Conceptual decision support model for retrofiting energy consuming equipment in existing buildings by considering LCA of waste hazardous substances

Abstract

The budget spent for retrofitting low energy efficiency equipment in buildings is normally planned after financial consideration of an internal rate of return and a simple payback period. The retrofitting has typically been done under forces from both mandatory and voluntary schemes in which an environmental review usually has not been considered. One of the overlooked aspects within the energy conservation measures is the cost of hazardous waste management from the removed. To facilitate consideration of all inventories and impacts, LCA (Life Cycle Analysis) is a good approach covering an environmental aspect,particularly hazardous waste, throughout the life cycle from raw material preparation, removal of existing equipment, installation, to appropriate waste disposal. This study takes into account only Hg in fluorescent tubes and CFC in air conditioners as representative of the wastes due to their potential emission during retrofitting. The LCA result is used to construct a conceptual decision making model, named ENVIROGY that clearly shows the components and structures of investment in retrofitting. In the model developed ENVIROGY is composed of energy, net waste recycling, violence impact from hazardous waste, investment for retrofitting, risk in terms of money, operating impact, gevernment intervention, and yeild from CDM (Clean Development Mechanism) by the UNFCCC (United Nation Framework Convention on Climate Change). The calculated ENVIROGY shows that for the whole lifetime of a retrofitting of 36 Watt fluorescent lamp, an investor has to pay for a net internal and external cost of -1,483 Baht/10 years. The value of ENVIROGY is -1,272 Baht/10 years for the base case which accounted only for energy consumption and investment for retrofitting. Likewise, a 12,000 Btu air-conditioner, ENVUROGY value is -56,572 Baht/10 years whereas the value of ENVIROGY is -46,962 Baht/10 years for the base case. The cost difference of ENVIROGY compared to base case should be managed by government at the phase of initial application for retrofitting. The ENVIROGY approach can be applied to other energy comsuming and conserving equipment.