Colorado's solar access laws, which date back to 1979, render void any covenants, restrictions, or conditions that prohibit “renewable energy generation devices” or “energy efficiency measures”. Renewable energy generation devices include solar energy devices and wind-electric generators that meet the state’s interconnection standards. Energy efficiency measures include awnings, attic fans, energy efficient lighting, and clotheslines, among other technologies. Some exceptions are made for both renewable energy devices and energy efficiency measures for safety requirements and aesthetic purposes that do not significantly increase the cost of the device or decrease its performance. Colorado also allows property owners to agree voluntarily to solar and wind easements with their neighbors for the purpose of protecting and maintaining proper access to sunlight and wind. The statute provides details about the process for filing an easement, and includes provisions regarding the reversion of easements.