Designing a house, a building or an entire community with shared facilities can decrease development and/or operating costs. By sharing indoor facilities such as a kitchen and common rooms, less space is required in each private unit. Eliminating corridors, stairwells or elevators to access self-contained units also reduces the overall footprint and cost of a development. Similarly, the use of shared appliances can reduce energy costs. Sharing outdoor facilities — such as parking and exterior social spaces — results in a more efficient use of land. The shared facility concept has been applied to different types of housing such as cohousing, Abbeyfield houses, congregate houses, single-room occupancy units, feminist design housing and secondary suites.