thermodynamic heating, heat pump: financial and ecological balance

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The thermodynamic heating, are heat pumps and geothermal energy in an environmentally and economically acceptable solution?

Article freely inspired by the reflections of this topic

This article concerns thermodynamic heating, very "fashionable", especially for individuals who are wondering about the choice of their future heating means because the information that circulates are quite vague ... The purpose of this article is to see clearer.

Indeed; provided that the heat pump is powered by a renewable source implanted in you (wind, solar ...) or electricity 100% green (green contract) the thermodynamic heating is far from being as clean as we do pretends!

It is, for example, misleading to speak of 100% renewable energy or green 100% or even free about geothermal. Now this is what we read too often in many commercial documentation.

Here's why: in France, electricity is a primary energy cost of 2.58 times the final energy consumer. Thus, for 1 kWh spent, it took spend 2.58 kWh at source. And a heat pump that will consume 1 kWh will actually consume 2.58 kWh in primary energy if we wanted to compare it to a gas or oil boiler.

Here are the different weightings primary energy / final energy according to different labels: RT2005, Minergie Effinergie and Passive House.

Points of reflections with respect to the choice of a thermodynamic heating (heat pump type water-water, ground water, air-water, air-air ...)

Some points of reflection for those who "hesitate" about the choice of their heating currently:

A) from an oil boiler with a heat pump, your electric bill may be multiplied by a coefficient ...! We understand better the promotion made by EdF and sellers of electricity for this solution!

A heat pump is not economical for your electricity bills.

B) If your electricity is produced from coal or oil, the total return on the CO2 may be of the same level with an oil boiler light of thermal power returns, line losses and COP your PAC.

Here are CO2 discharges per kWh for several European countries.

Concrete example:

- Oil heating. 2.6 CO2 kg per liter of fuel consumed for about 8.5 kWh of heat (85% yield).
CO2 releases: 2.6 / 8.5 0.3 = kg / kWh heat.

- Heating by heat pump in Germany (few nuclear) CO0,60 2 kg / kWh elec. If one has a COP average over the year 2.5. CO2 rejection: 0.6 / 2.5 0.24 = kG / kWh heat

The gain on the CO2 in this case is very low (20%) and requires that the average COP of the year is actually of 2.5. If it is less than 2, a fuel oil boiler becomes cleaner!

A heat pump supplied by a central oil or coal is not clean at the CO2

C) If your electricity is nuclear, certainly you will decrease your emissions more CO2 but you fund the maintenance and revival of the French nuclear fleet.

A heat pump finances and promotes the development of nuclear power or the construction of new plants (gas and coal) to power peaks, is environmentally friendly?

D) Maintenance costs are high and to add to your electric bill: 2 300 to € annually or every 2 years!

A heat pump has a high maintenance cost. Take it into account in the balance sheet.

E) The return on investment (for renovation) is usually to 10 20 years without correction of the electricity price rise necessarily. Work (horizontal ground water, vertical drilling ...) are quite substantial in case of renovation and usually very heavy financially.

The financial risk is important

F) The performance data by installers are generally the best performance laboratory (commes consumption data by auto manufacturers rarely achieved in actual use ...)

Actual performance will be short of performances

G) The life of the equipment is limited: there is not much fridge that lasts 30 years. But a heat pump is an inverted fridge, it is a complex system with moving parts and fluids that can "wear out" ... This goes against a saying well known to the professionel building: more it's simple plus it lasts a long time.

A heat pump has a limited lifespan compared to other heating equipment, especially considering the cost of installation!

H) For horizontal sensor, the deposit is not infinite since you cool your garden. Ca and in some cases can be annoying, for example, when there is snow cover! Geothermal energy, surface, is an indirect solar energy! The volume average heat capacity of the Earth is equivalent to that of water ... This remark is even more true with the heat pump Air-X: much ice up and no longer work under 0 ° C (although there are of less and less).

Heat pumps are more sensitive than other heating means to weather

I) The development of the thermodynamic heating (replacing boilers gas or fuel oil) contribute to power peaks on the electricity grid. These power peaks are very bad for the environment in France and widely increasing emissions CO2. See figures Release CO2 in France following the use of electricity.

The advantages of the thermodynamic heating

Finally still on good points, there are still advantages to thermodynamic heating, here are some a ...

A) In case of heat pump water-X, ie vertical field (depletion in the water table) the heat source is more constant than air or soil from your garden. But to do this, one must be "well" placed geographically and the cost of drilling is important!

B) Compared with the conventional electric heating (convectors), geothermal heating is more efficient éconologiquement!

But we must also compare the costs of return on investment. convectors of € 30, a storage tank at € 200 is a house equipped with heating for € 2000. This is 10 000 € under a small heat pump ...

C) A heating with reversible air-conditioning is the most interesting to replace convectors because the capital cost is much lower ... but attention to low temperature performance! Heating by air-air heat pump is very interesting in addition to another heating!

D) Geothermal allows the low temperature heating therefore the "overall" efficiency of the installation will be higher but the low temperature heating is possible with any other heat source provided the installation is well done!


The thermodynamic heating has many constraints and disadvantages (and there are others than those mentioned in this article, for example, we have not talked about the noise heat pump, here's an example with a CIAT Caléo) Which are, obviously, not put forward by the sellers and installers.

The development of the thermodynamic heating is driven by electricity producers who see here an economic boon. Exactly as was the electric heating (and still is in part because more than 2 million new homes are warming in France to electricity since 2000) ...

However, thermodynamic heating is a real breakthrough just when ecological and economic replaces the direct electrical heating.

Any investment, it is necessary to take stock and learn before, our forums can help you with your questions!

- heating and thermal comfort Forum
- Comparison of professional study. gas heat pump VS VS district heating.
- Feedback geothermal heat pump users
- Discussion on the issues discussed in this article
- Information on the thermodynamic heating and heat pumps


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