A Life Cycle Comparison of Light-Frame Wood and Insulated Concrete Form Building Envelopes: Energy Use and Green House Gases

Given the building sector’s substantial contribution to global energy use and green house gas (GHG) emissions, it is of great importance that only the most effective building envelopes are utilized. Conventional light-frame wood building envelopes are highly popular due to their ease of construction and building economy; however the life cycle performance of the building envelope is often overlooked when this selection is made. Although insulated concrete form (ICF) building envelopes generally require a substantially higher embodied energy input, it should be considered that improvements during a building’s operation phase can offers significant energy returns, ultimately reducing the building’s life cycle energy use and GHG intensity. Therefore, an assessment is conducted regarding the life cycle energy use and GHG intensity of the ICF building envelope, in addition to two light-frame wood building envelopes; the average light wood frame envelope (U.S. Department of Energy, 2007), and a more highly insulated wood frame envelope. The operation phase of the building envelopes proves to be of greatest significance, as it is attributed to 95- 97% of the total life cycle energy use, and 93-96% of life cycle GHG emissions, assuming a 100 year life cycle. Ultimately, the life cycle performance of the ICF building envelope is superior to the two wood frame envelopes due to its improvements in the operation phase. The ICF building envelope has a life cycle energy requirement of 11% to 14% less than the two light-frame wood envelopes, and a 10% to 12% lower life cycle GHG intensity. Although the increased thermal resistance certainly contributes to the superior life cycle performance of the ICF envelope, the improved infiltration leakage area of the envelope is key to its operational performance, and subsequently to its improved life cycle performance. End of life energy use for the demolition, recycle, and disposal of the building envelopes is nearly negligible, as it is attributed to less than 0.3% of the life cycle energy for any of the envelope scenarios.