Evaluating the technical and economic aspects of thermal performance of extensive green roofs:A GIS-based case study in the urban setting of Na dor,Morocco

The increasing demand for green spaces in cities underscores the urgent need for sustainable solutions to reduce the ecological impact of urban areas.This research focuses on converting unused rooftops into extensive green roofs in Nador,Morocco,offering an innovative approach to enhancing outdoor thermal comfort in this region.Several advanced techniques were used,including photogrammetric restitution(for creating land use maps),integration of light detection and ranging data(for three-dimensional urban modeling),and meteorological data collection(for modeling urban climate conditions).The urban-multiscale-environmental-predictor solar and longwave environmental irradiance geometry(UMEP-SOLWEIG)model was crucial for precisely evaluating the thermal performance of green roofs and their influence on urban microclimates.This model considers considered various parameters,such as the sky view factor,wall height and aspect,and shading conditions,for accurate,comprehensive analysis.Additionally,for accurate,comprehensive analysis,a comparative evaluation was performed between the UMEP-SOLWEIG and ENVI-met models to assess the UMEP SOLWEIG results.The findings were notable,demonstrating a substantial reduction(averaging over 3℃)in the mean radiant temperature on 60%of rooftops,covering 55%of the total surface area.This highlighted the effectiveness of green roofs in improving outdoor thermal comfort.Furthermore,green roofs were closely associated with reductions in air-conditioning energy consumption,with considerable reductions ranging from 17.53%to 43.82%.These savings translated to estimated financial benefits ranging from USD 1.63-4.07 million.These figures clearly verified the notable economic impact of green roofs despite their initially high costs(approximately USD 84.44 million).These potential long-term savings indicated that these investments are financially viable in the long run.The collected data were used to create thermal maps of the area using geographic-information-system tools.A thermal cadaster specific to green roofs was also developed,accessible online through Web mapping.Overall,this approach facilitates decision-making in urban planning by providing visual information on thermal variations,thereby aiding in the precise planning of measures against urban heat and promoting the use of green roofs to reduce environmental impact.

EFFECT OF GREEN ROOF AGE ON RUNOFF WATER QUALITY IN PORTLAND,OREGON

Green roofs have become a common method to increase water retention on-site in urban areas.However,the long-term water quality of runoff from green roofs is poorly understood.This study evaluated the water quality of stormwater runoff from a regular(non-vegetated)roof,a green roof installed 6 months previously,and a green roof installed 6 years ago in Portland,Oregon.Samples of runoff were taken during every rain event for 10 months,and analyzed for total phosphorus(TP),phosphate(PO_(4)^(3-)),total nitrogen(TN),nitrate(NO_(3)^(-)),ammonia(NH_(3)),copper(Cu),and zinc(Zn).Runoff from the green roofs had higher concentrations of TP and PO_(4)^(3-)and lower concentrations of Zn compared to the regular roof.Average TP concentrations from the 6-year old roof and 6-month old roof were 6.3 and 14.6 times higher,respectively,than concentrations from the regular roof,and average PO_(4)^(3-)concentrations from the 6-year old roof and 6-month old roof were 13.5 and 26.6 times higher,respectively,compared to the regular roof.Runoff from the 6-month old green roof had higher concentrations of TP and PO_(4)^(3-)than the 6-year old green roof during the wet season,but lower concentrations during the dry season.The 6-month old green roof installations where receiving waters are sensitive or impaired may need additional treatment methods to reduce phosphorus levels.As green roofs age,water retention decreases and phosphorus leaching increases during the dry season.

GREEN ROOFING IN INDIANA: CASE STUDIES AND DESIGN NOTES

Green roof technology and implementation are taking root in North America at an accelerating pace.Growing recogni-tion of the benefits of green roofs and increasing interest in green infrastructure are leading to expansion of green roof tech-nologies that have been in use for decades in Europe and elsewhere.While some regions have adopted the use of green roofs on a large scale,other areas are warming up to the concept more slowly.Large-scale implementation of green roofs has not yet occurred in Indiana,but a number of exemplary projects have been constructed,and there are signs that interest in the technology is increasing in the state.The purpose of this article is to provide an overview of green roof technology,analyze selected green roofs in Indiana,explore trends in the state,and address issues for future development of green roof technol-ogy in the region.A variety of green roofs were investigated throughout the state.Discussions were held with individuals involved in each project to obtain technical and logistical details of green roof design,installation,and performance.

MEDIA COMPOSITION INFLUENCES GREEN ROOF PLANT VIABILITY IN THE OZARK HIGHLANDS

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.

Assessment of green roof performance for sustainable buildings under winter weather conditions

A green roof is a specialized roof system that supports vegetation growth on rooftops.This technology is rapidly gaining popularity as a sustainable design option for buildings.In order to contribute to an understanding of green roof in regions with cold winters and snow,an on-site experimental investigation was present with a focus on the assessment of green roof performance during the winter.This field experiment took place on a six small buildings during the winter of 2010-2011.The work monitored three buildings with green roofs,two buildings with reference roofs and one building with a bare soil coverage for the roof.These six buildings were identically constructed and instrumented with sensor networks to provide heat flux data through the roofs.The 15 min averaged data were statistically analyzed for a week under the two separate periods,first without a snow cover and second with a snow cover.The results show that the roof type is a significant factor in affecting the thermal performance of these buildings.Most importantly,green roofs reduce heat flow through the roof and thus reduce the heating energy demand during the winter.However,the energy savings for buildings with the green roofs are reduced under snow conditions because the snow diminishes thermal resistance of the roof and increases the heat transfer process through the roofs.

Ecological Function of Urban Green Roof and Analysis of Its Influencing Factors

Based on the analysis of the multiple ecological functions of green roofs, the main factors affecting the ecological functions of green roofs are expounded and the numerical simulation methods for quantitative calculation of ecological functions of green roofs are summarized in order to provide theoretical and method support for the construction of urban green roofs.

PV-green Roofs植被层高度对系统性能影响

绿化屋顶(GR)和光伏发电系统(PV)在调节室内热湿环境与降低建筑能耗中发挥着重要作用,利用两系统互效性耦合而成的光伏-绿化屋顶(PV-green Roofs)是推进建筑节能的创新型举措。结合PV-green Roofs数学模型,分析植物高度对系统性能的影响,通过实验测定,以落地生根和佛甲草为绿化屋顶植被层材料,实测不同工况下PV-green Roofs系统的电量输出值,同时结合EnergyPlus数值模拟结果分析采用不同植株高度的PV-green Roofs系统对建筑消耗净能量的影响。结果表明:植物高度通过改变绿化屋顶种植层蒸发阻力和植被层冠状层风速影响系统性能;在夏热冬冷的气候条件下,植物生命中期对应的高度对光伏系统工作环境的冷却效果最为明显,引起输出电量的增值最大,且环境湿度对系统性能存在影响。

Green roofs for storm water management:a review

The rapid urbanization and industrialization involve an unsustainable use of natural systems,leading to various problems in cities.The urban hydrological system experiences fluctuating amount of surface runoff water when it rains heavily.It has been suggested that green roofs significantly mitigate storm water runoff generation even in tropical climate.Green roofs have become popular due to its proven benefits by mitigating urban heat island effects and protecting biodiversity.The annual rainfall and runoff relationship for green roofs is determined by the depth of the substrate.Water retention capacity mostly depends on substrate's physical conditions such as dry or wetness.Generally 6 mm to 12 mm rainfall is required for dry substrate to initiate runoff whereas response of wet conditions is mostly straight.Besides,there are some other factors affecting runoff dynamics such as type of a green roof and its slope,age of green roof,type of vegetation,soil moisture characteristics,weather.The review indicates that there is not much research in green roofs performance over storm water runoff;hence there is a need for further research.This paper reviews and addresses the role of green roofs in urban storm water management.

Application of Green Roof in Relieving Urban Waterlogging: A Review

Green roof plays a critical role in regulating roof runoff by reducing runoff, delaying runoff generation, reducing runoff peak flow and improving runoff water quality effectively. On the basis of introducing significance and role of green roof, this paper reviewed domestic and international researches on the green roof's control over roof runoff, and analyzed the factors that influence the control of green roof over the runoff, so as to provide a theoretical support and method for the construction of green roofs in urban districts.

Green Roof Performance for Stormwater Management in Equatorial Urban Areas Using Storm Water Management Model (SWMM)

Many Low Impact Developments (LIDs) have recently been developed as a sustainable integrated strategy for managing the quantity and quality of stormwater and surrounding amenities. Previous research showed that green roof is one of the most promising LIDs for slowing down rainwater, controlling rainwater volume, and enhancing rainwater quality by filtering and leaching contaminants from the substrate. However, there is no guideline for green roof design in Malaysia. Hence, Investigating the viability of using green roofs to manage stormwater and address flash flood hazards is urgently necessary. This study used the Storm Water Management Model (SWMM) to evaluate the effectiveness of green roof in managing stormwater and improving rainwater quality. The selected study area is the multistory car park (MSCP) rooftop at Swinburne University of Technology Sarawak Campus. Nine green roof models with different configurations were created. Results revealed that the optimum design of a green roof is 100 mm of berm height, 150 mm of soil thickness, and 50 mm of drainage mat thickness. With the ability to reduce runoff generation by 26.73%, reduce TSS by 89.75%, TP by 93.07%, TN by 93.16%, and improved BOD by 81.33%. However, pH values dropped as low as 5.933 and became more acidic due to the substrates in green roof. These findings demonstrated that green roofs improve water quality, able to temporarily store excess rainfall and it is very promising and sustainable tool in managing stormwater.

Thermal Behaviour in Buildings with Green Covers Combined with Natural Ventilation, Green Facades and Green Roofs

The main aim of this paper was to study the influence of ventilation during a typical experimental day, in the internal air temperature as well as in internal surface temperatures under the conditions of the outer environment, using an experimental method which allows a comparison of the thermal performance between four cell tests： a prototype called control （no vegetation） and three with different combinations of vegetation （roofs and facades） installed in a region of tropical climate. The experiments were developed in four test cells with dimensions 2.0 m × 2.50 m × 2.7 m. Measurements of internal surface temperatures and internal air temperatures were collected with the use of specific equipment, a data logger （CR1000, Campbell Scientific Inc.）, connected with two multiplexers 32 channels （416AM Campbell Scientific Inc.）. Data were recorded over a year and a typical heat day was selected, which was September 24, 2015. The results show that ventilation affects the internal temperature of the air, so that this gets even surpass the external temperature. Regarding surface temperatures, increased temperature, except those which are provided with vegetation, namely, the surfaces which have green walls and green roofs file the lower temperatures. Therefore, we can confirm the ability of vegetation to maintain more pleasant internal conditions compared to the test cells built with conventional materials, thus it can reduce cooling load efficiency.

Thermal Response to Heat in Buildings with Green Covers for Tropical Climate： Green Facades and Green Roofs

The main aims of this paper were to study and demonstrate the benefits the plant systems can provide indoors in a critical heat day. This study proposed an experimental method to try to understand the thermal response to heat of four different systems： a prototype called control （no vegetation） and three with different combinations of vegetation （green roofs and green facades） installed in a tropical climate region. The experiments were developed in four test cells with dimensions 2.0 m × 2.50 m× 2.71 m. Measurements of internal surface temperatures and internal air temperatures were collected with the use of specific equipment, a data logger （CR1000, Campbell Scientific Inc.）, connected with two multiplexers 32 channels （416AM Campbell Scientific Inc.）. Data were recorded over a year and a critical day heat was selected, which was September 24, 2015.The results show that the use of plant systems in buildings establishes a passive technique in reducing energy consumption because of the high incidence of summer solar radiation which is reduced and simultaneously, it maintains thermal internal conditions more pleasant than external ones, because of the best thermal behaviour, which was observed in the test cell with vegetation on both roofs and facades. The biggest difference between maximum internal air temperatures registered was 2 ℃.

Understanding the Challenges of Implementing Green Roofs in Multi-Family Apartment Buildings:A Case Study in Khulna

Green roofs are widely recognized for their multifaceted benefits to the environment,economy,and society,constituting the fundamental pillars of sustainability.These roofs contribute to the enhancement of bio-physical diversity,provision of food resources,regulation of temperature and rainfall-runoff patterns,creation of wildlife habitats,and augmentation of aesthetic and recreational value.While Bangladesh,with its favourable climatic conditions and rapid urbanization,possesses immense potential for harnessing the advantages of green roofs,their adoption remains limited in both research and practical applications within the country.Addressing this research gap,the present study aims to investigate the barriers impeding the implementation of green roofs in existing or new multi-family apartment buildings,focusing specifically on the city of Khulna.Through a combination of case studies and a comprehensive questionnaire survey administered to diverse stakeholders including apartment dwellers/owners,architects,developers,and government officials with varying levels of expertise,this research sheds light on the obstacles hindering Green Roof Implementation(GRI).The identified barriers encompass a lack of governmental policies,inadequate technological advancements,inaccurate estimation of economic benefits,and individual resistance.In light of the perspectives of various GRI stakeholders,strategic proposals encompassing policy,technical,economic,and social dimensions are presented to surmount these barriers.The outcomes of this study contribute to the dissemination of knowledge pertaining to the impediments to GRI implementation,thereby inspiring further research endeavours and enabling decision-makers to formulate robust policies facilitating the widespread adoption of green roofs.

REFERENCE COMMUNITY: ADAPTING NATIVE PLANTS TO NORTH AMERICAN GREEN ROOFS

The North American design community typically regards green roofs as inhospitable environments for native plants due to the infrastructure’s characteristic thin soils,low organic matter,temperature fluctuations,and wind exposure.Consequently,green roofs are often planted with an industry-standard palette of non-native Sedum and Phedimus species that are adept at withstanding stress,but lack biodiversity and visual interest,and offer little food or shelter to native birds and insects.Regionally specific reference plant communities that thrive in similarly harsh growing conditions can positively influence green roof design throughout North America,and consequently provide ecosystem services,contribute to habitat conservation,and increase human exposure to the beauty and benefits of native plants.

PRAIRIE-BASED GREEN ROOFS:LITERATURE,TEMPLATES,AND ANALOGS

Native prairie species have been both promoted and questioned in their ability to serve as vegetative covers for green roofs.The green roof environment with its exposure to intense sun and wind and limited moisture restricts the capacity for a large diversity of species.The result has been,in many cases,a standard,low-diversity mix of Sedum species often focused on ornament and minimizes the potential for wider environmental benefits.We reviewed the ecological literature on prairie and grassland communities with specific reference to habitat templates from stressed environmental conditions and examined analogs of prairie-based vegetation on twenty-one existing green roofs.We found that many,but not all prairie and grassland species will survive and thrive on green roofs,especially when irrigated as needed or given adequate growing medium depth.We raise several important questions about media,irrigation,temperature,biodiversity and their interactions needing more study.

EFFECT OF SUBSTRATE DEPTH AND TYPE ON PLANT GROWTH FOR EXTENSIVE GREEN ROOFS IN A MEDITERRANEAN CLIMATE

Although numerous examples of green roofs can be found in Turkey,limited research has been conducted on plant material and substrate type in this climate.Both plants and substrate are very important components in green roof design,it is essential to determine the proper substrates and plants in green roof systems for domestic green roof design.Two types of growing substrates:a commercial substrate consisting of crushed brick and clay(45%),pumice(45%),and organic matter(10%),and a recycled substrate including 90%coarse pumice(10-20 mm)and municipal compost(10%),were tested in three depths of 4,7 and 10 cm.Tested plant species included Achillea millefolium,Armeria maritima,Sedum acre and Sedum album.Overall,the commercial substrate performed better than the recycled pumice.In addition,deeper substrates promoted greater survival and growth for nearly all species tested.Either A.maritima or A.millefolium survived in the recycled pumice at any depth,whereas they did survive when grown in the commercial substrate in greater than 7 cm and 10 cm,respectively.They both likely would require supplemental irrigation to be acceptable for green roofs in Istanbul or locations with a similar climate.Both Sedum species survived in all substrate types and depths.Information gained can be utilized by green roof professionals in the Istanbul region and in other parts of the world with a similar climate.

THE ADOPTION OF AN INNOVATION:BARRIERS TO USE OF GREEN ROOFS EXPERIENCED BY MIDWEST ARCHITECTS AND BUILDING OWNERS

While green roof technologies are increasingly employed in Northern European countries,adoption is progressing at amuch slower rate in the US.This manuscript discusses results of a survey that quantified knowledge,barriers,and perceivedcosts and benefits to use of green roof technology among a sample of architects and building owners in the Midwest.The survey also examined conditions that may encourage use of this technology among the respondents.Resultsshow that many respondents do not fully recognize the economic or performance advantages offered by green roof technologies.The payback period for economic advantage is longer than owners are willing to consider.Both owners andarchitects possess a wide range of misconceptions about the performance advantages of green roofs.While green roof technologyoffers clear environmental advantages such as reduced stormwater runoff,increased habitat,and cooler temperaturesthat mitigate heat island effects,many building owner respondents either do not know about or value these advantages.This research quantified potential adopters’perceptions of an innovative technology and the survey results areinterpreted and discussed within the conceptual framework of innovation diffusion literature.Strategies to hasten theadoption of green roof technology are suggested.

THERMAL PERFORMANCE OF GREEN ROOF PANELS IN SUB-ZERO TEMPERATURES

To date,much of the research on green roof technology has focused on the capacity for these systems to contribute to the cooling of buildings during summer months.The thermal performance of green roofs in cold climate conditions is critical to understanding the potential of these roofs to decrease energy use in buildings during winter.This paper compares the behavior of two green roof systems with that of a conventional built-up roof by making use of a novel hot box testing apparatus.The green roofs tested are classified as extensive systems.Each system included:a 3 mm thick styrene butadiene rubber waterproofing membrane,0.2 mm thick polyethylene slip sheet,a 76 mm thick extruded polystyrene insulation layer,2 mm thick filter fabric,a 51 mm drainage layer followed by a 2 mm thick filter cloth,either 100 mm or 150 mm growing medium,and a 25 mm thick wild flower vegetated mat.The conventional roof consisted of a 2 mm thick layer of Kraft™vapour retarder bonded with insulation adhesive,51 mm of isocyanurate insulation,25 mm of fibreboard,a three ply(2 mm)cold-applied built-up roof membrane,and a gravel ballast finish 51 mm thick.Each roof was subjected to temperatures between 0℃ and–25℃,while the temperature within the hot box was held at 21℃.The effect of vegetation on a green roof to reduce wind speeds or increase snow cover were not considered in this study.The power required,as well as the temperatures throughout each system at steady state conditions,were monitored for 5 hours.The data collected from thermal testing suggests that the R-value of green roofs with 100 mm or 150 mm thick layers of growing medium is 37%higher than a conventional roof when subjected to temperatures of 0℃ to–25℃.

PLANTS INFLUENCED BY GROWING MEDIA AND COMPOST ADDITION ON MOCK GREEN ROOFS WITHIN THE OZARK HIGHLANDS

Green roof technology and other low impact development practices help mitigate hydrologic impacts from urbanization.Green roofs are widely recognized for stormwater retention,and these systems provide many other ecological functions,such as habitat,air quality improvements,insulation,reduced noise pollution and aesthetic quality.Green roofs are composed of a plant palette(species selected for a specific condition),growing media and drainage system on top of a traditional roof membrane.This study investigated species survival under local environmental conditions,in the southwestern Ozark Highlands from September 2008 through 2009.There were four treatments consisting of two different growing media particle sizes and two different fertilization regimens(with and without compost).Sixteen plant species and/or varieties were monitored to determine the effect of treatments on survival and spread.Plant response varied by species,but the fine media with compost provided the greatest survival and spread.However,the fine media without compost treatment had similar survival rates and may provide similar cover over time.The coarse particle media treatments had greater mortality rates in most specimens and less coverage after one year.Local environmental conditions were detrimental to some species(Sedum moranense L.),whereas other species(Sedum reflexum L.;Phedimus sp.L.;and Sedum spurium L.‘Summer Glory’)thrived.Our results provide valuable knowledge on creating an appropriate plant palette for green roof designs.

THERMAL PERFORMANCE OF AN EXTENSIVE GREEN ROOF UNDER SEMI-ARID CONDITIONS IN CENTRAL ARGENTINA

Extensive green roofs improve the provision of ecosystem services in urban environ-ments,particularly in semiarid regions.The aim of this paper is to compare their thermal performance during six months between two rooms,one with a green roof and the other with a conventional roof,in Córdoba(Argentina).The room with a green(planting)roof showed a lower inside surface temperature since the begin-ning of the study than the control room(between 5-6°C of difference).During the selected period,the indicators such as temperature amplitude(the difference between the maximum and the average temperature)and the anti-interference characteristics of the layers to the outdoor air temperature are produced a better performance for the green roof compared to the conventional roof.The pattern of a better perfor-mance was consistent across the study for the green roof,characterized by a higher cooling and warming of the roof surface during the day and night,respectively.The green roof was more effective at blocking an upward heat flux during the day and suppressing heat loss during the night.Evaporation,conductive flux and climatic conditions seem to dominate the thermal performance of green roofs in areas with semiarid climate conditions.