Within the scope of the conducted experiment the authors analysed the efficiency of runoff reduction by the system of extensive type green roofs. The observations were based on storm events in the area of Lower Silesia at the Agro and Hydrometeorology Station Wrocław-Swojec. The authors analysed the thickness of plant substrate, and also estimated the quality of runoff waters under the conditions of periodic atmospheric deposition. Also considered were such indicators as electrolytic conductivity, N, NO3−, NO2−, NH4+, P, PO43−. The experiment included roof substrates designed in two variants, with known hydraulic and physical properties of the soil material. The analysis was performed for models with vegetation layer based on pumice and zelolite, covered with five plant species from the sedum family. The modelling of the hydraulic properties was conducted with variably saturated medium, using the Hydrus 1D software. The performance of systems with primary layer thickness of 11 cm and 9, 8, 7, 6 and 5 cm was estimated. The designed models reduced the average peak flows to 89%, and in addition they caused a delay in the initiation of the runoff which was dependent on the intensity and distribution of rainfalls in time, and on the initial moisture of the profiles. Simulations, performed for variable substrate thickness, permit the conclusion that in the case of thin-layer profiles (5 cm), the relative retention index was decidedly lower and amounted to 35.9% for the substrate with zeolite (originally 60.6%) and 41% for the substrate with pumice (originally 65.7%). In the case of total nitrogen and phosphates, statistical analysis revealed significant differences (p < 0.05) in relation to specific concentrations in the rainwater and in the control surface. The total nitrogen in the runoff from the green roof was nearly twice as high as that in the rainwater and amounted to, on average, 8.3 mg L−1.

Green architecture, including green roofs, can limit the effects of urbanization. Green roofs soften the thermal effect in urban conditions, especially considering the significant increase in the European and global population and that a significant share of the age group, mainly the elderly is exposed to diseases caused by high temperatures. We studied runoff and the quality of water from green roof systems in Lower Silesia, within the area of the Agro and Hydrometeorology Station Wrocław-Swojec, in the years 2012–2016. In the study, two systems with a vegetation layer based on light expanded clay aggregate and perlite were analyzed. The studies were based on the assessment of peak flow reduction, rainwater volume preservation and peak wave reduction. The calculated maximum retention performance indicator, relative to rainfall, for perlite surfaces was up to 65%, and in relation to the control surface up to 49%. In addition, the quality of water from runoff was estimated in the conditions of annual atmospheric deposition, taking into account such indicators as electrolytic conductivity; the content of N, NO3, NO2, NH4, P, PO4; and the content of metals, Cu, Zn, Pb and Cd. The load of total nitrogen exceeded the values of concentration in rainwater and amounted to 7.17 and 13.01 mg∙L−1 for leca and perlite, respectively. In the case of the metal content, significantly higher concentrations of copper and zinc from green surfaces were observed in relation to precipitation. For surfaces with perlite, these were 320 mg∙L−1 and 241 mg∙L−1, respectively, with rainwater concentrations of 50 and 31 mg∙L−1.

Current fast development of cities causes obsolescence of green areas, which is partly the reason for the rise in temperature within cities, and for the creation of the "urban heat island" effect. In order to limit the heating of the agglomeration, alternative ways of introducing greenery to urban areas should be explored. One of these is the use of green walls on the façades of buildings. The vertical garden affects the air temperature, reducing the temperature on the surface of the heated building; furthermore, green walls improve the aesthetic values of the city, introducing peace into the harsh landscape of modern architecture, and they clean the air of toxins. In the present work, we discuss the problems pertaining to green wall thermals. Tests were run on experimental models during 2016 in Lower Silesia Province at the Agro-Hydrometeorology Observatory Wrocław-Swojec of Wrocław University of Environmental and Life Sciences. The main objective of those tests was to check impact of green walls on the environment and on the temperatures inside green wall. Observations were run on the south elevation on building. Performed tests indicated that plant cover works as isolation on wall. Due to these properties, it is possible to stabilize conditions on the wall behind the green panel. All the measurements were run simultaneously on the green wall, and on the reference model-a wall without plant cover. Comparing both models indicated that the green wall limits heating of the outer part of building, which can hold down variation of temperature inside the building.