Questions, Questions always Questions to be evaluated.
- Is there a modular construction facility near the project site?
- Can the design meet the dimensional challenges of transporting?
This particular educational session also included, defining and calculating the green house gas avoidance benefits of the recovery and reuse of building materials. Deconstruction VS Demolition.
We can consider demolition is quick compared to deconstruction.
In part thanks to LEED and in part due to the increased cost of virgin building materials much of the demolition waste can be recycled. This process is limited to down cycling. Recycled wood from demolition is processed into wood chips.
Deconstruction is more time consuming. Therefore more energy intensive, employees need to commute to the site for a longer period of time. The benefit is materials can often be reused for their original purpose. Wood 2 x 4s are still 2 x4s. Sometimes materials can be up cycled to higher purpose
Again Design Teams need to evaluate the project and consider the type of construction that is being demolished or deconstructed. The most sustainable solution would be to reuse a portion of the building in the new project.
Projects that are designed with an end of life strategy for deconstruction can be quickly deconstructed and repurposed in the future. This would save the employee’s commute and the down cycling of the building materials.
Design teams do not consider their projects end of life strategy as much as they should. Something to think about early in the design stage.