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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
141

Finite Element Analysis of the Wind - Uplift Resistance of Roof Edge Components

Dabas, Maha January 2013 (has links)
Wind-induced damages on low-slope roofs are a major and common problem that many buildings located in high wind areas suffer from. Most of these damages are initiated when the metal roof edge fails first, leading to overall roof failure. This is because peak wind pressures occur at the edges and corners of low-slope roof buildings. Currently, there are not enough wind design guidelines for the Canadian roofing community to quantify the dynamic wind uplift resistance of the roof edge system. The objective of this research is to evaluate the effect of wind-induced loads on roof edges using a finite element model, verify the numerical results with those obtained from controlled experiments, and perform parametric investigations for various design variables. In this research, the overall roof edge system was modelled using the commercial finite element software package ABAQUS, by simulating the roof edge system with shell elements and applying a uniform static pressure against the face of the edge cleat or coping. Results of the modelling were compared to the experimental ones in terms of deflection of the coping under uniform pressure. The results of the numerical model and the experiments show a good agreement. Furthermore, a parametric analysis of the system was conducted under the effect of varying parameters. i.e., coping gauge, nail spacing, coping and cleat length and wind and thermal load application.
142

Quantification of the environmental impacts of urban green roofs

Speak, Andrew Francis January 2013 (has links)
Urban populations worldwide are expanding rapidly and consequently a large number of people are becoming exposed to hazards inherent in cites. Phenomena such as the urban heat island can exacerbate the effects of heatwaves, and land surface sealing can lead to flash flooding. Cities are also the sites of enhanced air and water pollution from non-point sources such as concentrated motor vehicle use. Climate change predictions for the UK include increased winter precipitation and an increase in frequency of summer heatwaves. This will put further pressure on urban residents and infrastructure. Roof greening can be used within climate change adaptation schemes because green roofs have a range of environmental benefits which can help urban infrastructure become more sustainable. This thesis empirically quantifies several of these benefits, and the processes influencing them, by monitoring real green roofs in Manchester. A number of novel discoveries were made. Green roofs act as passive filters of airborne particulate matter. 0.21 tonnes of PM10 (2.3% of the inputs) could be removed from Manchester city centre in a maximum extensive green roof scenario. Species and site differences in particle capture were exhibited and related to morphology and proximity to sources respectively. An intensive green roof was able to lower the monthly median overlying air temperature at 300 mm by up to 1.06 oC. A combination of drought and mismanagement caused damage to the vegetation on one of the green roofs, with a subsequent reduction in the cooling effect. Daytime air temperatures were higher than over an adjacent bare roof for a larger proportion of the day than over the undamaged roof, and lower cooling was observed at night. A site-specific methodology was devised to monitor the rainwater runoff from an intensive green roof and an adjacent bare roof. Average runoff retention of 65.7% was observed on the green roof, compared to 33.6% on the bare roof. Season and rainfall amount had significant impacts on retention, however, many other explanatory variables such as Antecedent Dry Weather Period (ADWP) and peak rainfall intensity had no demonstrable, significant impact. Intensive roof construction on 10% of the rooftops in Manchester city centre would increase annual rainfall retention by 2.3%. The runoff was characterised with regards to heavy metals and nutrients. Nutrient levels were found to be not a significant problem for water quality, however, Environmental Quality Standards (EQS) values for protection of freshwater were exceeded for concentrations of Cu, Pb and Zn. High metal concentrations within the sediments may be acting as sources of pollution, particularly in the case of Pb. The age of the green roof means that past atmospheric deposition of Pb could be contributing to the runoff quality. The multi-benefit aspect of green roofs is discussed in the light of the results of this thesis and recommendations made for policy makers and the green roof construction industry.
143

Re-Imagining Nature in Dense, High Rise Urban Environment: the Present and Future of Green Building Infrastructure in Singapore

Yi, Claire 01 January 2020 (has links)
From the futuristic Jewel at Changi Airport, the healing gardens at Khoo Teck Puat Hospital in Yishun to School of the Arts at Orchard Road, greenery has sprouted in buildings vertically and horizontally in Singapore, painting a growing green canopy for the dense, high rise city. This paper combines both analyses from first-hand site visits and case studies from external scholar studies to examine the performance of existing Green Building Infrastructures (BGIs) within Singapore’s unique urban context. The study reveals that the success of BGIs is highly dependent on the programming (i.e. thermal comfort design, accessibility, amenity facilities etc.), as well as the function and users of the existing building. Designs and planning that take those factors into consideration while being in line with the city’s general development goals, such as storm water management and pervasive greenery, are likely to bring out the most benefits in BGIs. To demonstrate, this paper also proposed several policy and planning recommendations that included several sets of rudimentary yet relevant parameters. Future research is encouraged to explore more complex combinations of considerations, their incorporation in design and policy making process, as well as a scientific and systematic method to evaluate BGI performance that includes both objective environmental impacts and subjective user experience that might be achieved through smart city developments.
144

Jämförelse av olika kvalitetsmått vid kartering av hustak med hjälp av LiDAR-data : Metod för utvärdering av kartering med ArcGIS Pro, QGIS och FME / Comparison of different quality measures when mapping roofs using LiDAR data : Method for evaluation mapping with ArcGIS Pro, QGIS and FME

Jaber Noaaemi, Fadi January 2020 (has links)
Teknisk utveckling och ökad användning av GIS har ökat behovet av data som snabbt kan insamlas över stora geografiska områden. Behovet är internationellt samtidigt som det också kräver samarbete mellan alla berörda parter då systemet har förmågan att presentera geografisk information med ett brett användningsområde. Höjdförhållanden i terräng erhålls genom flygburen laserskanning och presenteras i 3D med olika klassningar för att bemöta variation i signalens reflektion. Behovet av sådan information har använts för produkter baserat på data erhållen från laserskanning. I examensarbetet användes laserdata från två skanningsomgångar beställda av Lantmäteriet. Den första laserskanningen (2011) utfördes i syfte att skapa en noggrann nationell höjdmodell innehållande klassificering av de laserpunkter som representerar mark och vatten. Den senare (2019) i syfte att uppnå en punkttäthet >1 punkt/m2 utan kriterier för vad som skall klassificeras. Syftet med examensarbetet är att testa och utvärdera olika metoder i ArcGIS Pro, QGIS samt FME för att kvalitetssäkra kartering av hustak. Målet är att visa om extraheringen kan utföras med en tillräcklig kvalitet för att metoden ska rekommenderas. Tidigare studier har fokuserat på att skapa tre olika typer höjdmodeller DEM/DTM, DSM och nDSM, samt hur man kan skapa en markyta med objekten över marken. Examensarbetet fokuserade på att klassificera oklassificerade punkter som byggnader finns inom. Detta utfördes med olika metoder i de program som användes med samma parametrar. Klassificering, extrahering och skapande av polygoner var de tre steg som användes för att extrahera hustak. Extrahering av hustak gav ett bättre resultat med ArcGIS Pro med 97 % från båda skanningsomgångarna. Detta värde berodde på cellstorlek som användes och hur buffertzoner omkring varje punkt påverkas på polygoner som i sin tur påverkades av hustakens areal. En enkät utfördes för att svara på en fråga och resultatet gav att ArcGIS Pro är bäst med 93,5 %. De problem som uppstod berodde främst på att vegetation inte kunde tas bort. Extrahering av byggnader från laserdata rekommenderas för ett punktmoln med den senare laserskanningen som har mer än 1 punkt/m². Vidare rekommenderas att använda ArcGIS Pro för att extrahera hustak från laserpunktmoln. ESRI’s ArcGIS Pro är ett komplett program som har alla verktyg som behövs. / The development of technology within GIS has increased the need for the data that being quickly added while covering large geographical areas. Such need is at the international level, while requiring a willingness to cooperate for all parties involved, as the system can present geographical information with a wide range of applications. The need for such information has been used for products based on data obtained from laser scanning. In this thesis, laser data from two scanning sessions ordered by the Swedish Land Survey were used. The first laser scan (2011) was carried out with the aim of creating an accurate national elevation model (RH 2000) containing a classification of the laser points representing soil and water. The latter (2019) was done to achieve a spot density >1 point/m2 without criteria for classification. The purpose of the current thesis is to test and evaluate the available methods in ArcGIS Pro, QGIS and FME to ensure quality mapping of roofs. The aim was to investigate whether the extraction of roofs? can be carried out with an adequate quality so that the method can be recommended for the future works. Previous studies have focused on creating three types of elevation models DEM / DTM, DSM and nDSM. So, one can create an earth surface with the objects above the ground. In this thesis, the focus was on classifying point clouds for unassigned points (unassigned == 1) in which the buildings are located. This was done by testing different methods on different programs while keeping the parameters same. Classification, extraction and creation of polygons are the three steps used to extract roofs. Extraction of rooftops showed better results using ArcGIS Pro with 97 % from both scanning sessions. This was due to the cell size used in the study and that the buffer zones around each point were affected by polygons, which in turn were affected by the rooftop area. A survey was conducted to answer a question and the result showed that ArcGIS Pro is the best with 93,5 %. Problems that arose the study were mainly caused by the vegetation cover that could not be removed. As a conclusion, extraction of buildings from LiDAR-data is recommended for a point cloud with the latter laser scan with more than 1 point/m². Furthermore, it is recommended to use ArcGIS Pro to extract rooftops from laser scanning which is a comprehensive program i.e. that all the tools used in this thesis were freely downloaded from ESRI's ArcGIS Pro.
145

Planera för hållbara städer med gröna tak / Plan for sustainable cities with green roofs

Jonsson, Amanda January 2021 (has links)
Expected effects from climate change are increased precipitation and rising temperatures. This in combination with urban densification where green areas are replaced by hard surfaces contributes to a higher risk of floods and heat islands, since green areas provide ecosystem services which disposes local stormwater and has a cooling effect. The aim of this study was to investigate how green roofs and its ecosystem services can contribute to more sustainable cities. This study was conducted by literature data combined with interviews. The result of this study showed that the most important function of green roofs is stormwater management. The space in cities is limited and many functions e.g., infrastructure and buildings should fit in limited surface. The lack of space is a problem to ensure that there are sufficient green spaces that provides ecosystem services. This problem could decrease by using the roofs to a greater extent to ensure ecosystem services in form of e.g., stormwater management. However, the municipalities’ room for maneuver to plan with green roofs showed to be limited by regulations. In conclusion, there is potential to build green roofs to a greater extent as they have many benefits that are useful in urban densification and to counteract negative effects of climate change, e.g., stormwater management and temperature control. The municipal actors would therefore need more room to maneuver to be able to implement green roofs in community planning to a greater extent.
146

Influence of the types of grass of green roofs for the design of thermal comfort in buildings

Rodríguez, José, Vilela, Karina 01 January 2022 (has links)
The main objective of the research was to study the effect of the Stenotaphrum secundatum and Zoysia japonica grasses on the higher and lower environment temperature and lower relative humidity; the secondary objective was to compare whether the Stenotaphrum secundatum grass has a greater impact on the environment parameters of comfort than the Zoysia japonica species. Six materials were used for the extensive green roof, each one forming a layer of the system, which were placed on the concrete slab and in an upward direction, including: PVC geomembrane, Polyester asphalt carpet, Pumice stone, Planar geodren, Prepared soil with guano, compost, muss, and Substrate. In order to make measurements of the higher and lower ambient temperature, a digital thermometer and lower relative humidity meter was used. Stenotaphrum secundatum and Zoysia japonica were used as grass species, as they were the most representative of the grasses used in extensive green roofs. The experimentation was carried out for 2 months from September to October of 2021, having built 3 modules of 1000x600mm roofs, including 1module of the concrete roof with ceramic covering and 2 modules of extensive green roof with two types of grass: Stenotaphrum secundatum and Zoysia japonica. The readings of the environment temperature and relative humidity of the higher and lower part were taken in six points of each module to have a greater number of representative measurements. The watering of the 2 green roof modules with grass was carried out twice a week, applying 5L of water per module. The results indicate that the Zoysia japonica grass is the one that presents a better behavior before the higher ambient temperature and that the Stenotaphrum secundatum grass behaves better before the lower ambient temperature and lower relative humidity. The conclusions indicate that the Stenotaphrum secundatum grass behaves better temperature and relative humidity; the two grass types exhibit different behavior.
147

An Examination of the Plant and Fungal Communities on Green Roofs and Their Ability to Influence Ecosystem Services

Droz, Anna Gabriella 08 April 2022 (has links)
No description available.
148

Hur ska det gå för Malmö stads gröna tak?

Larsson, Kajsa January 2018 (has links)
Sustainable urban planning is becoming more and more important. Ecological sustainability holds greats opportunities for urban areas in order to avoid some of the consequences climate change might cause. In sustainable planning Grönytefaktorn (The Biotope Area Factor) is one important tool and one which Malmö Stad has used in order to increase sustainable planning in the city. Since the beginning of 2015, municipalities in Sweden are no longer required to use The Biotope Area Factor, which might threaten the development of e.g. green roofs. The aim of this study is to investigate how real estate companies experience their role as investors in sustainable planning. Planning is a political activity with multiple stakeholders and in order to try to understand the difficulties sustainable solutions face in this context, Planning theory and Theory of Planned Behavior have been used. The results show that the companies are not willing to invest in sustainable solutions like green roofs, unless the market demands it.
149

The Influence of Ambient Temperature on Green Roof R-values

Cox, Bryce Kevin 01 January 2010 (has links)
Green roofs can be an effective and appealing way to increase the energy efficiency of buildings by providing active insulation. As plants in the green roof transpire, there is a reduction in heat flux that is conducted through the green roof. The R-value, or thermal resistance, of a green roof is an effective measurement of thermal performance because it can be easily included in building energy calculations applicable to many different buildings and situations. The purpose of this study was to determine if an increase in ambient temperature would cause an increase in the R-value of green roofs. Test trays containing green roof materials were tested in a low speed wind tunnel equipped to determine the R-value of the trays. Three different plant species were tested in this study, ryegrass (Lolium perenne), sedum (Sedum hispanicum), and vinca (Vinca minor). For each test in this study the relative humidity was maintained at 45% and the soil was saturated with water. The trays were tested at four different ambient temperatures, ranging from room temperature to 120ºF. The resulting R-values for sedum ranged from 1.37 to 3.28 ft²h°F/BTU, for ryegrass the R-values ranged from 2.15 to 3.62 ft²h°F/BTU, and for vinca the R-values ranged from 3.15 to 5.19 ft²h°F/BTU. The average R-value for all the tests in this study was 3.20 ft²h°F/BTU. The results showed an increase in R-value with increasing temperature. Applying an ANOVA analysis to the data, the relationship between temperature and R-value for all three plant species was found to be statistically significant.
150

What’s Up with Green Roofs? : A study on why property owners should invest in Green Roofs and what benefits tenants receive from it. / Gröna tak, vad är grejen? : En studie om varför fastighetsägare borde investera i gröna tak samt vilka fördelar gröna tak ger hyresgäster

Szecsödy, Emma, Lilja, Jacob January 2020 (has links)
The building sector has for a longer period of time been responsible for a considerable part of the negative environmental imprint. The increased interest for the environment and sustainability in the industry has led to technological developments which has reduced the negative environmental impact from buildings. This, combined with the fact that buildings take up more space in cities reducing green spaces, has increased the use of green roofs. This research paper includes a study on the competitive advantages green roofs can offer property owners and what the driving forces behind the use of green roofs are. The study also includes a research on what benefits tenant’s experience from having offices in properties that have green roofs. Lastly, the study attempts to present why buildings should have green roofsand what motivates property owners to use them more often. The literature review reveals that green roofs have become popular due to their ability to absorb carbon dioxide, cool down cities, manage urban runoff and increase biodiversity. The literature review describes both the practical aspects of constructing a green roof and the management of green roofs. It also examines the cost of green roofs compared to conventional roofs. The main challenges with green roofs are said to be the increased risk of leakage, increased weight on roofs and the steep slopes of Swedish roofs. Green roofs are said to have a longer lifespan compared to regular roofs. The literature review also discusses market value and the parameters which affect the market value of a property. The research results demonstrate that it is difficult to link green roofs to an increased market value. Due to the regulation against particular, structural requirements the municipality cannot require property owners to implement green roofs. However, the municipality of Stockholm have requirements stating that each property owner is responsible for the management of urban runoff within the property lines. One way of solving this management is by using green roofs. The municipality may also require the GYF factor to be fulfilled during new construction, which means that a certain amount of green space is required. This is something green roofs can help property owners achieve as well. The LEED and BREEAM green building certification programs also require a certain amount of green spaces in order to generate a higher rating. Here, too, green roofs could be used for this aspect. The study also examines if LEED and BREEAM have any economic benefits. Interviews were conducted with property owners, tenants, architects and employees at the municipality of Stockholm. The results were relatively similar to that of the results of the literature review. Among the most important factors when considering building a green roof according to the property owners, were green certifications, the factor of green areas (GYF),stormwater management and biodiversity. The study revealed that the most important benefit for tenants was the ability of green roofs to help companies with their environmental profiling. The conclusion of the study is that the main driving factor for utilizing green roofs above all is that it helps the property owner to achieve a higher certification rating. For property owners this is important as they want to profile themselves in a sustainable and environmentally friendly way, which attracts tenants and investors. Certification programs are also leading to economic benefits for the property owners. Other driving forces for property owners to use green roofs are to meet the requirements of the municipality regarding urban runoff management and to reach the level of GYF required. As tenants often have strict sustainability policies, green roofs provide an added value as they are sustainable. In terms of cost, green roof is said to have initial costs of 300-600 kr/m2 which is higher than for conventional roofs. The short-term risk of leakage is refuted by this study, but the longtermrisk is still unknown. Even though higher initial cost and unknown long-term risk of leakage the study believes that implementing a green roof is justifiable; the positive environmental and social aspects outweighs the higher costs. Green roofs can provide a financial profit for the property owner when it’s combined with a green building certification;green roofs are a factor to implement in order to reach higher levels of green building certification systems LEED and BREEAM, which, in turn, can lead to a higher market value.The study also reveals that accessible green roofs can result in an increased revenue for the property owner.

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