Life cycle cost optimization for schools energy retrofit under climate change: Methodological approach and analyses in five different climates

The energy renovation of existing schools has become a priority, to address which cost-effective retrofit strategies should be identified, considering the unavoidable climatic changes, to maximize the benefits during the whole service life. This paper presents a methodology useful for comparing different retrofit proposals by adopting a cost-optimal approach, in which the effects of future climate variations on energy needs were also considered. The methodology was applied to school buildings located in Italy, considering 5 different cities, with the aim of assessing whether an over-performing building − exceeding the minimum regulatory requirements − could provide economic benefits, considering future climatic evolutions and consequent energy needs variations. Different retrofit measures (active and passive) were identified, each of which was associated with different performance targets, starting with those required by the current national energy standard. Accordingly, 900 retrofit proposals were compared against a baseline retrofit option, that brings the building into compliance with current regulations. Optimal solutions were found through a single-objective optimization, performed combining Python and EnergyPlus, which aimed to minimise the global cost of the intervention over a 30-year time horizon. The evolution of climate conditions was also considered in this time interval, generating future weather files on the basis of the most recent SSP5-8.5 scenario. Results highlighted the importance of careful selection of retrofit measures, showing that exceeding regulatory standards does not automatically lead to economic benefits.