Stress-Testing Prescriptive Building Thermal Code Under Climate Non-Stationarity: Quantifying the Compliance–Performance Gap in Algiers Residential Buildings

Prescriptive building thermal regulations, premised on stationary climate assumptions, risk masking operational performance deficits as warming accelerates. This study defines and quantifies the compliance–performance gap as the divergence between the climate-driven response of a regulatory criterion and the climate-driven response of the building’s thermal performance over the same transition from a reference climate to a projected future climate. A standardised residential archetype representing the mass-housing stock in Algiers, calibrated against billing data from 177 dwellings and compliant with DTR C3.2/4, was simulated in EnergyPlus under morphed CMIP6 weather files (SSP2-4.5, SSP5-8.5 for 2050 and 2080). The official single-hour compliance test was reapplied alongside time-integrated metrics the code omits: over-heating degree-hours (OHDH28), night-time exceedance hours (NEH26), thermal autonomy (TA) and energy use intensity (EUI). The archetype remained formally compliant under all scenarios, while the summer compliance margin decreased from 7.14% to 0.05%. Under SSP5-8.5 in 2080, OHDH28 increased by 297%, NEH26 reached 98.1% of summer night-time hours, TA decreased from 51.8% to 43.4%, and cooling EUI increased by 351%. Over the same transition, the regulatory response changed by only 7.6%, yielding divergence ratios of 38.9 for OHDH28 and 45.9 for cooling EUI. Present-day compliance with thermal regulations does not ensure building resilience under future climate conditions. A staged transition toward time-integrated performance metrics and climate-linked revision cycles is necessary to improve the climate resilience of prescriptive codes, particularly in Mediterranean climates (Köppen Csa).