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Digitized by Kansas Correctional Industries

Thesis (M.Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH. / Bibliography: p. 55. / by Suzanne Stewart. / M.Arch.

Thesis--Danmarks tekniske Højskole. / Errata slip inserted. "Dansk resumé": p. 266-268. Includes bibliographical references.

Roofs are the single enclosure element common to artificial shelters constructed by all cultures in all climate regions. The hygrothermal performance of insulated, sloped, wood-framed roof assemblies has long been of interest to building scientists and building codes alike. Requirements for the ventilation of roof assemblies have been included in building codes for more than 50 years, however moisture problems still occur. Unvented roof assemblies have been suggested as an alternate and potentially superior solution. While unvented roofs have become relatively common in the warmer southern climates of North America, some technical issues remain unclear and the need exists for further study and demonstration of the hygrothermal performance of both ventilated and unvented roof assemblies in cold northern climates. This thesis seeks to address these issues through a review of existing literature, experience and industry practice, field investigation and measurement, analytical calculation and computer simulations.

Roofs are the single enclosure element common to artificial shelters constructed by all cultures in all climate regions. The hygrothermal performance of insulated, sloped, wood-framed roof assemblies has long been of interest to building scientists and building codes alike. Requirements for the ventilation of roof assemblies have been included in building codes for more than 50 years, however moisture problems still occur. Unvented roof assemblies have been suggested as an alternate and potentially superior solution. While unvented roofs have become relatively common in the warmer southern climates of North America, some technical issues remain unclear and the need exists for further study and demonstration of the hygrothermal performance of both ventilated and unvented roof assemblies in cold northern climates. This thesis seeks to address these issues through a review of existing literature, experience and industry practice, field investigation and measurement, analytical calculation and computer simulations.

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With the growing urbanized population, cities have become a major contributor to global energy consumption and greenhouse gas (GHG) emission. The urbanization processes also cause local climate change through excessive anthropogenic heat emission and modification of the land biophysical properties. The resultant urban heat island (UHI) effects and aggravating human heat stress have become key environmental issues in city management. Cities can be designed to be climate-conscious and energy-efficient not only to contribute to urban sustainability, but also address global climate-change issues at the local level. Green roof presents a feasible strategy for climate-conscious urban design (CCUD). With the notable thermal effects in microclimate amelioration and energy conservation, it has great potential to help cities tackle local and global climate issues. Understanding the status and underlying mechanism of green-roof thermal effects can inform optimal design and management, and provide scientific basis to promote green-roof application. This study formulates a multidisciplinary framework to assess green-roof thermal effects at building, neighborhood and district scales, based on a case study in Hong Kong. Firstly, the building-scale field measurement found that the 484 m^2 experimental extensive green roof can significantly ameliorate rooftop microclimate and cut building energy consumption. The peak surface and air temperature can be reduced by 11℃ and 4.5℃ on sunny summer days, and 7.2℃ and 2.3℃ on cloudy days, leading to an electrical energy saving of 2.80×〖10〗^4 kWh for a summer of air conditioning. The thermal performance was sensitive to background environmental factors. Solar radiation and relative humidity governs the seasonal and diurnal variation of air and surface temperatures reduction. Substrate moisture can significantly regulate the subsurface temperature but has limited effect on evapotranspiration (ET). Based on correlation and scenario analyses, this study has formulated an irrigation scheme which could balance between plant growth, thermal performance and water efficiency to achieve sustainable management of tropical extensive green roofs. Secondly, the neighborhood-scale modeling revealed that greening all roofs in residential communities can extend the cooling effects from the rooftop to the entire neighborhood. Urban design factors such as building height, distance, site coverage and orientation can affect the diurnal, horizontal and vertical pattern of the “cool-islands” created by green roofs. Green roof can also enhance the rooftop thermal comfort by alleviating the intensity and duration of heat stress. The findings suggest that compact cities can green the roof and podium space to provide thermally comfortable and recreational venues for urban residents. Thirdly, the district-scale cost-benefit analysis found that large-scale construction of green-roof infrastructure in Hong Kong can be well justified by its thermal benefits. The extensive green roof has an annual monetary benefit of HK$0.9–1.7 billion, and the intensive, HK$1.4–2.6 billion, in terms of energy saving, CO2 and air pollutant reduction. The life-cycle benefit-cost ratio (BCA) is 3.7–7 for extensive green roof, and 1.4–2.7 for the intensive, indicating the high cost-effectiveness of both types, with the extensive being more economically attractive than the intensive. / published_or_final_version / Geography / Doctoral / Doctor of Philosophy

Owing to the concern about the serious factors influencing global warming and climatic change, the process of sustainable landscape construction as well as ecologically friendly developments needs to be addressed. In particular, the questions to ask is are we nearer to accepting sustainable growth advantages in South Africa , primarily the greater eThekwini Municipal Area? In this research paper an analysis of both a theoretical and practical approach to conventional understanding s relating to development practices and issues that encompass greening of cities and the notion of rooftop gardens will be assessed. In so doing it will investigate the discourse surrounding urban ecology and sustainable landscape developments and how both processes incorporate the topic of rooftop gardening, urban agriculture and people’s attitudes towards nature in the city, which regrettably from a South African perspective has very little comprehensive literature written about it. The research will give clarity and hopefully show that there is sufficient evidence to demonstrate that rooftop gardens form an intricate part of urban ecology. In addition to this that they can provide general environmental, associated aesthetic and health benefits for cities and their inhabitants. Hopefully in culmination this research study will promote a greater insight into rooftop gardens benefits for city management systems. / Thesis (M.T.R.P.)-University of KwaZulu-Natal, Durban, 2009.