Mechanical scenario yielded the highest NOx emissions because the steel was not

recycled. The recycling of steel produced negative emissions of NOx (emissions savings)

for the manual deconstruction scenarios, thus allowing 100% manual deconstruction to

yield lower NOx emissions than 100% mechanical demolition.

 Impact Analysis

 An impact assessment was performed on each of the four scenarios to determine

their effects on Global Warming, Ozone Depletion, Acidification, Eutrophication, Human

Toxicity, and Ecotoxicity. As stated earlier two published impact assessment methods,

CML and EDIP, were used for this LCA to compare and contrast the results of three

hypothetical cases-1) where no reuse was considered, 2) where reuse but no

transportation to a salvage warehouse was considered, and 3) where both salvage and

transportation to the Habitat for Humanity warehouse in Austin, TX were considered.

 Case 1: No Salvaging

 Figures 3-3 and 3-4 show impacts (calculated using EDIP and CML 2000,

respectively) resulting from the scenarios where no reuse was considered. In this option,

all salvaged materials are disposed of in a landfill. All scenarios that involve manual

deconstruction show comparable or larger contributions to all impact categories

calculated by the EDIP method (Fig. 3-3) compared to the mechanical demolition

scenario. All of the environmental impacts were lowest for the 100% Mechanical

scenario because of the significantly lower emissions resulting from lower total mileage

for transportation of the employee's to/from the site and the lowest total hours of

equipment use. Specifically, ecotoxicity and human toxicity impacts are higher in the

scenarios involving manual methods because of the increased need of diesel fuel and

gasoline for machine and automobile operation, respectively. These impacts are most