Time for city estates to go green is now


What you need to know:

  • Cities like New York and Singapore’s urban areas are bold examples of “green space” initiatives to remove concrete and make room for trees and vegetation.
  • According to WHO, trees play an important role in climate change mitigation, especially in cities with high levels of pollution to improve air quality, thus, making the environment healthier to live in.
  • Strategic placement of trees in cities can help to cool the air by two to eight degrees Celsius, thus reducing the urban “heat island” effect, and helping urban communities to adapt to the effects of climate change.

When builders of the ‘Lunatic Express’ railway line arrived in Nairobi in 1899, the Kenyan capital was just a swamp for herders and their animals.

The city’s dramatic perch between many green hillocks and a national park made it an instant attraction.

Over the years, however, rapid urbanisation accompanied by real estate development has seen Nairobi’s green spaces cleared to create concrete jungles.

Today, few city residents would be lucky to see any trees or vegetation in their estates. Most of them see trees along the streets and in open spaces such as Uhuru Park, City Park and the Arboretum.

The irony is that most city residents would prefer to live in more ‘natural’ neighbourhoods away from the hustle and bustle of the capital city. No wonder Nairobians openly marvel at the blooming Jacaranda trees in the month of October.

Some of them even take to the social media to thank those who planted those trees. Indeed, there are even cases of foreign tourists, who visit the City of Nairobi just to admire jacaranda in bloom.

Path of destruction

Sadly, many property developers, driven by the profit motive, are reluctant to let architects include green spaces and trees in their housing plans.

Instead, real estate developers want to squeeze as many houses as possible into the available space, especially in residential housing. The result is that estates end up becoming concrete jungles.

In Nairobi, the Eastlands estates of Imara Daima, Embakasi, Umoja, Huruma, Donholm and parts of Nairobi West and South B, are characterised by less trees and more multi-storey buildings, providing good examples of the concrete jungle.

Residents of these areas will agree that their estates are sunnier, dryer and dustier than those with more vegetation cover.

But it is not only real estate developers who are cutting down trees to put up houses; we have witnessed the government doing the same to create space for road expansion.

And yet major cities like New York and Singapore’s urban areas are bold examples of “green space” initiatives to remove concrete and make room for trees and vegetation.

Mr Raphael Obonyo, a policy specialist and member of the UN-Habitat Youth Advisory Board (YAB), reckons that Nairobi has few trees compared to world cities such as New York City, Turin, Toronto, Canada, and Johannesburg.

Born and raised in the Eastlands, Mr Obonyo says that Nairobi is trailing its peers with a tree cover of 7.78 per cent. The City of Singapore leads the world at 29.3 per cent tree cover.

“Cities such as Nairobi should be encouraged to grow more trees beyond parks and streets. We need more green spaces, and denser greenery in our cities,” he says.

Dr Alice Kaudia, former Environment Secretary. PHOTO| COURTESY

Environmentalists point out that living in a concrete jungle does not only lower the quality of life, but could also result in stress.

They argue that the presence of nature in a living environment is beyond a “nice to have thing”; rather, it is a way of counteracting the psychological downside of increased interaction in cities.

High levels of pollution

A study by the Stanford Woods Institute for the Environment in 2015 indicated that people who walked for 90 minutes in a natural area had a lower risk of depression compared to their participants who walked in a high-traffic urban setting.

A mature tree, according to the World Health Organisation (WHO), can absorb up to 150kg of carbon dioxide per year.
Therefore, trees play an important role in climate change mitigation, especially in cities with high levels of pollution to improve air quality, thus, making the environment healthier to live in, WHO says.

By enhancing liveability, green spaces make cities more desirable places to live and work in.

Former Environment Secretary at the Ministry of Environment and Natural Resources Alice Kaudia says a multi-sectoral effort is needed to ensure we have sufficient vegetation cover in the city.

Dr Kaudia, who currently chairs the Climate and Clean Air Coalition — a global network that seeks to improve air quality and ward off climate change — says that the housing sector should ensure green growth and replicate such efforts in the counties.

Adopting green buildings, she says, is one way of fighting air pollution, which can also be addressed by having a clean transport sector.

Increasingly, researchers are suggesting that planting more trees in urban areas, if done correctly, could save tens of thousands of lives around the world each year by soaking up pollution and cooling down deadly heatwaves.

Strategic placement of trees in cities can help to cool the air by two to eight degrees Celsius, thus reducing the urban “heat island” effect, and helping urban communities to adapt to the effects of climate change.

Even though air conditioning is the usual choice for many urban dwellers to cool their homes, air conditioners are electricity powered and it can be expensive to run them, besides that fact that they also add to atmospheric carbon pollution.

To help cities adapt to rising temperatures, green technology which includes street trees, green roofs, vegetated surfaces and green walls — is emerging as a viable way to help cities adapt to increased heat.

While Nairobi isn’t entirely left behind in green infrastructural development, a concerted effort is needed to push the agenda beyond cleaning of rivers and planting trees in forested areas.

Extensive tree cover

Compact city land-use policies and urban forest policies need to work together to ensure that cities have high-quality built environments and extensive tree cover.

“We need to create more awareness, give people more information on the importance of having green cities, and give incentives to encourage landlords to plant more trees.

“Also make urban planning more accessible to people outside the field,” underscored Mr Obonyo.


Cleaning up plastic waste by turning it into building materials

If 27-year-old Nzambi Matee was to take something you don’t need in your house, she would go for your plastics. Not to dispose of them, but because she has a noble idea on making good use of them.

Ms Matee, a Bachelor of science in Physics graduate from JKUAT, and a material scientist, is the founder of G-Jenge Makers Ltd.
The aim of the Nairobi-based social enterprise, she explains, is to address the prevailing issues of plastic waste pollution.

She does this by recycling and upcycling waste plastic into strong and beautiful construction products such as paving bricks, paving tiles, hatch and manhole covers.

“We use polymers from plastics and rubber to make building products,” she says.

Through partnerships with skilled and unskilled youth and women’s groups, Ms Matee and her two co-founders are able to collect plastic waste from the community around Industrial Area and South B neighbourhoods.

Strength of materials
The co-founders are Ms Paula Aschenbrenner, an environmental physicist based in Germany and Ms Margret Matee, the board adviser.

The latter happens to be Nzambi’s mother, of whom the daughter says: “She brings on board 20 years of experience in business management”, to explain why she was brought on board.

Paving blocks made from plastic waste. They come in different beautiful designs. PHOOT| COURTESY

After collection, the plastic waste is sorted, cleaned and then crashed before being put into an extruder machine where the polymers are heated and combined with sand and a hardener in a process referred to as extrusion.

At the moment, G-Jenge Makers is producing paving blocks to prove the concept and strength of the materials. They are also producing bricks for affordable house construction.

Brick colour and shape

She says: “After casting the columns, construction work becomes easy. Since bricks are already pre-moulded and pre-cast, it is only a matter of stacking them together using steel beams to reinforce them. This eliminates the need for mortar and makes the process less laborious.”

According Ms Matee, pre-casting allows the client to customise their houses to taste in terms of brick colour and shape, and even match the pavers.

Also, the resulting house is sturdy, less costly and consumes little time during construction, since no time is lost in mixing mortar and placing it between bricks. There is also no time needed for curing.

All these efforts lead to a reduction in time and construction cost. “If all goes according to plan, we expect to build a two-bedroom house in one month, at a cost of Sh800,000,” Ms Matee says.

Kenyans are not known to embrace alternative methods of construction, afraid that they could be inferior to conventional methods that they are familiar with. This explains why Portland concrete (cement-based concrete) has dominated at the expense of polymer concrete (a type of concrete that uses polymers to replace lime-type cements as a binder), despite the latter penetrating other countries.

Ms Matee is banking on the renewed commitment to affordable housing to push the idea through the market.

“The concept and science behind making buildings and reinforcing them with polymer is as old as time. A good example is the Colosseum, an oval amphitheatre in the heart of Rome, Italy. It is the largest amphitheatre ever built and now a heritage building,” says Ms Matee says.

Its builders used cement concrete and reinforced that with polymer, she adds.

Nzambi Matee, founder G-Jenge. PHOTO| COURTESY

Most people favour Portland cement concrete because of its arguably adhesive nature and the strength when it comes to binding the sand and the ballast, but Ms Matee says polymer concrete is even stronger and less brittle.

“If you were to hit a building constructed using Portland concrete with a wrecking ball, it would shutter almost immediately. However, a house built with polymer-based concrete will behave like a plastic, bending for a long time before shuttering,” she says.

“I consider myself a futurist”, Ms Matee says, and adds:

“It is estimated that by 2050, the world’s population will be somewhere around 8.6 billion people, with about 1.3 billion of these living in Africa. Already, decent affordable housing is a problem and when you look at it, apart from land, the cost of materials is the other factor that pushed construction costs up, yet we have so many resources like plastics that we have not exploited.”

By converting plastic waste into useful products, she points out, Ms Matee has found her purpose in life. She told DN2 that she resigned from a prime job with a major petroleum company to chase her dreams, much to the disapproval of family and friends.

Cleaning the environment

She has since received training on how to make building materials from plastics at Wastson Institute in USA and the Germany-based European Organization for Nuclear Research, also known as CERN.

“This is my little way of killing two birds with one stone. Other than cleaning the environment, we will be providing shelter, which is a human need,” she says.

Ms Matee revealed that she is working closely with chamas (groups) keen on providing affordable housing. This is a market-penetration strategy, which is already bearing fruit. She told DN2 that she has 34 orders to run this year.

At ShelterTech Accelerator, a Habitat For Humanity’s start-ups acceleration programme happening at Strathmore University-based iBiz Africa, Ms Matee, alongside other young people, is gunning for the top prize: a Sh5,000,000 worth of investment into her business and a chance to pitch to investors.

Besides the co-partners, she has a staff of three, who are brought on board on a need basis.

Ms Matee believes that if young people, like her, were to be accorded the necessary support from the government and private entities during their baby steps, they would not only create employment for other young people, but they would also help the country find local solutions to local problems. byDelfhin Mugo