What does it mean to be ‘green’?
September 6, 2012
COMMERCIAL, FABRICATION : CODES & STANDARDS
One of the reasons the construction codes have held my interest for decades is that they always seem to present a new challenge. Just when we start to figure something out—whether it be compliance with the Americans with Disabilities Act, three-second gust or ultimate-strength design wind speeds, terrorist-resistant buildings, impact-resistant windows or energy efficient buildings—some new issue comes along.
The most significant of these recently has been green construction. Just what does it mean to be "green"? Every manufacturer, it seems, wants to call their product "green" these days.
AAMA has been working diligently to wrap its hands, and collective mind, around the "green" concept for a few years now. And in partnership with what other groups are doing, it seems it might be getting a handle on it.
As an engineer, I like to be able to quantify things. "Will the units of satisfaction you enjoy per cookie diminish if you have a second bag of cookies this week?" This is the type of conversation my poor children were subjected to growing up – and the type of conversation they now subject me to!
When it comes to building green, it's all well and good to say we want to build in a sustainable manner and create an earth-friendly building. But what does that really mean? If we reduce energy use, is that good for the planet? Certainly, it would seem so. How about recycling materials? That also appears to be of value.
Which is better for the environment: reusing an existing building that might be bigger than we really need and not very energy efficient but is close to public transportation? Or, building a new, smaller and more energy efficient building out of recycled materials on a previously undisturbed site?
Most product manufacturers I work with want their products evaluated against their competitors on a fair and level playing field. But how is a designer to choose which product best satisfies their objective of building a green building, if one has the best thermal properties, a second has more recycled content, a third has a higher percentage of indigenous materials, and a fourth promises a longer service life than any of the others?
Is there a metric for measuring just how "green" a building is? Or just how "green" a building product is? And if so, how do we apply it?
Life Cycle Assessment
Efforts to answer this question appear to center around a concept called Life Cycle Assessment. According to people who testified at the Final Action Hearings for the International Green Construction Code in November 2011, scientists around the world agree on how LCA is to be performed. But for those of us who have not been privy to that discussion, it's all pretty new and still somewhat of a mystery.
LCA was mentioned in the 2008 edition of the NAHB National Green Building Standard/ICC 700. A limited number of points were available for a designer who could demonstrate that "a more environmentally preferable product or assembly" had been selected for an application based upon an LCA tool that compares "the environmental impact of building materials, assemblies or the whole building."
Life Cycle Assessment/Analysis was defined in 2008 NAHB NGBS/ICC 700 as "an accounting and evaluation of the environmental aspects and potential impacts of materials, products, assemblies, or buildings throughout their life—from raw material acquisition through manufacturing, construction, use, operation, demolition and disposal."
Although these provisions indicated there might be some basis of comparing product to product that goes beyond prescriptive, they did not provide much guidance as to how that was to be done. Nor were the incentives very high for a designer to try to take advantage of these provisions.
LCA is also addressed in LEED v.3 as an option for a limited number of points for materials and resources. At the present time, it appears that LEED v.4 will award a significantly higher number of points for third party-certified LCA.
The 2012 IgCC permits whole building LCA as a project elective if the jurisdiction adopting the IgCC chooses to adopt the Appendices. The 2012 IgCC defines Life Cycle Assessment as "a technique to evaluate the relevant energy and material consumed and environmental emissions associated with the entire life of a building, product, process, material, component, assembly, activity or service."
To qualify for the project elective in the 2012 IgCC, a designer must demonstrate that the whole building achieves at least a 20 percent improvement in environmental performance for global warming potential and at least two of the five following impact measures:
- Primary energy use
- Acidification potential
- Eutrophication potential
- Ozone depletion potential
- Smog potential
This improvement is to be made in comparison to a reference building of similar useable floor area, function and configuration. The reference building that serves as the model for comparison must meet the minimum energy requirements of the IgCC and the structural requirements of the International Building Code.
Now, I don't really have much of an understanding of what the five impact measures are, or how they, or global warming potential, are assessed. I can look at the USGBC's LEED website and get a brief summary of each. But that is still not going to give me the information I need to determine how it applies to a specific window manufacturer's product.
What I do know is that if a building designer chooses to use one of the LCA options provided in the 2012 IgCC, NAHB NGBS/ICC 700, or LEED v.4, they will need to have this type of information about your product.
Environmental Product Declaration labels
AAMA—together with the Insulating Glass Manufacturers Alliance, Glass Association of North America, and Window and Door Manufacturers Association—has formed the Joint Product Category Rules Task Group to try to address this need. The JPCRTG is working with Earthsure, the Ecolabel program of The Institute for Environmental Research and Education, to develop a program that will help window manufacturers provide the information described above. The program will basically establish a protocol for developing an Environmental Product Declaration label.
The protocol will prescribe how a manufacturer is to do the following:
- Establish a list of materials in their window assemblies
- Quantify what percentage of the assembly each material is, based upon mass
- Determine the anticipated environmental impact of the extraction and transportation of each material
- Evaluate the anticipated environmental impact of the assembly of the window
- Evaluate the anticipated environmental impact of the use of the window
- Evaluate the anticipated environmental impact of the disposal of the window at the end of its service life.
The proposed label will then provide the total anticipated environmental impact of that product. At the present time, the environmental impact measures to be listed on products' EPD labels are:
- Climate change
- Respiratory Effects
- Stratopheric Ozone Depletion
- Photochemical Smog
- Land Use.
The building designer could then use that information in their calculation of the environmental impact of the proposed building, to determine if it meets the criteria of the IgCC, NAHB NGBS/ICC 700, or LEED.