Evapotranspiration Performance of Vertical Indoor Greening—Influence of Indoor Climate Conditions on the Transpiration Performance of Tropical Ornamental Plants and Contribution of Greenings to Indoor Comfort in Offices

In indoor offices, it is often difficult to ensure high air quality and thermal comfort. Common problems are low relative humidity and the need for cooling. Previous research has shown that indoor greening can contribute to keeping the relative humidity and temperature at an appropriate level. In order to quantify the contribution of transpiration to evapotranspiration of vertical greening systems, various tropical ornamental plants were characterized in this study with regard to their transpiration rate and stomatal conductance under different indoor climatic parameters. Light intensity (PAR) showed a positive and air temperature a negative correlation with transpiration rate and stomatal conductance, while the dependence on relative humidity and soil moisture was not significant. Furthermore, two vertical greening systems with Philodendron hederaceum ‘Brasil’ were investigated in a parallel room set-up, where one room contained the greening system and the other room served as a reference. The vertical greening systems showed an evapotranspiration rate in the range of 55 to almost 100 g m⁻² h⁻¹, which increased the relative humidity from 20%–40% in the reference room to 40%–60% during the 3-week measurements in March 2023. This improved the comfort in the rooms.