In hot climates, such as sub-Sahara Africa, window sizing and orientation pose challenges as they add, through solar insolation, to the building cooling energy demand and thus the cause of indoor overheating risk. This risk can be reduced through passive building-design-integrated measures, e.g., optimizing the window size, orientation and solar shading strategies. Through an IDA-ICE building performance simulation tool, the current study explores the impact of window size, optimization and building-integrated PV panels as shading strategies on cooling energy demands in three cities (Niamey, Nairobi and Harare) in sub-Sahara Africa. Results show that thermal comfort and cooling energy demand are sensitive to a window-to-wall ratio (WWR) > 70%, while the need for artificial lighting is negligible for a WWR > 50%, particularly in the north for cities in the Southern hemisphere and the south in the Northern hemisphere. A WWR > 70% in the east and west should be avoided unless shading devices are incorporated. Internal blinds perform better in improving occupant thermal comfort but increase artificial lighting while integrating PV panels, as external shading overhangs reduce cooling energy but also produce energy that can be utilized for building services, such as air conditioning. In this study, the results and implications of the optimization of window size, orientation and building-integrated shading and operation are discussed.

An experimental study was conducted in a room resembling an office in a laboratory environment. The study involved investigating the ability of corner-placed stratum ventilation in order to evaluate the ventilation’s effectiveness and local thermal comfort. At fixed positions, the air temperature, air velocity, turbulence intensity, and tracer gas decay measurements were carried out. The results show that corner-placed stratum ventilation behaves very similar to a mixing ventilation system when considering air change effectiveness. The performance of the system was better at lower supply air flow rates for heat removal effectiveness. For the heating cases, the draught rates were all very low, with the maximum measured value of 12%. However, for the cooling cases, the maximum draught rate was 20% and occurred at ankle level in the middle of the room.

Insulating building envelopes is crucial for maintaining indoor thermal comfort, particularly in large-space enclosures like greenhouses having transparent envelopes. Transparent envelopes allow natural light but challenge temperature regulation due to their low thermal mass and high U-values, which enable significant heat transfer between indoor and outdoor environments. This field study aims to experimentally investigate whether warm wall confluent jets (WCJs) can maintain the required indoor climate conditions in a greenhouse exposed to dynamic meteorological conditions in winter. It analyzed the impact of the airflow rate, number of nozzle rows, and room air temperature setpoint on WCJ heating performance on the ceiling, external wall, and room air. Measurements were performed with thermocouples and constant current anemometers, and the response surface methodology evaluated the effect of design variables on WCJ flow, thermal behavior, and the indoor environment. The results show that WCJs provided recommended air velocities and temperatures indoors, with the airflow rate having the strongest effect on flow and thermal behavior, while the number of nozzle rows had a moderate effect. This study developed response surface models related to room air temperature, ceiling surface temperature, external wall temperature, and supply air temperature. Supply temperatures between 27 °C and 40 °C suggest using low-exergy heat sources, like industrial waste heat, to sustain greenhouse operations during winter.

This study experimentally evaluated the performance of a wall confluent jet (WCJ) cooling system in a greenhouse under real summer and autumn weather conditions. It examined the effects of indoor air temperature setpoint (T_spt), number of nozzle rows (n) on the WCJ diffuser, and external wall shading on WCJ’s cooling performance. Thermocouples and constant-current anemometers measured air and surface temperatures and air velocity, while pyranometers measured solar radiation. The WCJ system dynamically regulated inlet air temperature between 14 °C and 25 °C to counter solar and conductive heat gains, maintaining indoor air temperature within ±1.5 °C of the setpoint. Increasing T_spt by 4 °C reduced inlet cooling demand by 25% but increased indoor air temperature by 20–25% and raised ceiling, wall, and floor surface temperatures by 17%, 20%, and 16%, respectively. Increasing n reduced surface temperatures by up to 8% and indoor air temperature by 6%. External wall shading reduced solar heat gain, lowering interior surface temperatures by 10–30%, peak and mean indoor air temperatures by up to 35% and 15%, and net power peaks by 40%. Autumn conditions reduced cooling loads by 50% relative to summer. Overall, WCJ cooling demonstrates strong potential as an alternative or complementary system for greenhouse thermal regulation without increasing primary energy demand.