Global standards for heating comfort are largely based on cooler, northern hemisphere climates. How relevant are these benchmarks in low-cost housing in warmer African regions?
Mak Okay-Ikenegbu did his doctoral research on thermal comfort in low-cost housing for warm and humid climates in Nigeria. His research showed that people in tropical environments can withstand higher temperatures than current global standards assume. The findings open the door to affordable housing designs that are climate-appropriate, without relying on energy-intensive solutions like air conditioning. He told us about his research.
How do you define comfortable housing for people in tropical Africa?
Comfortable housing in the tropics is housing that allows people to live, work and rest without experiencing excessive heat or discomfort. This can be without air conditioning as well. It supports well-being by allowing natural ventilation, reducing heat build-up and adapting to local climate conditions.
It is housing that keeps people thermally comfortable using passive design techniques such as cross-ventilation, shading and use of breathable materials. These materials can be adobe, earth blocks, or bamboo, which reduce indoor heat.
What did you find out about people’s housing needs?
My research found that people in low-income, tropical settings like informal settlements in Nigeria adapt to higher indoor temperatures than international standards suggest.
I developed a local thermal comfort model based on real-life experiences of people living in naturally ventilated earth and makeshift homes in Nigeria. My data came from low-income residents in low-cost homes.
This model is unique to the study context, as it directly reflects the comfort responses of people living in this environment. Adaptive thermal comfort models have been developed before, for example, the American ASHRAE 55 model and the European EN 16798 model. These are based primarily on data from temperate climates and mechanically cooled buildings.
Models like this are scarce for sub-Saharan Africa, particularly in the context of low-income or informal housing. This model has potential application for design and policy. It can inform architects, urban planners and housing authorities on how to design buildings that align with how people actually experience and adapt to heat.
This is crucial for creating affordable, climate-responsive housing that doesn’t depend on expensive mechanical cooling systems. It shows that people in tropical climates are comfortable at higher indoor temperatures than the international comfort standards suggest.
What does better housing look like in these conditions?
Affordable, climate-responsive housing solutions use local and thermally appropriate materials.
In my research, earth-based construction materials like mud or adobe walls were found to be more comfortable than materials such as scrap metal, timber planks and plastics. In earth-based housing such as those built with adobe or compressed earth blocks, indoor temperatures typically ranged from 20°C to 43°C. In contrast, in makeshift housing, often constructed from materials like corrugated metal sheets and tarpaulin, the temperatures were even higher, ranging from 25°C to 47°C.
This shows that makeshift structures tend to trap more heat and expose occupants to more extreme indoor conditions. The findings highlight the importance of building material choice and passive design in helping to reduce indoor heat and improve comfort, especially in settings without access to mechanical cooling.
I didn’t test the thermal performance of specific materials, but based on previous studies, materials like adobe or compressed earth blocks are known to offer natural insulation and reduce heat gain.
Corrugated metal roofs, which are common in low-income tropical informal settlements, often trap heat. So, incorporating insulation and ventilation beneath roofing can make a significant difference at very low cost.
Combining passive design strategies like shaded outdoor spaces, high ceilings, wide eaves, and cross-ventilation with materials that are affordable and climate-appropriate would help achieve better comfort.
What is significant or new about your findings?
My findings highlight the limitations of applying international comfort standards like ASHRAE 55 and EN 16798 in tropical climates. These standards were developed by organisations in the United States and Europe.
ASHRAE 55 is from the American Society of Heating, Refrigerating and Air-Conditioning Engineers, and EN 16798 is from the European Committee for Standardisation. They set out detailed guidelines for what indoor temperature are considered comfortable based on studies mostly from cooler climates and mechanically cooled buildings.
I found that many of the indoor temperatures that international standards would label as “too hot” were actually considered fine by residents. This was done by creating a comfort guide based on how people in the local area experience heat in their homes.
Based on the European standard, depending on outdoor conditions, comfortable indoor temperatures are expected to fall between 22°C and 32°C in the buildings surveyed in this study. The American standard shows a narrower range of approximately 23°C to 29°C. But the model or guideline developed in this study, based on actual feedback from residents in low-income homes in Nigeria, showed that people were comfortable at higher temperatures than those predicted by the international standards.
In this local context, comfort temperatures ranged from 24°C to 40°C, reflecting a greater tolerance for heat. This higher threshold suggests that people living in tropical climates, particularly in naturally ventilated and informally built homes, have adapted to their environment in ways that global models do not fully account for.
This matters because it affects how we design, build and improve low-cost housing in hot climates. If we rely only on international standards, we risk pushing for expensive cooling systems like air conditioning in order to meet recommended indoor conditions. Simpler, low-cost solutions based on how people actually adapt to heat could work just as well, or even better.
What policies or interventions can make this feasible?
Local adaptive comfort standards do not exist for sub-Saharan African contexts like Nigeria. Housing policies should therefore recognise the value of local comfort models and not impose global standards. Governments and other local stakeholders should allow and promote context-specific benchmarks when designing or delivering affordable housing schemes.
Building codes, urban development policies and political interventions should encourage residents and builders to adopt passive design techniques. These can be shading and ventilation, for example. Interventions must support the use of local, sustainable materials that perform well in hot, humid climates.
Investment is needed in community-led housing upgrades, especially in informal settlements. Even small improvements to insulation or adding windows for cross-ventilation can greatly improve comfort without incurring major costs.
Mak Okay-Ikenegbu does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
