Greening structures attract worldwide attention because of their multidisciplinary benefits. Green roofs are considered one of the best ways to eliminate summer overheating, mitigate climate change, or reduce the urban heat island effect. The winter season and its impact on building energy consumption are often overlooked. Common standards do not take a green roof structure into consideration because of possible high water content in their layers. Additional roof layers may have a positive effect during the winter; they help reduce surface overcooling in cloudless winter nights. This paper analyses experimental measurements taken on two different extensive green roofs and compares the results with a single-ply roof (R) with a PVC membrane. Surface overcooling of the R due to radiation reaching up to 10 °C, whereas the green roof membrane is protected. The influence of thermal loss is not so important for the current climate in Central Europe, as the required U-values are lower than 0.1. The temperature difference is reduced from 17 °C on the membrane to 0.7 °C on the top of the concrete slab. The green roof is still advantageous, and the vegetation surface has better thermal stability. The advantage is clearly recognisable in the area of the condensation zone. The difference between these two extensive green roofs is very small in regard to the accuracy of the temperature sensors. The outcome showed the thermal loss reduction compared to the common flat roof; however, after analysis, it was more marginal than expected.
Green structures such as roofs or facades are great examples of ways to mitigate climate change, and they have multidisciplinary benefits. One of them is water retention during storms and high rainfalls. In this paper, the impact on the temperature of a membrane after excessive watering was investigated. The results of watered samples were compared to the non-watered ones. This test was carried out on five equal samples. The results showed that the actual foliage cover is very important. The worst results were obtained by the samples that did not have sufficient plant (foliage) cover. Notable differences in courses after watering reached up to 7 °C and lasted up to five days. Visible differences after watering were also exhibited by other samples. The type of drainage/retention layer also influenced the results, whereas the hard-profiled plastic board had high practical retention, which impacted temperatures over a long time period. The actual water content influenced and reduced the daily amplitude from 13 to 7 °C for at least five sunny days. This confirms the theoretical evapotranspiration calculations and actual water content in green roofs. In this case, the water content in the samples proves the cooling effect on the waterproofing membrane.
Current building envelope greening systems are not just areas covered with vegetation. Today’s systems can maximise the functional contribution of vegetation to a building’s performance and become part of a sustainable urban renewal strategy. The impact of the vegetation layer directly affects the building in its immediate vicinity, from the outside, while also having a significant impact on the indoor environment. Green roofs are the most widespread vegetated structures worldwide. This paper aims to demonstrate the behaviour of the temperature regime of an extensive green roof over a production hall and an administrative area in comparison to that of a roof without vegetation cover. In evaluating the results, a period with weather representative of winter and summer was selected to show the importance of seasonality. The fact that this is a new building, and that the extensive roof is not fully covered with vegetation, is very well reflected in the results, as the absence of a vegetated area significantly affects the temperature of as well as the heat flux through the roof structure. The dark colour of the substrate absorbs significantly more solar radiation than the light surface of the waterproofing, resulting in an increase in temperature and heat flux into the structure.
Green façades with an active water regime and the water flowing through the substrate itself are not common. This system reduces the temperatures and incorporates the evapotranspiration, which could be more effective than by the regular green façades. The use of a double-skin façade with a ventilated air cavity can reduce the heat load, but the evapotranspiration can reduce it even more with additional benefits. Green façades could also serve as a key element for reducing the surface temperatures of the insulated metal panels (IMP), which are mostly used as a façade system for production facilities or factories. In this paper, a prototype of a double-skin façade, which consisted of vegetation board from recycled materials and IMP, is tested in a climate chamber to evaluate the function and benefits of such a combination. The outdoor skin is made from board, the surface of which is covered by the rooted succulent plants. Measurement results are represented as a direct comparison of single sunny day surface temperatures with and without a double-skin (green) façade. The use of the green façade reduces the indoor surface temperature of IMP by 2.8 °C in this measurement. The use of water circulation through the outdoor skin reduces the temperature of the vegetation board by 28 °C. This could have a great impact on the microclimate around the façade. Because of the controlled environment and ventilation system in a climate chamber, it is not possible to investigate the airflow and solar chimney effect within the ventilated cavity. In addition, it is complicated to show the potential of microclimate change caused by the wet vegetation surface. For the mentioned reasons, the need to carry out “in situ” tests on a model wall under the real conditions was indicated.
Scientific research in the area of building simulations has a great potential and it is continuously developing and advancing. Computer simulations are helpful in many areas of Civil Engineering, such as energy demand, moisture transport, thermal comfort, ventilation etc. Climate data measured by experimental weather station are analyzed in this article. Weather station is located within the University campus and data recorded with a short are used in a non-steady heat-air-moisture simulation. Climate parameters differences caused by the various averaging periods are shown. This differences are also analyzed in term of outdoor surface temperatures calculated with WUFI Pro simulation software.