Costs and Benefits of Green Roof Types for Cities and Building Owners

Sita H Van Der Meulen

doi:10.13044/j.sdewes.d6.0225

Abstract

Increasing urbanization and the effects of climate change will bring new challenges for cities, such as energy saving and supply of renewable energy, preventing urban heat islands and water retention to deal with more frequent downpours. A major urban surface, the surface of roofs, is nowadays hardly exploited and could be used to make cities more ‘future proof’ or resilient. Many Dutch municipalities have become aware that the use of green roofs as opposed to bituminous roofs positively contributes to these challenges and are stimulating building-owners to retrofit their building with green roofs. This study aims at comparing costs and benefits of roof types, focused on green roofs (intensive and extensive) both on building- and city scale. Core question is the balance between costs and benefits for both scales, given varying local conditions. Which policy measures might be needed in the future in order to apply green roofs strategically in regard to local demands? To answer this question the balance of costs and benefits of green roofs is divided into a public and an individual part. Both balances use a strengths, weaknesses, opportunities and threats framework to determine the chance of success for the application of green roofs, considering that the balance for green roofs on an individual scale influences the balance on a public scale. The outcome of this combined analyses in the conclusion verifies that a responsible policy and a local approach towards green roofs is necessary to prepare the city sufficiently for future climate changes. http://dx.doi.org/10.13044/j.sdewes.d6.0225

Highlights

Many municipalities have become aware of their vulnerability towards future climate challenges
SWOT analysis made by Brudermann and Sangkakool [11] for green roofs in general which is shown in Table 1, is divided into two different spatial scales, one SWOT analysis for the private space and one for the public space
A general SWOT analysis made by Brudermann and Sangkakool, in which public and private factors are combined, shows different results if it is split into two different SWOT frameworks for each spatial scale

Summary

Introduction

Many municipalities have become aware of their vulnerability towards future climate challenges. Due to climate change rain showers will be heavier and occur more frequently, and the phenomena ‘Urban Heat Island’ can become a future challenge [1]. To prevent these climate changes becoming serious hazards Carbon dioxide (CO2) emissions must be reduced, and climate mitigations and adaptation measures must be implemented in urban planning [1, 2]. 21-25% [4] of hardened and unused urban area can be found on van der Meulen, S.

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