Environmental trade-offs in optimally controlled individual and collective heating systems: A life cycle perspective on cluster size, renovation level and control strategy

Collective heating systems using renewable and residual energy sources are promising for reducing the environmental impact of the building stock. However, their environmental impact depends on the balance between shared technical installations and additional distribution losses, which is influenced by cluster size, renovation level and control strategy. Existing Life Cycle Assessment studies focus on individual buildings or rely on simplified operational energy calculations, rarely combining dynamic simulations, optimal control and multi-indicator environmental assessment for collective systems. This study couples physics-based dynamic simulations with cradle-to-grave LCA to evaluate the environmental life cycle impacts (ELCI) of individual and collective heat pump (HP)-based heating systems for clusters of 3, 10 and 20 buildings under three renovation scenarios. Both air-source and ground-source HP configurations are assessed using rule-based control and optimal control. Results show that optimal control reduces total ELCI by approximately 30%–50% compared to rule-based control. This reduction is primarily driven by lower operational energy use. For collective systems, increasing cluster size reduces the per-building ELCI of technical installations through equipment sharing and lower required HP capacity, but this benefit can be offset by higher distribution losses. Consequently, for unrenovated buildings, collective systems show slightly higher (+5% to +7%) ELCI than individual systems. For renovated buildings, however, collective systems showquasi-constant ELCI (−3% to +3%) compared to individual systems. Sensitivity analyses show that unrenovated buildings and rule-based controlled systems are sensitive to electricity-mix assumptions. Overall, results highlight the need to combine heat electrification with an efficient system integrator.