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Radiant cooling systems are a subject of increasing scientific interest due to their efficiency and ability to use high-temperature cooling sources. In hot and humid conditions, they have generally been studied in combination with dehumidification systems. For retrofit projects, a control system that would eliminate the need for dehumidification would be beneficial. In the present study, a passive geothermal-based radiant high-temperature cooling system is studied in a Mediterranean climate. The system is operated with supply water temperature control using dew point temperature as a controlling variable. The system's performance is compared with that of an all-air cooling system. The systems are evaluated using IDA-ICE building energy simulations, validated with on-site measurement data. The results show that the radiant cooling system produces the same level of thermal comfort with 40% lower energy use and 85% lower exergy consumption than the all-air system. The risk of condensation limits the cooling capacity of the radiant cooling system. Consequently, insufficient cooling capacity causes thermal discomfort for the occupants due to the operative temperature exceeding 26 °C. Datasets: "Building energy simulation data results" and "Acquired data from existing and/or new installed meters or from existing BEMS (pre intervention EcoSCADA monitoring data)" - Raw data is available upon request. Follow the link and fill the request form.

Abstract In recent years, the increasing occurrence of heatwaves raises the cooling need of residential buildings in Scandinavian countries, which are traditionally not equipped with active cooling systems. Indoor overheating caused by such heatwaves leads to severe consequences for occupants, especially kids and seniors. Efficient and economical cooling solutions are urgently needed to cope with frequent heatwaves. The present study investigated the novel usage of the geothermal-assisted mechanical ventilation with heat recovery (GEO-MVHR) system for cooling purposes in typical Swedish multi-family dwellings. The cooling potential of the system and its contributions to thermal comfort were evaluated. Dynamic simulations were conducted to assess the system's cooling performance under two climate scenarios: the climate of 2018 representing an extreme year with excessively hot summer and the climate of a typical meteorological year. The GEO-MVHR system shows great potential in mitigating indoor overheating with improved thermal comfort. A ventilation airflow rate of 0.50–0.70 l/s/m2 is suggested for multi-family dwellings to maximize the cooling potential of the GEO-MVHR system. The indoor operative temperature could be reduced by up to 3 °C with the GEO-MVHR system operating for cooling. Modulating the supply air temperature of the GEO-MVHR system based on indoor thermal conditions is recommended, as it shows the advantage of avoiding unnecessary overcooling and energy saving.

This study evaluated the impacts of radiator designs and geometries. The aim was to map the thermal efficiency and performance differences of studied radiator types. A typical Swedish low-rise mul ...

Abstract This research explored the importance of airflow rate and convector plate design on the operational performance of heating radiators equipped with an air device (ventilation radiators). The radiator was analyzed according to European Norm EN 442-2 using numerical simulations. The largest benefit of using staggered convector plates was the more efficient preheating of the incoming outdoor air supply. With this plate design, the evaluated radiator increased the temperature of the incoming airflow of 10 l/s from -5 °C to 26 °C with water supply/return temperatures of 45 °C/35 °C. With these water temperatures, the radiator was able to cover a room heat loss of 34 W/m2 floor area. However, the design of the convector plate alone was found to have a limited impact on the heat output from the radiator. Neither did the plate design significantly affect the uniformity of heat distribution nor the vertical temperature stratification inside the room. The results also showed that ventilation radiators might cover a building heating load (kW) with a lower supply water temperature but not necessarily give a lower annual energy use (kWh) for the space heating of a building.

This study investigated the thermal potential of two renewable heat sources, residential wastewater and geothermal energy, for preheating the incoming air to the air-handling unit (AHU) in a multi-family building. The main purpose of preheating the inlet air was to avoid the frost formation inside AHU due to low outdoor temperatures during winter. Wastewater extraction flowrate and temperature, as two design parameters, were studied in detail by employing two types of wastewater storage tanks.

Sweden is actively engaged in accelerating the sustainable transformation of existing building and energy systems. Most traditional investigations of this subject have been based on final energy sa ...

Abstract An efficient use of waste heat recovery and geothermal heat can play an important role in lowering the overall energy use of buildings. This study evaluated the potential of geothermal energy and heat recovery from residential wastewater to reduce the energy need of building-ventilation in cold climates. The performance of the mechanical ventilation with heat recovery (MVHR) system in a multi-family building located in central Sweden was studied. The focus of the investigation was on reduction of frosting in the air handling unit during the coldest months. Three configurations of one air preheating system fed by two renewable heat sources, wastewater and geothermal energy, were studied. It was found that compared to building without an air preheating system, the suggested air preheating systems reduced the defrosting time to 25%. By controlling and maintaining the preheated air temperature to slightly above the defrosting start, air heat recovery efficiency of MVHR above 80% was achieved for 90% of the studied time during heating season when frosting occurs. The energy need for the circulation pumps in the suggested air preheating systems was 5% of the recovered thermal energy from wastewater. The simulation results suggested that the air preheating system using wastewater heat recovery with a temperature-stratified storage tank was the most efficient one among the studied systems.

Minimizing thermal losses through windows and maintaining large glazing areas to provide adequate natural lighting in residential buildings are essential considerations for modern architecture, sus ...