• Energy Research

This experimental study explores the possibility of using an existing Trombe wall as a space for year-round cultivation to increase building resource efficiency. To do so with the least cost to the building, a small 0.75 m2/5.45 m3 Trombe wall cavity space was retrofitted with shelves placed behind the glazing, additional ventilation, and a watering network to be able to grow 400 hydroponic Kratky basil plants in individual glass jars. Historical thermal observations made at the site over a year-long timespan were contrasted with the experimental readings. When fully equipped, the Trombe wall’s thermal mass increased by 51%, which had a balancing effect on the system, lowering the average daily thermal oscillations from 35.41 °C to 17.88 °C. The living plants and water have also had significant cooling (26.99 °C to 22.91 °C) and humidifying (39.88 to 47.74%) effects. The system’s energy efficiency, however, decreased from 26 to 18% (absorption) and from 85 to 46 (dissipation), lowering its energy contribution to the building by about 30%. The average plant’s lifespan within the Trombe wall was 46 days, with 15% of the specimens surpassing the 100-day mark. Over the course of a year, 20.55 kg of edible greens were grown in the Trombe wall. The experiment has shown that it is possible to grow the plants inside the Trombe wall cavity during the warmer half of the year, revealing many possible ways to improve the space’s comfort, yields, and energy efficiency.

This experimental study explores the possibility of using an existing Trombe wall as a space for year-round cultivation to increase building resource efficiency. To do so with the least cost to the building, a small 0.75 m2/5.45 m3 Trombe wall cavity space was retrofitted with shelves placed behind the glazing, additional ventilation, and a watering network to be able to grow 400 hydroponic Kratky basil plants in individual glass jars. Historical thermal observations made at the site over a year-long timespan were contrasted with the experimental readings. When fully equipped, the Trombe wall’s thermal mass increased by 51%, which had a balancing effect on the system, lowering the average daily thermal oscillations from 35.41 °C to 17.88 °C. The living plants and water have also had significant cooling (26.99 °C to 22.91 °C) and humidifying (39.88 to 47.74%) effects. The system’s energy efficiency, however, decreased from 26 to 18% (absorption) and from 85 to 46 (dissipation), lowering its energy contribution to the building by about 30%. The average plant’s lifespan within the Trombe wall was 46 days, with 15% of the specimens surpassing the 100-day mark. Over the course of a year, 20.55 kg of edible greens were grown in the Trombe wall. The experiment has shown that it is possible to grow the plants inside the Trombe wall cavity during the warmer half of the year, revealing many possible ways to improve the space’s comfort, yields, and energy efficiency.

This year-long experimental study, conducted in Kitakyushu, Japan, evaluates the performance of a retrofitted Trombe wall designed to cultivate hydroponically grown basil plants, aiming to enhance its year-round usability. The results show that the addition of plants reduced overheating and moderated temperature fluctuations, but also led to a 30.2% decrease in absorption and a 49.4% decrease in dissipation efficiency compared to a traditional Trombe wall. Seasonal variations influenced the suitability of the space for cultivation, with optimal conditions occurring in spring and summer, while autumn and winter posed challenges due to extreme temperature fluctuations. The daily energy balance was largely unaffected by factors such as leaf transpiration, spontaneous evaporation, additional ventilation, or increased appliance use, as these were overshadowed by the primary thermal processes: solar gains and conductive losses. Although the modified TW still provided passive heating, its energy output was reduced to approximately 10,000 MJ annually, compared to the baseline 14,000 MJ. The study suggests that alternative designs, including increased thermal mass, improved ventilation and better plant selection and could improve both cultivation and energy efficiency. Ultimately, while the green TW is best suited for seasonal use, it offers ecological and social benefits, such as local food production and CO2 fixation, highlighting its potential for integration into sustainable architectural practices.

This year-long experimental study, conducted in Kitakyushu, Japan, evaluates the performance of a retrofitted Trombe wall designed to cultivate hydroponically grown basil plants, aiming to enhance its year-round usability. The results show that the addition of plants reduced overheating and moderated temperature fluctuations, but also led to a 30.2% decrease in absorption and a 49.4% decrease in dissipation efficiency compared to a traditional Trombe wall. Seasonal variations influenced the suitability of the space for cultivation, with optimal conditions occurring in spring and summer, while autumn and winter posed challenges due to extreme temperature fluctuations. The daily energy balance was largely unaffected by factors such as leaf transpiration, spontaneous evaporation, additional ventilation, or increased appliance use, as these were overshadowed by the primary thermal processes: solar gains and conductive losses. Although the modified TW still provided passive heating, its energy output was reduced to approximately 10,000 MJ annually, compared to the baseline 14,000 MJ. The study suggests that alternative designs, including increased thermal mass, improved ventilation and better plant selection and could improve both cultivation and energy efficiency. Ultimately, while the green TW is best suited for seasonal use, it offers ecological and social benefits, such as local food production and CO2 fixation, highlighting its potential for integration into sustainable architectural practices.