Manfred Köhler

Green roofs are still often seen as a pure aesthetical element in architecture, as a spleen of some “greenies”. In fact green roofs already contribute, to some extent, to a better microclimate through evaporation, filtering of dust from the air and a decrease in temperatures at the rooftop. In cities like Berlin and Munich many green roofs have already been realised. Coupled with this microclimate improvement, is the thermal comfort improvement under such roofs by more mass, dry or wet substrate, and shading through the plants. Besides improving the microclimate and the indoor climate, the retention of rainwater is another important advantage. That means an important reduction of the rainwater input in the sewage system during rainfalls, cutting the peak load, avoiding an overload of the system, which might cause flooding and serious health problems. The risk of flooding in cities, which is increasing in many cities due to a ground sealed by buildings, asphalt and concrete, can be diminished. One recent example of the use of green roofs with this purpose is the Potsdamer Platz in the centre of Berlin, where 100 percent of the rainwater has to be evaporated or used for toilet flushing on the building site. Scientific knowledge on green roofs is still limited to temperate climates, due to a development which took place in central Europe. Since 2000 a scientific project in Rio de Janeiro is checking local parameters, like possible vegetation, which can be used and substrate composition. Parallel to this, four prototype roofs, three greened and one blank, are used to measure the retention rate of the rain water and the temperature on the underside of the roofs in order to analyse the possible improvement of the thermal comfort in buildings. This paper will describe the scientific results of Germany and discuss the practicability on a larger scale under tropical conditions.

... 4026 KWpeak and the Cells above Bitumen 8 degree angel (are all the fields NEG, 1,2,3,4,11) with 6472 KWpeak Bitumen 30: NEG 5 ... 2007 Conference Proceedings 14 ... During the last five years about 80,000 kWh electrical energy output had been produced here on this project. ...

... From other cities a few roof garden projects are known, eg from São Paulo (see Delduque, 2001). ... Lepidium pseudodidymum (Brassicacea) L. virginicum Sinapsis arvensis (Bras.) Mormodica charantia (Curcubitaceae) Cyperus esculentus (Cyperaceae) C. ferax, C. rotundus ...

In this paper, I evaluated the long-term vegetation dynamics of two extensive green roof (EGR) installations in Berlin. The first, installed on two inner-city residential buildings in 1985, consisted of 10 sections ("sub-roofs") with a combined area of 650 square meters. The 10 sub-roofs differed in exposure and slope. Ten plant species were initially sown on the sub-roofs. Observations were made twice yearly (with a few exceptions) from 1985 to 2005. Altogether, 110 species were observed over the 20-year time period; however, only about 10 to 15 of these were dominant over the long term and could be considered typical EGR flora in Berlin. Allium schoenoprasum was the dominant plant species over the entire time period on all sub-roofs. Festuca ovina, Poa compressa, and Bromus tectorum were also typically present over the course of the study. Statistical tests revealed that weather-related factors such as temperature and rainfall distribution were the most important factors...

A total of 27 existing measures of stormwater management were studied across scales from building level (vegetated buildings, rainwater use) to city quarter level (infiltration, de-paving, artificial lakes and streams, decentralised treatment) and catchment level (centralised treatment, storage). For each measure, the same performance indicators were quantified based on literature, monitoring and simulation results regarding six potential benefits (water/energy saving potential, improvement of landscape quality, increase in biodiversity, reduced urban heat exposure, improvement of groundwater and surface water bodies), indirect resource use (life cycle assessment) and direct cost. Results show that each measure has its strengths and weaknesses. Thus, it is expected that different combinations of measures will lead to increased benefits for different locations/settings. The developed measurebenefit/cost-matrix may support the finding of such improved combinations and is currently tes...

A decade ago, the journal Urban Habitats—the precursor to Urban Naturalist— devoted a special issue to the topic of green roof biodiversity. At the time, green roof research was exclusive to some regions and not widely distributed, and the special issue was the first published in English that collected important ecological work on green roofs from around the world. The special issue has been widely read and attracted many new researchers to the study of green roofs, initiating a network of colleagues that today continues to push this exciting field forward. In the last 10 years, green roof installations have increased around the world, with the term “green roof ” joining the vernacular of the everyday citizen. In some cities, hundreds of green roofs have been constructed, many of which have been supported through municipal by-laws, construction standards, and incentives. A multi-pronged approach to encourage green roofs in cities integrates new and interesting design, ecosystem serv...

Green roofs are multi-beneficiary elements of sustainable or "biophilic architecture ". Over the past decades, numerous studies have been performed in this field of urban ecology Many of these works have been initiated byGerman research groups. The green roof benefits will be explained on the basis of own measurements made in Berlin and in Neubrandenburg. The principal advantages of the green roof technology are to be seen in biodiversity, reducing the urban heat island, and in storm water retention. Scientific guidelines derived from this research assist architects in their design tasks. Open questions in green roof research are modelling of the climatic effects for whole neighbourhoods, and quantification of the energy savings of different green roof types. In recent years, successful international cooperation has been established among different working groups worldwide. Thus, at last, green roof benefits can be calculated for urban agglomeration zones around the world.

The reduction in evaporative surfaces in cities is one driver for longer and hotter summers. Greening building surfaces can help to mitigate the loss of vegetated cover. Typical extensive green roof structures, such as sedum-based solutions, survive in dry periods, but how can green roofs be made to be more effective for the longer hot and dry periods to come? The research findings are based on continuous vegetation analytics of typical extensive green roofs over the past 20 years. -Survival of longer dry periods by fully adapted plants species with a focus on the fittest and best adapted species. -Additional technical and treatment solutions to support greater water storage in the media in dry periods and to support greater plant biomass/high biodiversity on the roofs by optimizing growing media with fertilizer to achieve higher evapotranspiration (short: ET) values. The main findings of this research: -The climate benefits of green roofs are associated with the quantity of phytoma...

Urban environments are characterized by dense development and paved ground with reduced evapotranspiration rates. These areas store sensible and latent heat, providing the base for typical urban heat island effects. Green roof installations are one possible strategy to reintroduce evaporative surfaces into cities. If green roofs are irrigated, they can contribute to urban water management and evapotranspiration can be enhanced. As part of two research projects, lysimeter measurements were used to determine the real evapotranspiration rates on the research roof of the University of Applied Sciences in Neubrandenburg, Germany. In this paper, we address the results from 2017, a humid and cool summer, and 2018, a century summer with the highest temperatures and dryness over a long period of time, measured in Northeast Germany. The lysimeter measurements varied between the normal green roof layer (variation of extensive green roof constructions) and a special construction with an extra r...

Green roofs are still often seen as a pure aesthetical element in architecture, as a spleen of some “greenies”. In fact green roofs already contribute, to some extent, to a better microclimate through evaporation, filtering of dust from the air and a decrease in temperatures at the rooftop. In cities like Berlin and Munich many green roofs have already been realised. Coupled with this microclimate improvement, is the thermal comfort improvement under such roofs by more mass, dry or wet substrate, and shading through the plants. Besides improving the microclimate and the indoor climate, the retention of rainwater is another important advantage. That means an important reduction of the rainwater input in the sewage system during rainfalls, cutting the peak load, avoiding an overload of the system, which might cause flooding and serious health problems. The risk of flooding in cities, which is increasing in many cities due to a ground sealed by buildings, asphalt and concrete, can be d...

planning of stormwater management requires a quantitative description of positive and negative effects of possible measures. We suggest quantifying these effects with generic performance indicators within eight categories: building physics and services, landscape quality, urban climate, biodiversity, groundwater, surface water, direct costs and indirect environmental costs. First results indicate that the defined performance indicators allow an objective pre-selection of measures based on their ability to reach local stormwater management goals. The final selection of measures should be based on an evaluation for a specific city quarter (to reduce indicator uncertainty) and reviewed by local stake holders.

The cultural center “UFA-Fabrik” in Berlin-Tempelhof has been known for years for its use of ecological technology. The original structures were completely renovated in 1984 and fitted with greened roofs at that time. Today the entire complex includes ca. 4,000 m 2 of greened roofs. Since 1992 a monitoring program has tracked development of the vegetation, microclimate and retention of precipitation. The first solar panels were installed on the UFA Factory in 1998. A year later, an array consisting of ten 2 kWp photovoltaic panels was added on a greened roof. One part of the monitoring includes tracking the efficiency of fixed versus steered panels; another regards the interaction between the greened roof and the photovoltaic panels. While this is a preliminary report, several tendencies seem clear: the tracked solar panels are generating ca. 10 – 15% more electricity than the fixed ones. The greened roof is notably cooler than conventional bituminous roofs: While lower temperatures...

Approximately 10 km2 of new green roofs are built in Germany every year. About 85% of these are Extensive Green Roofs (EGR). An EGR with several research features was installed on new buildings belonging to the University of Applied Sciences Neubrandenburg in 1999. The results of the almost 20-year permanent survey of the climate effects of the green roof in contrast to gravel roofs are presented here. High-quality sensors, similar to those used by official weather stations, are in use, and data is collected every 10 s and aggregated to hourly values which enable comparisons to official measurements made by the DWD in Neubrandenburg and Berlin. The results show the typical urban heat island effect (UHI) and the mitigation effect of EGR. Whilst the temperature increased over the years due to the urban heat island effect, the temperature within the growing media in the green roof remained constant. The EGR has a stabilization effect of 1.5 K. This is good news for all those seeking a ...

Recommendations for planners and architects on rainwater management are based mainly on findings from the monitoring of a new building project for the Institute of Physics at the Humboldt University Berlin‘s Adlershof campus, a project in which innovative rainwater management and facadegreening approaches were planned and implemented and that has since attracted international attention. A monitoring and evaluation programme began in the final phase of planning and continued during the construction and operation of the installation after the property was transferred to the HU Berlin. The goal was and is to develop recommendations for optimising and economically operating such installations in individual project phases, thereby minimising operating costs. A further focus of the project was to develop practically relevant and application-oriented findings as tools and guidelines for the planning, construction, operation and maintenance of future projects.

Within the last decades, the trend to ever larger dwellings and the increases in industry and traffic have resulted in the continuous growth of cities. The settlement surface in Germany has doubled within the last 40 years and present growth amounts to 1.1% per year. In the USA, the built on surface extends by 3% per year; in Brazil this number may be much higher. Together with increasing emissions, especially caused by traffic, industry and domestic burning, this increase in settlement surface has led to a noticeable impairment of the urban climate. The climate of cities, in comparison to the climate of open land, in most cases has negative effects on urban inhabitants. For example, sleep disturbances and heart disease may be more prevalent. The limited available space in cities makes roof gardens an attractive possibility to improve the urban situation. In Europe, green roof technology has become increasingly important within the last 20 years. In the USA, green roof technology st...

Cities can support biodiversity and provide the ecosystem services upon which life depends. Green roofs are increasingly common in cities and could be designed to increase biodiversity, but community assembly and succession patterns on green roofs are poorly documented. We used long-term vegetation surveys at 6 extensive green roofs and sampled a 1–93-year chronosequence at 13 extensive green roofs in northeast Germany to determine if plant and arthropod diversity increased over time in a deterministic pattern. We also explored abiotic factors that may contribute to community diversity on green roofs. We found that vegetation cover increased over time, but beyond the first 2 years, vegetation richness and diversity did not. There is no evidence for broadly applicable patterns of succession of plant communities on green roofs. Although the abundance, richness, and diversity of arthropods increased slightly over time, this trend was not statistically significant for ants, bees, beetle...