scholarly journals Increasing Evapotranspiration on Extensive Green Roofs by Changing Substrate Depths, Construction, and Additional Irrigation

Buildings ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 173 ◽  
Author(s):  
Daniel Kaiser ◽  
Manfred Köhler ◽  
Marco Schmidt ◽  
Fiona Wolff
Keyword(s):  
Green Roof ◽  
Green Roofs ◽  
Urban Environments ◽  
Normal Green ◽  
University Of Applied Sciences ◽  
Daily Evapotranspiration ◽  
Urban Heat ◽  
Cooling Effects ◽  
Cool Summer ◽  
The University

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 retention layer and damming. The results show that the average daily evapotranspiration rates can be enhanced from 3 to 5 L/m2/day under optimized conditions. A second test on a real green roof with irrigation was used to explain the cooling effects of the surface above a café building in Berlin.

URBAN HEAT ISLAND MITIGATION USING GREEN ROOF APPROACH

2018 ◽  
Vol 80 (3) ◽  
Author(s):  
Johan Sohaili ◽  
Leong Kar Yan ◽  
Shantha Kumari Muniyandi ◽  
Siti Suhaila Mohamad
Keyword(s):  
Air Pollution ◽  
Solar Radiation ◽  
Urban Heat Island ◽  
Air Pollutants ◽  
Green Roof ◽  
Green Roofs ◽  
Urban Environments ◽  
Heat Island ◽  
Urban Heat ◽  
Reduced Temperature

In urban environments, vegetation has largely been replaced by impervious and often dark surfaces. These conditions contribute to an Urban Heat Island (UHI) effect. This phenomenon is demonstrated in many cities and produced effects such as higher atmospheric temperatures, intensive precipitation, excessive solar radiation and increasing air pollution. Therefore, reducing the surface temperature of roofs in a building may play an important role in improving the conventional roof surfaces with green roofs that offer much lower temperatures throughout a day to reach their thermal performance and reduce the absorption of solar radiation. Thus, this study is focused on determining the effectiveness of the existing green roof in reducing the ambient temperature and humidity of the air above it by comparison with conventional open roof top without vegetation. This study also aims to evaluate the potential of green roof to reduce the air pollutants in improving air quality in urban cities. As a result, by adopting green roof system, it has reduced temperature during the hottest hour in a day at 1230 hour (hr) by 4.3°C when compared to open roof. Green roof has also recorded higher percentage of humidity compared to open roof. Most importantly, it was proven through this study that green roof has the potential of absorbing pollutants in the air by reducing the concentrations of Sulphur dioxide (SO2), Ammonia (NH3), Nitrogen dioxide (NO2), Ozone (O3) and Carbon monoxide (CO) compared to open roof. Thus, green roofs can be considered to be one of the effective methods to mitigate UHI effects in urban cities.

scholarly journals Surface temperature analysis of conventional roof and different use forms of the green roof

2019 ◽  
Vol 28 (4) ◽  
pp. 632-640
Author(s):  
Anna Baryła ◽  
Agnieszka Bus ◽  
Agnieszka Karczmarczyk ◽  
Joanna Witkowska-Dobrev
Keyword(s):  
Green Infrastructure ◽  
Urban Areas ◽  
Imaging System ◽  
Plant Cover ◽  
Effective Means ◽  
Green Roof ◽  
Green Roofs ◽  
Temperature Changes ◽  
Urban Heat ◽  
Thermal Imaging System

Increasing urban populations raises a number of problems and risks that are strengthened by observed and projected climate change. An increase in green areas (so-called green infrastructure) has turned out to be an effective means of lowering temperature in the city. Green roofs can be one of the possible measures leading to achieving this aim. The aim of the study was the analysis of temperature changes of different roof surfaces (conventional roof, board, intensive roof substrate without plant cover, substrate covered with plants (shrubs). Studies on comparing the temperature between a conventional roof and green roofs were carried out in the period from April to September 2015 on the roof of the building of the Faculty of Modern Languages, University of Warsaw. The measurement was performed using the FLIR SC620 thermal imaging system. As a result of the tests, it was found that in the summer months the differences between the temperature of the green roof and the conventional roof amounted to a maximum of 31.3°C. The obtained results showed that the roof with vegetation can signifi cantly contribute to the mitigation of the urban heat island phenomenon in urban areas during summer periods.

scholarly journals Cladonia lichens on extensive green roofs: evapotranspiration, substrate temperature, and albedo

F1000Research ◽  
2013 ◽  
Vol 2 ◽  
pp. 274 ◽  
Author(s):  
Amy Heim ◽  
Jeremy Lundholm
Keyword(s):  
Substrate Temperature ◽  
Water Loss ◽  
Vascular Plant ◽  
Green Roof ◽  
Green Roofs ◽  
Urban Environments ◽  
Substrate Temperatures ◽  
Extensive Green Roofs ◽  
Harsh Conditions ◽  
Vegetation Layer

Green roofs are constructed ecosystems that provide ecosystem services in urban environments. Shallow substrate green roofs subject the vegetation layer to desiccation and other environmental extremes, so researchers have evaluated a variety of stress-tolerant vegetation types for green roof applications. Lichens can be found in most terrestrial habitats.  They are able to survive extremely harsh conditions, including frequent cycles of desiccation and rehydration, nutrient-poor soil, fluctuating temperatures, and high UV intensities. Extensive green roofs (substrate depth <20cm) exhibit these harsh conditions, making lichens possible candidates for incorporation into the vegetation layer on extensive green roofs.  In a modular green roof system, we tested the effect ofCladonialichens on substrate temperature, water loss, and albedo compared to a substrate-only control. Overall, theCladoniamodules had significantly cooler substrate temperatures during the summer and significantly warmer temperatures during the fall.  Additionally, theCladoniamodules lost significantly less water than the substrate-only control. This implies that they may be able to benefit neighboring vascular plant species by reducing water loss and maintaining favorable substrate temperatures.

scholarly journals MEDIA COMPOSITION INFLUENCES GREEN ROOF PLANT VIABILITY IN THE OZARK HIGHLANDS

2012 ◽  
Vol 7 (4) ◽  
pp. 73-84
Author(s):  
D. C. Toland ◽  
C. P. West ◽  
M. E. Boyer
Keyword(s):  
Plant Species ◽  
Climatic Factors ◽  
Green Roof ◽  
Green Roofs ◽  
Roof System ◽  
Ozark Highlands ◽  
Rooting Medium ◽  
Growing Medium ◽  
Critical Components ◽  
The University

Plant selection and establishment are critical components for green roof health and success. Plant palettes (sets of plant species selected for specific conditions) for green roofs vary in their ability to confer benefits depending on the species make-up and their adaptation to particular environments and climates. The response of various species to climatic factors on rooftops is unknown for the Ozark Highlands region. The objective of this study was to compare plant survival and spread in three growing medium treatments (course and fine texture with compost and fine texture with no compost) installed as part of a green roof system. The study was performed on a green roof system at the University of Arkansas in Fayetteville over 3 years. Data were collected on 13 species installed in September of 2006 and surveyed on three dates thereafter: April 30, 2007; May 19, 2009; September 10, 2009. The treatments with added compost had statistically greater vegetated cover (from 73 to 87%) compared to the fine medium without compost (36 to 43%). In most cases the spread of individual plants was not significantly different between treatments. Results indicated that rooting medium containing compost increased survival and overall vegetated roof coverage, and identified various potential green roof plant species for the Ozark Highland environment. Two species, Sedum middendorffianum var. diffusum and Sedum spurium ‘Roseum’, did particularly well in all treatments. One species, Sedum kamtschaticum, did well only in the treatments with compost.

scholarly journals Green Roof Enhancement on Buildings of the University of Applied Sciences in Neubrandenburg (Germany) in Times of Climate Change

Atmosphere ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 382
Author(s):  
Manfred Köhler ◽  
Daniel Kaiser
Keyword(s):  
Plant Biomass ◽  
Green Roof ◽  
Green Roofs ◽  
Growing Media ◽  
Extensive Green Roof ◽  
The Media ◽  
To Come ◽  
The Right ◽  
The University ◽  
Micro Structures

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 phytomass. Selecting the right growing media is critical. -Typical extensive green roof substrates have poor nutrition levels. Fertilizer can significantly boost the ecological effects on CO2 fixation. -If the goal of the green roof is a highly biodiverse green roof, micro-structures are the right solution.

scholarly journals An Evaluation of the Potential Energy Benefits of Installing Green Roofs in Hong Kong

2021 ◽  
Author(s):  
Rina D. Parker
Keyword(s):  
Hong Kong ◽  
Potential Energy ◽  
Green Roof ◽  
Green Roofs ◽  
Cool Roof ◽  
Island Effect ◽  
Margin Of Error ◽  
Urban Heat ◽  
Annual Reduction ◽  
Story Building

Green roofs help mitigate the urban heat island effect, increase available green space, and reduce energy consumption of buildings. This thesis estimates potential energy benefits of installing green roofs on buildings in Hong Kong. EnergyPlus, a building energy simulation program, is used to model an extensive green roof installed on a two-story building in downtown Hong Kong. Indoor and outdoor temperature data were collected from the green roof. Model calibration is performed using monitoring data, meeting the set acceptable margin of error of ± 20%. Air conditioning usage from April to September is approximately 232 kWh less in the room under the green roof that for the original roof showing that green roofs can reduce heat flux from the roof into buildings. Compared to other energy saving technologies, the cool roof provides a savings of 184 kWh over the green roof, translating to a $55 annual reduction in energy costs.

scholarly journals Evidence of the Climate Mitigation Effect of Green Roofs—A 20-Year Weather Study on an Extensive Green Roof (EGR) in Northeast Germany

Buildings ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 157 ◽  
Author(s):  
Manfred Köhler ◽  
Daniel Kaiser
Keyword(s):  
Urban Heat Island ◽  
Green Roof ◽  
Green Roofs ◽  
Good News ◽  
Urban Heat Island Effect ◽  
Climate Mitigation ◽  
Heat Island ◽  
Case Scenario ◽  
Island Effect ◽  
Urban Heat

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 UHI mitigation solution for city centers. In a best-case scenario, the green roof potential of cities in Germany is between 3 and 8%. A value of 50% can be achieved for all buildings; roofs represent about ¼ of urban surfaces, and the cooling effect of 1.5 K in 20 years is a reasonable contribution to cooling cities and achieving environmental goals by greening urban surfaces.

scholarly journals Mitigation of Urban Heat Island Effects through “Green Infrastructure”: Integrated Design of Constructed Wetlands and Neighborhood Development

Urban Science ◽  
2020 ◽  
Vol 4 (4) ◽  
pp. 78
Author(s):  
Victor Ruiz-Aviles ◽  
Anthony Brazel ◽  
Jonathan M. Davis ◽  
David Pijawka
Keyword(s):  
Urban Heat Island ◽  
Green Infrastructure ◽  
Outdoor Recreation ◽  
Integrated Design ◽  
Urban Environments ◽  
Heat Island ◽  
Neighborhood Development ◽  
Artificial Wetlands ◽  
Urban Heat ◽  
Cooling Effects

Extreme heat threatens desert city residents throughout the hot summer months and inhibits outdoor recreation and activity. Ecosystem services provide various benefits for urban environments. For desert cities, few are more critical than microclimate regulation and water treatment and conservation. This study evaluates the degree to which artificial wetlands support cooler microclimates and reduce the local urban heat island effect. The authors use (a) remotely sensed temperature data for Avondale, Arizona, to measure temperature differences between neighborhoods with and without water features and (b) resident surveys to evaluate perceptions of potential cooling effects. Results show substantial differences in the daytime surface temperatures for the wetland neighborhood compared to those without water features. More than a third of residents perceived a cooling effect throughout the year. The authors conclude that artificial wetlands within a desert city increase human comfort by reducing surface and air temperature and should be considered an urban heat island mitigation strategy.

scholarly journals Environmental factors of energy saving for buildings with green roofs at Russian cities

2020 ◽  
Vol 175 ◽  
pp. 14021
Author(s):  
Elena Sysoeva ◽  
Andrey Benuzh ◽  
Margarita Gelmanova ◽  
Aleksey Bogachev
Keyword(s):  
Green Roof ◽  
Noise Pollution ◽  
Green Roofs ◽  
Ecological Efficiency ◽  
Scientific Justification ◽  
Area Increase ◽  
Urban Heat ◽  
Overall Resistance ◽  
Roof Design ◽  
Resistance To Heat

Green roofs can increase the energy efficiency of the coating by lowering the temperature of the roof in the summer, and in winter - by possibly increasing the overall resistance to heat transfer of the coating. In addition, they reduce the volume and intensity of runoff due to the moisture saturation of the substrate and the processes of total evaporation, improve the microclimate of the urban area: increase air humidity, soften the effect of the urban heat island, reduce noise pollution, significantly reduce the volume and density of dust massesin densely built-up areas of large megacities. Experimental and analytical researches are needed to create a methodology for scientific justification of the ecological efficiency of the green roof design and the district model, to confirm the need and possibility making of a green roof in the II climatic zone of Russia, taking into account the temperature difference (up to 50 °C) in summer and winter seasons.

scholarly journals Experimental Winter Monitoring of a Light-Weight Green Roof Assembly for Building Retrofit

2021 ◽  
Vol 13 (9) ◽  
pp. 4604
Author(s):  
Fabiana Frota de Albuquerque Landi ◽  
Claudia Fabiani ◽  
Anna Laura Pisello
Keyword(s):  
Urban Areas ◽  
Green Roof ◽  
Green Roofs ◽  
Cold Season ◽  
Positive Energy ◽  
Light Weight ◽  
Building Retrofit ◽  
Island Effect ◽  
Urban Heat ◽  
The Impact

Green roofs are a recurrent solution for improving environmental quality in buildings. Such systems can, among other things, reduce the urban heat island effect, improve indoor thermal comfort and visual quality, and reduce energy consumption in buildings, therefore promoting human comfort. This work presents the winter monitoring of a light-weight green roof assembly with the potential to be implemented in extensive urban areas. The green roof monitoring was compared to those of previous bituminous and cool-coating applications. Results show that the system was able to decrease heat losses maintaining a positive energy flow from solar radiation gains and a more constant indoor temperature. In a well-insulated construction, the impact during the cold season was discreet. However, compared to the reference building, a slightly lower indoor air temperature (about 1 °C) was registered.

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