Italy is one the largest consumers of fossil fuels in Europe, in fact, it is the third country after UK and Germany, in terms of natural gas consumption.
In particular, most of the consumption of the residential sector is due to space heating, which has natural gas as preferential fuel. This choice derives from an energy policy strategy of ~30-40 years ago, when it was decided to build an effective, efficient and widespread natural gas distribution network, able to reach most of the flats and houses of the Italian citizens.
The supply was ensured by building pipelines which directly connect Italy with producing countries (i.e. Libya and Algeria) and by signing long term supply agreements, with oil indexed prices.
The aim of this policy was to reduce the consumption of expensive and pollutant oil products and it demonstrated to be successful to some extent, because a relevant reduction of fuel oil consumption for buildings heating was achieved with the consequent reduction of a relevant amount of pollutants.
Nowadays, the context is completely changed and there are concerns about the security of supply and the reduction of carbon emissions, as well as the implementation of energy efficiency policies.
Security of supply is related to the reliability of the supply, in order to have a continuous source of natural gas. This issue is strictly connected with the geopolitical stability of the suppliers, which strongly worsened in the last years. Moreover, another issue is represented by the depletion of the resources in the supplying countries and in the increase of their internal demand. All these factors increase the risks linked to the supply.
In the last years, European Union decided to push aggressive renewable energy policies, which resulting in binding agreements with the member states for the implementation of determined quantity of renewable energy plants in the electricity sector. This fact reduced massively the carbon intensity of the electricity sector, because of the large development of renewables, especially solar photovoltaic and wind in Italy.
Another fundamental pillar of the European energy policy of the last years is represented by the implementation of energy efficiency measures, in order to reduce the consumption of fossil fuels. In this framework building sector has a relevant role, in fact it accounts for ~40% of the total energy consumption and it represents the largest sector in the end-users area, followed by transport with the 33%.
An approach to reduce primary energy consumption for buildings heating purposes in the residential sector is to use air to air heat pumps.
The idea is based on the fact that this kind of heat pumps are very easy and fast to install, they do not require special maintenance and they are perceived as simple household appliances.
Moreover, in a relevant share of dwellings, this equipment is already installed and utilized for summer cooling; therefore it would be only necessary to stimulate the utilization for winter heating.
The energy input for heat pumps is electrical energy, which is now generated in relevant part by renewables, even though, in Italy, a substantial part is still obtained from fossil fuels, mainly natural gas, but the “electricity to heat” conversion performance of heat pumps could result to be convenient in any case.
Bianco et al. analyzed this scenario in detail by employing a simple model based on the second law efficiency of heat pumps. In particular, they estimated that if 25% of the current dwellings surface is heated by heat pumps having a second law efficiency of 0.2, an increase of 26 TWh of the electricity demand is achieved in 2024 by assuming a linear penetration of heat pumps from 0% in 2014 to 25% in 2024 (Figure 1). This would a corresponding saving of natural gas equal to ~2bcm per year (Figure 2).
It is authors’ opinion that the utilization of air to air heat pumps for buildings heating is one of the simplest and cheapest options to implement, in order to promote energy savings in buildings. In particular, even promoting the use of the heat pumps that are already installed in many dwellings may allow to obtain significant results in terms of primary energy savings, mainly natural gas.