Energy Breakthrough Proposal The third proposal (Table 16-3) is from a new firm that specializes in the design and construction of energy-efficient structures. They based their B/C ratio, _ on assumptions of 40 years of use and costs and benefits that flow continuously over that time (distributed rather than end-of-period cash flows). Table 16-3 Energy Breakthrough Proposal Construction: 1 year: $3.9 million Annual operation: Gym: $ 65,000 City offices: $100,000 Theater: $15,000 Annual benefit: Gym: 60 hours/week at $200/hour Theater: 16 hours/week at $450/hour