• Energy Research

Abstract The viable solution to the high latent load that naturally occurs in tropical regions requires an alternative system that runs at relatively low energy consumption yet be able to provide indoor thermal comfort by effective handling of the excessive humidity. Although the existing outdoor air treatment system is a proven approach, it is unpopular in developing countries due to its high initial cost. In this paper, a new system termed Dual Air Handling Unit system is proposed to be the answer. The function of Humidity-control Air Handling Unit is to remove the moisture from the conditioned room up to the desired humidity level and in the process the room temperature is also fractionally reduced. The Temperature-control Air Handling Unit completes the task by removing the remaining sensible heat so that the room temperature is maintained at the required set-point. By reducing the relative humidity to 50%, a much lower value than that of the normal air-conditioning could offer, room temperature of the new system is shifted higher to 26 °C in order to reduce the energy consumption. The simulation result shows that the proposed system offers energy savings up to 13.2% compared to the conventional air-conditioning system, without compromising the thermal comfort of the occupants.

There are many reports about faulty status in building air-conditioning systems recently. It becomes difficult to keep indoor air temperature appropriately as faults occur, and the faults cause waste of building energy consumption. The model-based fault detection and diagnosis (FDD) methods have been researched for specific parts of air-conditioning system such as chillers, coils, variable air volume units (VAV units), etc. It needs, however, much time and labor to monitor and check every single part because we cannot predict where and when the faults occur. The purpose of this study is to examine indoor air temperature changes and energy consumption increase when faults occur and to develop an easy-to-use FDD tool that helps to find out the faulty place through the whole building air-conditioning system. And then, we treat the reliability of the proposed FDD tool and effectiveness to control of indoor environment deterioration and energy consumption increase by the tool is evaluated based on building air-conditioning system simulation in this paper.

Passive design, which has strong dependency of climate and areas, is the most economical effective strategy for reducing energy consumption inside residential buildings. A total of 25 representative cities of China were selected for optimum analysis. This paper presents an approach in which the orthogonal method and the listing method are integrated to explore how energy consumption is minimized in residential buildings by optimizing 7 passive design measures for each city: wall thickness (WT), roof insulation thickness (RIT), external wall insulation thickness (EWIT), window orientation (WO), window-wall ratio (WWR), glazing type (GT), and sunroom depth/overhang depth (SD/OD). With the optimization, the passive design could reduce annual thermal load of building considerably, even could replace air-condition systems in winter for the areas with high solar radiation such as Lhasa. The results reveal that neighbor cities have the same optimal combinations and the similar effects of energy-saving measures. A total of 7 passive design zones were summarized in a map. The architect could be guided in his choice of appropriate passive measures directly from the map or handling of exact passive design by the optimal approach proposed in this paper for different areas in China.