Urban Morphology and Outdoor Microclimate around the “Shophouse” Dwellings in Ho Chi Minh City, Vietnam

Hung Dang,Adrian Pitts

doi:10.3390/buildings10030040

Abstract

The underestimation of population growth has resulted in the disruptive and uncontrolled expansion of settlements in Ho Chi Minh City (HCMC). The outcome is a complicated mix of new spontaneous dwelling areas featuring a number of distinct urban morphologies. Previous studies have shown the impacts of urban morphologies on comfort levels in outdoor environments. The paper examines the correlation of microclimatic conditions and constituents that create the urban spatial form of residential neighbourhoods, particularly around ‘shophouse’ buildings. Understanding that relationship is significant for improving the future planning and design of residential zones and the creation of a pleasant external environment. Seven urban dwelling patterns were studied. Thermal variables were measured on-site over a summer season, while meteorological data were recorded. Additionally, numerical studies of the microclimate around two sample sites showed variations owing to different urban contexts. During summer, the outdoor conditions for the types surveyed ranged from 29.5 to 38.0 °C air temperature, 41% to 79% humidity, and 0.1 to 0.9 m/s airspeed at the occupied level. Environmental variations averaged 1.5 °C, 7% relative humidity, and 0.3 m/s between the urban geometries. Occupant thermal satisfaction was found around formally planned dwelling blocks, while compact neighbourhoods were characterised by cooler temperatures, but poor airflow and daylight. The outcomes are significant for optimising urban and building design.

Highlights

Thermal comfort is a complex issue and studies of occupied environments have two main conceptual backgrounds: the predicted mean vote (PMV) approach, originally devised by Fanger [1], which was derived from laboratory experiments; and the adaptive approach, which was derived from the assessment of real building environments in which occupants could adapt themselves and their building space
10 m show that the average temperature was 32.6 ◦ C (SD 1.63), mean relative humidity (RH) was 61% (SD 8.06), and air velocity was 0.32 m/s (SD 0.19) during the two months of April and May (Table 2)
The study confirms thermal discomfort in exterior climates in cities of the tropics such as Ho Chi Minh City (HCMC). This is associated with urban development and human activities and is likely to subsequently affect indoor comfort and lead to higher levels of energy use

Summary

Introduction

The adaptive approach is more closely associated with free-running buildings rather than closely-controlled (often air-conditioned) buildings. In relation to the adaptive approach, and arising from a process of plotting data collected from world-wide field surveys, Humphreys found a close linear regression for the indoor neutral temperature (which is the temperature of the thermal environment in which people sense neither warm nor cool) against the outdoor temperature in naturally ventilated buildings, and a complex relationship in air-conditioned buildings [2]. In free-running buildings, is a result of a complex interplay of external climate patterns, building (design, building type, and cooling principle), and people (physiology, psychology, and behaviours) [3,4,5,6]

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