Life Cycle Analysis of a Residential Home in Michigan
A 2,450 ft2 residential home (referred to as SH for Standard Home) built in Ann Arbor, Michigan was analyzed to determine total life cycle energy consumption of materials fabrication, construction, use and demolition over a 50 year period. Life cycle global warming potential (GWP) and life cycle cost were also determined. The home was then modeled to reduce life cycle energy consumption by employing various energy efficiency strategies and substitution of selected materials having lower embodied energy (referred to as EEH or Energy Efficient Home). The total life cycle energy was found to be 15,455 GJ for SH (equivalent to 2,525 barrels of crude oil) of which 14,482 GJ (93.7%) occurred during the use phase (space and water heating, lighting, plug loads and embodied energy of maintenance and improvement materials). The life cycle energy of EEH was reduced to only 5,653 GJ (equivalent to 927 barrels of crude oil) of which 4,714 GJ (83.4%) occurred during the use phase. The purchase price of SH was $US 240,000 (actual market value) and determined to be $22,801 more for EEH. Four energy price escalation scenarios were run to determine un-discounted life cycle cost using falling, constant, and rising future energy costs. Accordingly, the un-discounted life cycle cost of SH varied between $791,500 and $875,900 and between $796,300 and $824,100 for EEH. Using a 4% discount rate, the present value cost varied between $423,500 and $454,300 for SH and $433,100 and $443,200 for EEH. Life cycle GWP for SH was determined to be 1,013 metric tons of CO2 equivalent (91.9% during the use phase) and 374 metric tons for EEH (78.6% during the use phase). EEH use of energy efficiency strategies and materials with lower embodied energy reduced pre-use phase energy by 37 GJ (3.9%) while use-phase energy was reduced by 9,768 GJ (67.4%). Total life cycle energy was reduced by a factor of 2.73, and life cycle GWP decreased by a factor of 2.71.