Nature Based Strategies for Urban and Building Sustainability

Gabriel Perez, Katia Perini

• Publisher: Butterworth-Heinemann
• Year: 2018
• Print ISBN: 9780128121504
• eBook ISBN: 9780128123249
• Topic: Technology & Engineering
• Subtopic: Civil Engineering
• Index: Technology & Engineering

Nature Based Strategies for Urban and Building Sustainability reviews the current state-of-the-art on the topic. In the introduction, the editors review the fundamental concepts of nature elements in the built environment, along with the strategies that are necessary for their inclusion in buildings and cities. Part One describes strategies for the urban environment, discussing urban ecosystems and ecosystem services, while Part Two covers strategies and technologies, including vertical greening systems, green roofs and green streets. Part Three covers the quantitative benefits, results, and issues and challenges, including energy performances and outdoor comfort, air quality improvement, acoustic performance, water management and biodiversity.- Provides an overview of the different strategies available to integrate nature in the built environment- Presents the current state of technology concerning systems and methodologies on how to incorporate nature in buildings and cities- Features the latest research results on operation and ecosystem services- Covers both established and new designs, including those still in the experimental stage

Section III

Nature Based Strategies: Benefits and Challenges

Outline

• Chapter 3.1 Vertical Greening Systems to Enhance the Thermal Performance of Buildings and Outdoor Comfort
• Chapter 3.2 Green Roofs to Enhance the Thermal Performance of Buildings and Outdoor Comfort
• Chapter 3.3 Green Streets to Enhance Outdoor Comfort
• Chapter 3.4 Vertical Greening Systems for Pollutants Reduction
• Chapter 3.5 Green Roofs for Pollutants’ Reduction
• Chapter 3.6 Green Streets for Pollutants Reduction
• Chapter 3.7 Vertical Greening Systems for Acoustic Insulation and Noise Reduction
• Chapter 3.8 Green Roofs for Acoustic Insulation and Noise Reduction
• Chapter 3.9 Green Streets for Noise Reduction
• Chapter 3.10 Vertical Greening Systems to Improve Water Management
• Chapter 3.11 Green Roofs to Improve Water Management
• Chapter 3.12 Green Streets to Improve Water Management
• Chapter 3.13 Vertical Greening Systems as Habitat for Biodiversity
• Chapter 3.14 Green Roofs as Habitats for Biodiversity
• Chapter 3.15 Green Streets as Habitat for Biodiversity

Chapter 3.1

Vertical Greening Systems to Enhance the Thermal Performance of Buildings and Outdoor Comfort

Gabriel Pérez, Julià Coma and Luisa F. Cabeza

Abstract

This chapter provides an overview to the ability of vertical greening systems to provide passive energy savings at building scale and to reduce the urban heat island effect in the built environment. The main influencing aspects for energy performances and outdoor comfort, i.e., the differences between the current constructive systems (basically green facades and green walls), the climate and plant species (climber plants vs shrubs and herbaceous, or perennial vs deciduous), and the operating methods (shade effect, cooling effect, insulation effect, wind barrier effect) will be analyzed. Moreover, a short review throughout the main promising research findings on the topic will be presented to finish with some suggestions for further research.

Keywords

Vertical greening system; green wall; green facade; energy savings; passive system; building

Chapter Outline

• Introduction 99
• Main Influencing Aspects 100
  • Differences Between Construction Systems 100
  • The Climate Influence 102
  • Plant Species Influence 102
• Operating Methods 103
• Main Research Findings 103
• Conclusion 107
• Acknowledgments 107
• References 107

Introduction

Recently, the concept of urban green infrastructure has been defined by the European Commission-Environment (2012) as a set of man-made elements that provide multiple ecosystem services both at building and urban scale. Among these functions, the building energy savings as well as the reduction of ambient temperatures and urban heat island (UHI) effect stand out. Some of the most innovative and interesting construction systems for this purpose are the vertical greening systems (VGS).

Since the vertical surface available in a building is much larger than the horizontal, especially in high rise buildings, it seems obvious that the potential of VGS in providing these services will also be proportionately higher. In view of these opportunities in the last years, a set of rigorous research studies have reviewed the use of VGS as a passive tool for energy savings, at building scale, as well as for the reduction of the UHI effect at city scale (Pérez et al., 2014).

In this chapter, the main influencing aspects for this purpose, which are the differences between the current construction systems, the climate and plant species influence, and the operating methods, will be analyzed. Moreover, a short review throughout the main research findings on the topic will be presented to finish with some suggestions for further research in the conclusions.

Main Influencing Aspects

Differences Between Construction Systems

Over the years, different VGS construction systems have been developed, in terms of materials and layers that make up the system, in the used support elements, the plants species as well as the maintenance requirements (extensive or intensive), etc. (Fig. 1). According to Pérez et al. (2011), these differences can have a big influence on the ecosystem services provided by each vertical greening system, e.g., energy savings or UHI reduction that must be taken into consideration already from the design phase. Table 1 summarizes the main VGS constructive systems, their layers and the level of maintenance (water and nutrients) (Pérez et al., 2011), and the great differences between systems, which results on different thermal behavior can be observed.

Figure 1 Examples of different vertical greening systems. Green facades (traditional and double-skin) and green walls.

Table 1

Main Vertical Greening Constructive Systems and Their Layers Composition

VGS System		Layer				Level of Maintenance
		Support Structure	Air Gap	Substrate	Plants
Green façade	Traditional	No	No	No	Climber plants	Extensive
	Double-skin	Very light, steel wires or mesh	Yes, usually open	No	Climber plants	Extensive
	Perimeter flowerpots	Flowerpots	Yes, usually open	Only in the pots	Climber and hanging shrubs	Intensive
Green wall	Geotextile	Geotextile felts	No	No	Shrubs and hanging shrubs	Intensive
	Modular panels	Heavy and strong, anchored to the facade wall	Yes, open or closed	Yes, inside the modules	Shrubs	Intensive

In order to deal with the dispersion on designs, and with the aim to compare research studies relating to the thermal performance of these systems; in Pérez et al. (2014) the building external wall surface temperature reduction (°C) due to the effect of the VGS was established as the most relevant parameter for the research studies comparison, because it is the first and most direct effect arising from the presence of sunscreen. In addition, neither the heat fluxes through the wall nor the interior surface wall temperature are comparable due to the differences between constructive systems of the facade building wall between case studies or research studies.

The Climate Influence

When the passive energy saving potential of vertical vegetation systems for buildings is the aim, the big influence of climate conditions over their operation must be considered. Weather not only affects directly on the thermal performance of the building but also on specific aspects relating to plants such as their growth (foliage density, plant height, etc.) and their physiological responses (transpiration, position of leaves, etc.), and consequently over the thermal behavior of the whole system. In this regard, the most influential climatic parameters will be solar radiation, temperatures and relative humidity, rainfall, and finally the wind.

This fact is very important for two main reasons. On one hand, it must take it into account in the most suitable system choice during the design phase so that it fulfills the local climatic constraints. On the other hand, from research’s point of view, these aspects should be taken into account when comparing research results. Pérez et al. (2014) suggested the use of Köppen classification in order to unify criteria and to properly compare research results relating to the VGS as a passive tool for energy savings, because it is based on the annual and monthly temperature and precipitation averages which are the most influential parameters for vegetation development.

In this study it was found that there is still a lack of research regarding the use of VGS as a tool for passive energy saving in many climatic zones of the world. Specifically, a lack of studies in areas of the world that receive more radiation is observed and therefore where these systems could be more effective is due to the shade effect.

Plant Species Influence

Another aspect to consider in VGS (when used as passive energy savings systems) is the plant species used because each constructive system uses different types of pl...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• List of Contributors
• Introduction
• Section I: Nature Based Strategies for Urban Environment
• Section II: Nature Based Strategies and Technologies
• Section III: Nature Based Strategies: Benefits and Challenges
• Section IV: Nature Based Strategies: Social, Economic and Environmental Sustainability
• Summary
• Index