Eco-efficient Materials for Mitigating Building Cooling Needs

Design, Properties and Applications

F. Pacheco-Torgal, Joao Labrincha, Luisa F. Cabeza, Claes-Göran Granqvist, F. Pacheco-Torgal, Joao Labrincha, Luisa F. Cabeza, Claes Goeran Granqvist, Claes-Göran Granqvist

• Publisher: Woodhead Publishing
• Year: 2015
• ISBN:
  9781782424017
• Topic: Technology & Engineering
• Subtopic: Civil Engineering
• Index: Technology & Engineering

Climate change is one of the most important environmental problems faced by Planet Earth. The majority of CO 2 emissions come from burning fossil fuels for energy production and improvements in energy efficiency shows the greatest potential for any single strategy to abate global greenhouse gas (GHG) emissions from the energy sector. Energy related emissions account for almost 80% of the EU's total greenhouse gas emissions. The building sector is the largest energy user responsible for about 40% of the EU's total final energy consumption. In Europe the number of installed air conditioning systems has increased 500% over the last 20 years, but in that same period energy cooling needs have increased more than 20 times. The increase in energy cooling needs relates to the current higher living and working standards. In urban environments with low outdoor air quality (the general case) this means that in summer-time one cannot count on natural ventilation to reduce cooling needs. Do not forget the synergistic effect between heat waves and air pollution which means that outdoor air quality is worse in the summer aggravating cooling needs. Over the next few years this phenomenon will become much worse because more people will live in cities, more than 2 billion by 2050 and global warming will aggravate cooling needs.

• An overview of materials to lessen the impact of urban heat islands
• Excellent coverage of building materials to reduce air condtioning needs
• Innovative products discussed such as Thermo and Electrochromic materials

1

Introduction to eco-efficient materials to mitigate building cooling needs

F. Pacheco-Torgal C-TAC Research Centre, University of Minho, Guimarães, Portugal

Abstract

Climate change is a worrying problem of unprecedented magnitude originated by greenhouse gas emissions. It encompasses increased mean temperature and heat waves that are responsible for aggravating urban heat island (UHI) effects. This is not only responsible for an escalation of health problems and human deaths, but it also leads to an increase of building cooling needs. This chapter reviews aspects of climate change, including UHIs. Attention is dedicated to adaptation and mitigation related issues, especially to the greening of the building envelope. An outline of the book is included.

Keywords

Climate change

Heat waves

Urban heat island

Adaptation to climate change

Building cooling needs

1.1 Climate change and urban heat islands (UHIs)

Climate change is one of the most important environmental problems on the planet (Garcia et al., 2014; IPCC, 2007; Rockström et al., 2009; Schellnhuber, 2008).

This is due to the increase of carbon dioxide (CO_2eq) in the atmosphere, for which the built environment is a significant contributor, with around one-third of global carbon dioxide emissions. In the early eighteenth century, the concentration level of atmospheric CO_2eq was 280 parts per million (ppm). At present it is 450 ppm (VijayaVenkataRaman et al., 2012).

Keeping the current level of emissions (which is unlikely given the high economic growth of less developed countries, with consequent increases in emission rates) will imply a dramatic increase in CO_2eq concentration to as much as 731 ppm in the year 2130, leading to a 3.7 °C global warming above pre-industrial temperatures (Valero et al., 2011).

As temperature increases, vector-borne illnesses, which rely upon organisms such as mosquitoes (Aedes aegypti, Aedes albopictus, Aedes japonicus) and other insects that have an active role in the transmission of a pathogen, have been projected to increase both in geographic reach as well as severity (IPCC, 2012; McMichael et al., 2006). Even northern latitudes in Europe will be reached (Githeko et al., 2000). West Nile fever is one that worries Europe (Hubalek and Halouzka, 1999; Sambri et al., 2013). The European Centre for Disease Control (ECDC, 2013) has reported several cases of West Nile fever in Europe and neighboring countries.

In addition to increased mean temperatures, climate change is likely to be responsible for more frequent heat waves, such as the 2003 European heat wave that claimed the lives of more than several thousand people (Table 1.1).

Table 1.1

Excess mortality attributed to the 2003 heat wave in Europe

Location (date)	Excess mortality (% increase)
England and Wales (Aug 4–13)	2091 deaths (17%)
Italy (Jun 1–Aug 15)	3134 deaths (15%) in all Italian capitals
France (Aug 1–20)	14,802 deaths (60%)
Portugal (Aug)	1854 deaths (40%)
Spain (Jul–Aug)	4151 deaths (11%)
Switzerland (Jun–Sept)	975 deaths (6.9%)
Netherlands (Jun–Sept)	1400–2200 deaths (not reported)
Germany (Aug 1–24)	1410 deaths (not reported)

Haines et al. (2006).

Heat waves also are associated with nonfatal impacts such as heat stroke and heat exhaustion (IPCC, 2007). Heat waves have a much bigger health impact in cities than in surrounding suburban and rural areas because urban areas typically experience higher—and nocturnally sustained—temperatures due to the urban heat island (UHI) effect (Hulley, 2012; IPCC, 2007).

UHIs are originated by heat generated in urban environments that is entrapped by urban structures being aggravated by greenhouse gases and the lack of green spaces. Dark-colored surfaces (like dark asphalt pavements) have low reflecting power (or low albedo characteristics). As a consequence they absorb more energy, and in summer can reach almost 60 °C, thus contributing to higher UHI effects. Some authors reported a 10 °C temperature increase in the city of Athens due to the UHI effect (Santamouris et al., 2001), and a 8.8 °C increase in London (Kolokotroni and Giridharan, 2008), while a recent three-year investigation in the city of Padua reported an increase up to 6 °C (Busato et al., 2014). According to Li et al. (2014), the waste heat discharged by air conditioners alone was responsible for an increase of almost 2 °C of Beijing’s average air temperature in 2005. It’s worth noting that since 2005, the population of Beijing has increased from 15 to 21 million people, and by 2020 it will reach 25 million.

According to Santamouris (2013), a renowned expert on energy and solar technologies, UHI is probably the most documented phenomenon of climate change for various geographic areas of the planet. As a result of the urbanization and industrialization of human civilization, UHI has become one of the major problems of the twenty-first century (Rizwan et al., 2008). A recent work published in Nature/Letter (Zhao et al., 2014) also addresses this position. If no adaptation measures are taken, the social cost of climate change can be significant. This could mean an additional 26,000 deaths per year from heat waves (and their synergic effects with air pollution) by the 2020s, rising to 89,000 deaths per year by the 2050s and 127,000 deaths per year by the 2080s. These predictions do not even take UHI effects into account.

1.2 Adaptation to climate change and mitigation of UHI effects and of building cooling needs

Even if all the greenhouse gas emissions suddenly ceased, the amount already in the atmosphere would remain there for the next 100 years (Clayton, 2001). In other words, the rise in the sea level, ocean acidification, and extreme atmospheric events will continue.

Hansen et al. (2013) are even more pessimistic, believing that the climate has already been changed in an irreversible manner. This means that adaptation to climate change as well as mitigation of greenhouse gas emissions should be a priority to the built environment (Georgescu et al., 2014; Kwok and Rajkovich, 2010; Olazabal et al., 2014; Reckien et al., 2014).

The rapid increase of river floods and excessive hot days for the next decades is very worrying (EEA, 2012).

That is why the words of the European Commissioner for Climate Action, Connie Hedegaard, on the launch of the EU Strategy on Adaptation to Climate Change in Brussels on 29 April 2013, make a lot of sense: “Investing now in adaptation will save lives and much greater costs later.”

According to the COM 216 (2013), “The minimum cost of not adapting to climate change in the EU is estimated to range from €100 billion a year in 2020 to €250 billion in 2050.” On 25 June 2014, a study (Ciscar-Martinez et al., 2014) on the effects of climate change in Europe was released, stating that if no further action is taken, climate damages in the EU could amount to at least €190 billion and heat-related deaths could reach about 200,000.

The future of the built environment will therefore involve the adaptation towards climate-resilience. Unfortunately, a detailed study that analyzed the climate change adaptation and mitigation plans of more than 200 large and medium-sized cities across 11 European countries concluded that 35% of European cities studied have no dedicated mitigation plan, and 72% have no adaptation plan (Reckien et al., 2014).

Greening of the building envelope by using vegetation is a growing trend both in the adaptation to climate change and in the mitigation of UHIs. Green roofs date back to the fifth century in Babylon, when hanging gardens were implemented, and to ancient Mesopotamia, where they were used in the ziggurats (Berardi et al., 2014).

Though not an innovative technique (first attempts to quantify energy benefits occurred in the 1960s), the greening of the building envelope by using vegetation is a growing trend, and some countries show a remarkable acceptation of such “technology.” For instance, Germany has almost 100 million m² of green roofs, and the state of Singapore intends to target 0.75 ha of green roofs per 1000 inhabitants (Pacheco-Torgal, 2014).

Green infrastructure is important enough to merit special attention in EU policy. On 6 May 2013, the EU adopted a new strategy for encouraging the use of green infrastructure (IP 404, 2013). The European Commission planned to develop guidance to show how green infrastructures could be integrated into the implementation of these policies from 2014 to 2020 for several areas, including adaptation to climate change. The green building envelope is particularly important, as recent investigations show a strong correlation ...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• List of contributors
• Woodhead Publishing Series in Civil and Structural Engineering
• Foreword
• 1: Introduction to eco-efficient materials to mitigate building cooling needs
• Part One: Pavements for mitigating urban heat island effects
• Part Two: Facade materials for reducing cooling needs
• Part Three: Roofing materials for reducing building cooling needs
• Part Four: Phase-change materials (PCMs) and chromogenic smart materials for reducing building cooling needs
• Index