New method of retrofitting of kindergartens resulting in increase of energy self-sufficiency

In recent years, a number of retrofittings have been carried out in terms of insulation and technical equipment of buildings. However, due to the introduction of the zero-emission obligation for buildings, it is necessary to search for new modernization opportunities that will reduce the use of non-renewable primary energy and increase energy self-sufficiency. This paper assesses the existing condition of two typical kindergartens located in north-eastern Poland, Bialystok. The thermal properties of buildings and heating systems and domestic hot water preparation were assessed through ex-post audits and in-situ measurements: U-value, indoor air quality (IAQ) and thermal imaging inspection. A novel method was developed for simplifying the estimation of the effect of renewable energy sources (RES) integration, based on actual building climatic and utility data. The method was used to analyze three variants of retrofitting of the heat and electricity sources taking into account air-to-water heat pump, photovoltaic installation and an electrical energy storage. The energy self-sufficiency of kindergartens with the thermal quality of the envelope meeting the requirements of the nearly zero-energy building (nZEB) in Poland may amount to 45% when use air heat pump cooperating with a PV system, an electricity storage and heat substation as the peak heat source. The proposed retrofitting of heat and electricity sources resulted in a reduction in the demand for non-renewable primary energy by 14% in kindergarten B and by 18% in kindergarten A compared to the pre-modernisation state.