Plants as the climate saviors? That's right! Greening on our roofs and facades definitely helps our climate. It binds CO2 and particulate matter, increases the humidity, and contributes to lowering the temperature during hot summers. Less hot air means less air movement, less whirled up dust and dirt... in short, greater conditions for life to flourish! Climbing plants, particularly those with full-face greening, are so important, especially for the micro-climate.
Climbing plants absorb CO2 and form carbohydrates, i.e. sugar from leaf fibers and wood pulp. This aspect is interesting, but ultimately it is only a small amount that comes through with the autumn leaves, the thick growth of trees, and possibly the fruit. It is only the dry mass that is measured in kilograms; that is per house wall, per year then about 2-3 car tank fillings worth of CO2 that have been 'captured' by the plants from the air, unfortunately not more ...
A chemical by-product of the decomposition of CO2 and the binding of carbon (C) is the release of oxygen (O2), which spreads into the ambient air through the stomata on the undersides of the leaves into the ambient air.
When sunlight hits the dark green leaves, it is partly transformed into heat, like a collector does for a water heater. However, the chemical processes of binding the CO2 need consistently low temperatures; therefore, the heat must be dissipated. This happens through the evaporation of water on the leaf surfaces into the ambient air. The evaporated water then increases the humidity, and the water sucked up by the roots, in turn, contributes to building moisture removal and drying.
Green facades will "eat" unwanted heat in the summer and provide you with air and wall cooling benefits. How is this possible? On the one hand, it is the previously described evaporation process which consumes the (heat-) energy; on the other hand, it is the chemical processes around the carbon. The heat created during combustion of carbon to carbon dioxide is needed more or less again when captured and consumed, if the carbon is again involved in photosynthesis... So the surrounding air cools and falls down, similar to a forest with the palpable coolness one feels. But what is even more important is that the emergence of strongly heated air is slowed down and air velocities in the ground reduced. There will be less dust whirled up, which will then limit smog formation. This topic is now even the content of scientific study!
Leaves in the garden facade also absorb dust, especially most toxic particulate matter. Once "captured," these extremely small nano-particles are hardly dangerous and are then washed away with the next rain or composted during autumnal leaf-fall.