Search

Abstract: In Hong Kong, conventional air-conditioning (AC) systems cause a high energy consumption and poor indoor thermal comfort. This paper investigated the AC load profiles of three typical local commercial buildings, i.e. office, hotel and retail, and examined the energy consumption of liquid desiccant cooling system (LDCS) for these buildings. Simulation results showed that the cooling load contributed to more than 98% of total annual load, with high latent load proportion from March to September. The high reheating ratio, i.e. from 60% to 90%, is found to be the main reason for the poor thermal comfort. Therefore, the LDCS which could handle sensible and latent loads separately was proposed. However, the electricity-driven LDCS was found not suitable for local commercial buildings. significant energy saving could be achieved by the solar-assisted LDCS system with thermal storage, when the installation area for solar collectors is larger than the minimum required one, i.e. 9.7m2/(kWm−2) for office and 12.7m2/(kWm−2) for hotel buildings. Energy saving of different system types with different installation areas was also studied. The solar-assisted LDCS shows more energy saving in winter but less in summer. Results and conclusions can be useful for researchers and local engineers. [Copyright &y& Elsevier]

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]

The air-conditioned thermal environments can have an important impact on human health. People stay in air-conditioned environments for a long period of time would tend to present weakened thermal adaptation and have weaker ability to endure hot environment, hence increasing the risk burden caused by heat stress on their physiological regulations to cause discomfort. In this study the relationship between human health – a prevalence of Sick Building Syndrome (SBS) – and air-conditioned indoor environment in summer was analysed using field studies. The results show that the discomfort could include physiological effects affecting the nervous system, the digestive system, the respiratory system, as well as irritation to skin and mucous membranes due to exposure to conditioned air. The frequency of such feelings of discomfort was higher for subjects who are acclimatised to air-conditioned spaces than for people who are not accustomed to air-conditioning. Thus, air-conditioning can be a cause of discomfort and could affect people’s health. [ABSTRACT FROM PUBLISHER]

It is costly to sample all major toxic pollutants in community air. Sampling should be conducted based on an assessment strategy and monitoring planning. Assessment methods that rely on monitoring some representative pollutants have been proposed variously at different times. In Hong Kong, the Environmental Protection Department (HKEPD) launched an Indoor Air Quality (IAQ) certification scheme to grade the IAQ in workplaces as "Excellent" or "Good" by measuring the levels of 12 indoor environmental parameters, i.e. carbon dioxide (CO2), carbon monoxide (CO), respirable suspended particulates (RSP), nitrogen dioxide (NO2), ozone (O3), formaldehyde (HCHO), total volatile organic compounds (TVOC), radon (Rn), airborne bacteria count (ABC), temperature (T), relative humidity (RH) and air velocity (V). The present study proposes an Express Assessment Protocol (EAP) to quantify IAQ problems by assessing the "dominant" contributors to unacceptable IAQ prior to any detailed assessment for benchmark purposes. To aid this, a comprehensive measurement of the 12 stated indoor environmental parameters was performed in some Hong Kong offices. The results were used to identify the dominant contributors and assess the performance of the proposed protocol in identifying the associated IAQ problems in an office environment. Comparing the results with the parameter measurements in the certification scheme they showed that for the "Excellent" IAQ level, 96% (94 to 98% for 95% confidence interval (CI)) of the "unacceptable" offices (414 samples) could be identified from the measurements of TVOC, RSP and HCHO; while those that achieved the "Good" level, 93% (90 to 97% for 95% CI) of them (201 samples) could be identified from the measurements of TVOC, ABC, RH, HCHO and O3. The EAP would be a useful tool for policymakers, building owners and professionals to quantify IAG problems in offices and to make improved decisions based on resources and manpower management for efficient mitigation actions. [ABSTRACT FROM AUTHOR]