In many parts of Africa, keeping a window open can be a complicated decision.
It allows air to circulate, making it cooler and easier to sleep through increasingly hot nights. But it can also provide an entry point for mosquitoes carrying malaria.
This is a CATCH story
This story is part of Dialogue Earth’s work on the Community Adaptations to City Heat (CATCH) project, in partnership with Boston University. The project is funded by Wellcome. All Dialogue Earth content is editorially independent.
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For Daniel Kwaro, a climate and health scientist at the Kenya Medical Research Institute, this dilemma is a useful shorthand for the larger challenge facing vulnerable communities across the Global South.
Kwaro and his colleagues are supporting communities to strengthen their resilience to the changes already underway in Africa.
In this interview with Dialogue Earth, he discusses how they have involved communities in designing cooler houses that keep mosquitoes out.
The interview has been edited for length and clarity.
Dialogue Earth: Why has your work concentrated on adaptation?
Daniel Kwaro: My overall goal is to build resilience among vulnerable populations and people without many resources. This is one of the parts of the world that suffers greatly from climate change. We say that so often that it can sound like a cliché, but it is true. We see it.
I do not feel that I have much influence over the people producing greenhouse gases. Where I feel I can contribute is in adaptation. We know climate change is already here. The question is what can we do about it? How can communities survive these crises and continue to thrive?
How is heat involved?
When it is very hot, people change their behaviour. They pace themselves so that they do not suffer from heat-related illness. On the coast of Kenya, for example, people may avoid physical work around midday and concentrate it in the early morning. The problem with climate change is that this cooler working window may continue to shrink.
Heat affects people through several pathways. There is the direct risk of heat-related illness, but there are also effects on sleep, recovery, movement and productivity.
When you sleep well, you recover and can be more productive the following day. Reducing the temperature inside the house may therefore have consequences beyond comfort.
How did that lead you to look at adapting houses?
We asked whether it was possible to resolve the tension between ventilation and mosquito protection. Both heat stress and malaria are climate-sensitive conditions. Through the window dilemma we can see clearly that you should not focus on only one problem when designing an intervention.
And how are you trying to resolve this tension?
We are renovating houses so that they can cool themselves passively, without electricity. We use reflective roofing so that radiant heat is reflected away from the house. We also provide windows for ventilation but add screening to prevent mosquitoes from entering.
We do not screen only the windows. We also screen the open eaves and the doors. At the entrance, there is a curtain-like screen that people can walk through and that closes behind them.
Essentially, the entire house is screened. That is completely different from the mosquito-net strategy.
How is whole-house screening better than bed nets?
Sometimes bed nets are distributed at a rate of perhaps two per household, even though the household may have four people.
There is also the question of timing. People may not go to bed until 10 pm, but mosquitoes may begin biting from around 6.30 pm. What protects people during the hours before they enter the net?
If the entire house is screened, mosquitoes do not get inside in the first place.
How did the communities shape the screening designs?
We held a workshop lasting roughly five days. After brainstorming possible solutions, participants developed physical prototypes. We gave them materials such as wooden planks, nails and other items they could use to build model houses. They worked in teams, deciding where windows should go, how large they should be, and what other features the houses required.
We analysed the prototypes and then held another co-creation workshop involving architects, engineers, the National Construction Authority, the Ministry of Health, and other experts. We showed them what the community wanted and asked, can you make this real?
The architects and engineers translated the community’s models into design specifications and architectural plans. They were improving on the community’s work, not starting from scratch. Many of the architects were impressed. They said they had learned a great deal from the community.
Does the same design work in every community?
The mechanism is the same: air can pass through, but mosquitoes cannot. The design, however, is different.
In coastal Kenya, humidity is very high, and people told us they wanted windows that remained open all the time but were permanently screened.
In Siaya, security was a greater concern. People wanted windows they could open and close. The screen therefore sits on one side while the window itself remains operable.
That difference is important. A standard solution would not necessarily work in both places.
What’s been the impact of the intervention so far?
In a pilot, we reduced indoor mosquito populations by about 70%. We also demonstrated a reduction in indoor temperature.
A larger study is intended to show what those environmental changes mean for people’s health and behaviour. We are looking at sleep quality, movement and heart rate, including data collected through wearable devices.
How have you tried to ensure things can continue beyond the trial?
The materials are locally available. That is very important because we do not want an intervention that cannot be implemented after the study ends.
We have also trained local artisans, the fundis who make and install the windows and other components. In addition, the curriculum in nearby vocational colleges has been updated so that students learning masonry and related trades are also taught about healthy housing and passive cooling.
Local fundis who are making the screened windows are already receiving interest from households outside the trial. People who are not participating in the research are asking for their services. That makes me happy because it suggests the intervention may be able to sustain itself through a business model.
What lessons can other places take from this success?
The main lesson is that climate-related health problems do not occur one at a time. An intervention that reduces one risk may unintentionally increase another.
Housing gives us an opportunity to address several risks together. But the solution cannot be developed only by scientists, architects or policymakers. It must also reflect the knowledge, preferences and aspirations of the people who will live in those houses.
The community may understand the climate better than the experts expect. However, the experts can then help translate that knowledge into something technically workable, safe and, of course, scalable.
