Statistical Viability of United States Air Force Sustainable \nConstruction Cost Estimation\n
Varying legislation and executive orders coupled with needs for energy resiliency have led the United States Air Force (USAF) to pursue sustainable construction. However, the limited understanding of initial costs to implement these changes have contributed to poor project cost estimating, resulting in 62 percent of USAF projects experiencing more than 5 percent cost growth. After reviewing 1628 USAF Military Construction (MILCON) construction projects in 922 category codes (CATCODEs), a two-tailed t-test for populations with unequal variance was accomplished on the final normalized contract cost for 340 projects in 16 CATCODEs executed between 2002 and 2017. This analysis provides a large sample size of projects with limited variation as they were built to the same standard. Analysis results comparing pre vs post sustainability requirements show no statistically significant difference in final contract costs for 15 of the 16 CATCODEs. The study also revealed projects are influenced by numerous criteria that impact costs, further highlighting that sustainable standards are a poor indicator of additional project costs. This validates similar research performed outside of the Department of Defense and shows there is not a basis for assigning a cost premium to sustainability requirements. Instead, each project should be considered on a case by case basis.
LEED, Sustainability, Cost, Construction, Criteria.