Energy efficient buildings can be defined as buildings that are designed to provide a significant reduction of the energy needed during day to day operation of the building.
Buildings use energy at different levels and for different purposes in every stage of the life cycle.
A large part of the energy (35–60%) is used for heating, air-conditioning, ventilation, and artificial lighting. Energy-efficient approaches aim to have a significant energy economy in buildings.
There are very different applications in uses aiming for the reduction of energy consumption of buildings.
For example, the pre-building phase includes the suitable site selection, site planning, building form, building plan, appropriate space organization, building envelope design choosing energy-efficient building materials, and energy-efficient landscape design.
The building phase includes the construction and usage processes of the building. The building phase is possible by choosing building techniques that consume less energy and using energy-efficient type equipment, such as energy-efficient bulbs and energy-efficient appliances. For example, the light-emitting diode (LED) is one of the most energy-efficient and rapidly developing lighting technologies today.
Lighting controls – Lighting requirements is related to the building design. The need for lighting, when during the daytime, will depend on the window size, placement, and the position of buildings. The need can be reduced by the use of automatic controls, which depend on the orientation of building windows, the supply of daylight, and the usage of the room.
The post-building phase comes after the completion of building usage. In this phase, we have to do the demolition of the building, recycle of reusable materials, and wipe out the building. During this phase, it is important to recycle the building materials used in the buildings, and reuse them as much as possible. Another possibility after the functional uses of buildings is the reutilization of the building for other functions instead of demolishing. It protects resources such as raw materials, water, money, and energy.