Preliminary Life Cycle Analysis of Modular and Conventional Housing in Benton Harbor, MI

Abstract

A 1,456 ft2 modular home and conventional site built home in Benton Harbor, Michigan are analyzed to examine how the different construction and design methods of two types of housing influence environmental impact over their 50 year life span. The chosen modular home is fabricated by Redman Homes in Topeka, Indiana and transported to the building site. The conventional home is modeled after the modular home in collaboration with Douglas Construction Company. Many assumptions and simplification were made due to data gaps, so results represent preliminary estimates. The total amount of the materials placed in the conventional home is 9% less than the amount of the modular home because the modular home is framed with larger 2X6 studs and requires additional structural components. The conventional home produces 2.5 times more construction wastes than the modular home. The lesser material consumption of the conventional home is offset by a larger amount of waste generation. The building use phase dominates more than 93% of the life cycle energy consumption and over 95% of the total greenhouse gas emissions for both homes. The total life cycle energy consumption for modular home is 5% less than the conventional site home. The total global warming potential for the modular home is 5% less than the conventional site built home. The use phase energy consumption and greenhouse gas emission differences are attributed to the expected higher air tightness (0.194 ACH) of the modular home over the conventional home. The conventional home was modeled with 80% lower air tightness (0.35 ACH) than the modular home, which results in 7% more of the natural gas consumption over its service life. The modular home requires additional transportation energy compared to the conventional home for delivering the fabricated modular home to the site. However, 4~5 days of the modular home’s short fabrication cycle time allows the modular home to significantly reduce the employee’s transportation energy compared to that of the conventional home.