Design challenges in implementing a building energy management system

Abstract

Since the Koyoto protocol was presented almost a decade ago, a great deal of effort has gone into spreading global awareness regarding greenhouse gas emissions and the negative effect it has. South Africa joined the race in 2007 with the founding of the green building council of South Africa. South Africa also adopted the Australian Green Star rating in order to rate buildings based on this rating system. With the Green Star rating buildings can be evaluated on a wide variety of factors of which energy consumption is only one part. However, because there is no penalty system in place and the Green Building Council of South Africa is a voluntary organisation; many developers do not invest in creating green buildings. Due to the recent increase in electricity tariffs, developers and end-users have become more energy conscious and are motivated to reduce their overall building energy consumption, rather than creating a green building. The literature review revealed that the control of light switching through occupancy sensors is an effective method to reduce a building’s overall energy consumption. The review further indicated that a saving of between 20 – 26% can be expected for office buildings. In the case study this energy saving method was expanded to include the HVAC system for offices as well. Due to initial capital investment constraints a large amount of the installation components for the control system was significantly reduced. The associated limitations of the system were not properly conveyed causing misconstrued expectations of the capabilities of the system. During the commissioning period extreme difficulty was experienced due to the reduced scope of the installation, and commissioning of the system became a tedious and lengthy process. This also created difficulty to determine the overall success of the installation of occupancy sensors as an energy efficiency measure. Even though the results were not definitive, it was clear that the occupancy sensors did improve the overall energy consumption of the building, when compared to other energy efficient technologies.