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Recycle Construction and Demolition (C&D) Debris
Construction Waste Handbook
Worksheet Economics
C&D Resources
Education Program
Understanding the huge amount of waste in these homes has been a difficult task. One would expect that, relative to material use, there would be an economy of scale as house size increased-that material use per unit area of floor area would drop as floor area increased. It has not been made any easier with additional research. The most normalized metric in the data is pounds of C&D waste generated by the square foot of constructed space. In house one, 85,242 pounds was generated for 7,929 square feet of building space. This house generated 10.75 pounds of waste per square foot. The second house generated 87,566 pounds of waste, 11.04 pounds per square feet but 72,066 pounds of that waste was diverted from the landfill. This equates to a diversion rate of 82.30 %. The fact that the diversion took place at such a high rate is a testament to the potential of on-site grinding. The fact that there was 87,566 pounds of waste is horrific.
There are seven reasonably well conducted studies that are recent in the literature. NAHB conducted four of those studies; one in Oregon, two in Maryland, and the last in Michigan. There is one house in Illinois, and a 9,000 square foot apartment complex, and one house studied by Cornell University in New York. The average amount of waste per square foot in these studies was 4.44 pounds per square foot. The range is from 2.46/lbs per sq ft at Cornell to 7.2lbs/sq ft in the Illinois house. By any standard it could be said, "Houston we have a problem."
HARC's contention that the bricks and mortar are the most significant contributor to the variance between the Houston houses and the national data models is supported with an examination of the waste components of these seven houses. Wood waste averaged 39.7 percent of total C&D waste in these houses. Wallboard averaged 29 percent, and cardboard 5.4 percent. This accounted for 74.1 percent of the total waste. Our argument is supported by the fact that there is no brick data reported for any of the houses in these studies, and further there is no data collection for asphalt shingles.
As HARC observes in this study, the National Association of Home Builders (NAHB) is uncovering and reporting similar findings. Although NAHB has not compiled data on material use as a function of house size, NAHB believes that, because larger houses tend to have taller ceilings and more features, larger houses may consume proportionally more materials. NAHB estimates that a new 5,000-square-foot house will consume three times as much material as the 2,082-square-foot house NAHB has modeled, even though its square footage is only 2.4 times as large. Total wood use in houses increased steadily between 1950 and 1992, as houses grew in size. But when total wood use per unit of floor area is examined NAHB found that it dropped between 1950 and 1970-perhaps due to the substitution of plywood sheathing for board sheathing and the introduction of more wood-efficient roof trusses. Then, around 1970, wood use per square foot of floor area began to increase again, and by 1992 it was up about 12% from the low point. HARC would argue that with this increase in total usage the total waste numbers have become exponential as previously stated. HARC also believes that the design shift to more complex geometries to create the "starter castles" that the Houston public is predisposed to demand contributes to the massive amount of waste produced per square foot.
HARC can only hope that this study can assist H-GAC in informing the builders and the public in obtaining more information about what might be possible in lieu of a continuation of the status quo with regard to new residential C&D waste practices. HARC's fear, based upon our interaction in the building community, is that this issue lacks traction. The builders, are like most of the Houston population, are largely uneducated about the environment and largely disconnected from the consequences and the implications that something so insignificant to there core business as C&D waste could have on ecosystems and the quality of life in the region. Let us remind the reader that C&D waste handling is less than 1% of the selling cost of the home they are building. Builders are businessmen first and foremost. The buying public is not creating any market pressure to handle C&D waste in a more responsible manner. The builder's are not advising builders that more responsible C&D waste handling will lead to better short term interest rates. Land developers are not requiring builders to handle C&D waste in any particular manner. Their prospective is cleanliness only and these developers de facto may make the situation worse by requiring large roll off containers. Builders are not facing any impending shortage of landfill space as confirmed by the latest published studies. The waste haulers are not providing price increases that would cause any builder to consider alternatives to the way they have always done it. Regulatory agencies are not publicly talking about any regulatory change that might induce builders into action be it to fight the change or be it to alter their practices.
The HARC summary of the issues, concerns, barriers, and changes in practices elsewhere in the nation clearly lead HARC to believe that the issue of C&D waste handling practices in the H-GAC area will ultimately change. However, it is our opinion that this will not occur in the short term and certainly no sooner than seven years in our area.
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