A public agency that decides to implement green design and construction features in its capital improvement program is actually adding an undetermined incremental cost to the initial cost of public buildings. Past research has portrayed these costs as a percentage increase, essentially creating an overall contingency for green buildings, but no work has been done to quantify the incremental cost on a building's actual design program that can be assigned directly to the project budget. This research sought to provide an objective approach to estimating sustainable design and proposes a framework for estimating the initial capital costs of sustainable building design and construction as measured by the Leadership in Energy and Environmental Design (LEED) certification program. The framework allows tracking of costs during design and can be utilized for estimating future projects. The framework is developed using case study analysis of green building projects in OK City, Oklahoma. The paper concludes that the cost of “going green” can be estimated as a unit price basis as a cost per LEED credit. The proposed framework can be used by any public agency to determine the additional cost of LEED certification and for budgeting future projects.