Staged envelope renovation and heating optimisation in an existing nonresidential building: An anonymised secondary analysis of modelled energy demand

Renovation roadmaps frequently express the benefits of successive interventions as cumulative savings, although implementation decisions also require an understanding of each stage's conditional contribution. This paper examines four nested renovation packages for an existing nonresidential building using a single energy consultancy report. The study is a secondary analysis of reported calculations, not an independent building simulation or a post-occupancy evaluation. Identifying information is suppressed, and results are expressed predominantly per unit of conditioned net floor area. The packages comprise window and door improvements, roof insulation, basement-related insulation, and heating-system optimisation. Reported final energy demand decreases from approximately 264.7 to 130.7 kWh/(m² year), equivalent to a calculated reduction of 50.6%. The four successive additions contribute approximately 34.4%, 30.7%, 22.4%, and 12.5% of the complete package's modelled saving. The envelope package accounts for most of the reduction in useful energy demand, whereas the last stage primarily reduces system losses. After renovation, ventilation and opaque-wall losses become prominent relative to the reduced roof and window losses. These findings identify priorities within the documented sequence but do not establish an optimal order of construction. Unverified model inputs, the absence of metered validation, and the exclusion of embodied impacts restrict interpretation. A verification framework is proposed to connect the reported scenarios with envelope detailing, hydraulic commissioning, and subsequent monitoring. The case illustrates how a privacy-conscious reanalysis can turn a consultancy output into an explicit and reproducible account of renovation mechanisms without representing calculated savings as observed performance.