Benefit–Cost Analysis of Green Roof Initiative Projects: The Case of Jung-gu, Seoul

Comparative analysis on the effectiveness of green roofs and photovoltaic panels as sustainable rooftop technologies

Photovoltaic (PV) panels and green roofs are considered as the most effective sustainable rooftop technologies at present, which utilizes the effective rooftop area of a building in a sustainable manner. To assess the most suitable rooftop technology out of the two, it is vital to have an idea on the energy savings potential of these sustainable rooftop technologies, alongside a financial feasibility analysis considering their overall life spans and additional ecosystem services. To achieve this objective, ten selected rooftops located in a tropical city were retrofitted with hypothetical PV panels and semi-intensive green roof scenarios to perform the present analysis. The energy-saving potential for PV panels was estimated with the assistance of PVsyst software, and green roof ecosystem services were evaluated through a range of empirical formulas. The financial feasibility of the two technologies was assessed by Payback Period and Net Present Value (NPV), through data obtained by local information sources such as solar panels and green roof manufacturers. The results indicate that PV panels achieve a rooftop PV potential of 244.39 KWh/yr/m2 during their 20-year life span. Furthermore, green roofs reach an energy-saving potential of 22.29 KWh/yr/m2 during a 50-year life span. Moreover, based on the financial feasibility analysis, PV panels demonstrated an average payback period of 3-4 years. Green roofs exemplified 17-18 years to recover their total investment for the selected case studies in Colombo, Sri Lanka. Although green roofs do not provide comparatively significant energy savings, these sustainable rooftop technologies aid in energy saving under different response intensities. In addition, green roofs offer several other ecosystem services that improve urban areas' quality of life. Collectively, these findings highlight the particular importance of each rooftop technology promoting building energy savings.

Comparative analysis of environmental standards to install a rooftop temperature monitoring station

Urban climate influences economic activities and the health and safety of urban residents. Therefore, monitoring temperature in urban areas is important. However, owing to the lack of space for an appropriate observation site, an automatic weather station (AWS) was installed on a building rooftop. The rooftop installation can indicate temperature differences depending on the intensity of strong solar radiation and radiant heat of the building, and wind speed. Therefore, in this study, we aimed to provide observation standards for measuring rooftop temperature according to the optimal rooftop material and observation height. Specifically, an AWS was installed on the rooftop of the Gochang Standard Weather Station (GSWO), Jeollabuk-do Province, to observe the urban climate in South Korea and establish suitable weather standards. Different temperatures, optimum surface materials, and optimum heights for measuring the temperature at the rooftop of GSWO were investigated and compared over 1 year. The temperature recorded after installing a palm mat on the rooftop was more similar to that observed in the grassland. Furthermore, the installation height of the temperature sensor of 2.5-3.0 m for the palm mat and 3.5-4.0 m for concrete was found to be the optimal height for observing temperature at the rooftop.

A systematic review for a highly accessible green roof for Malaysian public institution buildings

Purpose

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

Design/methodology/approach

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

Findings

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

Social implications

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

Originality/value

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

Urban Integration of Green Roofs: Current Challenges and Perspectives

Green roofs (GRs) are a sustainable alternative to conventional roofs that provide multiple ecosystem services. Integrating GRs into urban areas is highly relevant considering the rapidly increasing built-up in cities. Therefore, this paper systematically and comprehensively reviews the recent literature from 2011 to 2019 on GRs to identify the challenges and perspectives related to the urban integration of GRs. The review suggests that the effectiveness of GRs in delivering ecosystem services is largely dependent on context-specific parameters such as weather conditions and existing construction or design-related parameters. Integrating GRs into urban areas can be challenging given the diversity of actors, functions, and conditions characterizing these areas. Although significant research has already been conducted on GRs, research covering more geographical locations and contexts is needed. The review points out the need to include future urbanization scenarios, such as tall buildings while analyzing the impact of GRs on ecological networks. Additionally, the review emphasizes the inclusion of urban morphological parameters alongside an analysis of the impact of GRs on microclimate regulation and air quality. In terms of social acceptance, this review points out the need to consider the temporal cycles of vegetation for noting users’ perspectives. Additionally, further research is required on the social impact of GRs, considering their influence on property prices. Lastly, the review stresses the need for more city-scale studies on the impact of GRs on ecosystem services.

Techno-economic analysis of livestock urine and manure as a microalgal growth medium

Microalgae have the potential to utilize the nutrients in livestock urine and manure (LUM) for the production of useful biomass, which can be used as a source of bioindustry. This study aims to evaluate the economic benefits of LUM feedstock that have not been clearly discussed before. Two types of photobioreactors were designed with a capacity of 200 m³ d^-1. Using the experimental data, the economic feasibility of the suggested processes was evaluated via techno-economic analysis. Itemized cost estimation indicated that the submerged membrane photobioreactor has a lower unit production cost (5.4 $ to 5.1 $ kg^-1) than the conventional photobioreactor system (14.6 $ to 13.8 $ kg^-1). In addition, LUM-based growth is another good option for reducing the unit production cost of biomass. The revenues from lowering the cost of LUM treatment significantly contribute to enhancing the economic profitability, where the break-even prices were 1.18 $ m^-3 (photobioreactor) and 0.98 $ m^-3 (submerged membrane photobioreactor). Finally, this study provides several emerging suggestions to reduce microalgal biomass production costs.

Development of a Management Framework for Applying Green Roof Policy in Urban China: A Preliminary Study

Increased consumption of energy and resources by urbanization has caused increasing concerns regarding the sustainability of building practices around the world. Green roofs (GRs) are attracting increasing attention as an important means to overcome environmental challenges related to urbanization. Although GRs have been widely applied in some areas throughout the world, their development is lagging in China. This paper reviews international GR policies with the aim to develop a framework for applying GR policies in suitable areas of China. After summarizing the typical environmental characteristics and GR policies in China, policies that can expedite GR implementation were recommended. By analyzing the national conditions (climate conditions, economic development, urban construction and policy circumstances), 23 GR policies were identified and divided into three categories (i.e., mandatory policies, incentive policies and assistance policies). Based on the attributes, the policies were developed into a framework that combined the three development stages of GRs (i.e., the pilot exploration stage, the progressive promotion stage and the overall application stage). These findings will help to formulate a GR strategy in China and provide important insights for other countries.

Urban stormwater characterization, control, and treatment

This review summarizes over 280 studies published in 2019 related to the characterization, control, and management of urban stormwater runoff. A summary of quantity and quality concerns is provided in the first section of the review, serving as the foundation for the following sections which focus on the control and treatment of stormwater runoff. Finally, the impact of stormwater control devices at the watershed scale is discussed. Each section provides a self-contained overview of the 2019 literature, common themes, and future work. Several themes emerged from the 2019 literature including exploration of substrate amendments for improved water quality effluent from stormwater controls, the continued study of the role of vegetation in green infrastructure practices, and a call to action for the development of new models which generate reliable, computationally efficient results under the physical, chemical, biological, and social complexity of stormwater management. PRACTITIONER POINTS: Over 280 studies were published in 2019 related to the characterization, control, and treatment of urban stormwater. Studies on bioretention and general stormwater characteristics represented the two most common subtopics in 2019. Trends in 2019 included novel substrate amendments, studies on the role of vegetation, and advancements in computational models.

Determining the Increase in a Building’s Appreciation Rate Due to a Reconstruction

The reconstruction of buildings generally prolongs their useful life, increases their utility value, and last but not least, leads to an increase in their value. These assumptions only apply if an independent third party reaches the same conclusion together with the owner. However, the undesirable effect of the reconstruction of a building may be a decrease in its value. The aim of this contribution is to determine the change in value of an older sample building assessed in the included case study as a result of its reconstruction. Valuation methods are applied, which, as it turns out, reveal the inaccuracy of the subjective view of the person who reconstructed the building. The resulting change in the value of the sample building is discussed from the point of view of the applied valuation methods and other value-creating aspects (subjective view of the owner on the value of the building, historical value of the building, etc.). The contribution concludes with recommendations for maximizing the increase in value of a property through its reconstruction so as to eliminate the risk of a decrease in its value.

Green-Roof: The Role of Community in the Substitution of Green-Space toward Sustainable Development

The research challenge in the problem of the sustainable development goals is to find solutions for development control through the application of green roofs in residential areas, which is the feasibility of the role of the community. This research was based on the discipline of architecture by considering the role of the community in managing architectural green-space substitution. The purpose of this study was to identify patterns of the role of the community for green roofs feasibility based on housing, conducted in some parts of Sumatra, Java, and East Nusa Tenggara, Indonesia. Data were collected using a survey questionnaire. Data were calculated based on percentages and analyzed using the chi-square method. The results indicated that the optimization of the community role was needed for the sustainability of the green-roof from all economic levels, both urban and rural. The aspect of public awareness and knowledge of the benefits of the green-roof is very high, but the object of the green-roof in Indonesia is still very limited because participation is still not optimal. Therefore, it is necessary to promote the green-roof application to the community by adapting local culture in sustainable green-roof technology innovation.

Calculation of the Risk of Lawsuits over Construction Flaws in Flat Roofs

In order to achieve sustainability objectives in the use of a building, its elements’ operating problems should be minimized. From this premise, a total of 497 cases related to construction flaws in flat roofs were analyzed in this research. A matrix was developed indicating the risk of lawsuits by owners according to the degree of nuisance resulting from the construction flaws studied, their technical importance, and the type of pathological origin. Based on these factors, it is possible to predict a greater or lesser probability of an owner filing a lawsuit—risk factor (F). A wide range was found for this probability, with the largest value being 865 times greater than the smallest value. The value of F was divided into 5 categories to classify the diverse results obtained and determine the number of cases and interrelations ascribed to each category. Additionally, the level of presence of said cases was calculated through the analysis of 3 different demographic aspects, it being noted that a greater purchasing power and a higher concentration of urban population lead to more stringent requirements and, subsequently, to a greater number of lawsuits. With all these results, building quality can be improved while resulting in greater constructive-financial sustainability and in a reduction of the economic resources required of society (fewer lawsuits and associated human resources).