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Climate change may seriously affect the energy consumption of buildings by influencing their air conditioning loads, especially the ventilation loads which vary directly with the local weather conditions. Research on how the ventilation load responds to climate change is of great significance, especially in coastline subtropical regions like Hong Kong. This paper investigated the impacts of climate change on buildings' ventilation load and building energy use in Hong Kong with the hourly meteorological data from 1950 to 2007. Results have been well validated by the simulation of a typical local hotel building during this period. The results show that climate warming increases both sensible and latent parts of the cooling ventilation load. The latent part, which occupies ∼80% of the total ventilation load, increases at a higher rate, about twice of that of the sensible one. Furthermore, it is found that the urban heat island (UHI) effect causes a much higher growth rate of the ventilation load at night, which is about three times compared with that in the daytime. The latent part of the cooling ventilation load at night, which is found to be the most sensitive component to the climate change, plays a most significant role in the energy consumption increase. The possible measures were thus suggested to avoid negative changes of the ventilation load. Besides, reducing the UHI effect by better urban planning also significantly benefits the local buildings with a long air-conditioning operation time. [ABSTRACT FROM AUTHOR]

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]

Abstract: The provision of balcony to the living room of a residential flat offers a number of merits including improved view enjoyment, enhanced ventilation and increased planting space. In addition, a balcony can act as an overhang and provide solar shading as well as electricity saving of the air-conditioning system. This paper reports the findings on the energy and environmental impact due to the provision of a balcony. In this study, a typical residential flat with balcony constructed at the living room was modeled and the energy performance was investigated with the use of the typical weather data set of a subtropical city, Hong Kong. The effects of balcony''s orientation and glazing material of window were also evaluated. It was found that the residential flats facing various orientations (N, E, S, W, NE, SE, SW and NW) can offer substantial energy saving in air-conditioning system due to the shading effect of balcony. The building case with southwest facing balcony and clear glass glazed window gave the highest saving percentage of 12.3% in annual air-conditioning consumption. In terms of cost payback period, the values were estimated as 25.9 years (based on extra construction cost of a balcony) and over 100 years (based on extra purchasing cost), respectively. On the other hand, the energy payback period was 22.4 years for this building case. The provision of balcony to the living room of residential flat was found environmentally feasible in Hong Kong. [Copyright &y& Elsevier]

Abstract: The ground-coupled heat pump (GCHP) system is becoming attractive for air-conditioning in some moderate-weather regions due to its high energy efficiency and reliable operation capability. However, when the technology is used in buildings where there is only cooling load in hot-weather areas like Hong Kong, the heat rejected into the ground by the GCHP systems will accumulate around the ground heat exchangers (GHE). This heat accumulation will result in degradation of system performance and increment of system operating costs. This problem can be resolved by using the hybrid ground-coupled heat pump (HGCHP) system, which uses supplemental heat rejecters to reject the accumulated heat. This paper presents a practical hourly simulation model of the HGCHP system by modeling the heat transfer process of the system’s main components. The computer program based on this hourly simulation model can be used to calculate the hour-by-hour operation data of the HGCHP system. As a case study, both a HGCHP system and a traditional GCHP system are designed for a hypothetic private residential building located in Hong Kong, and the economic comparisons are conducted between these two types of systems. The simulation results show that the HGCHP system can effectively solve the heat accumulation problem and reduce both the initial costs and operating costs of the air-conditioning system in the building. [Copyright &y& Elsevier]

Abstract: Near-extreme outside dry- and wet-bulb temperatures are essential for the design of building HVAC systems. Coincident design temperatures currently defined by ASHRAE and CIBSE may not fully allow engineers to design an HVAC system that can match a risk level desired for the problem at hand. A rational method is therefore presented in this paper for the proper selection of coincident climate design conditions, which is based on the theory of probability. An average statistic risk level has been proved to be approximately equal to the annual percentile of coincident dry- and wet-bulb temperatures for HVAC systems whose thermal time constant is less than 1h. An algorithm is also developed to determine the contours of equal risk. Representative coincident design dry- and wet-bulb temperatures are obtained through statistic analysis of the 15 years of weather records in Hong Kong. These rationally derived outside design temperatures are compared with the coincident dry- and wet-bulb temperatures currently defined by ASHRAE and CIBSE. [Copyright &y& Elsevier]

Based on the data collected in recent surveys, models have been established to represent the energy characteristics of living and dining rooms and bedrooms in typical residential buildings in Hong Kong, in respect of the layout and construction; the density and pattern of occupation; the power intensities and operating patterns of lighting and appliances; and air-conditioner operation patterns. With the help of computer simulation, the impacts of varying these characteristics on the annual space cooling load have been evaluated, which allowed representative internal load patterns for residential units to be defined. These are essential data for predicting energy use in residential buildings, which, in turn, is an indispensable part of studies on ways to assess and minimise energy use in such buildings. This paper presents the building model and the internal load and air-conditioner operation patterns established in the study. [Copyright &y& Elsevier]