Why Bavarian heat-pump and gas-boiler emissions differ

For households across Bavaria, choosing a heating system is a practical question about annual fuel use, bills, and emissions. Homes in Munich, Augsburg, Regensburg, rural districts, and alpine areas can have very different heat-demand profiles, but the comparison follows the same principle: a gas boiler converts purchased fuel into heat at a seasonal efficiency below 100%, whereas an air-source heat pump uses electricity to move heat and can provide several units of useful heat for every unit of electricity it consumes. That difference can make a heat pump lower in both emissions and running cost even when electricity costs more per kilowatt-hour than gas.

This calculator turns that Bavarian heating choice into a transparent scenario comparison. It asks how floor area, annual heat demand, heat-pump SCOP, boiler efficiency, tariffs, and emission factors change the first-year and longer-term difference between retaining a gas boiler and installing an air-source heat pump. The result is intended to support an initial retrofit discussion, not to answer whether one technology is universally better for every building.

How the Bavaria heating comparison is calculated

The Bavaria heat-pump versus gas-boiler model begins with useful annual heat demand: the heat that must be delivered into the home during a year. It estimates that demand from conditioned floor area, specific heat demand, and a degree-day adjustment. Floor area represents the heated space, specific heat demand represents the building and system condition, and the percentage adjustment lets you raise or lower the estimate for local weather severity or actual use.

Here, Q is useful heat demand in kilowatt-hours per year, A is conditioned floor area in square metres, q is specific heat demand in kilowatt-hours per square metre per year, and D is the degree-day adjustment in percent. For example, 160 m² of conditioned space at 80 kWh/m²·year and a 100% adjustment produces 12,800 kWh of useful annual heat demand.

The calculator then converts useful heat into purchased energy for each heating option. Heat-pump electricity use is useful heat divided by SCOP; gas use is useful heat divided by boiler seasonal efficiency. Raising SCOP reduces the electricity needed to serve the same home, while raising boiler efficiency reduces gas use without changing the fact that a boiler produces heat by combustion.

For the Bavarian emissions comparison, the heat pump's electricity use is multiplied by an effective electricity emission factor. The model reduces the entered grid factor by the renewable-electricity share you enter. Gas use is multiplied directly by the entered gas emission factor. Operating costs are purchased electricity times the electricity tariff and purchased gas times the gas tariff. Across the selected horizon, gas emissions per kilowatt-hour remain constant, electricity carbon intensity declines at the entered grid-decarbonisation rate, and both energy prices change at their respective annual escalation rates.

The most important check is that every input describes the same annual heating scope. Use conditioned rather than gross floor area, avoid mixing monthly consumption with annual heat demand, and decide consistently whether domestic hot water is included. The calculator will perform the arithmetic either way, but inconsistent inputs can make a heat-pump and gas-boiler comparison misleading.

Choosing inputs for a Bavarian heating scenario

For this Bavaria heating calculator, specific heat demand is often the most influential building input because it scales every energy, cost, and emissions output. A poorly insulated post-war detached house can need far more heat than a renovated home with a stronger envelope and low-temperature emitters. Use an energy performance certificate, weather-adjusted measured consumption, or a designer's heating calculation when available. If an annual demand figure includes domestic hot water, it can represent total delivered heat provided it is used consistently for both technologies.

The degree-day adjustment is a climate and use multiplier, not an efficiency or tariff setting. A value of 100% uses the demand estimate as entered. Values above 100% model harsher weather, wind exposure, or a home that normally consumes more heat than its nominal demand suggests. Values below 100% model milder conditions or a more restrained heating pattern.

For an air-source heat pump in Bavaria, SCOP should be a seasonal value rather than a peak laboratory COP. It should reflect winter operation, defrost cycles, flow temperature, and performance across the full heating year. Because electricity use and associated costs and emissions are divided by SCOP, a change from 3.0 to 3.8 can materially affect the result.

Gas-boiler seasonal efficiency should likewise be a practical annual ratio, not only a brochure figure. Condensing boilers can perform well when they operate under suitable conditions, but return temperatures, cycling, sizing, and maintenance affect their seasonal result. The calculator treats this percentage as useful heat delivered divided by gas energy purchased.

Tariffs and carbon factors provide the local assumptions for the Bavarian heat-pump comparison. Enter the electricity price you expect to pay per kilowatt-hour and the gas price that reflects your expected bill. The renewable-electricity share affects the heat pump's effective first-year electricity factor, while the grid-decarbonisation rate changes the future carbon intensity of the remaining grid electricity.

Worked Bavaria heat-pump versus gas-boiler example

The form defaults provide an illustrative Bavaria heating scenario rather than a recommendation. With 160 m² of conditioned space, 80 kWh/m²·year of specific heat demand, and a 100% degree-day adjustment, useful annual heat demand is 12,800 kWh. At a SCOP of 3.4, the heat pump uses about 3,765 kWh of electricity in year one. At a boiler efficiency of 92%, the gas boiler uses about 13,913 kWh of gas. The heat pump therefore purchases substantially less final energy because it moves heat rather than generating it through combustion alone.

Under the default emissions assumptions, a grid factor of 0.32 kg CO₂ per kWh and a renewable-electricity share of 40% produce an adjusted electricity factor of 0.192 kg CO₂ per kWh. The heat pump therefore produces about 723 kg CO₂ in year one. The gas boiler produces about 2,797 kg CO₂ when 13,913 kWh of gas is multiplied by 0.201 kg CO₂ per kWh. The resulting first-year reduction is about 2,074 kg CO₂, or about 74%.

The default tariffs also create a first-year operating-cost comparison. At €0.32 per kWh, heat-pump electricity costs about €1,204.71; at €0.12 per kWh, gas costs about €1,669.57. The result list shows the year-one cost difference as heat pump minus gas, so a negative number means the heat pump is cheaper in that year. The lifetime line instead reports savings from the heat-pump perspective, where a positive number means the heat pump costs less over the full horizon.

The longer-term Bavaria scenario adds electricity-grid decarbonisation and separate annual electricity and gas price escalation. As the entered grid factor falls, the heat pump's annual emissions fall while gas emissions remain unchanged in this model. The future cost result depends on the relative price-escalation assumptions, so it should be read as a tested scenario rather than a forecast.

Reading the Bavaria heating results

The Bavaria heat-pump and gas-boiler results start with useful heat demand so you can check whether the building assumption is plausible. Heat-pump electricity use and boiler gas use show the purchased energy each option requires. The year-one emissions result gives the immediate carbon difference, while the lifetime emissions result accumulates every selected analysis year. If useful heat demand looks implausibly high or low, correct the building inputs before relying on downstream costs or emissions.

The comparison table separates annual and cumulative outcomes. Its energy row compares purchased electricity with purchased gas. Its year-one rows compare current tariffs and current emission assumptions. Its lifetime rows total costs and emissions across the chosen period. This helps distinguish an immediate bill difference from a longer-term emissions pathway.

When testing several Bavarian heating scenarios, change one major assumption at a time. Start with your best estimate, then test lower SCOP, a higher electricity tariff, or a smaller renewable share. If the direction of the result remains the same, the comparison is less sensitive to those assumptions. If it changes, the input driving that change deserves better evidence before a retrofit decision is made.

Limits of this Bavaria heating emissions comparison

This Bavaria heat-pump versus gas-boiler calculator does not model capital costs, subsidies, financing, maintenance, domestic hot water as a separate load, defrost strategy, flow-temperature redesign, thermal storage, room-by-room occupant behaviour, or hybrid controls. It is a scenario tool for annual energy, emissions, and operating cost, not a substitute for detailed system design, an EPC, or a compliance assessment.

• Use annual inputs consistently: do not mix monthly consumption, seasonal COP, and annual heat demand unless they have been converted properly.
• Use a realistic SCOP: retrofit heat-pump performance depends heavily on emitter temperature and installation quality.
• Check tariff scope: fixed charges, dual-rate contracts, and taxes can change bills even where energy-only prices appear favourable.
• Interpret renewable share carefully: a green tariff affects the model's electricity-emissions assumption, while rooftop PV output and self-consumption vary through the year.

A final check is whether the output follows the physical relationship behind the inputs. A heat pump with a strong SCOP and a low effective electricity carbon factor should generally have lower emissions per unit of useful heat than gas. If the result does not match that expectation, review the entered values. Conversely, a low seasonal performance factor can narrow the advantage, which reflects the importance of building fabric and heating-system design.

Used as a planning worksheet, the calculator can clarify how weather severity, SCOP, energy prices, and grid decarbonisation shape a Bavarian heating decision. It does not replace a detailed design, but it can make the next conversation with an installer, energy adviser, or finance provider more focused.