This study presents a model for designing and controlling energy-positive facades with radiant floor heating in perimeter zones of commercial buildings. The model integrates bifacial semi-transparent photovoltaic windows, motorized venetian blinds, and hydronic radiant floor heating systems. These components are modeled to optimize energy performance within occupant comfort constraints during the heating season. By implementing near-optimal control strategies for room air temperature setpoints, blind tilt angles, and controlled lighting loads, the perimeter zones achieve improved energy flexibility, efficiency, and thermal and visual comfort. Key design variables such as slab thickness, window-to-wall ratio, and packing factor were analyzed parametrically to determine optimal ranges when subjected to near-optimal control strategies. To evaluate the effectiveness of different control strategies, a specially designed and instrumented test-room at the Future Buildings’ Lab (FBL) was used as a case study. Balancing energy performance with occupant comfort is crucial, as prioritizing one aspect may compromise the other. The combined control of these systems demonstrates enhancements in both energy performance and occupant comfort across various design scenarios. By implementing near-optimal control of the room air setpoint and the blind tilt angle the heating efficiency can improve by 39.6%, the BEFIP was 94.8% and 96.8% in the morning and evening peak periods, all while maintaining occupant comfort on a cloudy and mild day in the heating season. The addition of active solar windows further improves the energy flexibility of the zone. Similarly, in limiting
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weather conditions, such as very cold and cloudy days, the system may achieve significant energy flexibility, reduce energy costs, while maintaining thermal comfort.