The ultimate objective is to make the building self sufficient in energy. To do so, the topic off energy is divided in three sub problems. Energy needs to be harvest and stored, but energy consumption can also be reduced.
For the harvesting of energy, methods can be used to harvest energy within the building or outside the building. The first type can consist of a bio-gas reactor that converts biogas from organic waste to electricity. Examples of outside energy harvesting are solar panels and sun-boilers to collect solar energy or a wind turbine to collect wind energy.
The reduction part of energy can be elaborated in many different ways. When looked to nature, it is found that the sunlight can be transferred more optimal to the inner parts of the building as the silica spicules of a sponge. Also energy can be saved when creating light. A firefly for example creates light in a very efficient way.
A last topic is the energy storage. As the sustainable energy from outside the building is not always available, a great amount of energy will need to be stored. Basic examples to do so is by pumping up water and store it as potential energy, compressing air or creating hydrogen to use in fuelcells.