ENERGY CONSERVATION AND MANAGEMENT OF BUILDING SERVICES SYSTEMS

Abstract

Energy conservation plays an important role in keeping our economic growth buoyant. Air conditioning consumes the major portion of the total electricity requirement for the operation of typical buildings. It has played a positive role for economic development especially in warm and humid climates like Singapore. Most of the existing buildings have oversized equipment and 99% of the time are not operating at the peak. Energy conservation measures that tackled component by component without considering the overall plant efficiency may not save energy due to component mismatch. Conventional building air conditioning system has been criticized due to energy and resource intensive mode of operation. The research attempts to investigate the factors leading to energy wastage in conventional chilled water plant (CCWP) using one of the academic buildings in Nanyang Technological University as a case study. The aim is to reduce the overall kW per Ton of the CCWP and increase the part load ratio of the operating chiller. The study was conducted using established building energy modeling software DOE-2 together with local weather data and utility energy charges. The study also investigates the feasibility of operating the smaller chiller during night operation and integrating the two chiller plants to improve the part load ratio and reduce the number of operating chillers. Comprehensive parametric studies were specifically carried out to simulate the effects of cost avoiding energy conservation measures and upgrading to energy efficient equipment. The former simulation includes : (a) improved control of chiller performance based on BTU load; (b) increase the chilled water supply temperature setting at 7.7 °C instead of the norm at 6.7 °C; and (c) increase the existing room temperature by 1 °C. The latter simulation includes : (a) using super efficient chiller at 0.48 kW/Ton and (b) upgrading CAV system to VAV system. The basis of optimized selection is the combination of the above mentioned simulation studies and high efficiency motors with VSD control that meets required load with the least energy usage. Through these combined efforts, the overall kW/Ton and part load ratio have been improved with an annual saving of one million dollars. The cost analysis revealed that energy cost accounts for a very large portion of the life cycle cost over its useful life. However, an often over-looked opportunity for energy management exists in basic purchasing. The low capital cost is always the selection criteria as air conditioning system accounts for a very significant portion of the total capital outlay. The benefits of incorporating energy efficiency into procurement decision can result in significant savings in utility payments. Hence, selection of systems should take into account the projected life cycle costs in order to examine the economic viability and financial justification of retrofitting building services. Energy efficiency improvements will be the single most important issue over the next several decades. By using energy efficient technologies, the results will be energy conservation and environmental protection. The response for energy conservation by building owners will result in energy savings in perpetuity. If it is energy wasteful, it remains so for several decades and constitutes a permanent drain on resources. Energy conservation must become part of our way of life.