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Global warming is increasing average air temperature, affecting energy consumption and thermal comfort inside buildings. This study investigates the relative impact of climate change on thermal energy needs and indoor thermal comfort conditions for a typical residential building located in different climates of Pakistan. Furthermore, the energy-saving potential and thermal comfort performance of various traditional and advanced retrofit measures are evaluated to mitigate the impact of climate change. Climate Change World Weather File Generator was used to produce weather files of typical metrological years of 2020, 2050, and 2080 under emission scenario A2 of the Intergovernmental Panel on Climate Change (IPCC). TRNSYS simulation software and ASHRAE adaptive discomfort model were used to calculate annual thermal energy demand and comfort conditions inside the buildings. The impact of climate is city-specific. Overall, results show that the temperature will increase in the range of 0.9-1.4 °C and 2.3-3.7 °C for the year 2050 and 2080 respectively from the present level (2020) while the absolute humidity increase range is 0.2-1.3 and 0.3 to 3.3 g/kg of air for the same years in the investigated cities of Pakistan. This would result in higher thermal energy needs for cooling in the range of 9.7-28.4 kWh/m2 by 2050 and 28.4-49.9 kWh/m2 by 2080. The climate-responsive retrofit solutions should be promoted by authorities and policymakers to strengthen a climate-resilient pathway of building stock in Pakistan.

International audience

International audience

International audience

Thermal energy and distributed electricity demand are continuously increased in areas poorly served by a centralized power grid. In many cases, the deployment of the electricity grid is not economically feasible. Small-scale Organic Rankine Cycle (ORC) appears as a promising technology that can be operated by solar energy, providing combined heat and power (CHP) generation. Additionally, thermal energy storage can ensure stable and continuous operation in case of scarce thermal energy availability. This paper evaluates the potential application of latent heat storage to enhance solar ORC performance at operating temperatures between 80 degrees C and 140 degrees C, aiming at improving the efficiency and capacity of ORC for low-cost non-concentrating solar-thermal collectors. Three thermal energy storage scenarios are considered. Scenario 1 and 2 consist of reference cases based on a solar ORC system integrated with a conventional hot water tank and a pressurised water tank. Scenario 3 implements a storage unit based on a phase change material. The simulation was carried out through models developed in TRNSYS for solar energy balance and ASPEN for ORC system performance. The results show that solar latent heat storage tank can provide 54% of useful collector gains with a higher and narrower temperature range in the evaporator, increasing the annual thermal energy capacity by 19%, reducing annual heat losses by 66% and decreasing the investment cost by 50% in comparison with a pressurised water tank. It also allows increasing the efficiency of ORC cycle by approximately 18% (from 8.9% to 10.5%) with a higher net generated power than a conventional water tank integration, scaled up from 498 W to 1628 W. These results highlight the potential benefits that latent heat integration provides to improve the low-cost solar ORC performance for powering electricity and thermal energy supply. Lizana, J (corresponding author), Univ Seville, Inst Univ Arquitectura & Ciencias Construcc, Avda Reina Mercedes 2, Seville 41012, Spain. Rajabloo, T (corresponding author), Hasselt Univ, Martelarenlaan 42, B-3500 Hasselt, Belgium; IMEC, Kapeldreef 75, B-3000 Leuven, Belgium. flizana@us.es; talieh.rajabloo@uhasselt.be