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A tracer element can help distinguish between indoor PM2.5 of outdoor origin and that of indoor origin. PM2.5-associated iron has been proposed as a tracer element of PM2.5 in Beijing. This study aims to examine the effect of particulate iron on tracking indoor PM2.5 of outdoor origin in temporal and spatial scales. From July 2018 to March 2019, we collected 24 pairs of indoor and outdoor PM2.5 samples in Nanjing, China. We calculated a normalized ratio (ratio of indoor/outdoor (I/O) ratio of iron to that of PM2.5). Results show a mean ± SD of the normalized ratio of 1.0 ± 0.38. It suggests that particulate iron tracks PM2.5 well during outdoor-to-indoor transport on average. This tracking performance varies temporally. The mean ± SD of the normalized ratio is 0.79 ± 0.17 from July to December 2018 and 1.2 ± 0.41 in March. The results from studies published in different regions of the world over recent years show a mean normalized ratio of 0.88, 0.67, 1.3 and 0.8 in Asia, Europe, North America and South America, respectively, indicating the spatial heterogeneity of iron's tracking effect. In comparison, sulphate appears to exhibit a less stable tracking effect than iron. [ABSTRACT FROM AUTHOR]

Previous studies on thermal sensation have mainly focused on offices and residential buildings, but rarely on underground malls. In this paper, field studies on thermal environment in six underground malls were conducted in Nanjing, China, particularly from customer's perspective. The results showed that when indoor operative temperature ( T op ) was more than 26 °C, the customers' mean thermal sensation votes (TSV) were lower than PMV. It indicated that they may perceive the warmth to be less dramatic than PMV predicted in underground malls. When T op was below 24 °C, a higher percentage of customers desired a warmer indoor environment. Customers' thermal acceptability (TA) decreased significantly when relative humidity ( RH) increased from 65% to 75% (p<0.01), and significant changes of TA were recorded when air velocity increased from 0.2 m/s to 0.4 m/s under RH ranging from 70% to 80%. The customers' duration time (DT) in malls were different, the mean TSV of customers with DT less than 1 h was significantly different from other customers' TSV (p < 0.01). Among customers, those who had spent less than an hour in underground mall perceived the thermal environment to be cooler. In addition, the customers' TSV under outdoor-indoor temperature drop in entrance regions in two underground malls was compared. It showed that setting the transitional space with non-air-conditioned system or at a slightly higher temperature would improve the customers' thermal sensation and save energy. [ABSTRACT FROM AUTHOR]

Human thermal adaptation is widely recognized to achieve building energy saving. However, the energy-saving potential of traditional dwellings based on adaptive thermal comfort of residents in cooling and heating periods has not been fully explored. This paper takes the traditional dwellings in the Small West Lake area in Nanjing, China as an example, and explores the thermal comfort of local residents. Then, based on the annual thermal neutral temperature of local residents, a dynamic control strategy of temperature setting points throughout the cooling and heating periods was proposed, and compared with the traditional constant indoor condition from the perspective of heat transfer. The results show that the proposed dynamic controlling method can reduce the energy consumption for maintaining heating or cooling by 26.87%–36.51% in the whole year under the climatic environment of Nanjing, China. The average thermal neutral temperatures are 27.63 °C in summer and 14.44 °C in winter. The thermal sensitivity of residents in traditional Chinese dwellings in winter is lower than that in summer. This study shows the applicability of the adaptive thermal comfort model to traditional Chinese dwellings and a relaxation in the presence of strict set-point temperatures. It is recommended to consider the adaptive thermal comfort of residents into the design of air conditioning or heating systems, which can achieve great energy-saving effect. • The field study of thermal comfort of residents in traditional Chinese dwelling was carried out. • The neutral temperature of residents in traditional Chinese dwellings is 27.63 °C in summer and 14.44 °C in winter. • A dynamic control strategy of indoor setting temperature was proposed. • The proposed control strategy was proved to have energy saving potential. [ABSTRACT FROM AUTHOR]

With the increasing demand for indoor thermal comfort in recent years, radiant heating & cooling systems have been very popular in China. However, for the household air-conditioning in hot-summer and cold-winter regions, an effective solution of heating and cooling source supply for radiant air-conditioning system remains to be developed. In this paper, an energy-efficient radiant heating/cooling system with fresh air supply is proposed and investigated for household utilization numerically. Under summer conditions, dehumidified fresh air supply is a tough problem in radiant cooling since the chilling water temperature for radiant cooling is much higher than traditional air-conditioning systems. In the proposed system, the fresh air handling unit is composed of both pre-cooling dehumidification coil and liquid desiccant dehumidifier, where high-temperature chilling water is used for cooling source and small part of condensing heat is used for liquid desiccant regeneration. The results indicated that the fresh air can be steadily supplied and sufficiently dehumidified for indoor air quality and humidity control. The chilling water flow rate in pre-cooling coil ( m w , c o i l ) and the solution flow rate from regenerator to dehumidifier ( m s , S S ) can be recognized as control parameters to reliably regulate the indoor air humidity. The load ratio of sensible heat to latent heat had no significant impact on C O P s y s , which means the system can operate with a steady energy efficiency despite of the indoor heat load. Satisfactory energy-saving potential was revealed in the proposed system with a COP improvement of 25.8%–30.1% compared to the conventional system under typical summer conditions in Nanjing. • An integrated radiant heating/cooling system is proposed for household utilization. • The system serves effectively for heating & cooling source supply for radiant air-conditioning. • The dehumidification capacity and energy-saving performance are evaluated. • The effects of m w , c o i l and m s , S S on dehumidification performance are analyzed. • Performance evaluation is conducted in one-day simulation under summer conditions. [ABSTRACT FROM AUTHOR]