Substitution of heating systems in the Italian buildings panorama and potential for energy, environmental and economic efficiency improvement

In many countries, old inefficient generators are used for heating purposes. A way to improve energy efficiency in those countries can be the choice of the most suitable heating generators to replace the current ones, without the inconveniences caused by other retrofit measures. In this context, we present a methodology to choose the most appropriate generator through dynamic simulations applied to building stock energy models. Economic, energetic, and environmental parameters guide the choice. The methodology is applied in the Italian residential building scenario, where the most widespread heating device is traditional boiler. Three options are considered: condensing boiler, heat pump, and hybrid heat pump (an alternative-working system with a condensing boiler and heat pump). For a detailed analysis, a white-box bottom-up building stock energy model is defined, through a statistical analysis, consisting of four building typologies in three different external climates. An hourly dynamic building-system simulation has been performed to obtain energy performance, emissions, and operational costs. The results have demonstrated that condensing boiler allows limited economic, environmental, and energy savings (8 - 14%), compared to traditional boiler. The highest economic savings are obtained with the hybrid heat pump (20%), while the heat pump alone leads to higher costs, but the highest savings in emissions and non-renewable primary energy (25 - 50 %). The flexibility offered by the hybrid heat pump allows to obtain high savings in different cost scenarios, but also to further reduce CO2 emissions by implementing an environmental-based control strategy.