'Renewables' is a catch-all phrase that suggests that the energy supply is inexhaustible.

The sun is essentially the source of all our 'inexhaustible' energy and we can harvest this in various ways.

• Directly as with solar domestic water heating.
• Indirectly such as from the wind, water or from the ground or air.

The standard indicator of "how green" is carbon dioxide since this is a 'Greenhouse Gas' closely associated with global warming. However, other atmospheric and water-borne emissions can also be considered along with disposal or recycling of appliances used in the energy cycle.

For a heating engineer, considerations of maximising the efficiency of heat processes in a safe, reliable and comfortable manner is the priority. The sections (select from the list on the left) are intended to assist existing engineers to become more familiar with these alternative energy sources in a context and language that is familiar.

The sections were produced by the Institute of Domestic & Environmental Heating Engineers Renewable Group for other members of the Institute. We hope you will enjoy them and look forward your constructive feedback and interest in the subject.