Suchergebnisse

Construction industries around the world have, in recent history, become increasingly concerned with the sustainability of building practices. Inherently, the development of the built environment results in partial or complete destruction of the natural environment. Advanced European and North American countries have turned to green roofs as a means of sustainable development. Australia, on the other hand, has yet to fully realize the potential of green roof technology. In the first case, an extensive review of green roof literature was undertaken to establish the dominant perspectives and over-riding themes within the established body of international literature. The collection of primary data took the form of qualitative, semi-structured interviews with a range of construction practitioners and green roof experts; landscape architects, consultants and academics. The information gained from the interviews facilitated the primary aim of the paper; to critically analyse the state-of-practice in the Australian green roof industry. Green roofs, despite their proven sustainability benefits and their international success, have experienced a relatively sluggish uptake in the Australian construction industry. With this being said, the Australian green roof industry is considered to have promising potential for the future; should there be legislative changes made in its favour or greater education within the industry. To advance the local industry, it was found that government authorities are required to adapt policy settings to better encourage the use of green roofs, whilst industry bodies are required to host better, more targeted educational programs.

International audience ; To face the consequences of climate change and unsustainable urbanization, green roofs are currently widely implemented in urban environments. Despite their benefits to restore ecosystem services are quite well established at the roof scale, green roofs need to be widely and appropriately distributed to perform efficiently at larger scales. However for now, this scale-factor is not considered to guide and conduct green roof implementation policies. Here we show that a multi-scale analysis based on fractal theory is helpful in providing information for green roof implementation and in assessing the relevance of these policies. We found the fractal dimensions computed for green roofs are sparse, ranging from 0.49 to 1.35 for the nine studied cities, and illustrate some different degrees of progress in urban greening. Our results demonstrate some significant inconsistencies between political ambition and their in situ realization, and the necessity to better take into account the spatial distribution of green roof implementations in order to optimize their performances.

International audience ; To face the consequences of climate change and unsustainable urbanization, green roofs are currently widely implemented in urban environments. Despite their benefits to restore ecosystem services are quite well established at the roof scale, green roofs need to be widely and appropriately distributed to perform efficiently at larger scales. However for now, this scale-factor is not considered to guide and conduct green roof implementation policies. Here we show that a multi-scale analysis based on fractal theory is helpful in providing information for green roof implementation and in assessing the relevance of these policies. We found the fractal dimensions computed for green roofs are sparse, ranging from 0.49 to 1.35 for the nine studied cities, and illustrate some different degrees of progress in urban greening. Our results demonstrate some significant inconsistencies between political ambition and their in situ realization, and the necessity to better take into account the spatial distribution of green roof implementations in order to optimize their performances.

As part of the low-carbon policy and development in Taiwan, the Bureau of Energy introduced the "Green Energy Roofs Project" in 2017, which encouraged homeowners to install green energy roofs. However, the incentives of homeowners and solar photovoltaic operators to participate in this Project were low. The aim of this study is to propose and evaluate alternative models for investing green energy roofs. The contributions of this study are that, first, we consider factors such as risk management schemes and crowdfunding that have not been considered in evaluating green energy roofs project. In addition, this study provides a solution to Taiwan government's current dilemma about how to encourage homeowners to install green energy roofs. This study adopts five common investment appraisal methods (including payback period, discounted payback period, net present value, internal rate of return and profitability index) to evaluate four different models for investing green energy roofs. The results show that when homeowners are fully responsible for installation costs of green energy roofs with partial funds borrowed from banks and with consideration of risk management, the homeowners have better investment returns. Therefore, the Taiwan government could consider the alternative strategy proposed in this study for promoting green energy roofs so that the country can x`move a bigger step forward towards the goal of being nuclear-free.

Green roofs can be considered as effective and esthetically appreciated passive tools for energy saving systems in buildings. In particular, the effect of evapotranspiration and the large thermal inertia of such solutions, represent highly attractive properties to be implemented in advanced building envelope components. Although these properties are deeply influenced by external factors such as weather conditions, and greenery dynamics, the materials used in substrate and drainage layers are too commonly assumed as constant thermal insulation layers depending only on their physical properties and water content. In particular, common disaggregated materials used in internal layers of extensive green roofs, generally are characterized by a highly complex matrix, and consequently, such materials usually lack of realistic thermal-acoustic properties evaluation. The main objective of the study is to investigate the impact of water content on the thermo-acoustic performance of different disaggregated materials from green roofs substrates commonly used in Mediterranean climates. In particular, the TPS method was used to assess the effect of humidification and raining processes on the final performance of the considered samples. An extensive acoustic characterization was also developed, based on the acoustic transfer function method. Results show that raining processes can highly influence the thermal performance of such materials, which depending on their density, can even triple their thermal conductivity value and achieve twice the volumetric specific heat at ambient conditions. Furthermore, the acoustic characterization procedure showed that the biggest modification on the final acoustic absorption and insulation capability, i.e. about 20 dB when the 80 mm samples, was produced by increasing the water content of the system from 10% to 30% RH. On the contrary, the conditioning at 90% RH does not produce significant differences of the final acoustic behavior of the substrates. Keywords: green roofs, substrates, dynamic ; Acknowledgments are due to the "CIRIAF program for UNESCO" in the framework of the UNESCO Chair "Water Resources Management and Culture". The research leading to these results has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No. 657466 (INPATH-TES). The work is also partially funded by COOL CRETE Project, under the framework of Call L. 598/94 Art. 11 – Industrial research and experimental development (Energy sector) supported by Luigi Metelli S.p.A., and by the Spanish governmentENE2015-64117-C5-1-R (MINECO/FEDER) in collaboration with the company Buresinnova S.A (Mercabarna Flor - Local n. 412 Ctra. Antiga de València, 1. 08830 Sant Boi de Llobregat. www.buresinnova.com). The authors would like to thank the Catalan Government for the quality accreditation given to their research group (2017 SGR 1537). GREA is certified agent TECNIO in the category of technology developers from the Government of Catalonia. Julià Coma would like to thank Ministerio de Economia y Competitividad de España for Grant Juan de la Cierva, FJCI-2016-30345.

This article presents a green roof cost-benefit analysis (CBA). Green roofs are roofs which are partially or completely covered by vegetation. We discuss the benefits and costs of light self-sustaining vegetated roofs. The benefits of the ecosystem services (ES) provided by green roofs can be classified into private and public benefits. We apply the selected valuation methods first in Helsinki, Finland and subsequently explain how results can be transferred to other urban locations. Past research and this study show that private benefits are usually not high enough to justify the expensive investment for a private decision maker. However, when the public benefits are added to the private benefits, social benefits are higher than the costs of green roofs in most cases.Past research quantified most types of the benefits, excluding scenic and biodiversity benefits. Scenic benefits denote the intangible benefits that people derive from the presence of green space, including at least aesthetic and psychological ones. In this article, special emphasis is placed on the valuation of the scenic benefits; these are among the most challenging benefits to valuate in monetary terms. We employ hedonic pricing theory, implemented via spatial regression models, and green roof implementation scenarios in order to estimate the aggregate willingness to pay for a "unit" of green roof. The results show that the scenic benefits can be a significant attribute in cost-benefit calculations. Yet, the amount of benefits strongly depends on the green roof design.

Abstract
Both vegetation abundance and community composition play important roles in functions of green roofs (e.g. stormwater retention, habitat provision, aesthetic appearance). However, green roofs' vegetation, and hence their functions, can change significantly over time. More understanding of these changes is required, particularly in cold climates. Therefore, this study investigated vascular plant covers and species compositions on 41 roof sections located in Sweden's subarctic and continental climate zones. For the roof sections with a known originally intended vascular plant composition (n = 32), on average 24 ± 9% of the intended species were detected in surveys, and unintended species accounted for 69 ± 3% of the species found. However, most colonizing species formed sparse cover on the roofs. Thus, they may make less contributions to green roofs' potential functionalities related to vegetation density (e.g. social perception, effectiveness in stormwater management and thermal performance) than the intended vegetation. The intended species dominated plant cover (93 ± 3%) and Sedum acre (58 ± 36% cover) was the most commonly detected species and as found in previous studies, substrate depth was positively related to both plant cover and species richness. Contrary to a hypothesis, the roofs' vascular plant cover was not related to species richness but was significantly and negatively correlated with moss cover. The results highlight the importance of substrate depth for both plant abundance and species diversity and show that even in a cold climate, colonizing unintended species can strongly contribute to green roofs' species richness.

Green roofs are considered structural components that act as an insulating layer for buildings. Among the factors that influence the choice of this type of horizontal green there are: the geographical location, the climate, and the need to improve the thermal insulation of the flat roof. Some types of layouts are proposed for the sustainable construction of green roofs. In addiction the structural and vegetation components suitable for the realization of green roofs are also described. The energy performance of an experimental green roof prototype located at the ENEA Casaccia Research Center shown that the horizontal green layer improves the thermal insulation of the flat roof by over 40%.