Budget-constrained maintenance in the building industry

Given records of building component renewals which occurred during the year and also the age profile of the building stock, the theory of alternating renewal processes in discrete time is used to deduce the underlying probability mass functions of the natural lifespan of building components and of delay due to limited resource. In an investigation into the economics of renewal delay, the expected number of component renewals in each year of the life of a building is deduced from the convolutions of the probability mass function of natural lifespan: these expected numbers depend on the chosen delay. The net present value of the expected cost associated with each specified delay is calculated, so that a judgement can be made as to the optimum delay (if any). These calculations are conveniently performed using a spreadsheet macro.