# Growing Kratky Basil in Trombe Wall Cavity: Energy Performance
### Research Parameters, Hypothesis, and Goals  
This study aims to explore the possibility of using the Trombe wall cavity to cultivate plants during warmer seasons, or even year-round, while maintaining its primary function as a heat-capturing device during the cooler months of the year. The proposed solution must be practical, low-maintenance, and environmentally sustainable without disrupting the Trombe wall's energy performance or the building's regular operations.  
To achieve this, the cultivation process can rely exclusively on passive heating using the Trombe wall's residual heat, supplemented by minimal appliances such as surface and cross-ventilation (already in place to ensure the Trombe wall's functionality) and simple watering systems. The setup must be low-cost, energy-efficient, and easy to maintain without requiring specialized staff. The approach prioritizes robustness and flexibility to ensure its adaptability to diverse locations and scenarios.  
The main hypothesis is that the additional plant and water mass within the Trombe wall will moderate temperature extremes, reducing overheating and enabling stable conditions for plant growth. Although this might slightly reduce the heat storage efficiency of the system, the added thermal inertia could offset heat loss by retaining more energy over time. Among the secondary hypotheses, we can mention:  
* Plants and water will absorb some of the heat through evaporation and transpiration, cooling the cavity during the day. Increased humidity from these processes may enhance the microclimate for plants as well. The cooling effects will be directly proportional to the amounts of solar radiation that the Trombe wall receives [71; 72; 73].
* Cross-ventilation will improve air circulation and temperature distribution in the Trombe wall. The air introduced from the outside will increase humidity levels, but may lead to energy loss due to increased air exchange with the exterior.
* The change in the materials and color of the surfaces of the Trombe wall may lead to increased radiative losses at night, despite those being limited by the low emissivity properties of the glazing.
* Plants may adapt to the Trombe wall's environment, though heat stress or nutrient assimilation issues may arise under extreme conditions. The Kratky hydroponic system should mitigate root aeration problems, but overheating and algae growth could still pose challenges.
* The Trombe wall's small size (as compared to the building that it serves to) makes it unlikely to significantly affect the overall building's environment, but it can contribute to energy savings by providing supplementary heat to the existing air-conditioning system.  
The goal of the study is to improve the environmental conditions within the Trombe wall by passive means (thermal mass, shading, evaporation, plant metabolic activities) to make them comfortable for cultivation. A sustainable green Trombe wall should ideally function as a self-regulating, productive system integrated into the building year-round, akin to a natural green space. This vision implies that the system should operate using minimal external inputs, relying instead on resources and energy available from the surrounding environment. In this scenario, the Trombe wall would be capable of supporting perennial plant growth, provide a habitat for local wildlife, and require only basic maintenance and periodic cleaning to remain operational.  
This study is the first to integrate living plants into the Trombe wall cavity and to apply the Kratky hydroponic system in this context. While water Trombe walls and green walls have been studied extensively, the proposed configuration combines energy capturing with plant cultivation, offering practical and scalable benefits. The results presented here could provide valuable insights for both scientific and engineering communities, with potential practical applications in sustainable architecture and urban agriculture alike.