Energy Efficiency - Low and zero carbon technologies

Renewable technologies e.g. wind, solar thermal, photovoltaics etc. Renewable technologies should only be considered after the building has been designed to have the lowest energy consumption possible. Only then is it sensible to consider these more expensive technologies. Each have their merits, however not all of these technologies are feasible for every location, e.g. a wind turbine will only be viable in an area likely to have enough wind to operate it, solar thermal will only operate if a sunny location for the equipment can be found. It is wise to carry out a feasibility study in the early stages of the design process to see which technologies will work for the site.

Biomass boilers run on wood pellets, these produce less carbon dioxide emissions than conventional heating. Usually biomass boiler are commercially sized as they require a large area due to the amount of equipment needed to operate the system and the area required store the fuel, however they can also be effectively used for groups of dwellings. There is an environmental impact from the transport in delivering the wood pellets, however there are usually local suppliers and this impact can be offset.

Combined Heat and Power (CHP) is usually designed for a building (or buildings) with a large heating load e.g. school, hospital, swimming pool. Generally the CHP plant is sized according to the heating load and the electricity generated as part of the process is then also used in the development. This simultaneous generation of usable heat and power (usually electricity) in a single process and is a highly efficient way to use fuels. The heat produced during power generation is recovered, usually in a heat recovery boiler and can be used for heating or with appropriate equipment, cooling. Because CHP systems make extensive use of the heat produced during the electricity generation process, they can achieve overall efficiencies in excess of 70% at the point of use (typically 38% - 48% in coal-fired and gas-fired power stations, which discard this heat). Efficiency at the point of use is lower still because of the losses that occur during transmission and distribution. CHP systems are typically installed onsite, supplying customers with heat and power directly at the point of use, therefore helping avoid the significant losses which occur in transmitting electricity from large centralised plant to customer.

Heat pumps can reduce energy consumption but need to be considered with all other environmental implications such as local ground conditions, ecology and water table level.