ASHRAE Journal - June 2010 - S44

Measuring Material Impacts
Concrete Although cement is only 7% to 15% of the material in concrete, by weight, it is a fired material with significantly more environmental impacts than sand, gravel, or water. Supplementary cementitious materials such as a fly ash, slag cement, and silica fume are recovered from other industrial processes. When used as a replacement for a portion of the cement in concrete, these materials can reduce significantly the environmental impact of concrete. Steel All structural steel produced in the United States used in the building process originates in electric arc furnaces. The recycled content of this steel typically exceeds 90%. Steel produced in electric arc furnaces uses one-third of the amount of energy with one-third of the carbon footprint as steel produced in basic oxygen furnaces. If the production process is not known and the material is of domestic origin, then the lower recycled value (typically that of the basic oxygen furnace process) is to be used for calculating recycled content.

Wood Chain-of-custody is an accounting system process that tracks wood fiber through the different stages of production. Standard 189.1 recognizes two approaches to meeting this requirement. • Physical separation approach: this is the only time a company can make a claim on the product that 100% of their fiber came from a certified forest. • Percentage-based approaches: − Volume credit method: used when the company wants to sell a portion of their product under a chain-of-custody claim. For example, if the company knows 60% of their supply comes from a certified forest, they can make claims on 60% of the output. − Average percentage method: used when a company wants to label 100% of their output under a chain-of-custody claim. Proper documentation can include a copy of a certificate or an on-product label from one of the certification programs, or other forms of documentation where a chain-of-custody number is disclosed and the certification program is identified.

Forestry Initiative (SFI), and the American Tree Farm System (ATFS) have the potential to meet these requirements. Vendorprovided wood building components are allowed to comply when the average annual amount of properly documented certified wood products purchased by the vendor exceeds 60%.
Performance Option: Life-Cycle Assessment

Simplified illustration of a life-cycle inventory (LCI) for a building.
CO CO2 SO2

Air Materials Energy Land Water

NOx CH4

N2O VOC

As an alternative to the prescriptive path outlined earlier, a performance path is available, which considers broader environmental attributes rather than a single characteristic. The performance path is met through performing a life-cycle assessment (LCA) on a base building and the proposed project building. The LCA must be performed in accordance to ISO Standard 14044. The proposed project building is required to show at least a 5% improvement in two of eight impact categories required for the analysis. The LCA is allowed to include the energy use over the life of the building, specified as 75 years for most buildings; however, the energy use does not need to be included. An LCA is a complex process requiring computer software and analysis. After defining the boundary conditions in an LCA, the next step is a life-cycle inventory (LCI). This is an accounting of the materials and energy (inputs) consumed for all of the assemblies and components of a building, and the emissions to air and water and solid wastes (outputs) that result. The process includes these inputs and outputs for extraction of raw materials and fuel sources, through manufacturing and transporting of components, construction, repair and replacement, and finally, deconstruction, demolition, recycling, reuse, and
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Extracting Processing

Disposal Assembly Transporting Maintenance

ultimate disposal. Once the LCI has been calculated, then simulation programs are available that calculate the environmental impacts for the building. Standard 189.1 requires that, at a minimum, the following impacts categories are included: land use (or habitat alteration), resource use, climate change, ozone layer depletion, human health effects, ecotoxicity, smog, acidification, and eutrophication.
Summary

Section 9 of Standard 189.1 addresses available green building strategies that will lessen the building’s impact on the environment including the atmosphere, materials and resources. It includes mandatory provisions for construction waste, legal requirements of the materials’ country of origin, refrigerants, and the collection of recyclables and discarded goods. In addition, building materials must also comply with a prescriptive path for recycled content, regional materials, or biobased content; or the performance path for a comprehensive LCA.
June 2010

ASHRAE Journal’s Guide to Standard 189.1 ashrae.org

ASHRAE Journal - June 2010

Table of Contents for the Digital Edition of ASHRAE Journal - June 2010