Eastgate Centre, Harare

Glass office blocks are typically expensive to maintain at a comfortable temperature, needing substantial heating in the winter and cooling in the summer.

Passive cooling works by storing heat in the day and venting it at night as temperatures drop.

After computer simulation and analysis, the engineering firm Ove Arup, gave Pearce a set of rules.

They asked for a balance between artificial and external light to minimise energy consumption and heat gain.

They said all windows must be sealed because of noise pollution and unpredictable wind pressures and temperatures, relying on ducted ventilation.

The pink-hued Eastgate Centre, with its distinctive chimneys
Schematic of the natural ventilation of the building