Environmental Heat Stress on Indoor Environments in Shallow, Deep and Covered Atrium Plan Form Office Buildings in Tropics

Upendra Rajapaksha

doi:10.3390/cli8020036

Abstract

Environmental heat stress on buildings through façades contributes to indoor overheating and thus increases demand for energy consumption. The study analyzed the problem, heat gain risk, of modern air-conditioned multi-level office buildings in tropics, for example Colombo. Plan form, orientation, sectional form and envelope were identified and theorized to understand design interventions to reduce the risk of getting heat stress on indoor environments. On-site thermal performance investigations in multi zones of identified three typical built forms, namely; shallow, deep and covered atrium plan forms, quantified the heat stress. Reaching the daytime indoor and surface temperature in peripheral zones of multi-story office buildings during air conditioning “off-mode” up to 38 °C–42 °C was seen as a critical heat stress situation to be addressed through building design. Shading or insulation on façades to control environmental heat gain and manipulation of building section for night ventilation to remove internal heat developed during the daytime are discussed. However, the significance of the plan form depth was found to be a main contributor in dealing with heat transfer to indoor space. Deep plan form was found to be more effective in controlling environmental heat transfer to indoor space across the plan depth.

Highlights

Thermal comfort experienced by the building occupants plays a vital role in enhancing climate responsive design
Despite growing need to avoid indoor overheating due to environmental heat stress, a lack of evidence exists on the scale of the problem in air-conditioned office buildings in tropics
The research analyzed a high prevalence of heat stress in contemporary office building types in Colombo, indicating the need to understand the plan depth as an important design consideration in dispersing the indoor air temperature due to heat stress through building façades

Summary

Introduction

Thermal comfort experienced by the building occupants plays a vital role in enhancing climate responsive design. Indoor overheating, in this context, is identified as one major problem. Indoor overheating is a condition where indoor air temperature moves above the upper limits of comfort zone. This can result in thermal discomfort while reducing the productivity of the occupants in buildings with free floating conditions. Controlling environmental solar heat gains into buildings due to high levels of ambient air temperature, internal heat generation from occupants and equipment together with enhancing heat escape from indoors determines the thermal balance in buildings [1,2]. Depending on the climate type and usage pattern of buildings, excess heat gain could contribute to indoor overheating [3]

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