Natural ventilation strategies to enhance human comfort in high-rise residential buildings in Thailand

Prajongsan, Pimolsiri Natural ventilation strategies to enhance human comfort in high-rise residential buildings in Thailand. PhD thesis, University of Liverpool.

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Abstract

In this study a thermal comfort ventilation strategy called ‘ventilation shaft’, which is a vertical shaft located at the rear of a single-sided unit and with an exhaust at the building’s flat roof, is proposed for a single-sided residential unit in high-rise buildings in Bangkok. The main aim is to investigate its potential to maximize the unit’s indoor air velocity and to extend the occupants’ thermal comfort, which, therefore, reduces high electricity consumption due to cooling systems. By using the validated CFD code in DesignBuilder simulation software, the ventilation shaft’s effectiveness was examined and its design was optimized. It was found that the proposed strategy can effectively increase the unit’s air velocity from 0.05ms-1 to 1.44ms-1 (approximately 36% of the external wind speed of 4ms-1under wind incident angle of 0°). The external wind speed and direction relating to the unit’s main window were found as the most influential external parameters, while the vertical shaft’s size as well as the inlet and outlet’s size and location with respect to the occupied area were the most influential design factors to determine its performance. A shaft height of at least 1m above the building flat roof, as well as an opening width of at least 50%-75% of the wall’s width, is recommended for ensuring the best results. Openings’ length, particularly the inlet’s, only to cover the occupied level is also suggested to avoid excessive solar heat gain from the environment. Regarding thermal comfort, the ventilation shaft with its optimal design was attached to the rooms from floor 6th to floor 25th of the hypothetical building and found able to produce the required air speed for creating physiological cooling effect in most units. This could extend the occupants’ thermal comfort time for up to 33% and 64% per day for a south- and a north-facing unit in the hypothetical building, respectively based on ASHRAE’s adaptive comfort model, and could lead to significant energy savings of up to 68.8MW per annum and 5,291MW per annum for a typical residential building in Bangkok based on a typical electric ceiling fan and a split type air conditioner respectively. In conclusion, the proposed ventilation shaft is an effective windinduced strategy to increase the air velocity and create cross ventilation in a single-sided residential unit, which can enhance the natural ventilation potential to provide thermal comfort and reduce the a/c systems dependency in typical high-rise residential buildings in Bangkok and other hot-humid climates.

Item Type:	Thesis (PhD)
Additional Information:	Date: 2014-08 (completed)
Depositing User:	Symplectic Admin
Date Deposited:	05 Feb 2015 14:52
Last Modified:	17 Dec 2022 01:54
DOI:	10.17638/02006523
URI:	https://livrepository.liverpool.ac.uk/id/eprint/2006523