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

Sustainability issues have become crucial to mitigate urban heat islands (UHIs) and reduce the global warming effect. The climate change news is frequently heard lately due to the extreme weather to the extent that the increasing earth’s temperature often causes disaster and loss of property and life. New adaptation needs to new climate context and limits the on-going effects. One of the ways is adopting green roofs on buildings. Implementing sustainable practices such as green roofs will help mitigate this adverse effect in urban areas. Green roofs provide many benefits such as enhancing the aesthetical quality of the built environment, reduce UHIs, reduce energy consumption, improve storm-water attenuation, roof longevity, and reduce noise pollution. However, only a few buildings in Malaysia have considering green roofs as a main green feature element. There is barely number of buildings that have green roof design even though it offers benefits to the community and environment. This chapter has emphasised the types of green roof systems that are potentially suitable in Malaysia climate and obstacles associated with the green roof system. The study found the barriers to implementing green roofs in Malaysia, especially during the stage of building operation in maintaining the green roof system. The survey has been done, which revealed nine factors that hinder the green roof application. This study also highlights the challenges to overcome the barriers of implementing green roofs in Malaysia.

The Greenery system on buildings is an interesting approach to address the urban, and environmental issues yet provide economic and social benefits. The educational campus in Higher Learning Institution (HLI) has been regarded as a small city that can implement the greenery system area. Green roofs have rapidly become a key in sustainable building development and design features for urban cities and have started being applied in a campus building. However, the built environment in the campus is mostly covered with the existing buildings. Several studies also conducted green roof aspects but with a vast focus on the new building design. Thus, there is an urgent need to identify retrofitting criteria on green roof implementation for existing buildings to achieve optimal solutions. This chapter aims to identify the influential criteria for implementing green roof initiatives in the educational building of HLI. A list of 12 green roof criteria has been identified based on design and economics. A questionnaire has been designed and distributed to architects as important stakeholders in green roof development. The results obtained were analysed with factor analysis based on principal component analysis with Varimax Rotation and Factor Score to categorise and rank according to the importance of criteria. The outcomes of this study showed that design criteria should concern waterproofing, drainage, and access; economic criteria are construction costs, return on investment, and maintenance cost. This study enables decision-makers to consider the criteria established during the decision of retrofitting an existing building with a green roof.

Green roofs are strategies for the ecological intensification of cities and a measure of meeting some of the sustainable development goals (SDGs). They have widely been adopted as an adaptation strategy against an urban heat island (UHI). However, they are conventionally soil-based making it difficult and expensive to adopt as a strategy for greening existing buildings (GEB). This paper, therefore, develops a novel green roof system using climbers for thermal-radiative performance. The paper explores the vitality of climbing species as a nature-based strategy for GEB, and for the ecological improvement of the predominantly used cool roofs in sub-Saharan Africa (SSA).

Simulation for the same building Kejetia Central Market (KCM) Redevelopment; the existing aluminium roof (AL), soil-based extensive green roof (GR1) and the proposed green roof using climbing plants (GR2) were performed using ENVI-met. The AL and GR1 were developed as reference models to evaluate and compare thermal-radiative performance of the conceptual model (GR2). The long wave radiation emission (Q_lw), mean radiant temperature (MRT) and outdoor air temperature (T_a) of all three roofing systems were simulated under clear sky conditions to assess the performance and plant vitality considering water access, leaf temperature (T_f) and latent heat flux (LE₀) of GR1 and GR2.

There was no short wave radiation (Q_sw) absorption at the GR2 substrate since the climbers have no underlying soil mass, recording daily mean average Q_lw emission of 435.17 Wm⁻². The soil of GR1, however, absorbed Q_sw of 390.11 Wm⁻² and a Q_lw emission of 16.20 wm⁻² higher than the GR2. The AL recorded the lowest Q_lw value of 75.43 Wm⁻². Also, the stomatal resistance (r_s) was higher in GR1 while GR2 recorded a higher average mean transpiration flux of 0.03 g/sm³. This indicates a higher chance of survival of the climbers. The T_a of GR2 recording 0.45°C lower than the GR1 could be a good UHI adaptation strategy.

No previous research on climbers for green roof systems was found for comparison, so the KCM project provided a unique confluence of dynamic events including the opportunity for block-scale impact assessment of the proposed GEB strategy. Notwithstanding, the single case study allowed a focussed exploration of the novel theory of redefining green roof systems with climbers. Moreover, the simulation was computationally expensive, and engaging multiple case studies were found to be overly exhaustive to arrive at the same meaningful conclusion. As a novelty, therefore, this research provides an alternative theory to the soil-based green roof phenomenon.

The thermal-radiative performance of green roofs could be improved with the use of climbers. The reduction of the intensity of UHI would lead to improved thermal comfort and building energy savings. Also, very little dependence on the volume of soil would require little structural load consideration thereby leading not only to cheaper green roof construction but their higher demand, adoption and implementation in SSA and other low-income economies of the global south.

The reduction of the consumption of topsoil and water for irrigation could avoid the negative environmental impacts of land degradation and pollution which have a deleterious impact on human health. This fulfils SDG 12 which seeks to ensure responsible consumption of products. This requires the need to advance the research for improvement and training of local built environment practitioners with new skills for installation to ensure social inclusiveness in the combat against the intractable forces of negative climate impacts.

Climbers are mostly known for green walls, but their innovative use for green roof systems has not been attempted and adopted; it could present a cost-effective strategy for the GEB. The proposed green roof system with climbers apart from becoming a successful strategy for UHI adaptation was also able to record an estimated 568% savings on topsoil consumption with an impact on the reduction of pollution from excavation. The research provides an initial insight into design options, potentials and limitations on the use of climbers for green roofs to guide future research and experimental verification.

Despite its worldwide reputation as an effective solution to sustainable building development and energy efficiency, green roofs in Malaysian cities are rarely accessible. The architecture of the building primarily influences public accessibility, crime watch and safety level and events that encourage the public's engagement, which is evident in crowd density. The purpose of this paper is to discuss the social potential of highly accessible Malaysian green roofs as public space, initiated by the lack of local published material discussing on this topic.

This study reviews the current issues concerning limited public accessibility on Malaysian public institution green roofs by systematic literature review and thematic analysis by comparing the effectiveness of applicable public space strategies on the green roof.

The criteria that have been identified and considered as study parameters include architecture, safety and surveillance, and active functions. Through systematic review of available literature, these characteristics contribute positively to public participation within the public realm.

The exploration of the social potential would establish a green roof as a thriving public space that welcomes the public from all ages and backgrounds, addressing the general public accessibility towards outdoor recreational areas, especially within dense urbanisation with diminishing green spaces.

This research highlights the key characteristics of the highly functional public space that could be applied in developing a guideline for designing future green roofs with high accessibility potential for the public in the city area, in parallel with the anticipated future growth in demand for green roofs infrastructure surrounding public buildings.

The key aspects that built environment professionals need to consider when evaluating roofs for the purpose of green roof retrofit and also when assessing green roofs for technical due diligence purposes are outlined. Although green or sod roofs have been built over many centuries, contemporary roofs adopt new approaches and technologies. The paper aims to discuss these issues.

A mixed methods design based on a systematic review of relevant literature from parallel disciplines was used to identify and quantify the social, economic and environmental benefits of retrofitted green roofs in commercial districts. The technical issues of concern were drawn from a desk-top survey of literature and from stakeholder focus groups undertaken in Sydney in 2012.

There are perceptions amongst built environmental practitioners that may act as artificial barriers to uptake. There is little direct experience within built environment professionals and practitioners, along with a fear of the unknown and a risk averse attitude towards perceived innovation which predicates against green roof retrofit. Furthermore projects with green roofs at inception and early design stage are often “value engineered” out of the design as time progresses. There is a need for best practice guidance notes for practitioners to follow when appraising roofs for retrofit and also for technical due diligence purposes.

The focus groups are limited to Sydney-based practitioners. Although many of these practitioners have international experience, few had experience of green roofs. A limited number of roof typologies were considered in this research and some regions and countries may adopt different construction practices.

In central business districts the installation of green roof technology is seen as one of the main contributors to water sensitive urban design (WSUD). It is likely that more green roofs will be constructed over time and practitioners need knowledge of the technology as well as the ability to provide best advice to clients.

The benefits of green roofs as part of WSUD are increasingly being recognised in terms of reduced flood risk, reduced cost of drainage, improved water quality and lower energy use, as well as other less tangible aspects such as aesthetics and amenity. This research highlights the lack of understanding of the short- and long-term benefits, a poor appreciation and awareness of these benefits; a lack of technical knowledge and issues to be considered with regard to green roofs on behalf of practitioners. The study has highlighted the need for specific training and up-skilling in these areas to provide surveyors with the technical expertise needed. There is also a need to consider how the emerging retrofit and adaptation themes are best designed into the curriculum at both undergraduate and postgraduate levels. Clearly, if the potential benefits of green roofs are to be realised in the future, building professionals need to be fully conversant with the technology and be able to provide reliable and accurate advice.

Green roofs are acknowledged as a method to substitute greenery washed out by the urbanization. They provide many ecological and sustainable benefits of greenery; reduce the adverse effects of high-rise building constructions. Though this concept is more popular across many countries over the past few decades, still, implementation of this technology in Sri Lanka is new and scant. Hence, the purpose of this paper is to identify and analyze the potential of green roofs in high-rise buildings in Sri Lanka.

The data collection was conducted through expert interviews and questionnaire survey. Expert interviews were carried out to validate the prospects and restraints identified through literature review to the Sri Lankan context and analyzed using content analysis. Questionnaire survey identified the most significant prospects and restraints using descriptive statistics and paired sample t-test. Purposive sampling was used to select participants.

Reduction of air pollution, aesthetical appearance, thermal benefits and energy savings, reduction of an urban heat island effect, the addition of points in the green rating system are the top most significant prospects that need to be highlighted in promoting green roof systems in Sri Lankan high rises. Less space allocation on rooftops, lack of technical competence and lack of awareness and research are restraints that need most effective elimination strategies to encourage green roof systems.

The first identified and quantified prospects and restraints for green roof system in Sri Lankan high-rise buildings can be utilized by the government, donors, multi-lateral agencies to promote the sustainable development in Sri Lanka and this knowledge could be used in different scale awareness programs. The value of this paper is such that the paper discusses the links of green roofs with the other facets of sustainability. The new legal reforms and amendments in Sri Lanka could potentially be pending with findings of this study.

The purpose of this paper is to illustrate the potential for green roof retrofit to commercial buildings in a city centre to property managers and other property professionals.

This paper addresses the research question: what is the potential of existing buildings in the CBD to accommodate a retrofitted green roof? Furthermore, it questions how many buildings are suitable for green roofs? The researchers compile a unique building database incorporating information about 536 commercial buidings and evaluate the potential suitability of each building to undergo a green roof retrofit. Assisted by other commercially available databases and software, the researchers are able to assess each roof based on criteria derived from an extensive literature review.

A relatively small proportion of roofs are found to be suitable, partly a result of local climate conditions and rainfall patterns, and the physical property stock. On a purely physical assessment, only a very small proportion of CBD stock is found to be suited. These buildings are most likely to be in low secondary locations, ungraded or B grade buildings, privately owned, concrete framed and not overshadowed by adjoining properties.

Property managers and other property professionals can now determine the potential of their portfolio stock for green roof retrofit based on the review of building attributes required for success adaptation in this paper. It possible that greater potential for green roof retrofit exists in the suburbs or regional towns where lower rise buildings may reduce the amount of overshadowing found in city centres. Follow‐up research could focus on a comparison of regional and suburban developments.

This is the first study of its kind and has assessed such a large number of buildings for their suitability for green roof retrofit; the findings provide a reliable guide for policymakers regarding the potential number of city centre buildings which would be possible to retrofit. Such findings should influence policymaking and incentives to target effective sustainability policies with regards to existing buildings.

This paper aims to assess factors that affect carbon sequestration on green roofs.

The most current academic literature related to carbon sequestration and green roofs carbon sequestration performance was reviewed.

Factors affecting carbon sequestration were discussed and classified into the following factors: plants, physical and maintenance factors. The authors’ findings are significant because they can be used to optimize green roofs performance for carbon sequestration.

Factors affecting carbon sequestration will optimize intensive green roofs performance.

The purpose of this paper is to explore perceptions of the advantages and disadvantages of green roofs for commercial real estate building owners/occupiers in a UK city and consider how these might affect the chances of their adoption.

Two sets of semi-structured interviews were conducted with purposively selected respondents, 10 with and 25 without green roofs, to compare and contrast differing perspectives. A grounded theory approach was taken to data analysis, allowing themes to emerge directly from the data.

Low awareness and understanding were observed amongst those without green roofs, which positively affected perceived costs whilst negatively affecting perceived benefits. Green roof owners gave weight to wider societal and ecosystem services benefits, whilst those without focussed much more upon building-level benefits and costs.

Because of the restricted sample size, the findings in themselves are not generalizable; rather, themes are drawn from the research for reflection.

Findings point to steps that might be required of regional and national government to increase green roof uptake. This could involve initiating conversations to raise awareness, shift discourse and perceived norms and best practice; offering incentives, education and training; and presenting high-profile exemplar projects of green roofing to begin to mainstream the technology and get it onto the radar of building owners.

Bringing together social research around cohorts with and without green roofs, the paper throws into sharp relief discussions around costs and benefits and points towards potentially more productive directions for action to encourage consideration and take-up of green roofs by building owners.