title: A parametric analysis of the thermal properties of contemporary materials used for house construction in South-west Nigeria, using thermal modelling and relevant weather data
Creators: name: Ogunrin, OS
Publisher: name: University of Liverpool Repository
Year: 2019

description: Climate change, its causes and effects have become a topical issue in the world today. Universal increases in temperature and sea levels, are evidences of this global phenomenon. In the field of architecture, climate-resilient and climate-responsive domestic buildings are being developed to adapt to changing climates, while being socio-economically suited to their geographical contexts. Much research in this area has been carried out in developing tropical countries such as Nigeria. Most studies concentrate on passive optimisation of building envelopes to promote thermal comfort and reduce reliance on active mechanical controls which worsen climate change. Thus, it may be said that thermal comfort has been established as a link between climate change and housing. In south-west Nigeria, where an abundance of tropical rainforests engenders a hot-humid climate, achieving thermal comfort in buildings is a major need. Studies show that of all house envelopes in south-west Nigeria through time, two housing styles namely the pre-colonial traditional and colonial modernist styles best demonstrate effective use of climatic design principles in achieving thermally comfortable interiors. However, due to cultural changes over time, a third style of housing which is referred to as contemporary south-west Nigerian housing, is currently the most preferred form of housing. South-west Nigerian contemporary house shows considerable influence from the International Style. This housing style features envelopes with minimum use of climatic design principles and maximum reliance on mechanical cooling devices such as air conditioners, in providing indoor thermal comfort. These mechanical devices, however, are known for aggravating south-west Nigerian climate change. To reduce the aggravation of climate change caused by south-west Nigerian contemporary housing envelopes, this study proposes a free-running contemporary house envelope which promotes thermal comfort in present and future south-west Nigerian climates. As such, the study extensively reviewed climatic design principles and thermal standards applicable in tropical climates as well as material on chronological south-west Nigerian housing developments. The study modelled and evaluated the thermal performance of a free-running, base-case contemporary house envelope in present and future climates, using DesignBuilder’s dynamic thermal simulations. South-west Nigerian present and future climatic data used in the simulations, were generated by the climatic data source and calculation software Meteonorm. South-west Nigerian present climatic data was validated by readings from data loggers placed in a real-live contemporary base-case house in the region. The results of this study’s simulations confirmed that the free-running, base-case contemporary house envelope does not promote thermal comfort in present climates, hence the current supplementary mechanical thermal controls. Additionally, the results showed that the contemporary envelope would not promote thermal comfort in future south-west Nigerian climates. As such, this study then proceeded to optimise the contemporary house envelope to improve its thermal performance in south-west Nigerian present and future climates. This optimisation involved adjusting the envelope specifications under the following parameters: headroom height, external wall (thermal mass, insulation and thickness), internal ground floor (thermal mass, insulation and thickness), roof (thermal mass, pitch, structure, overhang length, covering), external window (size, type, glazing thickness and type), azimuth angle (building orientation) and ground floor elevation distance. These parameters were based on Szokolay’s (2014) climatic design principles. The results showed that optimising the south-west Nigerian contemporary envelope under those parameters improved its thermal performance, enabling it to provide indoor thermal comfort in present and future south-west Nigerian climates. Accordingly, this study’s main contribution is the proposal of a free-running climate-responsive south-west Nigerian contemporary house envelope which promotes indoor thermal comfort in present and future climates. It recommends that: 1. without any need for mechanical cooling devices, the specifications of this optimised contemporary house envelope can be used to reform housing design policies in south-west Nigeria, and 2. using the optimised envelope would reduce reliance on mechanical thermal controls and therefore mitigate climate change in the region.