Controlled Night Ventilation for Cooling-Demand Reduction in Bahraini Residential Buildings: A Mixed-Mode Simulation Study

Residential electricity demand in Bahrain is strongly shaped by long cooling seasons, high air-conditioning dependence and the operation of standardised housing typologies. This paper evaluates the energy and comfort implications of applying a controlled night-ventilation mixed-mode strategy to a representative Bahraini Ministry of Housing residential unit. The study compares two DesignBuilder/EnergyPlus scenarios: S0, a replicated closed-window baseline with split air-conditioning at a 24 °C cooling setpoint, and S1, a controlled mixed-mode case in which windows are available only during night-time periods when outdoor conditions are suitable for passive cooling. The base model is grounded in a published and validated Bahraini residential dataset containing geometry, construction properties, schedules, HVAC assumptions and monthly electricity bills, and was cross-checked against this dataset (see Methods for the monthly error statistics used to qualify this comparison). The replicated baseline produced 34,729.46 kWh/year, which differs from the published reference value of 34,720.19 kWh/year by only 0.027%. The S1 case reduced annual simulated electricity consumption to 33,593.04 kWh/year, corresponding to a saving of 1136.42 kWh/year, or 3.27% relative to S0. The benefit was highly seasonal: January, February, March and December accounted for 96.2% of the annual saving, while May to September showed no meaningful reduction. Hourly January outputs showed 425 zero-cooling hours out of 744 h (57.1%), cooling electricity of 87.32 kWh and a mean operative temperature of 23.81 °C. January thermal-comfort indicators (mean PMV +0.94; only 0.5% of hours within the ±0.5 PMV band) show that the strategy delivers real electricity savings but does not, on the PMV metric, guarantee acceptable comfort in every hour; the strategy is therefore best understood as a seasonal, humidity-aware operational measure that reduces cooling electricity in cooler months while carrying a thermal-comfort trade-off that requires either a tighter control-temperature threshold or explicit acceptance of a wider comfort range. Because the strategy yields no savings during the peak summer months, it should be positioned as a complement to—not a substitute for—envelope and HVAC-efficiency upgrades, and its economic case under Bahrain’s subsidised electricity tariff is modest and is presented here as indicative potential rather than a demonstrated payback benefit. By reducing residential cooling electricity without requiring building-fabric retrofit, the findings support the United Nations’ Sustainable Development Goals (SDGs), particularly SDG 7 (affordable and clean energy), SDG 11 (sustainable cities and communities) and SDG 13 (climate action), by contributing to sustainable, low-carbon operation of the residential building stock in hot–arid Gulf climates.