African Design Magazine December 2015 - Page 18

design meant that this building was the first ‘passive tower’ in Nairobi. Important environmental design features include the solar control envelope, comprising of vertical and horizontal aluminium fins, while the landscaped sky courts will allow for natural ventilation through the building and the atrium. The environmental impact of the building design, construction and operations industry is enormous. Buildings consume more than 30% of the total energy and more than 60% of the electricity used in Kenya. “Green buildings can substantially reduce energy consumption while reducing or eliminating negative impacts to the environment. The design and construction of the Kenya Commercial Bank takes all environmental concerns seriously, and all systems have been designed to ensure minimum damage to the surrounds,” says Eric Loki, Architect at Planning Systems Services Ltd in Nairobi, Kenya. The hard bed rock in the Upper Hill area was the biggest challenge during the early months of construction, calling for ingenious ideas help make up for lost time. This was accomplished through the use of a precast concrete waffle floor system. On top of this, a 24 hour working day system was implemented to ensure speedier construction, with a floor completed every 10 days. “This building benefits greatly from green operations and maintenance-reducing operating costs. There is also enhanced building marketability, increased worker productivity, and reduced potential liability resulting from indoor air quality problems,” Loki added. Another major challenge was the location, as the site was on a flight path which meant a height limitation had to be imposed. KCB needed to make a compromise to ensure the full potential of the building site was used for it to make economic sense. The solution Nairobi’s tropical climate presents an interesting paradox: ambient natural light in the form of direct sunlight is abundant, yet very little of this light can penetrate interior spaces without leading to either overheating or glare. Since half of solar radiation is infrared (which causes heat), cutting direct sunlight to reduce overheating always results in a dramatic decrease in daylight levels. This leads to even darker interiors, particularly in contrast to the very bright exteriors. Various solutions to ensure adequate and well-distributed daylight levels in the building include the use of light reflecting finishes on the solar shading fins, high light transmittance glass and louvered horizontal shading. The horizontal shading components also act as maintenance platforms for cleaning and repairs, providing a sustainable all-round solution. 18 Further green elements include: • Rainwater collection and treatment, and a water recycling system to lower running costs. • Exposed concrete waffle floor systems will absorb internally generated heat during the day, and cool down at night. • Three sky courts, each within the three “fire compartments”, are created to limit the spread of fire and smoke. They allow air movement into the building and up through the atrium.