Comparison of predicted design efficacy and environmental assessment for tuberculosis care facilities in South Africa

Abstract

The impact of Tuberculosis (TB) is of epidemic proportions in South Africa (SA) being one of the developing countries. Furthermore, studies seem to indicate that health care facilities are contributing to the spread of Mtb (Eshun-Wilson et al. 2008). The contribution that the built environment has on airborne transmission, combined with erratic energy supply and the international sustainable agenda raised the need for research investigation for passive design building response for airborne contagion. Natural ventilation uses buoyancy or wind as the driving forces for air movement. In this paper Computational Fluid Dynamics (CFD) models were used to find out the optimum design for naturally ventilated Tuberculosis (TB) ward designs. Natural ventilation can reduce the concentration of airborne pathogens through removing and diluting airborne droplet nuclei. The effect of different parameters such as roof angle, window type and size, positioning of closures in the permanent ridge ventilators on natural ventilation performance were studied. The results indicated that the correct combination of the parameters mentioned can significantly improve the natural ventilation effectiveness. Tracer gas tests using carbon dioxide (CO2) were subsequently conducted for the real spaces with natural ventilation systems as designed using CFD to establish the actual ventilation rates achieved. The ventilation rates results indicate generally good to excellent ventilation rates especially in the coastal regions. These rates are in line with the recommended rates as per the World Health Organisation (WHO) and Centres for Disease Control (CDC). A Post Occupational Evaluation (POE) was undertaken through qualitative questionnaire and site assessment to evaluate the impact and potential success of the as built modelled design. It is evident though the various staff interviews and project team discussions that the new facilities have improved nursing standards and patient ward standards.