To structure all possible ways energy can be harvested to use in the advantage of the building, an overview is created. At the one hand, energy can be converted inside the building from primary energy to a more usable form or to electricity. On the other hand, energy can be harvested outside the building. Most obvious examples of the latter are harvesting solar and wind energy.
In house energy conversion can take different forms. A developed example is fermenting waste water, which produces gas that can be used in a gas-fired generator. Also food and garden waste can be used in a similar process. These methods are conventional and mostly used to produce electricity. When widening the scope beyond electricity production, other options become available. As nature shows, light can be directly generated from proteins. Fire-flies and Jellyfish make use of the chemical process needed.
External energy harvesting is mainly about harvesting solar and wind energy. For both forms of energy, developed technologies exist to harvest the energy and convert it to electricity. Solar panels and wind turbines exist for many years now. A newer technology to produce electricity is a vibro-wind turbines. Besides the production of electricity, energy can be collected using the greenhouse principle. The heat obtained can then be used for direct heating or for the production of electricity as in concentrated solar power.