Green Roof Cost-Benefit Analysis: Special Emphasis on Scenic Benefits

Abstract

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.

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

“…Green roofs are a green infrastructure technology that has been widely adopted in many different cities. There are two major types of green roof systems, according to their purpose and characteristics: Extensive and intensive [1][2][3]. Intensive green roofs are commonly referred to as rooftop gardens, consisting of large trees, and a variety of plant species, along with garden furniture.…”

“…Green roofs are also known to have many environmental, economic and social benefits. Many studies have proven that green roofs are effective in many aspects, including carbon sequestration, air pollutant removal, stormwater management, seasonal energy savings, urban heat island (UHI) effect mitigation, increasing rooftop membrane longevity and contributing to urban aesthetics [1][2][3][4][5][6][7][8][9].…”

Do Looks Matter? A Case Study on Extensive Green Roofs Using Discrete Choice Experiments

“…It therefore encourages further in-depth and large scale studies to link these insights to cost-benefit analyses (e.g., [67]) and other studies trying to value aesthetic benefits (e.g., [20]). A large-scale study, in which the self-selection bias towards participants interested in this environmental topic is taken into account, would allow for an in-depth analysis of preference heterogeneity and robust mWTP estimates when the necessary conditions (see Section 3.6) are met.…”

“…Furthermore, these vegetated roofs increase roof membrane longevity [13] and urban biodiversity [14,15], while also improving roof effluent quality [16,17] and air quality [12,18]. Finally, extensive green roofs can make an urban environment more aesthetically pleasing [1], thereby providing psychological [19] and economic [20,21] benefits.…”

Overadaptation to Climate Change? The Case of the 2013 Finnish Electricity Market Act

“…The situation we have chosen to analyse is thus far from being a discrete-choice case, in which the only decision would be whether to implement the Act or not. This is true of nearly all public good decisions, such as deciding on the size of a dam (Hallegatte et al 2012), the scale of proposed green infrastructure to prevent urban storm-water issues (Nurmi et al 2016;Nordman et al 2018) or the extent of early warning systems (Holland 2008).…”