What effect does lowering the heating thermostat one degree have on gas consumption?

The current supply crisis caused by Russia’s invasion of Ukraine has prompted the European Union to take various measures. In the energy field, these measures have been proposed from the REPowerEU package, which aims to reduce the demand for Russian gas by two thirds before the end of 2022.

Among them is the request to reduce the temperature of the thermostat of the heating systems of our homes by one degree. What effect would this measure have in a Mediterranean country like Spain? The Comillas ICAI Chair in Energy and Poverty has tried to answer this question.

the spanish scene

Although Spain is not as dependent on Russian gas as the rest of Europe – less than 10% of our consumption comes from Russia – it is worth exploring the path of REPowerEU at the national level.

In 2021, Spain consumed 379 TWh of natural gas, of which 15% was used for heating, 60% for industry and 25% for electricity generation through combined cycles.

To try to reduce the demand for gas, the International Energy Agency has recently proposed a set of ten measures for Europe that could be applied in the three gas-consuming sectors in Spain:

Industry. Residual heat recovery with heat pumps could be used to meet low-temperature demand, concentrating solar collectors for medium-temperature demands, and solid biomass and renewable gases for high-temperature demand.

Electricity generation. Investments in renewables would continue, but providing them with storage (pumped hydro and molten salt solar thermal power plants) and hybridization, undertaking active demand management techniques and even considering extending the life of nuclear power plants and exploring the construction of modular reactors small at existing power plant sites.

Edification. To reduce 15% of gas consumption corresponding to heating, gas boilers should be replaced by aerothermal heat pumps in areas with moderate winters and geothermal in areas with severe winters, as well as integrating biomass and biomethane as bridging technologies .

The demand for heating in Spain

While these changes, which are not immediate, take place, it is possible to act from energy savings. The Technical Building Code establishes a procedure – used by the National Strategy against Energy Poverty 2019-2024 to evaluate the required thermal expenditure – to determine the heating demand of a building. This procedure sets 20 ºC as the base temperature for calculating the heating demand.

After determining the reference demand for each climatic zone in Spain, we have estimated the thermal demand required for heating according to the level of insulation of the home. Averaging the results for the entire national territory and taking into account the average efficiency of the boilers (90%), the average size of homes in Spain (104 m²) and the number of homes with natural gas heating (32.3%). of the total), we have determined the average heating demand in Spain from which the gas consumption at a national level has been obtained.

Then, we repeat the calculations, reducing the base temperature by one degree each time to determine the gas savings by modifying the thermostat setpoint.

The impact of the drop in national consumption

According to our estimates, lowering the thermostat from 20 to 19 degrees causes a 2.9% reduction in total gas consumption nationwide. This reduction is not constant: putting the thermostat at 15 degrees would reduce consumption by a proportionally smaller amount, 11.8% of the total consumption at the national level. This is explained because by reducing five degrees, there is a reduction of only 2.2% for each degree.

The measure also implies the reduction of emissions, being an average of 2.2 million tons of CO2 for each degree in the mentioned interval, comparable with the CO2 emissions of all the cars in Spain for 10 days.

In addition, at a domestic level, lowering the house temperature by one degree would lead to an average reduction in consumption per household of 477 kWh/°C and an average annual saving of around 30 euros for each degree less, taking into account the price update and the taxes.

On the other hand, the measure analyzed would produce an average reduction in CO2 emissions in each home of 120 kg CO2/°C, which would mean cutting them by 3.5% (data for an average home in 2019).

Conclusions

Taking into account behavioral economics studies and the lower relative reduction in consumption by further lowering the temperature in the home, lowering the thermostat by one degree can be considered an effective saving measure. However, it is not applicable to vulnerable households that are already under-consuming, that is, households in hidden energy poverty.

On the other hand, Spain’s low dependence on Russian gas does not have to divert us from two of the main objectives of the energy transition in the residential sector: improve the insulation of homes and decarbonize air conditioning systems to drastically reduce the footprint of carbon.

This article is also signed by:

Eva Arenas Pinilla, professor and researcher at the Rafael Mariño Chair in New Energy Technologies, Comillas Pontifical University

José Carlos Romero Mora, coordinator of the Energy and Poverty Chair, Comillas Pontifical University

José Ignacio Linares Hurtado, Professor of Energy Engineering, Comillas Pontifical University

This article has been published in ‘The Conversation‘.