Ground source heat pumps use pipes buried typically in a garden or under concrete to extract heat from the ground, to heat water for radiators, hot water and underfloor heating. At a certain level under the surface the ground stays at a constant temperature, meaning a ground source heat pump can be used throughout the year. Heat from the ground is absorbed into a mixture of water and anti-freeze that is circulated by the pump through pipes buried underground. This is then pumped through a heat exchanger. The low grade heat is then extracted and after passing through a heat pump compressor, is concentrated into a higher temperature for heating domestic hot water. Although they need electricity to run, as the heat is extracted from the ground, the energy is constantly being renewed naturally.

Evans Easy House case study

Air source heat pumps absorb heat from the outside air. Again, this heat can be converted for all domestic uses such as hot water and heating.
These pumps, which also need electricity to run, can extract heat from the air even when the outside temperature is as low as minus 15 degrees Celsius.

There are two main types:

• Air-to-water systems use the heat to warm water, although to a lower temperature than a standard boiler system. This makes them more suitable for underfloor heating than radiators.
• Air-to-air systems produce warm air which is circulated by fans to heat a property.

Canary wharf case study

Solar thermal technologies use heat from the sun to offset the water heating demand of a building. The heat absorbed by the solar collector is turned into energy by a variety of components, the output being that the energy delivered to a water storage medium increases the temperature of the water stored within. This reduces energy input from the conventional system to heat water to the necessary temperature, which in turn reduces energy bills for the user. Solar thermal systems are generally designed to meet 90% of the heating demand in the summer and around 50% of the heating demand averaged over the year.

Hermitage River project case study

Solar electricity systems capture the sun's energy using Photovoltaic (PV) cells. The cells convert the sunlight into electricity, which can be used to run household appliances and lighting. The stronger the sunshine, the more electricity is produced, although you can still generate electricity even on a cloudy day. The strength of a PV cell is measured in kilowatt peak (kWp). A typical home PV system can produce around 40% of the electricity a household uses in a year.

Heat recovery ventilation (HRV) systems offer a solution, bringing fresh air into your home without letting the heat escape. They consist of two ventilation ducts running next to one another passing between the inside and the outside of a house. One carries cool, fresh air in; the other carries moist, stale air out. Airstreams run through a device called a heat exchanger that allows the outgoing air to pass most of its heat to the incoming air without the two airstreams actually mixing together. In winter, they can help save on your heating bills; in summer, they reduce the need for air conditioning. By keeping excess moisture out of your home, they're better for your building, your furnishings, and your health and they help to keep the "climate" inside your home at a more constant level.