What you need to know:
- The roofs are coated with reflective paints which absorb very little heat from the sun unlike ordinary corrugated iron sheets.
- Using a reflective coating is cheaper and environmentally friendly.
Millions of Kenyans living in iron sheet houses yet cannot afford air conditioners can turn to a roof coating technology which cools houses by reflecting away heat from the sun.
Commonly used in Europe and Asia, the roofing technology uses highly reflective materials to cool the rooms below.
Experts say roofs coated with the reflective paints absorb very little heat from the sun unlike the ordinary corrugated iron roofs, resulting into a cool and comfortable room.
Dr Nguchie Gathogo, technical director of Steam Plant Ltd — a firm dealing in reflective coats — says the technology can be handy for mabati houses in informal settlements or rural areas where electricity needed for air conditioning appliances is intermittent, costly or even non-existent.
“Using a reflecting coat is a cheaper and environmentally friendlier way of cooling houses as compared to buying and using an AC,”Dr Gathongo says.
While the global climate projections point towards a spike in the frequency and intensity of day-to-day temperatures, scientific research warns that heat stress could become a common phenomenon the world over, necessitating the need for air cooling appliances in homes.
In Kenya, for instance, a study conducted in 2017 by researchers from Johns Hopkins University in Kibera, Mukuru and Mathare slums indicated that informal settlements often experience ‘micro-climates’ warmer than urban neighbourhoods closer-by.
The researchers found out that temperature measured in the three slums were between five and 10 degrees Fahrenheit higher than at Nairobi’s nearby official weather station.
They later concluded that the difference in temperature was due to materials used in construction of houses, lack of ventilation, sparse green cover and poor access to electric power among other challenges witnessed in concrete jungles.
International Energy Agency (IEA) estimates that the world spends 10 per cent of its electricity trying to cool the air.
To eliminate over reliance on these expensive appliances, innovations around alternative cooling technologies particularly for developing countries is currently being promoted.
Dr Gathongo’s Steam Plant Ltd, a Kenyan company, was among 10 participants picked around the world to take part in a million square metres challenge to coat residential, commercial and institution buildings using passive reflective cool roofs coating technology.
The challenge was organised by The Kigali Cooling Efficiency Programme (K-CEP) in collaboration with Nesta UK and Global Cool Cities Alliance (GCCA).
“We are currently piloting the project mainly in schools, administration buildings, children homes and health facilities. The measurements and images taken before, during and after the coating show significant reduction of the ambient temperatures in the coated buildings, hence creating comfortable learning, working and living conditions,” Dr Gathogo said.
Mr William Owiti Aora, the deputy head teacher of Korogocho Glory Primary and Secondary School, says coating that was done on the rooftops of the classrooms during the long holiday occasioned by Covid-19 pandemic is a relief to the children and teachers.
Mr Aora says the children now feel more comfortable. “The heat was making children to dose off in class after lunch in the afternoons,” he says.
The 2019 Census estimates that approximately 1.2 million (10 per cent) families in Kenya live in mabati houses and have to brave the searing heat and heat stress from their tin houses.
In Nairobi alone, 393,000 families — which is equivalent to 26 per cent of families living in the city —call mabati houses home.
World Health Organization (WHO) recommends that the room temperature should be kept below 32 Celsius during the day and 24 Celsius at night.
WHO says excessive heat impacts negatively not only the health of people living with autism, cerebral palsy or epilepsy but is also dangerous to children below four years and the elderly above 60.