Operational Response Characteristics of Electronic Heat Cost Allocators: An In-Depth Single-Node Case Study

This study investigates the operational response of a two-sensor electronic heat cost allocator (HCA) installed on a high-inertia cast-iron radiator in a multi-family building. Over 164 days, reference temperatures recorded at 2-s intervals and aggregated into 30-min means were used to estimate radiator heat emission and compare it with the dimensionless units registered by the HCA. Zero allocation units were recorded on 50 of 95 days (52.6%) with positive model-based heat-emission estimates. These days accounted for 39.9% of the total estimated heat emission; after excluding the initial 24-day low-flow period, the corresponding share decreased to 10.6%. The daily Spearman rank correlation increased from 0.597 for the full period to 0.828 after this exclusion. The proposed Energy-to-Allocation-Unit Ratio (EAUR) varied from 0.20 to 4.042 kWh/unit across months, indicating substantial changes in the relationship between estimated emission and registered units. Comparisons with a theoretical allocation model revealed further differences, potentially related to transient thermal conditions, model limitations, and undisclosed HCA algorithms. As this was a single-node case study, these findings cannot be generalized to other devices or buildings without further investigation.