Post Occupancy Energy Efficiency and Indoor Environment Performance in Selected Commercial Buildings in Nairobi, Kenya (Pages: 68-75)

David Nzioka Mulei1, Paul Mwangi Njogu1 and David Wafula Wekesa2

1Institute of Energy and Environmental Technology, JKUAT, 63000, Nairobi, Kenya; 2Department of Physics, Multimedia University of Kenya, 30305, Nairobi, Kenya





Abstract: The cost of electricity and health of occupants inside buildings has led to an increased need for sustainable green buildings. The construction industry has come up with designs, construction and occupancy guided on sustainable principles. In Kenya, a few buildings have been built with such guidelines. It is imperative to conduct post-occupancy studies to ascertain that the green buildings are sustainable. This study sought to evaluate energy efficiency and indoor environment performance in green buildings. A total of four buildings, two green and two non-green, were considered in this study. Energy efficiency were determined using electricity bills provided by Kenya Power while indoor and outdoor carbon dioxide (CO2), relative humidity and temperature were measured using Carbon dioxide meters’ model HT-2000. The study found that energy consumption in green buildings was significantly different from that of non-green buildings (p_=_1.18E-12), but consumption for non-green buildings was not significantly different (p=0.7). Average mean CO2 concentrations in green buildings were 534 ppm and 608 ppm and 689 ppm to 695 ppm in non-green buildings. Mean temperature levels in green buildings were 210C and 250C and 230C and 260C in non-green buildings. Mean relative humidity in green buildings were 53% and 55% and 58% to 60% in non-green buildings. Mean airflow rates (ventilation rate) for green buildings were 0.06h-1and 0.03h-1 while non-green buildings were 0.006h-1 and 0.003h-1.

Keywords: Green building, Carbon dioxide, Relative humidity, occupants, temperature, correlation.