Balancing Maintenance Costs and Degradation Levels in Building Elements

Abstract

Maintenance strategies require a balance between maintaining assets at acceptable levels of service and minimizing maintenance costs. The latter is imperative especially for building elements, since they require less maintenance than machinery, and carrying out such maintenance can be disruptive and costly. This paper reports an inquiry into optimal maintenance strategies for 12 building elements, ranging from structural through finishes and opening to services ones, each with a differing service life. Element degradation was predicted using Markov chain models, while repair costs were based on lost value ratios associated with five discrete condition ratings, separately defined for each of the elements. The strategies considered were based on three different criteria, namely, minimizing maintenance cost, achieving the best the overall condition rating at end of service life, and optimizing a rating that combined both cost and quality. The maintenance cycles considered were 5, 10, and 20 years, and also the zero-maintenance case, costed at both zero and 5% net discount rates. The repair combinations involved upgrading elements in a single given Condition 2, 3, 4, or 5 to the as new Condition 1 or upgrading elements in all such conditions to Condition 1. It was found that performing regular maintenance on concrete slabs, floor tiles, timber windows, and especially ceiling fans and fan regulators was in fact cheaper than not maintaining them (and having to renovate at the end of service life), while a 20 year cycle was found to be optimal for the other elements studied.