Taking a tip from the termites

Drawing on the exquisite engineering abilities of termites, the new Alpine House, a glasshouse at the Royal Botanical Gardens at Kew, is the first building in the UK to use an evolved labyrinth cooling system. Designed by Atelier ten environmental consulting engineers, the system maintains the plants in near-alpine conditions, without the need for refrigeration.

At Kew, Atelier ten has developed the labyrinth solution combined with perimeter natural ventilation and shading to provide the ideal environment for the plants by replacing the conventional chilled shelves and big opening windows behind the plant beds that maintain the requisite airflow.

Since 1996 the company has been developing ideas for remote thermal storage, in the form of labyrinths and earth ducts, to exploit the passive heating and cooling effect available from the ground.

It did not come up with the idea first, though, termites did. Using soil mixed with saliva, these ingenious builders erect tall towers with complex duct systems that regulate airflow and fend off the African and Australian heat. For food, termites grow fungus in combs made from their own droppings. As the fungus breaks down the fecal matter, hot air is generated, which would turn the termitary into an oven were it not for their sophisticated, and completely passive, HVAC system.

Hot air rises through long, perforated stacks, releasing its carbon dioxide and taking on oxygen from the outside. It cools and sinks again to the core of the nest. This system keeps as many as three million termites comfortable. To illustrate their skill as architects, builders and engineers, the height of their nests, calculated in human terms, would be more than 180 floors.

using soil mixed with saliva, termites erect tall towers with duct systems that regulate airflow and fend off heat

Atelier ten is working on a number of other schemes throughout the UK, the US and Eastern Europe. The technology is still a rarity in the UK despite having been proven in other parts of the world.

The Kew Alpine House, designed with architect Wilkinson Eyre, makes use of the basic idea that air is exposed to a large surface area of concrete on its way into the building by passing at low velocity through a labyrinth of some 30 m in length, beneath the structure. The walls of the tunnel are cooled by night air and store it until it is needed to cool down hot outdoor air in the summer.

The Kew labyrinth is simply made from faceted concrete walls that form long air paths. The cool night air flushes the heat of the day out of the concrete, along with some of the moisture, so that the mass is cool again for the following day. The flow of air can be controlled through the various chambers to provide some responsiveness to external conditions. The labyrinth also eliminates the need for cooling in this space, which maintains comfortable temperatures even when it is up to 30°C outside.

Kew is a pioneering example of how alternative energy systems can be used to achieve environmentally responsible solutions to high CO2 emissions that contribute to escalating climate change problems.