Going green in these harsh climes
By MWAURA SAMORA email@example.com
Posted Wednesday, February 29 2012 at 16:25
Buildings account for at least 40 per cent of a country’s energy consumption, and one of the best ways to cut down on these huge energy needs lies in our roofs and walls. Discerning architects could create energy-saving concepts because those same walls and roofs are the links between the building and the outer environment
The collective attention of conservationists was last month directed towards Gigiri, Nairobi, where the United Nations Environmental Programme’s (Unep) global ministerial environmental forum debated ways to make the world as “green” as possible. Before this, Unep had already declared 2012 the International Year of Sustainable Energy for All.
But while the world’s attention is fixed on these lofty plans on how to reverse the wanton destruction of global habitats in years past and prevent — what scientists have called an ‘environmental Armageddon’ — a local architect says the journey to a sustainable world starts with the small steps of adjusting our building styles.
“Green architecture is not only aesthetically appealing and environmentally friendly, but also economically viable in the long run since it embraces methods that save on power and water usage,” explains Francis Gichuhi, an architectural consultant who specialises in designing green buildings.
“New structures are rapidly adopting this concept, not just because of its resource-friendly nature and cost-cutting, but also the now popular global obsession with matters green.”
Sustainable construction is a relatively new concept in Kenya, where the first truly green building is the Unep headquarters in Gigiri. Although several other projects are underway across the city, the Unep building remains one of the greenest beacons across Africa.
Through his company, Prism Designs Africa, Gichuhi has drawn from his 11-year experience of designing green houses across Africa and parts of India to come up with a concept called Diamond Eco-House, where one can complete an entire bungalow at a competitive rate by building in stages of one room at a time as long as one has a piece of land.
“One only needs to have a piece of land and Sh80,000 to get a one-room house in three weeks,” explains the architect, who says the house is called Diamond because of the shape it takes when all the rooms are complete. “The reason the house is affordable is that it utilises interlocking stabilised soil blocks which are much cheaper than ordinary stones.”
The blocks are made of sand that is pressed to a rock-hard status using a machine, hence it’s much cheaper than the ordinary stone while having the same hardiness and hardness. Although the stabilised soil blocks are better suited for residential buildings that rarely exceed one or two storeys, they are recommended for in-fills and partitions in high-rise commercial structures.
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“Another economic plus for using the stabilised soil blocks is the fact that you don’t need plaster since the blocks are made in such a way that they join by interlocking,” he observes. “The blocks can also be made on site if the soil quality is good, which, besides lowering the costs further, increases environmental relevance since no carbon is released during transportation.”
Unlike most standard homes, the Diamond Eco-House has a twin waste-water piping system, with one carrying foul water from the toilet while the other drains the grey water from kitchen sinks and washbasins. Gichuhi points out that while the foul water is hard to recycle since it needs complex specialised treatment, the grey water can be re-used — after simple filtration — in the toilet and to irrigate gardens.
“A 10-storey building with 50 tenants per floor, each using five litres of water per day for non-drinking purposes, leads to a total water consumption of around 2,500 litres on a daily basis,” the architect notes. “Recycling 30 per cent of this amount across the Nairobi Central Business District, for instance, would translate into hundreds of thousands of shillings in savings besides conserving many litres of the precious commodity”.
This, combined with run-off collections, which he says should be made mandatory for every building, would go very far in ensuring residents’ water needs are met even when the taps run dry.
Unfortunately, no building in the city has implemented an efficient recycling system, which means all the water flushed down the drains goes to waste.
According to Green Building Workgroup, an American environmental architecture organisation, buildings account for at least 40 per cent of a country’s energy consumption. This percentage is higher in countries that experience extreme winter conditions in the Northern Hemisphere.
One of the biggest solutions to cutting down drastically the energy consumption of a building, according to Gichuhi, lies in its roof and walls. These are the main areas where the architect can create energy-saving concepts because walls and roofs are the links between the building and the outer environment.
“When called upon to adopt green designs, one of the options is a technology called building integrated photovoltaic (BIP) system, where solar panels replace a piece of the wall, window or roof,” he says.
“While the solar panel still serves the purpose of the part it has replaced, it has the added value of generating energy.”
However, the popularity of this concept is still very low because solar panels are relatively expensive compared to other building materials. This is because, Gichuhi laments, they have to be imported, mostly from Asian countries, despite the fact that the technology required to make them is very basic and simple.
“In China, for instance, by the time children complete their primary studies, they are able to cobble together a fully functioning solar cell using a simple wire and a piece of silicon,” the architect says.
“By the time they get to university as architects, they have accumulated enough technical know-how to design complex photovoltaic designs that are exported to Africa for sale.”
Although there is no institution in Kenya that teaches students how to make solar panels, tutorial materials explaining the step-by-step procedure abound online, and these, Gichuhi says, should be used by the government to popularise the technology through the education system.
“The concept should be legislated so that every citizen who has electricity in their house is required by law to contribute power to the grid by mounting solar panels on their roof. This will help the country move away from weather-reliant power generation methods and reduce the frequent power blackouts.”
In Germany, one of the world’s greenest economies, elaborate government initiatives have triggered a national interest in green energy production by the citizenry in the last five years. As a result, 50 per cent of solar energy production, which contributes around three per cent to the national grid, is in the hands of private individuals.
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Through a system known as feed-in tariffs, grid operators are required by law to pay for renewable energy supplied to them by citizens for a fixed price in a period of 15 to 20 years, and this has created a surge in the production of renewable energy by citizens. The payment can either be in cash or electricity bill subsidies.
The German renewable energy production policy is backed by a legal requirement where every new house built should not waste more than 75kWh/m2 per year. With no meaningful energy-saving measures put in place in many Kenyan houses, it is obvious that we waste far much more than this annually.
“Assuming a metre square of solar panel in Kenya produces approximately 2kW per day after 10 hours of daylight — Kenya is right in the tropics — if just one per cent of the country’s total surface area is put under this system, it would produce approximately 14,000 MW daily,” Gichuhi analyses. “Nairobi consumes around 5,000 MW on a daily basis. Therefore the total energy generated by solar from one per cent of the country’s total surface area in a day can sustain the capital’s total energy needs for three days.”
Taking into consideration that Kenya enjoys more hours of sunshine per day than Germany, such a people-driven power production programme would be a huge boost to Kenya Power’s output.
“The blackouts that Kenyans have to endure on a daily basis would be drastically reduced while individuals and corporate entities will have their power bills drastically reduced.”
Another green initiative that high-rise building designers are gradually embracing is the concept of rooftop gardens, or “green roofs”. Although still not very popular in Kenya, Gichuhi says architectural consultants have been selling the idea aggressively to investors.
“Besides reducing carbon footprints and regulating the buildings’ temperatures, roof gardens improve the scenery by cutting the monotony of run-on mabatis and tiles,” he observes. “For these reasons, high-rise developers should be compelled to dedicate a fraction of their buildings to a garden, especially in the roofs.”
To jump-start the culture of green roofs in Kenyan urban centres, he says the up-coming Konza and Tatu cities should stipulate that every roof should have some greenery. “If need be, the Ruiru and Mavoko county councils, under whose jurisdiction these mega projects fall, should draft a law that will make green roofs mandatory,” Gichuhi adds.
Through simulations, Japanese scientists established that, if 50 per cent of high-rise buildings in Tokyo had roof gardens, they would reduce their internal air temperatures by almost a degree, with owners saving about $1.6 million dollars (Sh128 million) per day in electricity bills.
Construction of roof gardens is only possible where the roofing is flat, a concept that most green architects advocate for because, besides the ability to accommodate a garden, flat roofs also use less timber, hence reducing the number of trees that have to be felled.
Unlike in Southern Africa, where roofing styles are influenced by traditional flat-roofed concepts, East, Central and Western African building designs have high roof pitches which are more costly.
“Most of our styles follow the 1967 Building Code, which was heavily influenced by Europeans, whose roofs are made steeper in order to shed off snow during winter,” he says. “My hope is that the current Building Code that is awaiting approval by Parliament is drafted to reflect methods that are appropriate to our environment.”
Francis Gichuhi Kamau, Architect.