Alternative Heating

ABOVE: The rear of this energy efficient house faces south, and has extensive glazing to make the most of the views and passive solar gain from the sun. Read more about this project.

Ground Source Heat Pumps

There is no doubt that the alternative technol­ogy best adapted to underfloor heating (UFH) is the ground source heat pump, because it works most efficiently at low temperatures. The water in the UFH pipes tends to flow around at temperatures between 40°C and 55°C, whereas radiators require temperatures of 60°C to 80°C.

The ground source heat pump draws low-grade heat from large volumes of water being pumped around the garden and converts it into smaller volumes of high-grade heat that is then pumped around the house. In many ways, the typical heat pump application mirrors what happens in an underfloor heating system.

Ground source heat pumps are relatively expensive to install – typically costs are between £8,000 and £10,000 – but promise very low running costs because they produce three or four units of heat from every unit used to operate the system. As fuel prices rise, the payback time gets shorter and this has led to a surge in orders for heat pumps. They are eligible for grants under the Low Carbon Building Programme.

• Find out more about Ground Source Heat Pumps

Solar Panels

Solar panels come in two distinct varieties. The photovoltaic (PV) cells are used to generate electricity and are therefore not usually con­sid­ered appropriate for delivering heating. Hot water solar panels, in contrast, are widely used as additional heating sources, conven­tionally plumbed into the hot water tank and quite capable of providing the bulk of hot water used by a household during the sum­mer months. Both forms of solar panels are grant-eligible.

• Find out more about Solar Panels for Hot Water
• Find out more about Solar PV for Electricity

Combined Heat and Power

Think of a boiler that can also produce electricity and you have a combined heat and power plant. The basic idea has been around since Victorian times but it’s only recently that you have been able to get a single-house version, sometimes referred to as micro CHP.

There is currently a commercially available product called WhisperGen, which is marketed by Powergen and which Powergen is offering to install for just £3,000. Powergen is putting a lot of money into this product and has ordered 80,000 units from New Zealand manufacturer WhispherTech — so as a product it certainly has critical mass. It is designed to replace the mains gas boiler, so is obviously only an option where there is mains gas.

• Find out more about Combined Heat and Power (CHP)

Biomass Boilers

Biomass or bioenergy refers to the use of non-fossil fuels to power specialised boilers. The logic being that the fuel burned, although releasing CO2, is part of the normal carbon cycle and is therefore not adding to atmospheric CO2, because all plant life ends up producing CO2 at some stage.

However, unless you happen to own your own forest, you have to buy in a wood supply and the production is not always as green as would be hoped for. There are often high transport costs involved in getting biomass fuels to the point of consumption. In some parts of the world there has been a lot happening with pellet fuels, which compress ordinary biofuels and give them a similar calorific value to oil, so reducing the transport cost issue but, although you can buy pellet boilers in the UK, the supply of pellets is still rather thin on the ground. Cost-wise, wood pellets are currently cheaper than heating oil.

Biomass and pellet boilers are also expensive when compared to fossil-fuelled oil or gas boilers, though the best ones offer levels of automation which take most of the drudgery away from solid-fuel devices of yesteryear. As with many other renewable technologies, grants are available.

• Find out more about Biomass

Further Reading:

• The Death of Central Heating
• Install Your own Underfloor Heating
• Saving Energy in Your Self Build Home