3 years ago CU student leaders invested $500,000 in an endowment for energy-efficient projects. 37.8 percent is the annual return on investment for the CU green fund. $24,000 is the amount the school saved in efficiencies because of fund-related projects in its first year, followed by $59,583 last year and $143,500 this year. Projects include replacing radiator values and windows and switching to LED lights and must have payback periods under 5 years.