HVAC Design in Kenya: Ventilation and Cooling

Kenya spans very different climates. Many buildings in Nairobi and the highlands are comfortable for most of the year with good natural ventilation and shading, and need mechanical cooling only in specific spaces such as server rooms, kitchens or meeting rooms. On the coast, in Mombasa and Kisumu, heat and humidity make cooling and dehumidification a year-round question.

The cheapest cooling is the load you never create. Orientation, roof insulation, glazing area, external shading and cross-ventilation reduce the cooling a building needs before any equipment is chosen. We review these with the architect at concept stage, when changing them costs almost nothing, then size the mechanical system for what remains.

A cooling load calculation adds up heat from the sun through walls, roof and glass, from people, lighting and equipment, and from outside air brought in for ventilation. It is what tells you whether a room needs 2 kW of cooling or 5 kW. Installers who choose equipment by floor area alone often oversize, which costs more to buy and run and can leave rooms humid and clammy, or undersize, which leaves them hot.

The design also covers ventilation rates, where fresh air enters and stale air leaves, duct sizes, outdoor unit locations with enough clearance to work, condensate drainage, and electrical supply to the equipment. That last point matters: it feeds directly into the electrical design so the distribution board and cables are sized for it.