Energy saving potential for a high-rise office building

Abstract

Within the context of this study, a walk-through energy audit was performed for a typical office building in Hong Kong. The focus of energy saving opportunities was mainly on mechanical ventilation and air conditioning (MVAC) and lighting. The emphasis was mainly on more energy-efficient equipment, a better control of the equipment, indoor air quality and human behaviour. Among others, the measures considered to reduce MVAC energy were replacing the air-cooled reciprocation chillers with water-cooled centrifugal chillers; installing variable speed drives (VSDs) for the secondary chilled water pump motors; maintaining the indoor air quality within reasonable limits while monitoring the indoor CO2 concentration to adjust the fan speed of primary air-handling units (PAUs) by VSDs and re-adjusting the temperature setpoint to use less energy for air conditioning; and encouraging environmentally friendly human behaviour within the built environment, especially in hot and humid countries such as Hong Kong. The measures to reduce lighting energy were mainly replacing the lamps with energy-efficient lamps and preventing over-illumination. The results led to the conclusion that an annual saving of around 48% of MVAC and 62% of lighting energy is possible for this building. The measures discussed are also applicable to other similar office buildings in Hong Kong or similar areas, especially to old buildings. Considering that a tremendous amount of electrical energy is consumed by office and other commercial buildings, any measures to reduce the energy use in these sectors will contribute significantly to the reduction of CO2 emissions and preservation of the environment.