• Energy Research
• 13. Climate action close

Increasing the level of energy efficiency and using renewable energy sources in the design and existing buildings is an important aspect in minimizing the carbon dioxide emissions and mitigating the climate changes. One of such solutions may be the application of a heating system using residential thermal stations (RTSs) for heating and hot water preparation individually in the premises of a given building. The main purpose of this paper was to analyze long-term filed research results on the energy consumption and efficiency of heating systems in a dormitory (building B1) and two multifamily buildings (building B2 and B3) equipped with residential thermal stations (RTSs) that are used for supplying individual dwellings with heat, as well as hot and cold water. An additional aspect of the analysis is a presentation of the structure of total energy consumption for particular purposes in the analyzed buildings and the possibilities to increase the share of renewable energy sources using solar thermal collectors for supporting the analyzed heating system.

Nowadays, the attention of designers and service providers is especially focused on energy efficiency and integration of renewable energy sources (RES). However, the knowledge on smart devices and automated, easily applicable algorithms for optimizing heating consumption by effectively taking advantage of solar heat gains, while avoiding overheating, is limited. This paper presents a simple method for taking into account the influence of solar heat gains in the form of solar radiation for the purposes of forecasting or controlling thermal power for heating of buildings. On the basis of field research carried out for seven buildings (five residential buildings and two public buildings) during one heating season, it was noticed that it was justified to properly narrow down the input data range included in the building energy model calculations in order to obtain a higher accuracy of calculations. In order to minimize the impact of other external factors (in particular wind speed) affecting the heat consumption for heating purposes, it was recommended to consider the data range only at wind speeds below 3 m/s. On the other hand, in order to minimize the impact of internal factors (in particular the impact of users), it was suggested to further narrow down the scope of the input data to an hour (e.g., 10–14 in multi-family residential buildings). During these hours, the impact on users was minimized as most of them were outside the building.

Abstract Smart control of energy supply to the existing buildings may increase their energy efficiency. However, to the best of the authors’ knowledge, there are no simple, general, automated, widely applicable and accurate methods for the creation of energy model of the building, which may be used to calculate the actual energy consumption of a heating system or for their prediction. This work presents a new simplified method for generating the energy characteristics of buildings and their heating systems, without the influence of occupants. The method requires as input only the actual heat supplied to the heating system and the local outdoor weather conditions (i.e. temperature, wind speed and solar insolation) of a building. The output is a building energy model in terms of an equivalent outdoor temperature. It was found that when determining the correction due to the wind, the data from the night hours (e.g. from 11.00 p.m. to 4.00 a.m.) should be used in order to exclude the impact of solar radiation and minimize the interaction of users. On the other hand, the correction due to the influence of solar radiation should be obtained using data with low wind speeds and time periods from 10.00 a.m. to 2.00 p.m. on weekdays for residential buildings or from 10.00 a.m. to 2.00 p.m. on the weekend for public buildings in order to minimize disruptive effects of wind speed and the impacts from occupants. This method may be used to generate a simple building energy model and to accurately determine the duration and the amount of heat power supplied to a building for space heating, for periods when the impact of occupants and other internal heat gains are kept to a minimum.

Abstract Nowadays, modern heat supply technologies are preferred by the decentralized municipal sector because they considerably reduce heat transfer losses. One such solution is a heating system using residential thermal stations (RTS). The advantages of a heating system with RTS, as compared with hot water storage vessels, include stabilizing heat costs, saving energy and a decrease in heat transfer losses. This paper presents the results of an experiment investigating heat consumption in a residential building using RTS. The building, located in Lublin, Poland, was supplied by the local district heating network. The energy consumption was monitored from April 2007 to April 2009. The efficiency of this system was 71.4% during the period when heat was required (winter) and 61.5% during the summer; an annual average efficiency of 67.1%. The energy consumption of the space heating system varied from 0.03 to 0.53 GJ m−2 of the flat's surface area, with the average value being 0.22 GJ m−2. The influences of the location of the flat within the building and the surface area of the flat on the quantity of heat required for space heating were analysed. Specific attention was paid to the occurrence of local heat flows between flats.

AbstractThis work presents the results of experimental studies on the energy performance of an evacuated solar collector, heat pipe type, consisting of 24 tubes, over the period of 2 months. The solar collector with a gross area of 3.9 m2 is part the solar hot water test system located in Lublin (Poland). The effect of the weather conditions and operating parameters on the thermal and exergy efficiencies of the evacuated tube solar collector has been defined. The solar irradiation per month for July amounted to 80 kWh/m2, and for August, it equalled 112.8 kWh/m2. The average thermal gain was found to be in July 163 W/m2 and in August 145 W/m2, respectively. For the considered study period, the average value of energy yield in the solar collector was obtained at the level of 4.28 MJ/(m2·d). The average monthly energy efficiencies of the solar collector in July and August were 45.3% and 32.9%, respectively, while the average monthly exergy efficiencies reached 2.62% and 2.15%, respectively. Increasing the wind speed to 0.86 m/s decreases the thermal efficiency and the exergy efficiency by 67% and 41%, respectively.