Re-sizing energy retrofits for low-temperature district heating

Abstract

To connect dwellings to sustainable low-temperature district heating (LTDH), it is typically recommended that dwellings with low or moderately insulated envelopes undergo deep renovation. These recommendations are grounded in standardized assumptions about thermal comfort, which do not reflect the diversity of residents' heating practices. As a result, deep retrofit interventions often prove costly, highly disruptive, and may fail to achieve the projected energy savings. This study addresses this gap by integrating residents' heating practices into retrofit decision-making to reassess the scale of renovations necessary for LTDH readiness. Using a Dutch terraced house as a reference case, we apply a multi-criteria framework combined with parametric simulations to evaluate renovation strategies in terms of thermal comfort, heating savings, environmental impacts, costs, and resident nuisance. The results indicate that although deep retrofits with full radiator upgrades emerge as the most technically robust solution, their benefits are not distributed equally across resident profiles. For households with economical heating behaviour, deep renovation yields significantly lower-than-expected savings and carbon reductions, and considerably longer payback times. Conversely, less intensive strategies, such as radiator upgrades alone or combined with single or moderate retrofit packages, are technically sufficient to enable connection to LTDH, often at lower cost and reduced disruption. Rather than converging to one standardized solution, the analysis identifies up to 28 viable retrofit pathways depending on the resident profile. These findings challenge the prevailing one-size-fits-all deep renovations and demonstrate how integrating residents' practices can resize renovation, supporting flexible, resource-efficient, and socially just pathways toward low-carbon heating transitions.