ABSTRACT
Trombe walls figure among many passive devices used in the Mediterranean climate to minimize heating demands in residential buildings. The thickness of this massive wall is a critical parameter that influences the effectiveness of the system. Insufficient wall thickness conducts to an important interior temperature fluctuation, and huge wall thickness will increase costs and thermal resistance. In this paper, the optimum thickness of four different construction materials (concrete, stone, adobe, and brick), which can be used in the Trombe wall, was determined using an energetic and economic analysis. The energetic results with TRNSYS software show that the best materials, which can contribute to a reduction by 50% in heating loads of a single room, are stone and concrete. For the economic analysis, the life cycle cost and the payback period were calculated for each construction material. The results show that the optimum thickness for stone and concrete are, respectively, 34 and 32 cm with a payback period of 2.85 and 2.65 years.
ABSTRACT
Natural ventilation is considered the first suggestion for COVID-19 prevention in buildings by the World Health Organization (WHO). Solar chimney's viability in aged care centers or similar facilities was analyzed numerically and theoretically. A new solar chimney design was proposed to reduce the cross-infection risk of COVID-19 based on an airflow path through window, ceiling vent, attic, and then chimney cavity. Solar chimney performance, quantified by the natural ventilation rate, presented power function with window area, ceiling vent area, cavity height, and solar radiation. The ceiling vent is suggested to be closer to the corridor to enhance the performance and ventilation coverage of the room. A cavity gap of 1.0 m is recommended to balance the ventilation performance and construction cost. A theoretical model was also developed for aged care centers with multiple rooms and a joint attic. Its predictions obey reasonably well with the numerical results. Solar chimney's viability in aged care center is confirmed as a 7.22 air change per hour (ACH) ventilation can be achieved even under a low solar radiation intensity of 200 W/m2, where its performance fulfills the minimal ventilation requirement (i.e., 6 ACH) suggested by the WHO for airborne infection isolation rooms. This study offers a new design and a guideline for the future implementation of solar chimney in aged care centers or similar facilities.
ABSTRACT
Trombe wall is a simple and mature passive solar building design while its utilization of solar energy is limited to space heating. Aerosol transmission, as a potential transmission pathway of COVID-19, poses a serious threat to the public health especially in a closed indoor environment. The thermal disinfection of virus, which can be easily integrated into solar systems, seems to be a suitable method for controlling bioaerosols. Therefore, a novel disinfected Trombe wall for virus inactivation and space heating is proposed, providing a potential way to fight the current COVID-19 pandemic. After the proposal of the concept, its performance on space heating and virus inactivation was investigated through experimental and simulation methods. The main results were as follows: (1) The average thermal efficiency was 0.457 and the average indoor temperature was 20.7 â, 1.9 â higher than the ambient temperature. (2) The maximum single-pass inactivation ratio was 0.893, 0.591 and 0.893 while the total production of clean air was 112.3, 63.8 and 114.7 m3 for SARS-CoV-1, SARS-CoV-2 and MERS-CoV, respectively. (3) The increase of ambient temperature or solar irradiance may enhance the thermal efficiency while the former has little effect on the thermal disinfection process. (4) Extending the height or narrowing the thickness of the duct by 40% may contribute to an increase in total production of clean air by 510 m3 or 681 m3 per unit area during the heating seasons, but the later may cause a larger decrease (about 8%) in the heat gain of indoor air.