Does postponed retrofitting save money?

Abstract

When a building is to be retrofitted, or refurbished, it is always of importance to study the building as a complete energy system. At least in Sweden, the building process is divided between different professional categories, such as HVAC and ordinary building contractors. It is therefore not surprising that the HVAC contractor wants to maximise his profit by installing large and sophisticated equipment at the same time as the builder or architect wants to design a house with very thick walls and high performing windows. These competing interests will often result in a building where the heating system is not adjusted to the rest of the house, but is instead far too powerful. The recommendation from life-cycle cost analyses has therefore always been to study the building as a whole system and to apply an optimal solution at one specific base year; this is probably always the best solution in order to minimise the life cycle cost, but experience shows that the proprietor of the building often hesitates in doing so. The reason for this is his lack of money. Changing the building into an optimal energy system frequently requires a heavy investment in any one specific year, albeit the best solution in the long run. This paper will discuss what happens to the life-cycle cost when retrofits are postponed so as to fit into the proprietor's “10 yr budget”.