Article

Thermal performance of green roofs through field evaluation

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Abstract

Green roofs have the potential to improve the thermal performance of a roofing system through shading, insulation, evapotranspiration and thermal mass, thus reducing a building's energy demand for space conditioning. To quantify the thermal performance and energy efficiency of green roofs in Canada, the National Research Council of Canada (NRC) has constructed an experimental facility, the Field Roof Facility (FRF), in its Ottawa campus. A median divider separates the roof of the FRF in two equal areas: a generic extensive green roof and a modified bituminous roof. Both roof sections are instrumented to allow direct comparison of the thermal performance the Green Roof and the Reference Roof. Observations from the FRF showed that a generic extensive green roof could reduce the temperature and the daily temperature fluctuation experienced by the roof membrane significantly in the warmer months (spring and summer). The Green Roof also significantly moderated the heat flow through the roofing system and reduced the average daily energy demand for space conditioning due to the heat flow through the roof in the summer by more than 75%. The Green Roof was more effective in reducing heat gain than heat loss. Les terrasses-jardins peuvent aider à améliorer la performance thermique d'une toiture, grâce à l'ombrage, l'isolation, l'évapotranspiration et la masse thermique qu'elles engendrent, réduisant ainsi la demande en énergie d'un immeuble pour le conditionnement de ses espaces. Pour quantifier la performance thermique et l'efficacité énergétique des terrasses-jardins au Canada, le Conseil national de recherches Canada (CNRC) a construit une installation expérimentale, le Field Roof Facility (FRF), sur son site d'Ottawa. Le toit du FRF a été séparé en deux zones égales par une cloison. D'un côté, une grande terrasse-jardin générique, de l'autre un toit en bitume modifié. Les deux zones sont équipées d'instruments de mesure pour permettre une comparaison directe de la performance thermique de la terrasse-jardin et du toit témoin. Les observations relevées sur le FRF indiquent qu'une terrasse-jardin réduit sensiblement la température et les fluctuations des températures quotidiennes subies par le revêtement d'étanchéité dans les mois chauds (printemps et été). La terrasse-jardin modère sensiblement le flux de chaleur dans le système de couverture et réduit la demande moyenne en énergie quotidienne pour le conditionnement des espaces par plus de 75%, grâce au flux de chaleur emmagasiné dans la couverture pendant l'été. La terrasse-jardin s'est avérée plus efficace à réduire les gains que les pertes thermiques. RES

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... Indirect effects impact building surroundings and become realistic only with widespread deployment within a selected urban area such as the reduction of outdoor temperatures or the UHI effect (an elevation of temperature in urban areas relative to the surrounding rural or natural areas due to the high concentration of heat absorbing dark surfaces such rooftops and pavements). Interestingly, this reduction of the UHI effect has a positive feedback effect on building energy efficiency (Besir and Cuce, 2018;Liu and Baskaran, 2003;Saadatian et al., 2013;Xu et al., 2012). ...
... It is well established that green roofs can reduce building energy consumption and improve the comfort levels inside buildings during the spring and summer seasons by reducing and delaying peak temperatures as well as reducing temperature fluctuations (Liu and Baskaran, 2003;Sonne, 2006). The following are a few of the many experimental studies that have found green roofs to reduce roof surfaces temperatures and building heat flux relative to conventional roofs in warm seasons/climates: ...
... With these temperature decreases documented widespread application of green roofs could reduce the UHI effect, which would further lower energy consumption in the urban area (Liu and Baskaran, 2003). For example, Santamouris (2014) (Rosenzweig et al., 2006). ...
Thesis
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With global populations becoming increasingly urbanized, green infrastructure (GI) is progressively being recognized as a sustainable approach to mitigating urban environmental problems. Unlike traditional ‘hard’ engineering approaches that historically viewed problems in isolation and solutions in singular terms, implementation of GI promises some deferment from the effects of urbanization by providing a multitude of benefits such as reduced stormwater runoff and flooding, decreased heat waves, and enlivened local environments and ecological habitats. These benefits are important considering many cities are projected to be more vulnerable to the effects of urbanization with climate change, especially as the vast amount of the global population lives in coastal urban environments. However, the diversity of GI benefits has not been fully characterized, and they are increasingly applied in residential settings. Furthermore, current research has not fully explored the beneficial role of GI in achieving sustainable and resilient communities. Using an Integrated Water: Energy Monitoring System measuring meteorological, water, and energy fluxes over two years (July 2014-June 2016) on a sustainable home in Rockville, Maryland, U.S., the following objectives were explored: (1) Examined how a sloped modular extensive green roof, constructed wetland and bioretention designed in-series affected site hydrology. Furthermore, we studied the effect of season, antecedent substrate water content, storm characteristics (size, intensity, frequency), and vegetation development (green roof only) on hydrological performance. (2) Characterized the seasonal thermal performance of the green roof (to the building and surrounding environment) relative to the cool roof. Evaluated how green roof thermal performance related to evapotranspiration, solar reflectance (albedo) and thermal conductance (U-value). Additionally, the effect of substrate water content, vegetation development, and microclimate on evapotranspiration, albedo and U-values was assessed. (3) Green roof evapotranspiration was measured and compared to values predicted with the FAO-56 Penman-Monteith model. Furthermore, the effects of substrate water content, vegetation characteristics and microclimate on evapotranspiration rates was also evaluated. (4) Finally, using emergy theory, GI sustainability and resilience relative to a gray wastewater system and natural forest was explored.
... This often has a secondary effect on the poor environmental performance of buildings, especially in urban areas, contributing to outdoor 1 3 anthropogenic warming (Rizwan et al. 2008). More recently, there has been a considerable interest in passive methods of indoor temperature regulation, one of which is the use of vegetated roofs (Liu and Baskaran 2003;Jaffal et al. 2012;Lin et al. 2013). This method has the potential for being one of the most cost-effective for temperature moderation, of particular interest in the developing world (Peng and Jim 2015). ...
... A number of benefits have been claimed for vegetated roofs to mitigate some of the negative effects of urbanisation (Ismail et al. 2008;Kamarulzaman et al. 2014). These benefits fall into three main study areas, namely the ability to replicate natural stormwater performance in terms of hydraulic patterns and water quality (Carter and Jackson 2006;Kohler 2006;Dunnett et al. 2008;MacIvor and Lundholm 2011); the restoration of biodiversity (Dunnett et al. 2008;MacIvor and Lundholm 2011;Dvorak and Volder 2010); and the moderation of temperature through shading, improvement in insulation, and evapotranspiration (Liu and Baskaran 2003). ...
... The effect of a green roof in moderating temperature has been studied in relation to two phenomena: in mitigating the urban heat island effect by adapting the external surface temperature of a roof and the air temperature directly above it (Alexandri and Jones 2008;Ayata et al. 2011;Gunawardena et al. 2017); and in improving indoor comfort levels (Jaffal et al. 2012;Castleton et al. 2010). One area of particular interest in both of these groups of studies relates to reduction in energy demand, by reducing the ambient temperature of cities (Alexandri and Jones 2008;Lin et al. 2013;van Hooff et al. 2016) and through reduction in space heating and cooling (Liu 2002;Liu and Baskaran 2003;Theodosiou et al. 2014). All of the studies reviewed show that a vegetated roof outperforms a conventional roof in terms of mitigation of the urban heat island and in improving indoor temperatures. ...
Article
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Green roofs have been shown to improve comfort levels of rooms directly below them, since they act as insulators; however, global research suggests that the performance of green roofs in attenuating temperature extremes is dependent on local climatic conditions. This study is located in Johannesburg in the South African interior, in a climate that has not previously been researched. Using heat sensors on the exterior and interior, it explores the thermal performance of a scale model of a vegetated roof in comparison with a soil roof devoid of planting and a tile roof during the dry winter season. Four different methods of enclosure were used to simulate various walling conditions. The maximum, minimum and mean temperatures for the upper and under sides of each roof were compared with the ambient temperature. Exterior temperatures for the green roof closely matched ambient temperatures, suggesting that this roof type would help in minimising the urban heat island effect. The soil roof returned the highest minimum temperatures, thereby achieving the best thermal comfort levels at night; however, this roofing solution is not recommended since the exterior maximum temperatures were considerably higher than the ambient temperature. However, the interior under the green roof has a minimal improvement on ambient temperatures and well below the recommended minimum interior temperature of 19 °C promoted by SANS10400-XA. This study forms part of a broader research initiative into energy-efficient low-cost housing solutions.
... In contrast, intensive roofs can have wider planting selection and an increased substrate depth greater than 20 cm [12,13]. Vegetated roofs provide several benefits, as reviewed in the literature [14], by decreasing roof surface temperature and heat flux via different mechanisms compared to traditional roofs, such as the following [13,15,16]: ...
... The combined effect of substrate thermal mass, thermal resistance, and protection from UV radiation increases the lifetime of the roof membrane [14]. Thus, vegetative roofs are complex dynamic envelope systems that can affect outdoor and indoor conditions; simulating such conditions requires coupling building energy models with vegetated roof models. ...
... The complete reference information for each study can be found in the bibliography section. Note that this study does not include other green roof efforts that (i) model green roofs with R values [29,36,51], (ii) account for plant materials by further adjusting the radiative/spectral properties [14,52,53], (iii) combine latent heat flux and/or photosynthesis rates with an equivalent constant albedo [54,55], (iv) use statistical regressions [56], (v) focus primarily on hydrologic modeling [48,[57][58][59][60], or (vi) require inputs that are unknown in energy simulations [61]. In particular, Del Barrio's model [62] has been implemented and validated independently by Kumar [63] and Theodosiou [30]. ...
Article
Vegetated or green roofs are sustainable roofing systems that have become increasingly widespread across the world in recent decades. However, their design requires accurate numerical modeling to fully realize the benefits of this technology at the building and larger scales. For this reason, several heat and mass transfer models for vegetated roofs have been developed over the last 36 years. This paper provides a critical review of more than 23 heat transfer vegetative roof models developed between 1982 and 2018 that have been used for building energy or urban modeling purposes. Findings of the study include the following: (i) more than 55% of the vegetated roof models have been developed and validated using data from warm temperate climate zones; (ii) green roof validation efforts vary and do not follow a common verification and validation framework; (iii) four of the reviewed models have not been subjected to any simulation process; (iv) no model has been validated for semi-arid conditions or cold climates or during cold winter conditions; (v) the most common variable reported for validation (in more than half of the models) is substrate surface temperature; however, surface temperature does not fully test the accuracy of a model to represent all heat and mass transfer phenomena; (vi) practitioners access to these models is limited since only five of the 23 models have been implemented in whole-building energy models, such as EnergyPlus, TRNSYS, ESP-r, and WUFI; finally, (vii) despite the extensive studies on the impacts of vegetative roofs on building energy performance and urban temperature reduction, no studies have validated the model using whole-building energy data or at larger scales.
... Típicamente se compone de: 1) una capa externa de vegetación; 2) una capa de sustrato para el sostén y nutrición de las plantas; 3) membrana filtradora; 4) capa de drenaje; y 5) membrana anti-raíz, que es la capa en contacto con la loza del edificio (Oberndorfer et al., 2007). El enfriamiento pasivo que proveen los techos verdes se induce principalmente por la acción de la capa de vegetación (Berardi et al., 2014); ésta capta la mayor parte de la radiación solar (Del Barrio, 1998;Wong et al., 2003) y minimiza las fluctuaciones de calor (Liu y Baskaran, 2003). ...
... Typically it consists of: 1) an outer layer of vegetation; 2) a substrate layer for the support and plant nutrition; 3) a filtering membrane; 4) drainage layer; and 5) anti-root membrane, which is the layer in contact with the slab of the building (Oberndorfer et al. 2007). Passive cooling providing green roofs are mainly induced by the action of vegetation cover (Berardi et al., 2014.) it captures the most sunlight (Del Barrio, 1998;Wong et al., 2003) and minimizes heat fluctuations (Liu and Baskaran, 2003). ...
... The average temperature on the roof of the houses under study, observed during assessments of thermal comfort (20 and 26 September) was significantly lower in rooms with green roof, green roof in those without ( Figure 2); this is an indication that the proposed green roof prototype effectively mitigated the heat load of the ceilings of the rooms. Reductions in temperature observed (3.4 and 4.5 °C) are similar to those reported by Pandey et al. (2013) in conventional green roofs, although lower than that obtained by Liu andBaskaran (2003) andDe Nardo et al. (2005), but higher than the results of Jaffal et al. (2012). De acuerdo con el VMP, se esperaba que las personas de ambos grupos expresaran un menor confort que el mostrado por el VS. ...
Article
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Los techos verdes han tomado auge debido a los múltiples beneficios que brindan, entre ellos la mitigación térmica de los edificios, y la mejora del confort térmico (CT). Aunque es una tecnología deseable en zonas cálidas y tropicales, se requiere aligerar su diseño convencional, a fin de adaptarlos a la vivienda rural tropical. La investigación se realizó en Veracruz, México, para evaluar el CT brindado por un prototipo de techo verde basado en el uso de pérgolas y de la enredadera Cissus verticillata (Vitaceae). Se comparó la temperatura bajo la lámina del techo de habitaciones de viviendas rurales con y sin techo verde. El CT de las habitaciones fue medido por el voto subjetivo (VS), el voto medio predicho (VMP), y la proporción de personas a disgusto (PPD), obtenidos de un grupo de evaluadores residente y otro visitante, quienes también calificaron su grado de aceptación de esta tecnología. La temperatura promedio bajo la lámina de las habitaciones con techo verde fue hasta 4.5 °C menor (p< 0.05) que en las habitaciones sin techo verde. El VS, VMP, y la PPD fueron mayores (p< 0.01, p< 0.01, y p< 0.0001, respectivamente) en las habitaciones sin techo verde, indicando un menor CT en éstas. La aceptación del grupo visitante fue signif icativamente mayor que la del residente (p< 0.0001). Se concluye que mediante el uso de techos verdes como el propuesto se alcanza un mayor CT en las viviendas rurales tropicales.
... Field study in Canada shows that green roof reduces cooling energy by 75% as compared to typical insulated roof. As shown in Figure 10, green roof can act as a good insulation system because heat flux before insulation layer decreases by almost 35 W/m 2 (Liu & Baskaran, 2003). These characteristics are less dependent in plant species but it is best to consider local plants first. ...
... See Figure 11. (Liu & Baskaran, 2003). To cut-down extensive green roof's weight, climbing-plant panel is an option that can be used as roof or wall surfaces. ...
Article
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Under current energy and environmental concerns, buildings are targeted as problems required immediatesolutions. Generally, buildings consume plenty of resources, produce unwanted wastes, and sometimes demoteIndoor Environmental Quality (IEQ). Given these negative impacts, Green Building was introduced as ananswer to mitigate the current energy and environmental problems. Architects, engineers, and practitionersquickly adopt this green building idea but the direction was both diversified and unclear. At that time, proclaimedgreen building seems to be just promise lacking of solid evidences. Energy & Environmental rating systemwas initially proposed as a campaign attempting to quantify green buildings. Different measures were takenand then weighted for scoring purposes. Using these scores, green buildings are possible to be quantifiedand ranked afterward. In this review article, not only the rating systems, i.e. BREEAM, Green Star, and GreenGlobe, TEEAM, will be overviewed, but also LEED, the most dominating system in US, will be discussedin detail. The simplicity by having six sustainability measures including sustainable site, water efficiency,energy and atmosphere, material and resources, IEQ, and innovation in design, are the key success of LEEDrating system. Moreover, the flexibility of having different compliance methods and scoring options makes manydesigners are in favor of this approach. By using performance-base compliance method, designers can comparetheir design against the base case for winning the higher performances such as energy cost. The score willthen be interpolated and given by exceeding performances. In order to obtain high scores, practices andtechnologies that are acknowledged by rating systems, particularly LEED, should be systematically strategized.Xeriscaping, Green Roof, Geothermal Cooling, Displacement Ventilation, and Demand Control Ventilation, arethe examples of such technologies that greatly promote the scores across multiple categories. By reviewingcompositions, mechanism, practice, and technologies of green building rating systems, this article should bea useful source for practitioners who will or already involve in any green building project and looking forwardto quantify their buildings with any rating system in the near future.
... In this situation, -Rooftop Gardens‖ and -Green Roofs‖ (roofs with a vegetated surface and substrate) can be a potential alternative remedy to reverse the problem through applying this green technology on contemporary buildings in Dhaka city [11]. Green roofs improve the energy efficiency of buildings through a combination of shading, evaporative cooling and insulation from both green roof plants and growing substrate and the thermal effects of the growing substrate [8]. This reduces the energy demand for space conditioning significantly in spring and summer. ...
... Daily temperature fluctuations cause thermal stresses in materials and decrease their durability. Green roofs minimize temperature fluctuations by creating a barrier between solar radiation and structural layer [8]. ...
Article
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Dhaka, the capital of Bangladesh, is becoming exclusively urbanized day by day with an extreme environment. Rapid and unplanned urbanization is making the residential environment unsuitable for living. Application of greeneries in the prevailing infrastructures may be an effective option to minimize the problem. Therefore, the experiment was conducted in Dhaka, Bangladesh to observe the thermal performance of Rooftop Gardens in residential buildings. The data were recorded through two-way approach i.e., quantitatively and qualitatively. The quantitative data (Temperature and humidity) were measured both outdoor and indoor during the warmest week of the year (24th-30th April, 2016) in the roof garden over the four storied academic building of Sher-e-Bangla Agricultural University. Qualitative data were collected by questionnaire survey from the selected forty rooftop gardens of Mohammadpur and Dhanmondi metropolitan area of Dhaka city. The experimental analysis of thermal performance resulted that the average roof air temperature is reduced by 5.2°C with roof garden while average room temperature is reduced by 1.7°C with roof garden compared to bare roof in the diurnal period. Moreover, the temperature of the residence with roof garden stayed near the thermal comfort zone on maximum hour of the day. In the survey result, 60% of the respondents were found to stay within thermal comfort zone which was positively correlated to the vegetation coverage of that roof. Hence, green application on residential building is more appropriate into the contemporary building as a thermal comfort strategy for a climate smart urban planning of Dhaka city.
... Also green roof significantly moderated the heat flow through the roofing system and reduced the average daily energy demand for space conditioning due to the heat flow through the roof in the summer by more than 75%. (Liu & Baskaran, 2003).. There is a big gap in constructing green buildings especially in Oman and this could be due to several factors. ...
... Top Roof Garden is the type roof which will be provided in this green building project and that because of top roof garden has shown high thermal performance comparing with normal concrete roof. As the researchers (Liu &Baskaran, 2003) proved that green roof significantly moderated the heat flow through the roofing system and reduced the average daily energy demand for space conditioning due to the heat flow through the roof in the summer by more than 75%. ...
Article
Green building or sustainable building is an ecofriendly concept established by civil engineers to increase the efficiency of buildings in terms of energy, water, and materials, over the entire life cycle of the building. This study is aimed to develop a sustainable building at Al-Hail(Oman)with high energy efficiency and lower cost. Considering the wind and solar directions plan was selected. Based on the selection of materials and method, two proposals were considered for the simulation in Revit 2016 software [Proposal 1 (Green Roof + Double Glazed Windows + AAC Blocks + Terrazzo tiles) and Proposal 2 (Normal Roof + Single Glazed Windows + Hollow Blocks + Oman Marble)] were compared.The parameters identified were cost, thermal properties and U-values of the materials for the building.It was observed that estimated energy used in Proposal 1 due to air conditioning reduced 62% than Proposal 2 because of selected materials with high thermal resistance performance. The study enlighten the facts of conservation of energy by utilizing the available resources with minimum cost
... Sistema de naturación de azoteas Cinco experiencias exitosas en la Ciudad de Mérida, Yucatán Funciones y efectos de la naturación de azoteas En la figura 3.4 se puede observar la demanda diaria promedio de energía en un espacio con azotea naturada y de uno sin ella durante el verano y la primavera (Liu, 2003). Fuente: Dibujo propio con base en la gráfica original. ...
... Sistema de naturación de azoteas Cinco experiencias exitosas en la Ciudad de Mérida, Yucatán Funciones y efectos de la naturación de azoteas En un periodo de 24 horas la temperatura en un sistema tradicional de azotea fluctúa 45°C, mientras que en un sistema de azotea naturada se reducen las fluctuaciones a 6°C (Liu, 2003), además de que se protege a la membrana impermeable de microdesgarres y de la radiación ultravioleta. ...
... In situ analyses of hygrothermal behaviour of green roofs on real [6,[13][14][15][16] or experimental buildings [1,2,8] are often aimed at comparison of green roofs with conventional roofs. Reducing heat flux density through the roof by using vegetation, especially during summer period, is presented as the most important benefit. ...
... Reducing heat flux density through the roof by using vegetation, especially during summer period, is presented as the most important benefit. Depending on the roof's assembly, vegetation type and climate zone, reduction of an average heat flux across the roof with vegetation varies from 18-75% when compared to a conventional roof [14][15][16] . Frequently studied aspects are also temperature decreases within a roof assembly with vegetation as well as protection of the roof membrane layers from UV rays thus extending life cycle of such roof. ...
... Usually, costs vary depending on the growing medium, type of roofing membrane, quantity of plants and drainage system [6]. Nevertheless, cost is not a disadvantage as green roofs reduce thermal gain from plant shading, increase thermal insulation, and acoustical insulation, which cool air and surface temperatures, all of which decreases depending on HVAC system for building interiors [18,19]. ...
... In addition, green roofs reduce indoor temperatures through transpiration. [4] Green roofs not only can affect the building heat gain and loss, but also the reflected heat in the surrounding, humidity and air quality. They have a great role in creating microclimates. ...
Conference Paper
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Green roofs and walls are a rising technology in the global sustainable architectural industry. The idea takes great steps towards the future of sustainable design due to its many benefits. However, there are many barriers and constraints. Economical, structural, and knowledge barriers prevent the spread of the usage of green roofs and living walls. Understanding the benefits and expanding them will spread the idea. Benefits provided by these green spots interrupt and maintain the current urban cover. Food production is one of the benefits of green roofs. It can save money and energy spent in food transportation. The goal of this paper is to put a better understanding of implementing green systems. The paper aims to identify gains versus challenges facing the technology. It surveys with case studies buildings with green roofs and walls used for food production.
... The research analyses the contribution of such renovation project, in terms of mitigation solutions, those related to green envelopes in buildings: green roofs and green walls. According to related research studies on green roofs, the energy required for space conditioning due to the heat flow through the green roof, would be reduced by more than 75% [14]. In addition, green walls contribute significantly to the reduction of indoor air temperature in the summer, by reducing the external air temperature of a west-facing orientation up to 4º C on a clear August day in Japan [15] and by 5º C in South Africa [16]. ...
... The research analyses the contribution of such renovation project, in terms of mitigation solutions, those related to green envelopes in buildings: green roofs and green walls. According to related research studies on green roofs, the energy required for space conditioning due to the heat flow through the green roof, would be reduced by more than 75% [14]. In addition, green walls contribute significantly to the reduction of indoor air temperature in the summer, by reducing the external air temperature of a west-facing orientation up to 4º C on a clear August day in Japan [15] and by 5º C in South Africa [16]. ...
... Also, the transpiration of the vegetation on green roofs provides an evaporative cooling effect that can lower the air temperature locally to below ambient temperatures, helping to reduce the urban heat island effect globally. (Hopper 2007, Liu and Baskaran 2003, Feng and Hewage 2014 ...
... Green roofs reduce cooling and heating loads for the floors immediately beneath the roof [19] and [20] and some particulate atmospheric pollutants are adsorbed, while greenhouse gases as well as other gaseous pollutants are absorbed [21], CO 2 being removed through photosynthesis. Biodiversity improvements are indisputable compared with conventional roofs. ...
... Different strategies exist to protect the building from sun heat loads such as shading devices [3][4][5][6], surrounding vegetation [7][8][9], angular and spectral selective coatings [10][11][12][13][14][15][16][17][18] and double-skin facades or roofs [19][20][21][22]. Other technical solutions exist to exploit cooling from the environment, such as night sky cooling systems [23][24][25][26][27], natural ventilation [3,26,[28][29][30][31] and ground cooling [32][33][34]. ...
... A plant canopy and the growing substrate help shield traditional bituminous roofing membranes from ultraviolet radiation and wide day-night temperature fluctuations. For example, a study conducted in Toronto, Canada reported the membrane temperature on a convention roof reached 70°C (158°F) in the afternoon, whereas the roof membrane under the green roof was only 25°C (77°F) (Liu and Baskaran, 2003). The daily expansion and contraction of the roofing membrane due to swings in day-night temperatures stress the membrane, resulting in fatigue and eventual failure. ...
... The roof of the building is alone responsible for 70% of its heat exchange, thereby increasing heating and cooling load. Widely used bituminous roofs can reach temperatures as high as 60-70°C during summer, thus significantly increasing the cooling load (Liu and Baskaran, 2003;Teemusk and Mander, 2009). Several studies have been done on PCMs modified roofs and walls to minimize the undesirable heat exchange. ...
Article
Many phase change materials (PCMs) experience a change in transparency when undergoing a phase transition. These thermo-optically responsive materials can be used to generate passive temperature control systems for building enclosures. The integration of optical and thermal switches into smart temperature-controlling elements requires rationally designed PCMs featuring tunable optical and thermal properties. Two polymers, poly (Octadecyl methacrylate) (PSMA) and poly(2-(2-(octadecyloxy) ethoxy) ethyl methacrylate) (PE2SMA) were synthesized and evaluated for their potential use in passive thermal energy storage systems. UV-Visible Spectroscopy, Near Infra-Red Spectroscopy, and Differential Scanning Calorimetry were used to evaluate the effect that changes in the polymer chemical structure had on the optical and thermal properties of the resulting materials. Insertion of a 6-atom flexible spacer (diethylene glycol) between the pendant crystalline motif and the polymer backbone of PSMA resulted in increases of latent heat storage capacity from 62 J/g to 94 J/g and thermal conductivity from 0.218 W/mK to 0.318 W/mK. Notably, insertion of a flexible spacer also resulted in a melting transition temperature increase from 37.7 °C for PSMA to 48 °C for PE2SMA. The visible transmittance of the polymers increased from 0% to 90% upon transition from crystalline to amorphous state. This study presents a synthetic strategy to control thermal and optical properties of polymeric PCMs materials. The material properties and structure-property relationships derived from this study will enable the refinement of the models used to predict the performance of passive temperature-regulating systems. More accurate models will guide the development of the thermo-responsive polymeric materials required for better perfoming temperature-regulating building enclosures.
... Research carried out by [13] confirms that green roofs reduce the heat flow through the roof and thus reduce the energy demand for air conditioning of the building, and thus also reduce the effects of UHI in the building, but this is a separate issue related to the supply and consumption of energy in the building. ...
Article
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In the era of developing cities, it is extremely important to maintain an appropriate level of quality of the surrounding environment or to improve this level. Newly built buildings are not without impact on the city's environment. It is important to control and limit their negative impact. Multi-criteria investment assessment systems help with many problems related to urban development. They allow analysis and evaluation of various issues, including those related to the environment. The purpose of this study was to determine the spatial structure of buildings certified in the BREEAM system (Building Research Establishment Environmental Assessment Method) in Kraków by developing a map of their deployment, and then analysing the location of green buildings in terms of selected environmental issues. The selected certification system is one of the most commonly used multi-criteria assessment systems in Poland. The map was developed to assess the current spatial structure of green buildings. On the basis of the map, it is possible to indicate potential areas of the city where it would be advisable to locate a green building that meets specific environmental requirements. In Kraków, it can be noticed that objects with the In-Use certificate are mostly available individually. There are only two small clusters of such buildings. Upon analysing buildings with a final certificate, it can be observed that there are both single buildings as well as small and larger clusters (office parks). These facilities are located near or between the beltways. When analysing the distribution of buildings with the certificate obtained at the design stage, it can be observed that most of them are located near bypasses. Two clusters are located in the southern part of the city, but this is due to the expansion of existing office parks. Comparing the developed map with the location of the combined sewerage system in Kraków, it can be seen that the vast majority of certified facilities are within or in close proximity to the combined network. If in these facilities solutions related to the management of rainwater at the place of precipitation were used, each of them represents a significant relief for the sewage system in Kraków. Due to the fact that some of the green buildings in Kraków are present in clusters, their fulfilment of requirements related to the introduction of greenery to the plot (Land Use and Ecology, Surface water run - off and Flood risk categories) may affect the levelling of the urban island heat in the areas where they occur. Most green buildings in Kraków are located along the city's three bypasses. If these buildings have scored points in the category of Transport for specific activities, then in combination with their location this represents a positive value for the city's air quality. Among the requirements for green buildings in multi-criteria assessment systems are those whose fulfilment is a particular value for the city's environment only with a specific location of the building. For this reason, it matters to the city whether the newly constructed buildings are green. The most common positive effects can be expected in the central parts of cities, because that is where the combined sewerage system dominates, where there are problems associated with UHI (Urban Heat Island) or urban floods. The presence of several buildings near each other also generates a pro-ecological effect.
... Moreover, many field measurements have revealed that green roofs effectively attenuate the daily periodic temperature acting on the surface of the building [29][30][31][32][33][34][35], which is important for the reduction of building peak cooling load. Evaluation indices such as the decrement factor [35,36] were measured to quantify the resistance of green roofs against sol-air temperature fluctuations. ...
Article
This study investigated the thermal characteristics of an extensive green roof under air-conditioned and non-air-conditioned states by using experimental data obtained on successive sunny summer days. Two indices of the green roof, namely the equivalent thermal resistance and the equivalent decrement factor, were estimated through comparison with a common bare roof. Under the non-air-conditioned state, the distribution of the average temperature on the green roof profile was S-sharp. The lowest average temperature of the green roof was observed on the interface between the planting soil and roof structure, which were 1.8 and 0.9 °C below the outdoor and indoor air temperature, respectively. This finding indicated that the bottom of the soil layer functioned as a “cooling source” that absorbed heat from the upside and downside. The indoor critical air temperature that maintains the heat flux equal to zero was investigated on the basis of the experimental data. The influence of indoor critical air temperature on the equivalent thermal resistance was discussed; for the same green roof under the same outdoor climatic conditions, an indoor air temperature that is closer to the indoor critical air temperature yields a higher equivalent thermal resistance. Therefore, the equivalent thermal resistance of the green roof obtained under low indoor air temperature is recommended for practical use.
... Mentens et al. 2006). They can mitigate noise and bind dust and other air pollutants (Oberndorfer et al. 2007), extend the cycle of repair of roof structures beneath them (Getter & Rowe 2006;Liu & Baskaran 2003), cool buildings and the entire urban structure, thus relieving the so-called urban heat island effect that is feared to have adverse health effects also in Finland (e.g. Suomi 2014;Castleton et al. 2010;Näyhä 2007). ...
... However, it can reduce heat loss only through improved insulation and decreased radiation heat losses. This is effective on summer evenings, but not in winter when the growing medium is frozen and the improved insulation and decreased radiation heat loss effects were dominated by snow coverage (Liu and Baskaran, 2003). ...
Conference Paper
“Balancing environmental protection and social responsibility with a healthy economy over time” is the main concept of all sustainability definitions that have been made so far. It is not possible to mention just only social or economic dimensions of its, because sustainability is usually seen as a guide for economic and social policymaking in equilibrium with ecological conditions. So the main objective of each study with a vision of sustainability should represent all three aspects of sustainability; economic, environmental and social. Environmental sustainability is the ability to maintain the qualities that are valued in the physical environment. Environmental sustainability programs include actions to reduce the use of physical resources, the adoption of a ‘recycle’ approach, the use of renewable rather than depletable resources, the redesign of production processes and products to eliminate the production of toxic materials, the protection and restoration of natural habitats and environments valued for their livability or beauty. The most important activities to ensure environmental sustainability can be defined as the efficient use of energy and water resources. In recent years, efficient use of energy and water in the field of architecture highlights the sustainable building systems. For centuries, techniques which were used for energy and water efficiency (ex. green roofs that help to lower urban air temperatures and mitigate the heat island effect, collection and use of rainwater for irrigation, the use of natural, non-toxic materials such as stone/wood etc.) especially in rural settlement areas, has re-emerged as a part of the sustainable building systems (green buildings) today. The main reason of this concept emergence is just because of the increasing importance of sustainable energy and environment issues. Developing technology and a wide range of products/solutions have led to the development of certification systems in order to measure the sustainability of green buildings. Nowadays there are many certification systems that are used either on a global or a national scale. All these certification systems have structural similarities in common, especially in sub-categories and criterias. These certificates can only be given after an assessment mainly based on energy and environmental evaluation. In Turkey only 3 of them are currently used. These are LEED (USA), BREEAM(United Kingdom) and DGNB (Germany). Turkey’s green building certification system SEEBER-TR was introduced in January 2014. LEED is the most widely used system in Turkey. There are approximately 50 LEED-certified building in our country. In order to receive LEED certification, every green building project is required to take at least 40-49 points out of 100 from the specified titles of “New Construction and Major Renovations Project Checklist”. In the selected LEED-certified project, landscape planning studies, which provides energy and water efficiency, were described. The plant species used in the project were evaluated. It has been identified that getting points from structural credits was preferred instead of landscaping credits. The reason is that the scores which will be gained by landscape planning studies is not high enough. It is remarkable that, landscape architects who work on ecological based on design, planning, management and conservation of natural and cultural environment as a profession, can’t take place adequately in these green building projects.
... Simulation of modeled single family residential and low-rise commercial buildings [11] showed that the energy savings effect in Toronto could be over $11 M from the combined effects of cool roofs and shade trees. Detailed study in Canada [12] showed that the daily surface temperature variation with a green roof was approximately 6°C compared to a variation up to 45°C occurring with a bitumen traditional roof. Even in its starting phase, green living roof with LAI (Leaf Area Index) close to zero during the summer period had the external surfaces heated less than the traditional flat roof [13]. ...
Article
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Altering the surface cover of an area causes the change in the environment. By erecting buildings change in the flow of energy and matter through the urban ecosystems occurs creating multiple environmental problems. Built areas exert considerable influence over their local climate, amplifying problems such as heat waves, air pollution, and flooding. Greening the building envelope these problems can be partially mitigated. By combining nature and built areas in their designs, architects and urban planners can respond to these serious human health and welfare issues and restore the environmental quality of dense urban areas. Green living systems are not the only solution for new designs. Retrofitting existing buildings by altering the buildings' surficial properties can reduce buildings' energy consumption in case of older buildings with poor existing insulation. Implementation of green living systems in the building envelope, greening horizontal surfaces with intensive and extensive green roofs or using vegetation in vertical greening systems for façades, is a strategy that provides ecological, economic, and social benefits. This review paper presents collected evidence of effects and explores the important role that the green living systems can play in the dense urban areas. Benefits such as heat island amelioration, reduction of buildings energy consumption, air quality and indoor and outdoor comfort conditions improvement, stormwater management and improved water run-off quality, will be mainly considered. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III42008]
... Green roofs element use also can keep the temperature inside building at comfortable level that also reduce the energy use for conditioning. It is estimated by Liu et al. (2003) that dense green roof application may reduce the energy demand in the summer by over 75 percent. 5. Improving coastal resiliency Cities that mainly located in coastal area are the most vulnerable to the impacts ofclimate change. ...
Article
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As the climate change affectingon coastal cities by increasing the intensity and frequency of climate related disasters such as flooding, sea level rise, drought etc., the need to explore other urban infrastructure strategies than conventional one is required. This alternative not only mitigate the impacts but also improve the urban climate resilience. In line with it, green infrastructure/GI can be sustainable alternative in that way combine with gray infrastructure. Therefore, this paper reviews the concept of GI to advance the urban resilience associated with climate related disasters. Some strategies based on the current literature and projects are also recommended including managing flood risk, building resiliency to drought, reducing the urban heat island effect, lowering building energy demands, improving coastal resiliency, and reducing energy needed to manage water. Key words: Green Infrastructure, Climate Resilience, Urban Resilience, Sustainability, Flood, Drought,Sea level Rise.
... According to computer simulations, in a warm climate such as Madrid, cooling energy use reduction could reach up to 45% and heating reduction up to 23% (Laurenz, 2005). According to research studies on green roofs, the energy required for space conditioning due to the heat flow through the roof would be reduced by more than 75% (Liu and Baskaran, 2003). Studies on urban parks suggest that for every 100m2 of vegetation, air temperature is reduced by 1ºC, and that by increasing the ratio of green area to built area by 10% a 0.8ºC reduction is achieved (Dimoudi and Nicolopoulou, 2003). ...
Conference Paper
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This research argues the current practice of green façades in terms of the accomplishment of a broader range of opportunities they might realize. It analyses existing green façades according to different types, construction systems, and relationships with the immediate context. This reveals there are two major categories of green façades: opaque green façades, and transparent green façades. The research identifies a series of opportunities related to six areas: human comfort; expressive capacity; air & water quality; indoor-outdoor relationship; urban biodiversity; and carbon neutral architecture. It combines the classification of green façades and the identification of opportunities they offer to develop the Green Façades Framework. This framework enables the critique and evaluation of existing green façades in terms the extent to which they accomplish such opportunities, hence facilitating a determination of their appropriateness to different conditions, solar orientations, and user needs. The proposed Green Façades Framework is applied to five existing examples of green façades to evaluate their appropriateness to their particular conditions. This application detects the deficiencies of these green façades, enables a deeper critique of their design and reveals the usefulness and limitations of the Framework to improve the current practice of green façades by assisting designers to define more appropriate green façades.
... Las nuevas tecnologías verdes se presentan como estrategias apropiadas que han sido aceptadas como una opción viable para aumentar las áreas verdes en entornos consolidados, reducir el consumo de energía en la edilicia y aumentar el confort térmico. Las cubiertas vegetadas se han introducido como uno de los medios más eficientes de ahorro de energía en el sector de la construcción (Liu y Baskaran, 2003;He y Jim, 2010). Este tipo particular de techo reduce la demanda a través de la mejora del rendimiento térmico, mientras que la vegetación consume gran cantidad de la energía solar incidente a través de sus funciones biológicas-fotosíntesis y transpiración-, reduciendo la radiación que afecta a la temperatura interna en comparación con un techo desnudo ( Wong et al. 2003, Saadatian et al. 2013). ...
Article
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Las cubiertas vegetadas constituyen una estrategia de enverdecimiento urbano que contribuye a reducir los efectos del calentamiento global, disminuyendo las temperaturas urbanas y los consumos de energía en espacios interiores. Este trabajo evalúa a partir de ensayos experimentales, el efecto de cubiertas vegetadas en zonas de clima cálido-seco sobre el comportamiento térmico de espacios interiores y su consecuente ahorro energético. A tal fin se desarrollaron mediciones de temperatura de aire en box experimentales, mediante sensores del tipo Onset-HOBO, en la estación verano 2015. Los resultados indican que en espacios interiores conexos a la cubierta vegetada, variaciones de temperatura de 1.5 a 1.6 °C generarían ahorros de energía eléctrica destinada a refrigeración del orden del 32% al 34%. La experimentación de estas nuevas tecnologías verdes a nivel regional es importante para lograr su adecuada implementación en el marco de un ahorro energético y un uso racional de los recursos disponibles.
... Zelená střecha přes evapotranspiraci ochlazuje vzduch, a tím dochází ke snížení teploty povrchu střechy a okolí. V horkých letních dnech, může být povrchová teplota zelené střechy chladnější než teplota vzduchu, zatímco povrch konvenční střechy může mít až 50°C [8]. Exponované oblasti černé střechy můžou v létě dosáhnout až 80°C, v případě instalace zelené střechy je možné dosáhnout teploty 27°C [9]. ...
Article
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Green roofs are among the passive building systems that contribute to the thermal stability of the rooms under the roof in both summer and winter. Green roofs can provide a significant contribution to the thermal balance of the protected space. Over the past ten years, many studies have been carried out to investigate the energy benefits of green roofs in terms of the energy performance of buildings. These studies show that the installation of vegetated cover can achieve energy savings for both winter heating and summer cooling. The green roof, as a thermal insulation, reduces the amount of building operating energy costs and reduces heat losses. This article summarizes current literature and points to situations in which green roofs can play an important role in saving energy for heating and cooling due to improved thermal insulating function of the roof, in case of extensive vegetation coverage without significant overloading of the roof structure and associated over-dimensioning. It is important to note that these energy savings always depend on the particular climate, the type of building and the availability and the type of roof structure.
... Both mechanisms have been demonstrated to have a significant effect on estival heat gains. [53][54][55] Green roofs have the added benefit of reducing water runoff from roofs as well as providing some thermal insulation in previously uninsulated roofs. 56,57 This approach has also been successfully applied in façades, where similar cooling effects can be achieved. ...
Article
Energy in buildings—Policy, materials and solutions - Volume 4 - Matthias M. Koebel, Jannis Wernery, Wim J. Malfait
... A wet soil can store a large amount of heat to create a heat sink to work against the thermal insulation effect (Jim, 2014a(Jim, , 2014b. In winter, the snow accumulating on the sod roof, with abundant trapped air, can reinforce insulation (Liu and Baskaran, 2003). The grass growing on the roof can hold some stagnant air in the boundary layer to retard heat transmission. ...
Article
The origin of green roof could be interpreted as old wine in new bottle and traced to antiquity. Archaeological and historical records and contemporary geographical-ecological assessments provide ample evidence to interpret the birth and progressive evolution of the cultural heritage. Studies in different places find early shelters using different natural materials. Humans living in harsh climates need particularly effective weather-proof enclosures to survive. The Arctic region with natural resource deprivation furnished the cradle for green roof initiation and refinement. The versatile and rather ubiquitous earth, widely used since Neolithic times to build dwellings, offered learning opportunities regarding properties and applications. The primitive flimsy conical shelters were sealed by earth daubing, permitting nature’s seed rain to establish a vegetative cover to form the spontaneous meadow roof as green roof precursor. Subsequent progression to the house form, separating walls from roofs, required innovations to enhance weather-proofing and durability. Cutting from natural meadows mat-like sods with soil bound by dense fibrous roots into portable strips for roofing was better than plastering. Tantamount to transferring the sod ecosystem en masse from nature to roof, it permitted instant vegetation establishment and bypassed the erosion-vulnerable bare-earth stage. The invention denoted birth of the intentional sod roof. The materials and construction methods of the traditional multiple-layered sod roof are explained with the help of preserved technology. Employing research findings, eighteen hypothesized ecosystem services of sod roofs are identified and explained vis-à-vis modern counterparts.
... Another study in Singapore also verified the positive impact of green roofs in reducing the roof surface temperature swing [11], and it was reported that the integration of green roofs in buildings contributes to energy savings in different Greek cities [12]. In cold regions, such as Canada, green roofs have been reported to reduce daily surface temperature fluctuation significantly due to the absorption of solar radiation by green roofs [13]. Additionally, green roofs demonstrated the reduction of the heat flow in extreme climates with highly snowy winters [14], and other researchers reported that the impact of the green roofs on the surface temperature and the heat flux were low in winter (12% on average) [15]. ...
... A proposed partial solution to the issues discussed above would be to introduce green roofs to existing city buildings. Green roofs increase evapotranspiration, roof albedo (reflectivity of radiation by a surface), and thermal mass [18] thus reducing energy demand by reflecting incident light [30,32] and by passive cooling [33]. Roof gardens with dense foliage can decrease roof surface temperature significantly when compared to bare concrete roofs [7,33,38]. ...
Article
It is no secret to anyone living in Beirut or a similar modern city in a semi-arid tropical country in the summer that their home has become a concrete forest and an urban heat island. Old wood or stone houses and their gardens have been replaced by concrete towers and parking lots, in the name of development. The result is searing summer nights, a drastic loss of insect and avian biodiversity, and a large increase in energy usage for interior climate control. These problems are experienced in rapidly developing urban centers worldwide. Moreover, cities worldwide are struggling with waste disposal. Roof gardens can help solve both problems. They also can have a non-proportional effect on energy flux, especially if buildings are high and closely packed. The present work assessed the potential benefits of a roof garden on a bare flat roof in Beirut. The possibility of using recycled material as garden substrate was assessed; the effect of roof gardens on temperature variations below the roof was evaluated; and finally an assessment of whether enough water can be collected from air conditioner condensate to support a roof garden and whether the water is suitable for agriculture was performed. Results strongly indicate that post factum construction of rooftop gardens positively affects urban area and building environment in a variety of ways.
... With respect to environmental quality, vegetative growing spaces replace unused spaces on buildings to reduce runoff volumes and delay peak flows (Mentens et al., 2006;Carter and Jackson, 2007;Teemusk and Mander, 2007;Spolek, 2008). Replacing bare roofs with green vegetation and substrates can significantly change albedo values and decrease heat transfer into buildings (Liu and Baskaran, 2003;Tsang and Jim, 2011). Building temperatures are therefore lowered and heat island effects in urban areas are reduced (Takebayashi and Moriyama, 2007;Rowe, 2011). ...
Article
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The design of a low-rise residential building with an exploited green roof was studied. In order to improve the ecological condition and tourist attractiveness of the building in the city of Odessa, a project of eco-reconstruction of the "Rodokonaki" apartment building with the organization of a flat exploited green roof is proposed. The project involves a combined plan of an exploited roof with combined landscaping and landscaping, and can also be considered as a fifth facade. Using the example of the designed building, it was found that the steppe type of roof landscaping is the most promising for arid Ukrainian regions, in particular, the city of Odessa. It is proposed to place benches made of natural eco-material - wood on the exploited roof; small architectural forms (lamps, urns - also made of eco-wood). Bushes with a stone fence are planted around the perimeter of the roof. Stone paving with a fountain, green spaces and a small children's playground is designed on the territory of the house. The use of ecological finishing materials provides visual comfort and brings people closer to the natural environment. The use of green spaces on the roof ensures not only an increase in the standard of living of citizens, but also improves human health, makes the surrounding urban environment comfortable and close to natural conditions. Energy saving is achieved due to the increased thermal insulation properties of the green roof. Exploited roofs can be additional public spaces, sports areas and meeting places. The main advantages of this solution, structural features, calculated loads on the roof, as well as types of landscaping are analyzed. It has been proven that the principles and methods of "green roof" must be implemented in modern construction to improve the emotional state of residents, urban ecology, and tourism development.
Article
The evolution of rural to urban areas has a negative impact on the availability of green zones. The lack of space gives green concrete walls the opportunity to introduce vegetated areas in highly urbanized cities. However, cementitious materials are not the best substrate for plants. Still, diverse microbial communities are suitable for colonizing cementitious materials, allowing later introduction of other plants. One of the limiting factors for microbial growth under environmental conditions is the availability of water for the microorganisms. In this study, the bio-receptivity of cementitious materials under laboratory conditions was investigated, studying relevant parameters such as the porosity needed for the colonisation. Superabsorbent polymers (SAPs) were added in order to improve the water retention capacity and the colonisation of cementitious materials. These polymers, crosslinked networks able to absorb fluids up to hundreds of times their own weight, promote bio-receptivity and clear algal growth was observed. Recycled SAPs, obtained from a cleaning and crushing action of hygienic products, may show an added benefit in terms of sustainability and a circular economy. The best results were obtained with a SAP leading to a well-distributed overall macroporosity near the surface.
Chapter
The aim of this study is to create a checklist of roof garden design criteria. This scope of work includes an encompassing review of international standards studies such as German Landscape Research, Development, and Construction Society; the American Society for Testing and Materials; the U.S. Green Building Counci; and Green Roofs for Healthy Cities, whereas the generated checklist was evaluated in the Marmara Forum Mall. As a result of the study, an answer was sought to the question, “What are the prerequisites for a roof garden serving the needs of users in today's conditions?” whereas on-site detection, observation, and photography were used as working methods. As a result, in considering the evaluation of the checklist on a scale of the Marmara Forum Mall, climatic data, activities with its hard structure, promenade areas, and designs of plantlife and water elements in soft structure are moderately sufficient, whereas it was determined there is no problem in the roof furniture design and maintenance.
Chapter
The contribution follows the European guidelines for the adaptation of the built environment to climate change, illustrated at the COP21 (2015) and collected in the European Climate Adaptation Platform. The text concerns requalification process of the urban open spaces by connecting social and technological features characterizing the urban realm and the related environmental-climatic performance. Through an in-depth study of materials and possible combinations of innovative materials, urban vegetation, water elements and urban shades, the current knowledge of the complex issue of outdoor comfort and urban microclimate is being extended to provide innovative social and functional solutions. The paper comprises the relationship between energy use and urban morphology, studies on intermediate urban open spaces, on environmental and bioclimatic comfort, the interactions between biophysical and microclimatic factors, ultimately the tests of innovative technologies.
Article
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Three experimental green roofs in Melbourne with depth of 100, 150 and 300 mm have been assessed to quantify their thermal performance. To evaluate the benefit of substrate depth, temperature was recorded every 50 mm along a vertical profile. Green roofs consisted of scoria substrate and a mix of three species of plants: Lomandra longifolia, Dianella admixta and Stypandra glauca. Statistical analyses applying the hierarchical partitioning technique showed that solar radiation is the main driver affecting the green roof surface temperature, air temperature has strong correlations with the variations of the temperatures recorded below the surface, while moisture content has the least influence. Temperature profiles of the green roof show that the first 50 mm do reduce the heat flowing through the green roof substrate regardless the total green roof substrate depth. Differences in thermal performance arise at deeper points, where thicker green roofs are able to delay the change of substrate temperatures. Similar effects were found for the heat fluxes measured at the interface between the green roof and building roof. These results confirmed that green roofs may be used as a sustainable passive technology to reduce building energy consumptions for South-East Australia climate.
Article
Green infrastructure has received increasing attention in urban strategies in a sustainable and resilience context, since greenspaces provide diverse ecosystem services. Green roofs can be a form of compensating the loss of ecosystem services and biodiversity in urban areas, contribute to safe access to greenspaces, which is important in times of social isolation, due to viral pandemics, and can guarantee self-reliance food. Thus, this urban measure should be integrated in urban planning and management, by using urban indicators associated with citizens access to greenspaces. Hence, we study pedestrian accessibility to green areas and propose an urban solution to improve access to greenspaces. The assessment is developed using indicators related to the citizens living in the surroundings of green areas and the residential buildings that exist in these areas; the residents living in potential green buildings or blocks with private green roofs and the potential green buildings with private green roofs. The ideal standard distances were considered to analyze the proximity of green areas to the dwellings of residents. We used GIS for the assessment of distances over the pedestrian network. The results indicate the necessity of building green roofs through the private sector. The developed indicators provide an important contribution to the municipal management in the definition of criteria for the urban location of green roofs to promote better access to ecosystem services.
Book
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The present book reference is unique in the sense that it covers all the possible urban issues along with technological options. The book mainly divided in 5 parts. Part 1 is general in nature which include urban history and conceptual parameters for better understanding of urban attributes whereas part 2 deals with Cities of Tomorrow: 2050, Environmentally sustainable urban planning and Environmental Policy Parameters in Urban Planning. Part 3 include Urban air pollution, Urban Heat Island Effect, Effects of Albedo in Urban Planning, Sustainable Urban Transport, Environmental Sustainability - Global Need of the Day, Urban Atmospheric Conditions- A case study, Urban Automobile Air Pollution - A case study, Urban Municipal Solid Waste - A Case Study, Urban noise pollution, Urban Water Pollution, Green Buildings, and Green Urbanism. Part - 4 deals with Global Environmental Impacts in the form of Climate Change and Global Warming- An Emerging Concern whereas part - 5 deals with Governance.
Thesis
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This thesis presents the evolution of the energy situation in Algeria with a comparison to the situation prevailing in the United States, Canada and France. A comparative study is carried out in order to investigate the overall energy consumption by sector and type of energy and the energy policies that reflect this situation, in order to determine the initiatives that should be taken to improve the energy efficiency of buildings for both individuals and the public authorities. The passive energy efficiency measures applied to buildings are being showcased, because these measures lonely can divide the total energy demands of a building in the local weather data. The methodology of this work is based on numerical methods by the dynamic thermal simulation using the simulation software TRNSYS and TRNBuild interface. The result showed that the use of passive energy efficiency measures: the compactness of the building, the distribution of internal rooms and efficient windows with permanent sun protection and thermal insulation for the double wall with hollow brick improves energy efficiency by nearly 𝟐/𝟑, also the use of straw bale as a building material is the most efficient solution in heating, while the stone allows obtain the maximum benefit in term of cooling. Keywords: Energy Efficiency, Energy Requirement, Performance, TRNSYS, Building Simulation.
Article
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Various studies have been conducted regarding the heat problem of Libya’s building recently. The current method is to create a heat barrier in all parts of the building. Thermal insulation R-value of each material and the heat transfer coefficient such as U-value confirms to the Egyptian standards. This research was conducted by using a new design of double wall heat insulation materials which are available in Libya. This new design is to be compared to previous research. The proposed double wall and generated R-value provide higher efficiency than the best efficiency ever done.
Article
This paper aims to evaluate the possibility of using the roofs of habitations in Caruaru city in the semiarid region of Pernambuco, Brazil, for two purposes: as green roofs to mitigate extreme temperatures inside the houses and for rainwater harvesting and storage for potable purposes. For this, a preliminary study was carried out with inside and outside temperature monitoring of rooms with a green roof and conventional roof to verify the thermal variation in a real situation. Furthermore, the potential of rainwater harvesting for Caruaru city was evaluated based on precipitation data provided by the Water National Agency and an estimation of the available roof area (buildings and houses). In this context, two scenarios were analysed: (scenario 1) the whole roof surface was used for rainwater harvesting and saving and (scenario 2) green roofs were implanted in part of the roofs. The results of this preliminary study indicated that the use of green roofs resulted in lower temperature variations throughout the day, decreased internal temperatures, and decreased thermal amplitude in relation to a conventional roof (with tiles). Regarding the reduction of the catchment area because of the recommended use of green roofs in a semiarid region, considering green roof application just over the bedrooms (which was considered to cover 16 m² in total), the water saving potential of the public supply system decreased, with a monthly average of 23.13% versus 28.43% (without green roofs). Implanting green roofs in part of the roofs of houses, although there is a reduction in the rainwater volume that can be harvested, can result in an increase in thermal comfort, whereas this is not feasible with the use of the entire roof area to harvest potable water. Thereby, the results indicate that the simultaneous use of the two kinds of roofs (conventional and green) is feasible even in a semiarid climate.
Thesis
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Green roofs provide many benefits to the urban environment, but an adequate plant cover is crucial in order to achieve optimal performances from these infrastructures. Plant cover improves the roof insulation in winter and reduces summer temperatures by shading and transpiration. Succulent species, such as Sedum species, are widely used on green roofs, thanks to their drought resistance due to CAM metabolism, as well as to the reduced maintenance they need. CAM metabolism, however, without diurnal transpiration, is responsible for the poor cooling performances in summer. In addition, many succulent species have slow colonization rates and/or are subject to freezing injury during the winter. A reduced plant cover has direct negative consequences both on the cooling by shading and on the winter insulation. We investigated how to create green roofs with a good plant cover, optimal summer and winter thermal performances and reduced management needs. Primarily, we compared, thought indoor experiments, the water losses, the net CO 2 assimilation rates and the cooling performances of two CAM-facultative, three C3 and one C4 species, under well-watered and drought conditions. Our results confirmed that C3 and C4 tested species continue to transpire also when Sedum species adopt the CAM metabolism, suppressing the diurnal transpiration. C4 metabolism allows interesting transpiration performances, even under very droughty conditions. This has a positive effect on the substrate temperatures, but, at the same time, a good canopy cover is necessary. It is fundamental for shadow effect in summer, but also to increase the minimal temperatures of substrate in winter. We also monitored the way of growth of six native perennial species, cultivated on an experimental green roof under a low-input management. The six species, thanks to their different growth behaviors, could provide the good coverage necessary to guarantee the main green roof benefits.
Chapter
This chapter sharpens the relevant notions of gardens and urban gardening. It conceptualizes urban gardens as elements of a city’s green infrastructure, and highlights their importance as site of food production and tools of climate adaptation. The chapter also collects and presents empirical research on real-life experiments in urban gardening in different cities, and considers several ecological and social benefits that have been proven or can be reasonably expected to be delivered by the practice.
Chapter
Rooftop agriculture projects need to integrate with the social, economic and environmental infrastructure of the surrounding city. Their design needs to consider numerous technical and practical factors that affect the host building, site and neighbourhood. There are various potential synergies with other urban necessities such as water management, energy use, air quality, provision of green space, employment, and community support. This chapter will focus on the relationship between rooftop agriculture and the technical infrastructure of the building and its neighbourhood.
Chapter
Dachbegrünungen werden mit zahlreichen Vorteilen wie besseres Raumklima, Energieersparnis, Reduktion der innerstädtischen Wärmeinseleffekte oder Niederschlagsrückhaltung in Verbindung gebracht. Im Holzbau haben sie aber auch durch viele Schäden an der feuchteempfindlichen Unterkonstruktionen von sich reden gemacht. Vor- und Nachteile waren bisher nur schwer zu quantifizieren, da kaum Modelle zur Beurteilung des hygrothermischen Verhaltens von begrünten Konstruktionen zur Verfügung standen bzw. die verfügbaren Ansätze sich meist nur auf spezielle Teilbereiche beschränkten. Im Rahmen eines Forschungsprojekts konnte am Fraunhofer-IBP ein Berechnungsmodell für Dachbegrünungen erstellt werden, das eine Ergänzung für das bewährte hygrothermische Simulationsverfahren WUFI® darstellt. Es ermöglicht unter Berücksichtigung der Feuchtebilanz eine realitätsnahe instationäre Simulation der Begrünung mit Aussagen zum hygrothermischen Verhalten der Unterkonstruktion und zur energetischen Wirkung auf den darunter liegenden Innenraum.
Article
Planted roofs contribute positively to the improvement of the thermal performance of a building. They block solar radiation, and reduce daily temperature variations and thermal ranges between winter and summer. In this paper, a calculation has been done, using a stationary method, in order to determine the thermal behaviour of the planted roof and the way it influences the thermal protection of the building, in accordance with Greek climatic conditions. Planted roof elements with different heights of plants and different drainage layers are calculated and a comparison between a bare roof and a planted roof is made. All sections are calculated with and without thermal insulation. The results are illustrated in figures, in which the temperature of the layers of the planted roof is presented for both winter and summer. The planted roof contributes to the thermal protection of a building, but does not replace the thermal insulation layer.
Conference Paper
This paper addresses the general concept of sustainability and relates it to the building owner`s selection of a low-slope roof. It offers a list of performance features of sustainable roofs. Experiences and data relevant to these features for four unique roofs are then presented which include: self-drying systems, low total equivalent warming foam insulation, roof coatings and green roofs. The paper concludes with a list of sustainable roofing features worth considering for a low-slope roof investment. Building owners and community developers are showing more interest in investing in sustainability. The potential exists to design, construct, and maintain roofs that last twice as long and reduce the building space heating and cooling energy loads resulting from the roof by 50% (based on the current predominant design of a 10-year life and a single layer of 1 to 2 in. (2.5 to 5.1 cm) of insulation). The opportunity to provide better low-slope roofs and sell more roof maintenance service is escalating. The general trend of outsourcing services could lead to roofing companies` owning the roofs they install while the traditional building owner owns the rest of the building. Such a situation would have a very desirable potential to internalize the costs of poor roof maintenance practices and high roof waste disposal costs, and to offer a profit for installing roofs that are more sustainable. 14 refs., 12 figs.
Article
Four basic urban structural neighborhoods were exposed to typical summer/winter weather scenarios spanning latitudes 10N, 34N, and 50N. These scenarios included different human comfort levels for interior building temperatures. A numerical urban model (URBAN 3) was used to describe and analyze the systems' energy budgets and the resultant surface temperatures of streets, walls, and roof tops. The examined surface temperature histories are believed to be representative of the more complex urban environments observed in real cities.Vier strukturell charakteristische Stadtgebiete waren typischen Sommer- und Winter-Witterungsformen in Breiten von 10N, 34N und 50N ausgesetzt. Diese Witterungsformen umfaten verschiedene Behaglichkeitsstufen fr Innentemperaturen von Gebuden. Ein numerisches Stadtmodell (URBAN 3) wurde zur Beschreibung und Analyse des Energiehaushaltes der Systeme und der daraus resultierenden Oberflchentemperaturen von Straen, Wnden und Flachdchern verwendet. Es wird angenommen, da die behandelten Entwicklungen der Oberflchentemperaturen fr komplexere Teilgebiete in wirklichen Stdten reprsentativ sind.
Article
Two deterministic models were combined: one for canopy leaf energy budgets and one for street canyon energy budgets. The effects of street parks and roof gardens in contrast to non-vegetated city blocks were examined by the use of four typical urban morphologies, which were exposed latitudinally to summer and winter simulations. A variety of increases and decreases in shortwave radiation, net radiation, sensible heat flux, and system reradiation resulted. These changes appear to represent the generalized limits of the possible responses to the addition of vegetation to non-vegetated city blocks.
Article
This paper presents a mathematical model yielding a sensible, albeit simplified representation of the dynamic thermal behaviour of actual green roofs. Several parametric sensitivity analyses have been carried out to assess the cooling potential of green roofs in summer. The main conclusion of these analyses is that green roofs do not act as cooling devices but as insulation ones, reducing the heat flux through the roof. A relatively small set of parameters have been identified as relevant for green roof design: the leaf area index (LAI) and the foliage geometrical characteristics, the soil apparent density, its thickness, and its moisture content.
Greenery on the Roof: a Futuristic, Ecological Building Method For a More Human Architecture in Harmony with Nature
  • R Stifter
  • F Hundertwasser
Stifter, R.; "Greenery on the Roof: a Futuristic, Ecological Building Method", Hundertwasser, F., For a More Human Architecture in Harmony with Nature, Hundertwasser Architecture, Benedikt Taschen Berlag, GmbH, Cologne, p156-158, 1997.
Haeuser mit Gruenem Pelz
  • G Minke
  • G Witter
Minke, G. und Witter, G., Haeuser mit Gruenem Pelz, Ein Handbuch zur Hausbegruenung, Verlag Dieter Fricke GmbH, Frankfurt, 1982.