Theoretical study evaluating renewal of an air-conditioning system

Abstract

Evaluating an air-conditioning system (or units comprising the system) renewal plan is an important task for facility managers. For each renewal, it is necessary to judge the renewal time, maintain equipment, and optimize economic efficiency. This study aims to obtain a theoretical method to evaluate the renewal plan for an air-conditioning system or the unit thereof. This paper shows how to derive the probability density function to determine the need for renewal as a mathematical model to estimate the renewal time. These models can be evaluated from an economic perspective when making two types of investment decisions. 1) Whether to renew one unit of the air-conditioning system at some point, 2) Whether to renew the entire air-conditioning system configuration or keep the existing one. The life of air-conditioning equipment that facility managers should consider includes economic service life brought by obsolescence and useful life provided by deterioration such as wear and corrosion. The unit renewal assumes that these two lifespans may be close to each other. Therefore, we need to plan for the relevance of these renewals. This renewal model also includes a probability density distribution that shows the unit's future renewal prospect currently in use.