Performance Analysis of a Geothermal Radiant Cooling System Supported by Dehumidification

Article published in Energies

Title: Performance Analysis of a Geothermal Radiant Cooling System Supported by Dehumidification

Language: English

Authors: Henrikki Pieskä (*1) , Adnan Ploskić (*1,2), Sture Holmberg (*1), Qian Wang (*1,3).

*1: Division of Sustainable Buildings, School of Architecture and the Built Environment, KTH Royal Institute of Technology, Brinellvägen 23, SE, 10044, Stockholm, Sweden
*2: Bravida Holding AB, Mikrofonvägen 28, SE, 12637, Hägersten, Sweden
*3: Uponor AB, Hackstavägen 1, SE, 72132, Västerås, Sweden

Abstract: Space cooling demand is increasing globally due to climate change. Cooling has also been linked to all 17 sustainable development goals of the United Nations. Adequate cooling improves productivity and thermal comfort and can also prevent health risks. Meanwhile, policy initiatives such as the European Union’s Green Deal require participants to cut greenhouse gas emissions and reduce energy use. Therefore, novel cooling systems that are capable of efficiently producing high levels of thermal comfort are needed. Radiant cooling systems provide a design capable of fulfilling these goals, but their application in hot and humid climates is limited due to the risk of condensation. In this study, we compare the performances of radiant cooling systems with and without dehumidification. The studied systems are supplied by geothermal energy. The study is conducted using building energy models of a small office building belonging to a three-building school complex located in Sant Cugat near Barcelona in Spain. The studied location has a Mediterranean climate. The simulations are conducted using IDA Indoor Climate and Energy 4.8 simulation software. The results show that the radiant cooling system with dehumidification (RCD) produces considerably improved thermal comfort conditions, with maximum predicted mean vote (PMV) reached during the cooling season being 0.4 (neutral) and the maximum PMV reached by the radiant cooling system without dehumidification (RC) being 1.2 (slightly warm). However, the improved thermal comfort comes at the cost of reduced energy and exergy efficiency. The RCD system uses 2.2 times as much energy and 5.3 times as much exergy as the RC system. A sensitivity analysis is also conducted to assess the influence of selected input parameters on the simulation output. The results suggest that maximising dehumidification temperature and minimising ventilation flow rate can improve the energy and exergy efficiency of the RCD system while having a minor effect on thermal comfort.

Thermodynamic and Thermal Comfort Performance Evaluation of Two Geothermal High-Temperature Cooling Systems in the Mediterranean Climate

Journal Paper published in Journal of Building Engineering

Title: Thermodynamic and Thermal Comfort Performance Evaluation of Two Geothermal High-Temperature Cooling Systems in the Mediterranean Climate

Language: English

Authors: Henrikki Pieskä (*1) , Cong Wang (*1,2), Behrouz Nourozi (*1), Adnan Ploskic (*1,3), Qian Wang (*1,4).

*1 Division of Sustainable Buildings, School of Architecture and the Built Environment, KTH Royal Institute of Technology, Brinellv¨agen 23, SE-10044, Stockholm, Sweden
*2 College of Urban Construction and Safety Engineering, Shanghai Institute of Technology, 201418, Shanghai, China
*3 Bravida Holding AB, Mikrofonv¨agen 28, SE-12637, Hägersten, Sweden
*4 Uponor AB, Hackstavägen 1, SE-72132, Västerås, Sweden

Abstract: The European Commission aims to reduce the greenhouse gas emissions of the European Union’s building stock by 60% by 2030 compared with 1990. Meanwhile, the global demand for cooling is projected to grow 3% yearly between 2020 and 2050. High-temperature cooling systems provide cooling with lower exergy use than conventional cooling systems and enable the integration of renewable energy sources, and can play a crucial role in meeting the growing cooling demand with less energy use. The aim of this study is to analyse and critically evaluate two high-temperature cooling systems in terms of their energy and exergy use in a case study. We also consider thermal comfort performance, CO2 emissions, and sensitivity to changing operating conditions. The two systems considered are a mechanical ventilation system with heat recovery combined with geothermal cooling (GeoMVHR) and a radiant cooling system with ceiling panels connected to the same geothermal cooling (GeoRadiant) system. The study is conducted using building energy models of a typical office building belonging to a three-building school complex located in Sant Cugat near Barcelona, Spain. IDA ICE 4.8 simulation software was used for the simulations. The results show that the two different installations can produce near-identical thermal comfort conditions for the occupants. The GeoRadiant system achieves this result with 72% lower electricity use and 60% less exergy destruction than the GeoMVHR system. Due to the higher electricity use, the CO2 emissions caused by the GeoMVHR system are 3.5 times the emissions caused by the GeoRadiant system.