By Neil Parkinson

Published in French Property News, April 2006

 

 

heightened concern about greenhouse gases and an increase in oil and gas prices are throwing into question the way people heat their homes in France. As an incentive to use alternative energy sources, the French government is offering tax rebates to home owners who install central heating and hot water devices that use renewable energy sources or are energy saving. Rebates amount to as much as 40% of the cost of supplies if they fall into the three main renewable energy categories: solar, geothermal and wood. A little background on the technology needed to harness these limitless energy resources is given herein.

 

Say the words 'solar panel' to most people and they will think of electrical current generating kits that power a large array of small devices like calculators but also have applications in remote homes and public telephones. The technology involved in heating houses is however quite different and instead works on the principle that heat can be captured, like in a greenhouse. A translucent glazed plate exposed to the sunlight, and often on a roof, covers a black heat absorbing material around which a refrigerant (water or anti-freeze) is circulated and hence warmed. To convey this heat to the house, systems of differing levels of sophistication exist. One of the more common systems consists in circulating the hot refrigerant through a heat exchanger device which then dispatches the heat via the home heating circuit to the radiators or floor installed heating. It is also possible to circulate the hot refrigerant within the heating element of a hot water tank.

 

Requirements in terms of panelling will depend on exposure to sunlight - a function of the local climate - and the desired results in heating and hot water. Solar heating operates in daylight so complementary systems may be necessary. A spatious house (150m²) in Strasbourg will typically require 18m² of panelling to produce hot water or heating, thus achieving a 30% reduction in energy costs. Exposure to the 2600 hours of sunlight per year common along the Mediterranean coast implies that considerably less surface area is required - a 110m² house with a family of four requires as little as 13m² of panelling and can thus halve its requirements for traditional energy sources for heating / hot water.

 

Geothermal systems that capture warmth in the ground are rapidly gaining in popularity in France - undoubtedly because they are currently the most efficient of all the renewable energy systems. These work on the basis that the ground temperature at a relatively shallow depth of 60cm is generally stable between 10 and 15°C. They use means to capture this warmth, either by looped piping laid in the ground outside the house in which a refrigerant circulates, or by capturing the warmth in underground water reserves and conveying this into the house by means of a ground source heat pump which dispatches the heat via the home heating circuit to floors or radiators or hot water tank devices. The whole system is a sort of refrigerator in reverse.

 

An external ground area of 1.5 - 2 times that of the surface area of the house is required to snake the ground loop. The ground source heat pump is plugged into the mains but its efficiency is impressive: put in 1kWh of electrical energy and you can get as much as 4kWh of useful heat out. In addition the system can be reversed to operate to air-condition a house in summer.

 

The third of the main renewable energy sources is wood. French forests, currently 40 million acres are growing by 100,000 acres every year. Hence wood is considered neutral with regard to greenhouse gas emissions. Rare is a French house without a log fireplace, yet these have evolved greatly and while it is not impossible to see an open hearth in the most contemporary of houses, many alternatives exist. 'Firebox' designs which enclose the fire behind a glazed door and have ducting to convey heat to other rooms, stoves, which come in many shapes, sizes and decorations, and sophisticated central heating systems which burn wood pellets in programmable boilers, thus making them very 'hands off', make for a wide spectrum of products. Efficiency levels vary considerably between systems but 85% yields are possible in modern enclosed fireplaces.

 

The fireplace differs from the two former sources of renewable heat energy in that it often forms the centrepiece of a living room - hence aesthetics weigh more heavily in the equation during their installation. From the very rudimentary open fireplace to modern ceiling suspended or wall mounted units and ultramodern, perhaps less poetic but very practical, remotely-controlled systems, there is a fireplace for everyone.

 

Tax rebates are granted for equipment installed in a main residence by professionals. Rebates are available from 1st January 2005 to 31st December 2009 and the amount is a proportion of the purchase cost of the supplies. For a single residence, the amount of expenses taken into account cannot exceed the sum of 8000€ for a single person, 16,000€ for a couple, to which is added the sum of 400€ for a first additional family member, 500€ for the second and 600€ for the third. Households not subjected to income tax in France should nevertheless fill out a tax return, and will receive a refund from the French tax authorities.

 

To ensure requirements are satisfied throughout the year, often owners will tend to couple systems. A fireplace will come in handy to compensate for overcast skies when solar panelling is not operational. In the south of France, one such house, designed to take full advantage of the sunlight is an outstanding and unusual property, built 1982, and definitely a forerunner in the region in the use of renewable energy sources.

 

Three systems make this an environmentally friendly house with very minimal needs for traditional sources of energy. Firstly, air, ducted through channelling beneath the solar plates is warmed in the sunshine and then circulated by ventilators over a blanket of pebbles beneath the floor of the house. This gives the house a very high heat inertia and the added comfort of warm floors. A second set of solar panels serve to heat a refrigerant that runs through the heating element of a hot water tank. Secondly, earth heat exchangers, draw in air from outside and circulate it in ducting in the ground in front of the house to capture ground source heat. These also serve to bring in cool air in the summer. Finally, there is a log fireplace in the living room and a complimentary Godin stove, thus making for an exemplary house in the field of renewable energy. It is situated close to Pezenas and for sale for 398,000€.