Waste Prevention and Reuse

Green Building

Key findings from the Phase 2 Study

• Of the 30 different material reduction and reuse practices evaluated, reducing home size and multi-family living achieved the largest greenhouse gas reductions along with significant reductions in other impact categories.
• Reducing home size by 50 percent results in a projected 36 percent reduction in lifecycle greenhouse gas emissions.
• Reducing home size is a significant leverage point for environmental impact reduction and may be a more effective measure than achieving minimum levels of “green” certification.
• Various sizes of multi-family housing show significant lifecycle reductions in greenhouse gases and most other pollutants.
• Families who choose or require more living space than a “small” home may lessen a large home’s impact by adding green building practices and increasing the home’s energy efficiency.
• New and existing homes of any size could incorporate internal accessory dwelling units (sometimes known as “mother-in-law apartments”) within the home as an option to increase density and reduce the square foot/ person ratio, provide flexible living spaces, and achieve the environmental benefits of both small and multi-family living.
• More than 80 percent of greenhouse gas emissions over a home’s 70-year life occur during occupancy and are attributed to electricity and fuel consumption. Approximately 14 percent of greenhouse gas impacts are tied to producing the original and replacement building materials.  Constructing and maintaining the home account for about 2 percent and transportation of building materials accounts for less than 1 percent.  Oregon’s existing material recycling and energy recovery system reduces greenhouse gas emissions by 5 percent over the typical 70-year life of a home.
• For other types of environmental impacts, materials contribute 10 to 40 percent of life cycle impacts.
• Only a small amount – about 6 percent – of building material-related waste generated occurs during home construction, with about 50 percent of waste generation occurring during 70 years of home repairs and maintenance. The remaining 44 percent of waste generation occurs at the time of the home’s demolition.
• Material reuse significantly reduces the amount of waste generated and material-related impacts of production but provides limited greenhouse gas reductions over the home’s life because reuse does not typically affect the operational energy consumption of a home, as do other practices evaluated.

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