By Edouard Civel, Anna Creti and Marc Baudry.
We show that residential energy use responds non-linearly to modeled efficiency. Using about 126,000 French homes with both bill-based and model-based Energy Performance Certificates, we find that actual energy use in poorly efficient dwellings lies well below modeled need (a prebound effect), while efficient homes track more closely models. Leveraging shifts in building thermal norms as quasi-exogenous variation in modeled need, we estimate local energy efficiency-elasticities. In inefficient homes, shallow upgrades mainly relax comfort constraints ; deep renovations deliver measurable savings. Recognizing these non-linear behavioral responses is essential for evaluating retrofit benefits and setting renovation thresholds.