Want to Pay Less and Pollute Less? Here's the Heating System Science Ranks Far Above the Rest

Researchers from the Technical University of Munich have just published an unprecedented comparative study on domestic heating systems. Their verdict is clear: the air-to-water heat pump outperforms all other systems, both economically and environmentally. This methodical analysis, which scrutinized all available solutions—from wood to fossil fuels—provides concrete data to inform your heating choice.

What the German Study Says About Heating Systems

The Air-to-Water Heat Pump Tops the Rankings

The Munich research team evaluated each system according to three main criteria: overall operating cost, greenhouse gas emissions, and actual energy efficiency. The air-to-water heat pump stands out clearly with an average coefficient of performance of 3.5 to 4—in other words, for 1 kWh of electricity consumed, it returns 3.5 to 4 kWh of heat.

The researchers took into account the entire life cycle: equipment manufacturing, installation, annual consumption, maintenance, and estimated lifespan. Over a fifteen-year horizon, the air-to-water heat pump has the lowest total cost of ownership for a well-insulated standard home.

What surprised in the study is the significant gap between the heat pump and other solutions. Even compared to systems considered high-performing—condensing gas boilers or certified pellet stoves—the heat pump maintains a marked lead as long as the dwelling meets certain insulation conditions.

Other Systems Under Scrutiny

Wood heating ranks in the middle of the classification. Recent log stoves display good energy yields (up to 80% for Flamme Verte 7-star appliances), but their fine particle emissions and local carbon footprint penalize them in the overall analysis. Pellet boilers achieve better results thanks to more controlled combustion.

Condensing gas boilers come in third position. Their energy efficiency reaches 95 to 105%, making them a relevant option for older homes where heat pumps would not be suitable. However, their dependence on fossil gas and direct CO2 emissions put them at a disadvantage.

Classic electric systems—convectors, radiant panels—are clearly outdated with a coefficient of performance of 1 (1 kWh consumed = 1 kWh returned). As for oil and standard gas, they bring up the rear with the highest operating costs and heaviest carbon footprint.

Heat Pump Versus Wood Heating: What to Remember in the Field?

Real Consumption and Cost Figures

Take a 100 m² house properly insulated (RT 2012 level). With a correctly sized air-to-water heat pump, you consume approximately 5,000 to 6,000 kWh of electricity per year, or 900 to 1,100 € depending on your contract (standard base rate).

For the same area heated with wood, count on 8 to 10 steres of dry wood (oak or beech at less than 20% humidity). At an average of 70 € per stere delivered, your fuel budget runs around 560 to 700 € per year. Wood therefore seems cheaper in operation—but the equation changes when you factor in the initial investment and lifespan.

An air-to-water heat pump costs between 10,000 and 16,000 € installed, subsidies deducted between 5,000 and 11,000 € depending on your income. A quality log stove with flue lining and installation ranges between 3,500 and 7,000 €, subsidies included between 2,000 and 5,000 €. Over fifteen years, counting mandatory annual maintenance (150 € for the heat pump, 100 to 150 € for chimney sweeping and stove maintenance), the heat pump recoups its initial extra cost from the tenth year.

Among my clients equipped with heat pumps for five to six years, I observe heating bills divided by two to three compared to their old oil or gas boiler. Those who heat with wood appreciate the autonomy and controlled cost, but regularly cite the logistical constraint: storage, daily lighting, ash management.

Environmental Impact Decoded

In terms of CO2 emissions, an air-to-water heat pump emits approximately 30 to 40 g of CO2 per kWh of heat produced (counting the French electricity mix largely decarbonized thanks to nuclear and renewables). A log stove emits between 30 and 40 g of CO2 per kWh if wood is considered carbon neutral over its life cycle—but this neutrality is debated when forest exploitation, drying, and transport are factored in.

The real problem with wood is fine particles. Even a recent and well-operated appliance releases PM2.5 and PM10 that degrade local air quality. In Alpine valleys or poorly ventilated areas, the accumulation of these particles in winter poses real health problems. The heat pump emits strictly nothing on site.

The overall carbon footprint, manufacturing included, clearly leans in favor of the heat pump. Compressors and refrigerants have an impact during production, but over fifteen years of use, the heat pump displays a carbon footprint 40 to 50% lower than log wood and 60 to 70% lower than gas.

Why is wood still defensible? Because it constitutes a local and renewable resource if the forest is sustainably managed. In rural areas with direct access to quality wood, the balance can improve significantly. But at the scale of an urban area, generalizing wood heating would saturate the air with pollutants.

In Which Cases Is the Heat Pump Really Worthwhile?

Homes Where Heat Pumps Excel

The heat pump performs best in well-insulated houses: BBC (Low Energy Building) level, RT 2012 or higher. With limited heat losses, it operates at low temperature (35 to 45°C) and maintains its high coefficient of performance.

Areas between 80 and 150 m² represent the ideal playground. Configuration also matters: a single-story house or one with good air circulation will facilitate heat distribution. Underfloor heating is the perfect combination: large exchange surface, low water temperature, homogeneous comfort. Low-temperature radiators (50°C maximum) also work very well.

On the other hand, if you have high-temperature cast iron radiators (70 to 80°C), the air-to-water heat pump will have to work harder and its efficiency will drop. In this case, plan to replace the emitters or opt for a high-temperature heat pump—more expensive and less efficient.

Regions with temperate climates (Atlantic coast, Mediterranean rim, protected valleys) offer the best conditions. When temperatures drop below -7°C, the coefficient of performance of an air-to-water heat pump decreases significantly. It continues to heat, but consumes more. In mountainous areas or the northeast with harsh winters, backup heating often remains necessary.

When Wood Heating Retains the Advantage

In a poorly insulated old house, installing a heat pump amounts to heating the outdoors. You will consume enormous amounts of electricity without ever achieving the expected comfort. Here, wood remains a relevant solution: it produces powerful radiant heat that partially compensates for losses. But the ideal remains to insulate before changing heating systems.

Rural areas with direct access to local wood (forestry operation less than 20 km away, possibility to buy in bulk from an owner) completely change the economic equation. If you pay 40 to 50 € per stere and have a building to store it dry, wood becomes unbeatable in operating cost.

Dual-energy heat pump-wood deserves attention. You install a heat pump for daily use and keep or add a log stove for extreme cold or as backup heating in case of power outage. This combination offers security, savings, and autonomy. I've implemented it for several clients in Auvergne and Jura: they wouldn't go back.

Finally, if your installation budget is really limited (less than 6,000 €), a recent log stove or entry-level pellet stove will remain more accessible than a complete air-to-water heat pump. Subsidies reduce the gap, but not always enough for the most modest households.

How Much Does a Heat Pump Cost and What Subsidies Can You Get?

The Installation Price of an Air-to-Water Heat Pump

For a 100 to 120 m² house, count on between 10,000 and 16,000 € including VAT, installation included. This range varies according to several criteria:

• The necessary power (8 to 16 kW depending on insulation and region)
• The brand and quality of equipment (Atlantic, Daikin, Mitsubishi, Saunier Duval...)
• Installation complexity (distance between outdoor and indoor unit, duct routing, emitter replacement)
• Type of heat pump (monoblock or split, high or low temperature)

Add 300 to 500 € for thermal study and sizing performed by an engineering firm. This step is not optional: an undersized heat pump will run continuously and wear out prematurely; an oversized heat pump will cost more without providing additional comfort.

Annual maintenance is mandatory for heat pumps with more than 2 kg of refrigerant (virtually all air-to-water models). Count on 150 to 200 € per year for leak testing, filter cleaning, and parameter verification. Some contracts include troubleshooting, which can be worthwhile.

Subsidies That Reduce the Bill

Current subsidies can cover up to 50 to 70% of the total amount for the most modest households. Here's what you can claim:

MaPrimeRénov': depending on your income, you receive between 3,000 and 5,000 € for installing an air-to-water heat pump. Households with very modest incomes (thresholds defined by Anah) receive 5,000 €, modest incomes 4,000 €, intermediate incomes 3,000 €. Households with higher incomes are no longer eligible for this item.

Heating Boost Premium (enhanced CEE scheme): this subsidy, paid by energy suppliers, adds to MaPrimeRénov'. It varies according to your income and the type of equipment replaced. For replacing an oil or gas boiler with an air-to-water heat pump, count on an additional 2,500 to 4,000 €.

Standard Energy Savings Certificates (CEE): if you don't combine with the Boost, you can obtain between 1,500 and 2,500 € via standard CEE. Amounts depend on your climate zone and heated area.

Éco-PTZ (zero-rate eco-loan): you can borrow up to 50,000 € interest-free to finance your energy renovation work, including heat pumps. Repayment over a maximum of fifteen years.

Reduced VAT at 5.5%: it applies automatically to equipment and labor for energy renovation work in a dwelling over two years old.

Warning: the contractor must be RGE certified (Recognized Environmental Guarantor) for you to receive these subsidies. Verify their certification before signing the quote. And above all, never start work before submitting your subsidy application—afterward, it's too late.

Does Wood Heating Remain Relevant Compared to Heat Pumps?

Wood's Strengths That the Study Doesn't Fully Capture

The Munich study evaluates systems on measurable technical and environmental criteria. But it doesn't account for certain aspects that my clients regularly highlight.

Energy autonomy first. With stored wood, you depend neither on the electrical grid nor on an energy supplier. In case of prolonged outage (storm, transformer failure), you continue heating your home. This resilience has a value difficult to quantify but very real.

The fuel cost remains manageable if you source locally. A forest owner who sells wood directly, a neighbor clearing a plot, a sawmill disposing of offcuts: these short circuits drastically reduce the price per stere. In some rural areas, it drops below 40 € per stere, sometimes even free in exchange for clearing.

User pleasure systematically comes up in testimonials. The sight of flames, radiant heat that warms deeply, the ritual of lighting: all this creates a relationship with heating that the heat pump, however efficient, doesn't reproduce. It's subjective, yes. But for some households, this aspect matters as much as savings.

Finally, new Flamme Verte 7-star certified stoves have considerably improved their performance. Efficiency above 75%, particle emissions divided by three or four compared to old models, controlled secondary combustion: these appliances bear no resemblance to 1990s inserts. Combined with truly dry wood (less than 20% humidity), they offer an excellent compromise.

Where Wood Heating Regulations Are Heading

The trend is toward tightening emission standards. The Flamme Verte label evolves regularly, and only the cleanest appliances remain eligible for public subsidies. Old non-certified stoves and inserts are gradually excluded from funding schemes.

Several urban areas classified as low emission zones (LEZ) have begun restricting individual wood heating use during pollution peaks. Grenoble, Lyon, Annecy impose strict rules: prohibition to light during pollution alerts, obligation to own a recent and efficient appliance. These restrictions will likely extend to other Alpine cities and enclosed valleys.

Chimney sweeping obligations are reinforced: twice a year minimum, including once during heating season. Inspections are still rare, but multiplying, especially after incidents (chimney fires, carbon monoxide poisoning). A proper chimney sweeping certificate becomes essential for your home insurance.

Wood as future or transitional heating? Opinions diverge. For rural wooded territories with sustainable forest management, wood retains full legitimacy. In dense urban environments, heat pumps and district heating networks seem better suited. The truth probably lies in a territorialized approach: the right system in the right place, based on local resources and constraints.

What to Check Before Choosing Your System

Energy Audit: An Essential Step

Before investing in a heat pump or stove, have a complete energy audit performed. This assessment identifies your heat losses, evaluates your insulation condition (roof, walls, windows, ground floor) and calculates your actual heating needs.

If your house loses 30% of its heat through the roof and 20% through walls, installing a state-of-the-art heat pump will be useless. Insulation must always be the priority. Attics, exterior walls, single-glazing window replacement: this work reduces your heating needs by 40 to 60%, which proportionally decreases the power and therefore the cost of your future system.

Precise sizing follows from this audit. A 10 kW heat pump may suffice for 120 m² well insulated, where 14 kW will be necessary for the same poorly insulated area. Oversizing costs more to purchase and makes the appliance operate in spurts (short cycles), which deteriorates efficiency and accelerates wear.

Also verify compatibility with your existing installation. If you have high-temperature radiators, plan their replacement or installation of a hydraulic kit adapting temperatures. If you switch from oil to wood, ensure the existing flue is suitable for lining and meets standards (diameter, insulation, distance from combustible materials).

Finally, calculate profitability for your personal situation, not on national averages. Your current consumption, your electricity or wood rate, your planned occupancy duration, subsidies you're eligible for: all these parameters change the equation. An online simulator gives a first idea, but nothing replaces custom pricing by a professional.

Questions to Ask Your Installer

When dealing with a contractor, don't settle for a standard quote. Ask the right questions to assess their seriousness and experience:

• How many similar heat pumps or stoves have you installed in the last two years? An installer who does three heat pumps per year doesn't have the same expertise as one who installs fifty. Ask for references from projects similar to yours (same type of dwelling, same region).
• What warranties do you offer on equipment and labor? Manufacturers generally offer two to five years on heat pumps, but some installers extend coverage or include travel in case of breakdown. For stoves, check the warranty on the firebox (cast iron or steel) and wear parts.
• What follow-up after installation? A good professional returns within weeks following commissioning to check settings and answer your questions. They should also clearly explain operation and routine maintenance.
• Who handles the subsidy application? Some contractors do it for you, others leave you to manage. Assistance with MaPrimeRénov' and CEE can save you hundreds of euros and much time. Make sure this service is included or priced.
• What is your ten-year insurance? Verify it properly covers the type of work planned (air-to-water heat pump, flue installation, heating circuit modification). Request a recent certificate.

Never sign a quote on the day of a first visit. Take time to compare at least three proposals, verify RGE certifications and customer reviews. A good contractor understands you need to think it over. Beware of overly commercial pitches or exceptional discounts valid only today: these aren't methods of serious professionals.