Nurseries are often large buildings with a vast number of rooms. With these rooms being occupied at varied times throughout the working day, and at weekends, this can become a costly procedure. For example, in the summer season or on warmer days when the children are able to play outside, it is likely that doors will be left open for children to go in and out — meaning heating and energy is wasted. Additionally, there may be specific rooms or areas of the nursery that are infrequently used, with others that are used more frequently, so the heating is required to be higher in those areas than those that are used less frequently.