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 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 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.

The Thermal Influence of Green Roofs on Air Temperature in Taipei City

2010 ◽  
Vol 44-47 ◽  
pp. 1933-1937 ◽  
Author(s):  
Chen Yi Sun
Keyword(s):  
Air Temperature ◽  
Thermal Environment ◽  
Green Roof ◽  
Green Roofs ◽  
Heat Island ◽  
Environmental Benefit ◽  
Island Effect ◽  
Taipei City ◽  
Urban Heat ◽  
Thermal Influence

During the last decade, a large amount of research has been published in Taiwan on the reduction of the urban heat island effect for different strategies. The most important strategy for reducing ambient temperature and mitigating the heat island effect is to encourage citizens to build green roofs on their buildings. For analyzing the effect of a green roof on the thermal environment, this paper collects temperature and humidity data from two building roofs that have different greening levels and tries to analyze the thermal influence of a green roof on air temperature in Taipei City. The results of this research can give citizens an idea what kind of thermal environment they can benefit from; moreover, it also can provide useful data to governments for calculating the environmental benefit if they carry out a green roof policy.

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.

Design of a Cool Color Glaze for a Solar Reflective Tile

2014 ◽  
Vol 92 ◽  
pp. 159-167
Author(s):  
Chiara Ferrari ◽  
Alberto Muscio ◽  
Cristina Siligardi ◽  
Tiziano Manfredini
Keyword(s):  
Chemical Durability ◽  
Inorganic Pigments ◽  
Heat Island ◽  
High Chemical ◽  
Cool Roof ◽  
Island Effect ◽  
Solar Reflectance ◽  
Thermal Emissivity ◽  
Urban Heat ◽  
Cool Roofs

One of the most common materials-measures to counteract Urban Heat Island Effect can be identified in cool roof: white surface characterized by high solar reflectance and high thermal emissivity. One of the problems for the realization of cool roof is the difficult matching of white color with urban planning needs. In order to better integrate cool roofs into skylines cool colors were developed integrating pigments into cool roof surfaces. Cool roof market is actually dominated by organic based products with optimal solar performances but low durability against ageing. The use of ceramic-based products is crucial in the design of a new durable cool roof thanks to their naturally high thermal emissivity (ε=0.90) and their high chemical durability. The development of a new ceramic-based product made by a traditional porcelain stoneware tile as support, an inorganic engobe was started in the last years. In order to complete the product with a suitable glaze, eight different inorganic pigments were added to three different glazes, each one characterized by different surfaces features. Even if the addition of glazes, and pigments decrease the reflectance values of the solar reflective engobe, some promising results were achieved in this study especially regarding warm colored glazes.

scholarly journals Effect of Substrate Depth and Planting Season on Sedum Plug Survival on Green Roofs

2007 ◽  
Vol 25 (2) ◽  
pp. 95-99 ◽  
Author(s):  
Kristin L. Getter ◽  
D. Bradley Rowe
Keyword(s):  
Survival Rates ◽  
Green Roofs ◽  
Heat Island ◽  
Major Objective ◽  
Island Effect ◽  
Successful Establishment ◽  
Urban Heat ◽  
Growing Conditions ◽  
Substrate Depth ◽  
Planting Season

Abstract Green roofs, a roofing technology that entails growing plants on rooftops, provide many benefits such as improved stormwater management, energy conservation, mitigation of the urban heat island effect, increased longevity of roofing membranes, reduction in noise and air pollution, and improved aesthetics. Plants on rooftops are more susceptible to extremes in temperature and drought due to their shallow substrate and elevation above ground. Because of these unfavorable growing conditions, plant selection and season of establishment are critical. The major objective of this study was to quantify the effect of substrate depth and planting season on successful establishment of plugs of Sedum species on green roofs. Plugs of nine species of Sedum were planted in East Lansing, MI, in autumn (September 20, 2004) or spring (June 8, 2005) and then evaluated for survival on June 1, 2005, and June 1, 2006, respectively. Overall, spring planting exhibited superior survival rates (81%) compared to autumn (23%) across substrate depths. Sedum cauticola ‘Lidakense’, S. floriferum, and S. sexangulare were not affected by season of planting. Sedum cauticola barely survived at any substrate depth or planting season, whereas the latter two exhibited nearly 100% survival regardless of planting season. All other species had superior survival percentages when planted during spring.

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.

Living Architecture

2011 ◽  
Author(s):  
Graeme Hopkins ◽  
Christine Goodwin
Keyword(s):  
New Zealand ◽  
Open Space ◽  
Green Roofs ◽  
Natural Environments ◽  
Interior Space ◽  
Existing Structures ◽  
Island Effect ◽  
Wide Range ◽  
Living Wall ◽  
Urban Heat

Extensively illustrated with photographs and drawings, Living Architecture highlights the most exciting green roof and living wall projects in Australia and New Zealand within an international context. Cities around the world are becoming denser, with greater built form resulting in more hard surfaces and less green space, leaving little room for vegetation or habitat. One way of creating more natural environments within cities is to incorporate green roofs and walls in new buildings or to retrofit them in existing structures. This practice has long been established in Europe and elsewhere, and now Australia and New Zealand have begun to embrace it. The installation of green roofs and walls has many benefits, including the management of stormwater and improved water quality by retaining and filtering rainwater through the plants’ soil and root uptake zone; reducing the ‘urban heat island effect’ in cities; increasing real estate values around green roofs and reducing energy consumption within the interior space by shading, insulation and reducing noise level from outside; and providing biodiversity opportunities via a vertical link between the roof and the ground. This book will appeal to a wide range of readers, from students and practitioners of architecture, landscape architecture, urban planning and ecology, through to members of the community interested in how they can more effectively use the rooftops and walls of their homes or workplaces to increase green open space in the urban environment.

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