Evaluating Energy Calculation Methods for Energy-conscious Occupants in Three Belgian Heritage Townhouses

Achieving the EU's carbon-neutral target by 2050 requires a significant reduction in energy use within the building sector, which accounts for 40% of the total energy use. European historical cities, particularly heritage townhouses, pose a unique challenge due to their architectural and cultural value. The EU-Horizon project HeriTACE is addressing this challenge through a holistic renovation approach. This study investigates the impact of energy-conscious occupant behaviour on primary energy use for space heating in heritage townhouses in Ghent, Belgium. Three realities are compared: energy performance calculations, dynamic simulations, and actual energy use measurements. The energy performance calculations, based on the Belgian EPB software, tend to overestimate energy use by assuming a continuous heating system and a constant indoor temperature of 18°C. Dynamic simulations using Modelica incorporate actual occupancy behaviours and flexible heating patterns, leading to significantly lower energy use estimates. This actual heating patterns are derived from indoor temperature measurements in the case study buildings. Real energy use data, derived from energy bills, reveals that actual consumption can be up to seven times lower than EPB calculations. The findings suggest that dynamic simulations, which account for realistic occupant behaviours and lower comfort expectations, are more accurate in predicting energy use and are essential for developing effective renovation strategies for heritage townhouses.