C&D and GHGs

The Intergovernmental Panel on Climate Change has determined that "warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice and rising global average sea level."

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The U.S. Environmental Protection Agency (EPA) has proposed that climate change is primarily the result of greenhouse gas (GHG) emissions, its effects will worsen over time in the absence of regulatory action, and the overall rate and magnitude of humaninduced climate change will likely increase, such that risks to public health and welfare will likewise grow over time so that future generations will be especially vulnerable; their vulnerability will include potentially catastrophic harms.2

To respond to the risk associated with climate change, this document describes the link between climate change and the materials and land management programs carried out by the EPA’s Office of Solid Waste and Emergency Response (OSWER, now the Office of Resource Conservation and Recovery), and its federal, regional, state, tribal, community, and other public and private partners. The pur-pose of this document is two-fold. First, in order to increase understanding of the link between materials and land management and GHG emissions, this document presents an estimate of the portion of U.S. GHG emissions associated with materials and land management practices. Second, it presents a set of materials and land management scenarios— referred to as total technical potential scenarios—as a first step to identifying areas of opportunity for the EPA and its partners to reduce GHG emissions through materials and land management.

Increasing recycling of construction and demolition debris materials to 100% 150 MMTCO2E per year; to 50% 75 MMTCO2E per year; and to 25% 40 MMTCO2E per year.

The EPA’s Characterization of Building Related Construction and Demolition Debris in the United States, (the C&D Characterization Report) was used as the primary data source for estimating the potential GHG reduction from recycling C&D waste.1 WARM (Waste Reduction Model) was then used to quantify the GHG reductions from recycling all cardboard, lumber, metal, plastic, concrete, and clay bricks. The C&D Characterization Report provides estimates of the breakdown of the total C&D waste stream into construction, renovation, and demolition in residential and nonresidential sectors in 1996 (See Table 1).

The total volumes for cardboard, concrete, clay bricks, metal, plastic, and wood were entered into WARM. Since data on the current end-of-life treatment of C&D wastes were not available, the approach assumed that all C&D materials are 100% landfilled in the baseline, and that 100%, 50%, or 25% of the cardboard, concrete, metal, plastic and wood waste tonnage are recycled in the alternative scenarios. Clay bricks were assumed to be reused to offset the need for new bricks. The benefits of recycling asphalt, drywall, roofing, and the "other" categories of C&D materials were not calculated because recycling emission factors were not available for these streams. Tables 4, 5, and 6 display the WARM outputs for the baseline and alternative (recycling or source reduction) scenarios, and the results of the alternatives minus baseline, to give the net difference.

These estimates have a very high level of uncertainty due to the lack of comprehensive data quantifying and characterizing the national C&D waste stream. Some of the factors contributing to uncertainty in this area include:

• The total C&D waste stream estimate is based on the 1998 EPA study. Until better data is available, this is the only source available for characterizing this waste sector. Given the significant uncertainty with the older values, the estimates were not scaled up to 2006 to avoid introducing more error into the process.
• The composition of each of the six sub-streams (residential and non-residential construction, demolition, and renovation) is based on a study over a single week in Des Moines, Iowa, in 1995. There are huge regional variations in composition. For example, wood is more common in the northwest than in the southwest, and northern regions tend to have full concrete basements, while many southern or western regions do not.
• Not all materials in the C&D waste stream can be represented in WARM. For example, WARM does not include GHG factors for recycling asphalt shingles or gypsum wallboard. • Many of the recycling pathways covered by WARM may not be applicable to C&D waste. Lumber from new construction may be easily recycled, while wood waste from demolition and renovation often ends up as mulch or is burned for fuel.
• It is also not possible to say how much these potential savings compare with existing practices. The same C&D study estimates recycling at 30%-40% with no details on the recycling rates of individual materials. One industry group estimates steel recycling at 85%, so the marginal benefits likely vary by material.

In the main text and summary tables, the estimated GHG emission benefit associated with this total technical potential scenario is rounded to 150 MMTCO2E (100% scenario), 75 MMTCO2E (50% scenario), and 40 MMTCO2E (25% scenario).

Resources

1 U.S. EPA. Office of Solid Waste, Municipal and Industrial Solid Waste Division. 1998. Characterization of Building Related Construction and Demolition Debris in the United States. Report No. EPA530-R-98-010.
2 Ibid.
3 (Table 4) Used bricks were assumed to be reused (i.e., source reduced) to offset the demand for new bricks.
4 (Table 5) Used bricks were assumed to be reused (i.e., source reduced) to offset the demand for new bricks.
5 (Table 6) Used bricks were assumed to be reused (i.e., source reduced) to offset the demand for new bricks.

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