Implementation Of Green Roofs Research Articles

Performance study of an innovative concept of hybrid constructed wetland-extensive green roof with growing media amended with recycled materials

Implementation of green roofs requires a large amount of primary material, especially for constructing the growing media layer. In addition, irrigation of green roofs with potable water is uneconomical and unsustainable. The novel hybrid green roof system proposed in this paper is in line with the principles of circular economy as it incorporates recycled materials into green roof growing media and greywater for irrigation. Two experimental beds were built to evaluate the concept of treating greywater in a constructed wetland prior to using it to irrigate a dual-layer extensive green roof. The growing media in both two extensive green roof beds contained ca. 37.5% by volume of recycled crushed building rubble containing a large proportion of brick. One of the two beds additionally contained 9.5% by volume of sewage sludge-based biochar. The concept of the hybrid roof and novel growing media was evaluated based on laboratory analysis of the growing media and on onsite measurements of hydraulic and thermal performance. The growing media amended with recycled materials developed in this study had hydrophysical properties comparable to commercially available growing media without recycled materials. Observations made during one vegetation season from June to October and a ten day-intensive water quality monitoring campaign during September 2020 showed that the constructed wetland significantly reduced total nitrogen and orthophosphate concentrations in pre-treated greywater. Due to the irrigation method employed, in which water flowed predominantly through drainage mats below the growing media, nutrient-leaching by the irrigation water was avoided. Concentrations of nutrients in the effluent were observed to increase only in response to precipitation. The temperature peak of the bottom green roof layer was shifted by almost 9 h from the peak in air temperature, and temperature fluctuations were significantly reduced. Vegetation on the bed amended with biochar demonstrated more vigorous growth due to available nutrients in the biochar which increased the rate of temperature-reducing evapotranspiration. More water evapotranspirated more water, which provided more water retention capacity confirmed by a lower runoff coefficient. Simple storage routing hydraulic modeling of hybrid green roof runoff using a nonlinear reservoir was performed.

Optimización de la rigidez equivalente en estructuras de uno y dos pisos sometidas a cargas de techos verdes

Desde una perspectiva lineal y estática, el aumento de los desplazamientos de una estructura debido a la implementación de un techo verde podría ser contrarrestado con el incremento de la rigidez de la estructura. En este artículo se plantea el uso del algoritmo de evolución diferencial para optimizar la rigidez equivalente de una estructura de uno y dos pisos de altura, variando la carga de techo verde bajo el análisis de fuerza horizontal equivalente en la ciudad de Bogotá. A través del software MATLAB se programa y acopla el algoritmo de optimización y la metodología de análisis matricial de estructuras aporticadas tridimensionales sujetas al cumplimiento de la distorsión máxima de piso propuesta por la normativa de construcción colombiana. Un incremento máximo en la rigidez equivalente de 19.25% y 57.80% (estructuras de un piso), y de 11.12% y 32.97% (estructuras de dos pisos) para pesos de techos verdes de 100 kg/m2 y 300 kg/m2 respectivamente, es necesaria para cumplir requerimientos normativos. Se espera que esta investigación sirva como punto de partida para generar soluciones constructivas a la implementación de techos verdes en estructuras de uno y dos pisos en la ciudad de Bogotá.

Green Roofs as an Approach to Enhance Urban Sustainability: A Study of Public Perception in Riyadh, Saudi Arabia

This study focuses on highlighting the major effects and challenges being faced in the implementation of the green roof technique in Riyadh, Saudi Arabia. Green roofs have proven to be energy efficient, environment friendly, and economical in a long run. Due to the increasing global environment temperature, it has become necessary to implement such sustainable methods that help in the achievement of urban sustainability. Saudi Arabia has seen some reluctance in the implementation of green roofs in buildings. The reasons for not adopting this system have not been reported as yet. To study the level of awareness among the public and the challenges they are facing regarding green roofs, this study was taken up. A survey questionnaire was designed with a high level of flexibility covering the key issues, including the related areas that are affected in the daily life of a resident and also the challenges faced by the general public in the installation of such systems in their existing or new buildings. An extensive literature review and a reconnaissance survey were performed before shortlisting the major factors and challenges to be included in the survey questionnaire. An overwhelming response was received from the people of Riyadh City. Almost 94% of people agreed to the fact that green roofs enhance the aesthetics of the building, and the same number of people agreed that they play a role in controlling the air quality. On the other hand, 91% of the respondents identified the climate of the area as the biggest challenge in implementing green roofs on the buildings. The study concludes with strong recommendations for the local authorities to plan quick actions. The study shall help the building owners, city planners, and policy makers in identifying the major hurdles being faced by the residents in adopting green roofs and will help them to provide solutions to these issues.

Cost-effectiveness analysis of extensive green roofs for urban stormwater control in response to future climate change scenarios

Green roof, as a popular low impact development practice, has become important to mitigate adverse impacts of future climate change on urban stormwater. However, there is limited information regarding assessment of the effectiveness of green roofs in response to uncertain future climate change challenges. In this study, the validated model was used to simulate the reduction performance of green roofs on urban catchment outflow and assess their cost-effectiveness in response to design storms under climate change scenarios. Results showed that the median runoff volume of urban catchments increased by 12.5 %–14.6 % and 15.5 %–18.1 % and the median peak flow rate increased by 14.4 %–17.8 % and 17.9 %–22.1 % under SSP2-4.5 and SSP5-8.5 scenarios, respectively. This indicated the variability of runoff volume and peak flow changes for short return storm events caused by climate change was relatively high. Green roof implementation had reasonable mitigation effects on runoff volume and peak flow amplification in urban catchments caused by climate change. The median runoff volume reduction of green roofs for the 1-year storm was 15.2 % under SSP2-4.5 scenario. As rainfall intensity increased, the median runoff volume reduction of green roofs significantly declined to 5.6 % for the 100-year storm. However, the variations of runoff volume and peak flow reduction of green roofs were relatively smaller for longer return periods under climate change scenarios. Runoff reduction percentages of green roofs increased linearly with their implementation cost. The average value of the cost-effectiveness (C/E) index for green roofs was 91.2 %/million $ under base climate condition, and it decreased to 88.9 %/million $ and 88.4 %/million $ for SSP2-4.5 and SSP5-8.5 scenarios, respectively. The C/E values decreased with increasing storm return period, and the values were relatively lower in SSP5-8.5 scenarios. These results could help to understand the potential role of green roofs to mitigate the impacts of future climate change.

Can green roofs help with stormwater floods? A geospatial planning approach

Increasing urbanization, impervious space, and the impact of climate change are threatening the future of cities. Nature-based solutions, specifically urban green infrastructures, are seen as a sustainable strategy to increase resilience against extreme weather events, including the escalating occurrence of stormwater runoff flooding. Consequently, urban planners and decision-makers have pushed their efforts toward implementing green infrastructure solutions to reduce the impact of stormwater floods. Among others, green roofs help store water and decrease stormwater runoff impacts on a local scale. This research aims to investigate the effect of surface permeability and green roof implementation on reducing stormwater flooding and subsequently provide urban planners with evidence-based geospatial planning recommendations to improve urban resilience in Helsinki. First, we modeled the current impact of stormwater flooding using the Arc-Malstrom model in Helsinki. The model was used to identify districts under high stormwater flood risk. Then, we zoomed in to a focus area and tested a combination of scenarios representing four levels of green roof implementation, two levels of green roof infiltration rates under 40-, 60-, 80-, 100 mm precipitation events on the available rooftops. We utilized open geographic data and geospatial data science principles implemented in the GIS environment to conduct this study. Our results showed that low-level implementation of green roofs with low retention rates reduces the average flood depth by only 1 %. In contrast, the maximum green roof scenario decreased most of the average flood depth (13 %) and reduced the number of vulnerable sites. The proposed methodology can be used for other cities to develop evidence-based plans for green roof implementations.

Mandatory or voluntary approaches to green roof implementation: a comparative study among some global cities

Green roofs can deliver multiple environmental and social benefits by reducing the urban heat island effect, reducing building energy use and greenhouse gas emissions, improving air quality, providing habitat for biodiversity and access to the biophilia effect. Green roofs provide these benefits to differing degrees in different climate zones globally. Despite known benefits, uptake of green roofs has been slow. Different cities, globally, adopt various policies and programmes to increase their green roofs; the question is which approach is best? This research used an in-depth review, site visits and qualitative methods, to determine whether mandatory or voluntary approaches produced greater uptake. Green roof policies and practices from selected global cities, London, Toronto, Singapore, Rotterdam and Stockholm, Sydney and Melbourne were examined. Singapore’s voluntary approach led to the greater uptake of green roofs. The mandatory approach taken by Toronto, with financial grants provided meaningful outcomes. London and Rotterdam implemented useful voluntary programmes, and Stockholm required more time to evaluate the effectiveness of its voluntary approaches in increasing green roofs. A voluntary approach for retrofit and a mandatory approach for new build developments are suggested as recommendations for Australian cities. Given the increases in green roofs internationally, similar increases can occur in Melbourne and Sydney in Australia, and these findings may be transferable to other global cities investigating different approaches to the increased adoption of retrofitted green roofs.

Quantitative valuation of green roofs’ cooling effects under different urban spatial forms in high-density urban areas

In the context of global climate change, the increasing urban heat island (UHI) effect is a serious challenge to sustainable urban development. The construction of green roofs is an important means to optimize the urban thermal environment, especially in high-density urban areas. However, the cooling effect of green roofs in different urban spatial forms varies. Thus, the quantitative evaluation of the cooling effect of green roofs is significant for the scientific and effective mitigation of the UHI effect. This study took the central district of Chengdu City as a typical area, clearly classified urban spatial form types based on the LCZ theory, and quantified the relative land surface temperature (RLST) difference between before (2014) and after (2018) the implementation of green roofs based on Landsat 8 remote sensing image retrieval. Numerical analysis methods were used to statistically evaluate the cooling effect of green roofs under different urban spatial form types by GIS. The results showed that (1) the cooling effect of green roofs varied significantly among different urban spatial form types; (2) the best performance of the cooling effect of green roofs was in Compact Highrise (LCZ1), which could reduce RLST by 0.94 °C, while the worst was in Lightweight Lowrise (LCZ7). Based on the above performance of the cooling effect of green roofs, the construction of green roofs can be prioritized and zoned, and the design strategies of green roofs under different urban spatial form types can be proposed. Our study will provide a basis for developing design guidance for green roofs and scientific support for mitigating the urban thermal environment.

Assessing the potential of strategic green roof implementation for green infrastructure: Insights from Sumida ward, Tokyo

Urban green spaces, and green infrastructure more generally, provide multiple benefits that can enhance urban livability and sustainability. These range from the mitigation of air pollution and urban heat island (UHI) effect, to multi-dimensional benefits to human wellbeing and biodiversity. However, the expansion of urban green spaces is not always feasible in many cities. In such urban contexts, there have been proposals to utilize rooftops as green roofs in order to gain some of these benefits. This study spatially identifies areas where roofs have the potential to provide different types of benefits associated with urban green spaces if they are retrofitted with green roofs. Through a GIS-based approach we catalogue available roof space in Sumida ward in Tokyo for green roof implementation, and subsequenlty evaluate the potential of each roof patch to offer four types of benefits if retrofitted with a green roof, namely UHI effect mitigation, air pollution mitigation, and benefits to subjective wellbeing and biodiversity. Approximately 25% of the total roof surface in Sumida ward can potentially be used for green roof implementation. Furthermore, about 5.2% and 59% of this area has a respectively high and moderate potential to provide all four benefits if retrofitted with green roofs. This could increase the extent of green spaces by 10% and 120% respectively across the Sumida ward. In this sense, green roofs can become a major element of green infrastructure with ripple positive effects for urban livability and sustainability through the provision of UHI effect and air pollution mitigation, and benefits to subjective wellbeing and biodiversity.

Experience and benefits of using green roofs as an element in green infrastructure

Purpose. To analyze the international experience of using green roofs an element of green infrastructure as, to outline the main advantages of using this element, to analyze the ways of implementation in Ukraine and to identify difficulties in this process. Results. Modern processes of urbanization lead to a reduction in the number of green spaces, climate change, an increase in the city's heat island, the impoverishment of biodiversity and more. The use of green infrastructure strategy provides a foundation for further sustainable urban development. Green infrastructure plays a key role in finding a balance between nature and urbanization. It can solve a number of problems, as well as improve the quality of ecosystem services. An analysis of scientific sources on the use of such an element of green infrastructure as green roofs was performed. It has been established that green roofs have a very long history of creation in the Scandinavian countries, their use dates back to 1500 years, in European countries the most advanced country is Germany. The implementation of green roofs has significant advantages when properly implemented can provide a wide range of ecosystem services. However, there are some subtleties for their proper implementation. Conclusions. The implementation of green roof technology in different countries has different features, the common denominator is that when choosing plants it is necessary to use local plants that are adapted to the climatic conditions of a particular area, you need a legal basis to develop this idea. Taking into account all the benefits of using this technology, we can state that their implementation is a necessary today for adaptation to climate change.

The Sustainable Prescription: Benefits of Green Roof Implementation for Urban Hospitals

If worldwide healthcare was a country, it would be the fifth largest emitter of greenhouse gases on the planet. The increase in global temperatures, combined with the negative impacts of urbanization, has made it more important than ever to introduce green spaces where possible. With climate change worsening, human health, both physically and mentally is on decline, making the effects of climate change especially pressing to the stability of healthcare systems. In order to mitigate the lasting impacts of climate change on healthcare facilities, a holistic solution is needed. Access to green space in hospitals has been shown to reduce emotional distress, improve mental health, increase socialization and community connection, increase physical activity, decrease cardiovascular and respiratory diseases, decrease pain management needs and hospital stay lengths and increase both patients' and staffs' overall satisfaction at the facility. Beyond benefiting those interacting with the hospital, green roofs have the ability to reduce the urban heat island effect, improve stormwater mitigation, increase biodiversity, and absorb toxins and pollutants through air filtration. Additionally, green roofs can offer lower maintenance costs and higher energy savings than traditional roofs, and improve patient satisfaction, which can result in future funding opportunities. However, the upfront and upkeep costs of installing a green roof can vary and must be considered before implementation. In this review, we explore the symbiotic relationship between urban green roofs and hospital/patient wellness through the lens of sustainability, which includes environmental, societal, and economic impacts. We review scientific journal articles investigating benefits of green space and green roofs and highlight examples of green roofs on hospitals in the United States; together, these approaches display the environmental, societal, and economic benefits of green roofs installed on healthcare facilities. This review offers insight to hospitals, decision makers, and government systems on the importance of green roofs in urban areas and how these infrastructures can support the economic growth of the institute. Using our framework, decision makers and planners for urban hospitals can evaluate how the addition of green roofs to their healthcare facilities can contribute to increased environmental resiliency, community health, and patient satisfaction.

Strategies for implementation of green roofs in developing countries

PurposeReportedly, green roof (GR) makes a significant contribution towards a truly sustainable-built environment; however, its implementation is yet to hit a sufficient level in developing countries. Thus, this study assesses GR implementation strategies in developing countries by providing a comparative analysis through experts in Kazakhstan, Malaysia and Turkey.Design/methodology/approachThe study adopts a four-step methodological approach to achieve the research aim: literature review, focus group discussion, fuzzy analytical hierarchy process (FAHP) analysis and correlation analyses. First, a literature review followed by a focus group discussion is used to determine 18 (out of 25 initially) strategies for the selected context and these are classified into three categories: governmental and institutional support, knowledge and information and policy and regulation. Afterward, the identified GR strategies are evaluated using the FAHP with the data gathered from the experts in the countries studied. Finally, correlation analyses were used to observe the strength of agreement between the assessments of experts from the included countries.FindingsThe findings indicate that financial incentives, low-cost government loans and subsidies and tax rebates are the essential strategies for the wider adoption of GR. Evaluating the policy and regulations strategies also showed that mandatory GR policies and regulations and better enforcement of the developed GR policies are ranked as the most prominent strategies. The findings show a low level of agreement among respondents from Kazakhstan, while there is a high level of agreement between the experts in Malaysia and Turkey.Research limitations/implicationsThe research contribution is twofold. First (research implication), the study identifies the strategies through a complete literature review. Second, the identified strategies are evaluated through the lenses of experts in three developing countries which are hoped to provide (practical contribution) a better understanding of the most effective strategies that require attention and enable the frontline stakeholders (particularly government authorities) to focus on them.Originality/valueThe study findings provide a good point of departure to explore the strategies for broader adoption of GRs in developing economic setting.

Green Roof Hydrological Modelling With GRU and LSTM Networks

Green Roofs (GRs) are increasing in popularity due to their ability to manage roof runoff while providing a number of additional ecosystem services. Improvement of hydrological models for the simulation of GRs will aid design of individual roofs as well as city scale planning that relies on the predicted impacts of widespread GR implementation. Machine learning (ML) has exploded in popularity in recent years, however there are no studies focusing on the use of ML in hydrological simulation of GRs. We focus on two types of ML-based model: long short-term memory (LSTM) and gated recurrent unit (GRU), in modelling GRs hydrological performance, with sequence input andsingle output (SISO), and synced sequence input and output (SSIO) architectures. Results of this paper indicate that both LSTM and GRU are useful tools for GR modelling. As the time window length (memory length, time step length of input data) increases, SISO appears to have a higher overall forecast accuracy. SSIO delivers the best overall performance, when the SSIO is close to, or even exceeds, the maximum window size.

EFFECT OF IRON ORE TAILING AND GLASS POWDER ON CONCRETE PROPERTIES

In the search for adopting methods that provide more comfort in the housing system, they require better structural performances in current buildings. Construction practices in the region have been discredited over time, conceiving vulnerable buildings whose inhabitants are subject to risk. The objective of this research is to comprehensively analyze the technical, construction, and design characteristics of reinforced concrete slabs regarding their implementation as a reinforcing structure for green roofs in the city of Tuxtla Gutiérrez, Chiapas, Mexico. To carry out the structural analysis, the intrinsic properties of the supporting members (slabs) were considered, as well as their current condition, and design based on durability standards. The research results revealed that the slab depth and the amount of steel were lower for average spans, as stipulated by the corresponding technical standards. Corrosion damages in steel bars are expected and they were found under an inadequate design standard, combined with deficiencies throughout the construction process. The constructions analyzed and developed with formal construction or self-build processes show similar pathologies. The city of Tuxtla Gutiérrez lacks training centers for homeowners and workers to be able to adopt self-build methods. Moreover, the authority is not rigorous regarding the compliance with building codes. These members have become a key knowledge gap. Finally, the implementation of green roofs in these structures is unlikely without prior significant changes in the entire construction.

Towards the Development of a Comprehensive Lifecycle Risk Assessment Model for Green Roof Implementation

A green roof (GR) provides numerous social, environmental, and personal benefits through its lifespan, while exploiting these benefits is associated with several uncertainties. Since these risks to GR adoption have not yet been investigated and analyzed comprehensively, this research is aimed at developing an original risk assessment model to ensure the objectives of GR adoption are fully achieved. To this end, two novel approaches were employed, namely Monte Carlo-DEMATEL and fuzzy parsimonious analytic network process to determine the inner dependencies among the risk factors and rank them based on their relationships and importance, respectively. The findings showed that “irregular maintenance” and occurrence of “fire” are the most influential threats, while “flash flood reduction” and “achieving green building certificate award” are among the most influential opportunities. Moreover, it was shown that although “tax abatement” and “monetary loss” are the most important opportunity and threat, respectively, the ranking order of risk factors varies among an intensive GR and an extensive GR. Finally, it was concluded that with such analyses, the decision-makers have clear insights on the most influential positive and negative risks for managing purposes. The novel methods used in this research can be replicated to achieve more accurate and efficient results.

Green roofs – good regulatory practices with potential to be applied in Bulgaria and North Macedonia

Green roofs are used worldwide to mitigate the impacts of extensive urbanization, bringing benefits on social, economic, and environmental levels. In order to promote and facilitate the construction of green roofs by private investors, many countries have developed specific legislative requirements and incentives. However, there still are countries where the construction of green roofs is not properly addressed in the legislation, and where no incentive mechanisms are developed.  The good practices in three European countries, leaders in regards to the implementation of green roofs – the Netherlands, Belgium, and Germany, are analyzed in this article. A variety of incentives is introduced to accelerate the construction of green roofs. Different requirements are also set to ensure that the roofs will be designed and maintained to provide the desired benefits. The existing local regulations in Bulgaria and North Macedonia were analyzed as well. The only incentive in Bulgaria is the possibility of reducing the legally required green area by compensating it with a green roof. In North Macedonia, no legislative documents or incentives related to green roofs were found. The regulations, applied in the Netherlands, Belgium, Germany, and other countries can be used as good practice examples, modified, and applied from the authorities of countries that still have not developed their own, in order to motivate the investors and facilitate the construction of green roofs.

Socio-Ecological Dimensions of Spontaneous Plants on Green Roofs

Green roofs have the potential to provide socio-ecological services in urban settings that lack vegetation and open space. However, implementation of green roofs is limited by high construction and maintenance costs. Consequently, green roof projects often disproportionately benefit wealthy communities and can further marginalise disadvantaged communities by increasing property values and housing costs. Vegetation cover on green roofs is crucial to their provisioning of socio-ecological services. Evidence suggests that green roof plantings change over time, especially with limited maintenance, and are replaced with spontaneous “weedy” species. This is often perceived as a failure of the original green roof design intent and spontaneous species are usually removed. However, where good coverage is achieved, spontaneous vegetation could provide beneficial services such as stormwater mitigation, habitat provision, and climate regulation. While social norms about “weediness” may limit the desirability of some spontaneous species, research suggests that their acceptability on green roofs increases with coverage. As spontaneous species can establish on green roofs without irrigation and fertiliser, reduced input costs could help facilitate adoption particularly in markets without an established green roof industry. Construction costs may also be reduced in hot and dry climates where deeper substrates are necessary to ensure plant survival, as many spontaneous species are able to colonise shallow substrates and can regenerate from seed. If implemented based on socio-ecological need, green roofs with spontaneous vegetation coverage may apply less pressure to property values and housing costs than conventionally planted green roofs, increasing the resilience of urban communities while limiting gentrification.

Identifying city-scale potential and priority areas for retrofitting green roofs and assessing their runoff reduction effectiveness in urban functional zones

Green roof is a popular green infrastructure type implemented in highly urbanized areas, but it is difficult to reliably translate local results to urban or watershed scales. It is necessary to develop appropriate methods to quantitatively identify prioritization of green roof retrofitting at urban functional zones (UFZs) where green roof implementation is most needed and suited. In urban regions, various UFZ types may have diverse demands and suitability levels of green roof retrofitting, thus they should be given different spatial prioritization in location planning of green roof practices. In this paper, the spatial potential of green roof retrofitting at UFZs scale was estimated and mapped, a priority index considered the demand for green space, runoff risk and suitability for roof greening of UFZs was developed to identify the priority areas for retrofitting green roofs, and runoff reduction effectiveness of hypothetical green roof retrofitting scenarios under three storm return periods were assessed. Results indicated that the total potential area for green roof retrofitting is 143.62 km2 within the Fifth Ring Road of Beijing, which accounts for 21.52% of the study area; The developed priority index was able to appropriately reflecting the differences on demands and suitability levels of green roof retrofitting in various UFZs; Compared with the baseline scenario (0% retrofitting), the average runoff volume was reduced by 1.34%–2.73% with 10% green roof retrofitting; The maximum average reduction effectiveness achieved was 9.17%–19.05% under a 100% green roof retrofitting scenario. The runoff coefficient within COZ (commercial zone), EGZ (education & government zone) and HRZ (high-density residential zone) was significantly reduced as green roof retrofitting percentages increased. These results can inform urban planners of a meaningful estimator of UFZs scale green roof potential and support for identifying the priority areas for partially implementing green roofs.

Life cycle benefits and challenges of large – scale green roof implementation in a mediterranean compact city: the case of Thessaloniki

Green roof installation is considered to be an effective practice in restoring green spaces to high – density urban areas, in an effort to mitigate environmental problems that arise from their growing expansion. The present study attempts to further investigate this claim by assessing the environmental and economic life cycle benefits and challenges of two extensive green roof large – scale implementation scenarios (on existing or on well – insulated roofs) in the compact mediterranean city of Thessaloniki, Greece. In both scenarios green roofs provided energy savings (13-19%), greenhouse gas emissions (22-29%) and waste production (57-60%) reductions but also led to a significant increase in water consumption (279-291%), with performance being better in the latter case. They also accrued significant public economic benefits in both a low and high discount rate scenario, although they were not an efficient choice for private owners in the second one. These results seem to imply that green roofs could potentially be a viable urban green infrastructure solution, if their water use is minimized in a sustainable way and additional state incentives are considered.

Procedure for the selection and evaluation of prefabricated housing buildings for the implementation of green roofs in the context of Urban Heat Island mitigation. The example of Wrocław, Poland.

The assessment of the suitability of existing buildings for implementation of green roofs is an important research issue, especially in the context of Urban Heat Island (UHI), the negative impacts of which are locally exacerbated by the global warming. The studies carried out so far have covered a variety of buildings and have taken into account a range of different conditions. Relatively little attention has been paid to the possibilities of greening the roofs of prefabricated apartment blocks from the second half of the 20th century in the context of the potential climate effect. Yet, these buildings are found in many cities around the world, and seem in fact attractive for greening. In view of the above, we proposed a three-stage investigatory procedure to: (I) identify and classify buildings based on the number of floors and the rooftop available area; (II) select buildings by designating priority areas depending on the highest UHI intensity and roof density; (III) analyse the roof load capacity to develop retrofit scenarios. The procedure was applied to prefabricated housing estates built in the 1970s and 1980s in Wrocław, Poland. The research shows that there are 1962 buildings of different heights and roof area of 722405 m2, of which 480 buildings with a roof area of 122749.1 m2 were selected for greening within priority areas. The structure of the studied roofs was not designed to carry additional loads, which requires the application of complementary solutions. Scenario 1 assumes extensive greening provided that the existing ventilated roof is strengthened, scenario 2 –semi-intensive greening, which however requires the conversion of the ventilated roof to a non-ventilated one. The presented procedure can be applied in any other city with prefabricated apartment blocks and available UHI data, and serve to support the decision to implement green roofs to mitigate UHI.

Challenges and Way Forward for Implementing Green Roof in Construction Industry in Sarawak, Malaysia

There is a growing global concern about the adverse effects of today's rapid economic growth and development, which impact the environment and deplete energy supply. A green roof may lower a building's energy consumption and minimise air pollution by reducing dust particles in the air. The primary impediment to green roof implementation in Malaysia lacks local knowledge and unskilled green roof specialists. As a result, there is a shortage of green roof installers and specialised firms in the country. This article discusses the problems and solutions of adopting green roofs in building projects based on construction industry experience in Sarawak. A survey utilising a questionnaire is used to obtain data for this research. The paper revealed the possible challenges of adopting a green roof for the construction industry. The study is critical in order to adopt green roof technology quickly in Malaysia.