AN ASSESSMENT OF SINGLE-SIDED NATURAL VENTILATION POTENTIAL OF FORT BEAUFORT, SOUTH AFRICA

Abstract

Natural Ventilation Potential (NVP) is the possibility to ensure acceptable indoor air quality and thermal comfort through natural ventilation only. Natural ventilation is possible if the building envelope is strategically oriented in such a way that the occupied zone can harvest relevant quantities of wind and solar commensurate with seasonal needs. Strategic orientation of the building envelope is a requirement that calls for a site specific natural ventilation potential assessment prior to construction. However, site specific natural ventilation assessment may increase construction costs and even delay the construction exercise. Knowledge of the Natural Ventilation Potential of the host region is therefore fundamental as it gives an overview of how the ventilation system will perform under different weather conditions. The paper presents an assessment of the natural ventilation potential of Fort Beaufort and identifies ideal geometrical orientation of buildings for optimum use of wind and solar energy for natural ventilation. The Pressure Difference Pascal Hours concept was used to quantify natural ventilation potential of Fort Beaufort. It was observed that inlet openings should be concentrated on the South while outlets should be on the North for optimum wind induced natural ventilation. Also, the inlet openings should be avoided in the range 230o-260o so as to protect occupants from cold winter winds but concentrated within 160o-185o so that occupants can enjoy the cooling summer winds. Average seasonal NVP values are all positive therefore, meteorological conditions for Fort Beaufort are suitable for natural ventilation.