Building a Greener Future: Eco-Friendly Architecture

Green architecture revolves around a philosophy of using sustainable energy sources and conserving energy, recycling building materials, and respecting the environment by considering the impact a building will have on the world around it. In many respects, it’s nothing new. But as the stakes for human survival increase, so too, does the multiplicity of solutions being put into action.

Green may be a mere buzzword for many of us, but architects and eco-crusaders are taking their role in changing the future very seriously. Many realise that our future depends on a radical rethink and tangible efforts to conceptualise our built environment according to different criteria. Most reliable sources say that buildings now account for just under 40 % of carbon emissions.

Earlier this year South Africa saw its 50^th Green Star certification by our own fledgling Green Building Council (www.gbcsa.org.za). This certification hints at growing respect for the need to build sustainably. The good news is that going green needn’t cost the earth and many of the solutions aren’t based on high-end, futuristic engineering, nor state-of-the-art materials. Some require a simple reconsideration of our most basic resources, reusing what we have, or even putting our faith in fast-growing crops that transform into excellent building materials.

Imitating Nature

Zimbabwean architect, Mick Pearce (www.mickpearce.com), is globally recognised for his prodigious use of biomimicry, which imitates nature to achieve more effective and sustainable architectural solutions. Pearce’s design of Harare’s Eastgate Centre – Zimbabwe’s biggest office and shopping complex – is a large-scale example of

using technology inspired by the self-cooling mounds of African termites. Opened in 1996, it replicates the termites’ ventilation system, creating energy-efficient cooling for the building without any conventional air-conditioning. Instead, it uses passive cooling, storing heat in the day and venting it at night as temperatures drop. The ventilation system costs one-tenth of what conventional air conditioning for a building of its size might cost, and the building consumes 35 % less energy.

Material Gains

Cement is said to account for 6 to 8 % of global carbon dioxide emissions. Production of steel for reinforced concrete also has a major environmental impact. This suggests that cement should be used more sparingly, and that alternatives require urgent consideration.

Capetonian eco-campaigner, Tony Budden, has long advocated for the use of hemp (www.hemporium.com) as an alternative building material. To demonstrate its potential, Budden built his own Hemp House in Noordhoek. Completed in 2011, Budden’s is the first African house built using industrial hemp, which is now being used fairly widely in parts of Europe where hemp is cultivated for industrial use. Not only does hemp have a speedy growth cycle, but it thrives on little water, and is eco-friendly. It’s also considered a “mop-crop”, meaning that it is able to purify and rejuvenate contaminated soil that has been depleted by other crops. Growing hemp generates very little waste, and what there is, is entirely biodegradable.

The house was fashioned from a range of industrial hemp materials, including hempcrete, hemp plaster, hemp insulation, and hemp chipboard. A green alternative to concrete, hempcrete is a combination of hemp stalk chips, a lime-based binder, and water. It’s lightweight, yet strong, and possesses incredible thermal and insulation properties. When lime is added, the carbon in the hemp combines with the calcium in the lime, forming very hard calcium carbonate, similar to sea shells and coral. What’s more, hempcrete stores carbon, rather than emitting it into the atmosphere. Each ton of hempcrete traps the equivalent of 330 kg of carbon dioxide, acting as a “carbon sink”. It’s believed that building with hemp can save in the region of 50 tons of carbon dioxide emissions per house.

Beyond its hemp construction, Budden’s house has a green roof, energy-saving LED lights, a solar geyser, proper insulation, and interior climate-control by means of thermostat-driven motors that automatically open and close windows. Budden reports that his winters have been warm and his utility bills extremely low. What he wants, though, is for the building model to be widely replicated. Industrial hemp-growing trials are currently underway in South Africa.

Passive Resistance

In so-called “passive houses”, heat and energy loss is reduced by trapping solar heat along with the energy created by occupants and household devices. The trick, really, is to keep that heat inside and put it to use. Buildings functioning in this manner follow diurnal temperature changes so that the internal temperature remains constant. Typically, this is achieved by double-glazing (or even four-glazing) windows, ensuring that the building is extremely air tight with excellent insulation of walls, roofs, and windows.

To ensure maximum insulation of No. 1 Silo at the V&A Waterfront in Cape Town (www.vdmma.com), the entire glass façade is double-glazed for interior temperature regulation and to retard heat loss. This is but one of many measures taken to help make Allan Gray’s headquarters the country’s largest six-star green-rated building. The glass façade serves an energy-saving function by relying as much as possible on inbound natural light rather than artificial lighting. To optimise this, the sun’s path is tracked by automatic blinds.

 

Many of its best design innovations, though, are based on practical reconsideration of available resources, such as using easily available cold seawater from the adjacent Atlantic to cool the building. Meanwhile, heat generated by the IT server room provides under-floor heating in the lobby.

Traditionally a common source of so-called “sick building syndrome” elsewhere, conventional air conditioning at Silo No. 1 has been replaced by a system of displacement ventilation that circulates fresh air drawn directly from outside. Water management is another key issue, so there’s a grey water system that recycles used shower and wash basin water into the flush toilets.

Don’t think it’s only big business that can afford to go green, though. In fact, budget-restricted facilities and publically owned buildings **must** necessarily incorporate sustainable practices that not only reduce running costs, but will ensure long-term feasibility. Port Elizabeth’s Helenvale Multi-Purpose Community Centre, for example, incorporates both passive and active measures to ramp up sustainability, reduce carbon emissions, and conserve energy wherever possible. Measures include automatic management of lighting to reduce electricity wastage, rainwater harvesting, and “super-insulation” of walls and roofs.

Out of the Box

For a school in Alexandra, Johannesburg, Architects of Justice (www.architectsofjustice.com) have designed a fantastical semi-permanent library, known as Seed (Supplementary Extended Education Device). It expands on the idea of repurposing disused shipping containers by stacking two of them perpendicularly to form a two-storey, cross-shaped structure. Books are kept in the ground-level space, with reading rooms upstairs. To enhance the structure, it was retrofitted with proper insulation, and mechanisms for cross-ventilation and passive cooling were added. This modular construction model means that it can be moved easily, while the ready availability of discarded containers makes it replicable, meaning libraries can be set up in multiple locations.

<Sidebar> Sustainable Stays: Africa’s Greenest Hotel

Adjacent to Cape Town International Airport, Hotel Verde (www.hotelverde.co.za) was designed to incorporate alternative strategies for reducing waste, and conserving energy and water. The list of solutions is inspirational.

Water recycling: A grey water plant biologically filters and UV-sterilises used bath and shower water, that’s recycled for flushing toilets and washing cars.

Rainwater harvesting: Rain water is collected in a 40,000 litre basement tank. Subsoil drainage water is also collected and used for outdoor watering and cleaning.

Concrete reduction: Some 1,279 tons of concrete were spared during construction by inserting 100 % recycled polypropylene balls into concrete slabs. These balls displace concrete without compromising structural integrity and dramatically reduce the amount of concrete required, consequently reducing carbon dioxide emissions by over 100 tons.

Geothermal air conditioning: The hotel uses a geothermal field, with piping that reaches 65 metres below the surface of the earth to warm the building in winter and alleviate excess heat in summer.

Wind and solar energy: Three on-site wind turbines contribute renewable energy, while photovoltaic panels on the hotel’s northern façade and roof contribute solar power to offset grid power reliance.

Ecological swimming pool: The hotel Eco Pool works as a living eco-system, utilising plants and organisms to keep the water clean and eliminate algae growth.

Plant wall: A “living wall,” watered by drip irrigation, thrives inside the hotel, contributing to cleaner, better oxygenated air.

Energy-recycling elevators: The hotel’s three regenerative drive elevators have motors that can act as generators and actually produce power. They recapture almost one-third of the energy used to operate them, which is distributed back to the building.

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