Residential indoor humidity control in tropics and sub-tropics

Ming Yin Jonathan Chan, Shiming Deng, X. G. Xu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

1 Citation (Scopus)


The use of direct expansion (DX) air conditioning (A/C) systems is widely seen in residential buildings in tropics and sub-tropics. However, most DX A/C systems are equipped with single-speed compressor and supply fan, relying on On-Off cycling as a low-cost approach to maintain only indoor dry-bulb temperature, whereas the indoor air humidity is not controlled directly. This also leads to potential inefficient energy use due to space over-cooling. This paper suggests a novel control strategy (termed Hi-Lo strategy) of using two-speed compressors in DX A/C systems for better indoor thermal environment control and higher energy efficiency. Experimental work has been carried out to test the Hi-Lo control strategy. Experimental results suggested that the novel control strategy can help improve the indoor humidity control without sacrificing energy efficiency. Practical application: The use of ON/OFF control at part load conditions in conventional DX A/C systems will lead to undesirable relative humidity levels. The problem is more prominent when the latent load is dominant. In order to have a better dehumidification effect, a lower indoor dry bulb temperature has been often set. On the other hand, the use of variable speed compressors in DX A/C systems can be a solution to the problem of humidity control, but its cost is comparatively high. The suggested novel control strategy is a low cost approach, which can save energy and provide a better indoor humidity control using DX A/C systems.
Original languageEnglish
Pages (from-to)169-173
Number of pages5
JournalBuilding Services Engineering Research and Technology
Issue number2
Publication statusPublished - 7 May 2009

ASJC Scopus subject areas

  • Building and Construction


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