Ratio of Operating and Maintenance Costs to Initial Costs of Building Services Systems

This article addresses two critical issues associated with reliability and maintenance of building services systems. The first is the ratio of operating and/or maintenance costs to initial costs for building services systems. It is an important parameter for life cycle costing and maintenance policy development. The second is the proportion of items among building services systems that need preventive maintenance. In this article, the example used is to estimate the ratios based on a cost dataset. Correctly estimating the ratio is important, but using a constant ratio in life cycle costing may result in wrong decisions. The proportion of preventive maintenance for building services systems is estimated on the basis of the distribution of failure patterns.