671

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Coordinating Lead Authors:

Oswaldo Lucon (Brazil), Diana Ürge-Vorsatz (Hungary)

Lead Authors:

Azni Zain Ahmed (Malaysia), Hashem Akbari (USA / Canada), Paolo Bertoldi (Italy), Luisa F. Cabeza

(Spain), Nicholas Eyre (UK), Ashok Gadgil (India / USA) , L. D. Danny Harvey (Canada), Yi Jiang

(China), Enoch Liphoto (South Africa), Sevastianos Mirasgedis (Greece), Shuzo Murakami (Japan),

Jyoti Parikh (India), Christopher Pyke (USA), Maria Virginia Vilariño (Argentina)

Contributing Authors:

Peter Graham (Australia / USA / France), Ksenia Petrichenko (Hungary), Jiyong Eom (Republic of

Korea), Agnes Kelemen (Hungary), Volker Krey (IIASA / Germany)

Review Editors:

Marilyn Brown (USA), Tamás Pálvölgyi (Hungary)

Chapter Science Assistants:

Fonbeyin Henry Abanda (UK), Katarina Korytarova (Slovakia)

This chapter should be cited as:

Lucon O., D. Ürge-Vorsatz, A. Zain Ahmed, H. Akbari, P. Bertoldi, L. F. Cabeza, N. Eyre, A. Gadgil, L. D. D. Harvey, Y. Jiang, E.

Liphoto, S. Mirasgedis, S. Murakami, J. Parikh, C. Pyke, and M. V. Vilariño, 2014: Buildings. In: Climate Change 2014: Mitiga-

tion of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel

on Climate Change [Edenhofer, O., R. Pichs-Madruga, Y. Sokona, E. Farahani, S. Kadner, K. Seyboth, A. Adler, I. Baum, S.

Brunner, P. Eickemeier, B. Kriemann, J. Savolainen, S. Schlömer, C. von Stechow, T. Zwickel and J.C. Minx (eds.)]. Cambridge

University Press, Cambridge, United Kingdom and New York, NY, USA.

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Contents

Executive Summary � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 675

9�1 Introduction � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 677

9�2 New developments in emission trends and drivers � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 678

9�2�1 Energy and GHG emissions from buildings

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 678

9�2�2 Trends and drivers of thermal energy uses in buildings

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 681

9�2�3 Trends and drivers in energy consumption of appliances in buildings

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 683

9�3 Mitigation technology options and practices, behavioural aspects � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 686

9�3�1 Key points from AR4

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 686

9�3�2 Technological developments since AR4

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 686

9�3�3 Exemplary new buildings

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 687

9.3.3.1 Energy intensity of new high-performance buildings

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 687

9.3.3.2 Monitoring and commissioning of new and existing buildings

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 688

9.3.3.3 Zero energy / carbon and energy plus buildings

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 689

9.3.3.4 Incremental cost of low-energy buildings

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 689

9�3�4 Retroﬁts of existing buildings

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 690

9.3.4.1 Energy savings

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 690

9.3.4.2 Incremental cost

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 690

9�3�5 Appliances, consumer electronics, ofﬁce equipment, and lighting

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 690

9�3�6 Halocarbons

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 692

9�3�7 Avoiding mechanical heating, cooling, and ventilation systems

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 693

9�3�8 Uses of biomass

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 693

9�3�9 Embodied energy and building materials lifecycle

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 694

9�3�10 Behavioural and lifestyle impacts

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 694

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9�4 Infrastructure and systemic perspectives� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 696

9�4�1 Urban form and energy supply infrastructure

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 696

9.4.1.1 District heating and cooling networks

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 696

9.4.1.2 Electricity infrastructure interactions

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 697

9.4.1.3 Thermal energy storage

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 697

9�4�2 Path dependencies and lock-in

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 697

9�5 Climate change feedback and interaction with adaptation � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 697

9�6 Costs and potentials � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 699

9�6�1 Summary of literature on aggregated mitigation potentials by key identity

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 699

9�6�2 Overview of option-speciﬁc costs and potentials

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 702

9.6.2.1 Costs of very high performance new construction

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 702

9.6.2.2 Costs of deep retroﬁts

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 704

9�6�3 Assessment of key factors inﬂuencing robustness and sensitivity of costs and potentials

� � � � � � � � � � � � � � � 704

9�7 Co-beneﬁts, risks and spillovers � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 705

9�7�1 Overview

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 705

9�7�2 Socio-economic effects

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 705

9.7.2.1 Impacts on employment

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 705

9.7.2.2 Energy security

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 707

9.7.2.3 Beneﬁts related to workplace productivity

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 707

9.7.2.4 Rebound effects

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 707

9.7.2.5 Fuel poverty alleviation

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 708

9�7�3 Environmental and health effects

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 708

9.7.3.1 Health co-beneﬁts due to improved indoor conditions

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 708

9.7.3.2 Health and environmental co-beneﬁts due to reduced outdoor air pollution

. . . . . . . . . . . . . . . . . . . . . . . . 709

9.7.3.3 Other environmental beneﬁts

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 709

9�8 Barriers and opportunities � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 709

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9�9 Sectoral implication of transformation pathways and sustainable development � � � � � � � � � � � � � � � � 710

9�9�1 Introduction

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 710

9�9�2 Overview of building sector energy projections

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 710

9�9�3 Key mitigation strategies as highlighted by the pathway analysis

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 712

9�9�4 Summary and general observations of global building ﬁnal energy use

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 714

9�10 Sectoral policies � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 715

9�10�1 Policies for energy efﬁciency in buildings

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 715

9.10.1.1 Policy packages

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 718

9.10.1.2 A holistic approach

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 718

9�10�2 Emerging policy instruments in buildings

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 719

9.10.2.1 New developments in building codes (ordinance, regulation, or by-laws)

. . . . . . . . . . . . . . . . . . . . . . . . . . . 719

9.10.2.2 Energy efﬁciency obligation schemes and ‘white’ certiﬁcates

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 719

9�10�3 Financing opportunities

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 720

9.10.3.1 New ﬁnancing schemes for deep retroﬁts

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 720

9.10.3.2 Opportunities in ﬁnancing for green buildings

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 720

9�10�4 Policies in developing countries

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 721

9�11 Gaps in knowledge and data � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 721

9�12 Frequently Asked Questions � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 722

References � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 723

675675

Buildings

Chapter 9

Executive Summary

In 2010 buildings accounted for 32 % of total global ﬁnal

energy use, 19 % of energy-related GHG emissions (including

electricity-related), approximately one-third of black carbon

emissions, and an eighth to a third of F-gases (medium evidence,

medium agreement). This energy use and related emissions may dou-

ble or potentially even triple by mid-century due to several key trends.

A very important trend is the increased access for billions of people

in developing countries to adequate housing, electricity, and improved

cooking facilities. The ways in which these energy-related needs will be

provided will signiﬁcantly determine trends in building energy use and

related emissions. In addition, population growth, migration to cities,

household size changes, and increasing levels of wealth and lifestyle

changes globally will all contribute to signiﬁcant increases in building

energy use. The substantial new construction that is taking place in

developing countries represents both a signiﬁcant risk and opportunity

from a mitigation perspective. [Sections 9.1, 9.2]

In contrast to a doubling or tripling, ﬁnal energy use may stay

constant or even decline by mid-century, as compared to today’s

levels, if today’s cost-effective best practices and technologies

are broadly diffused (robust evidence, high agreement). The technol-

ogy solutions to realize this potential exist and are well demonstrated.

Recent advances in technology, design practices and know-how, cou-

pled with behavioural changes, can achieve a two to ten-fold reduction

in energy requirements of individual new buildings and a two to four-

fold reduction for individual existing buildings largely cost-effectively or

sometimes even at net negative costs. New improved energy efﬁciency

technologies have been developed as existing energy efﬁciency oppor-

tunities have been taken up, so that the potential for cost-effective

energy efﬁciency improvement has not been diminishing. Recent devel-

opments in technology and know-how enable construction and retroﬁt

of very low- and zero-energy buildings, often at little marginal invest-

ment cost, typically paying back well within the building lifetime (robust

evidence, high agreement). In existing buildings 50 – 90 % energy sav-

ings have been achieved throughout the world through deep retroﬁts

(medium evidence, high agreement). Energy efﬁcient appliances, light-

ing, information communication (ICT), and media technologies can

reduce the substantial increases in electricity use that are expected due

to the proliferation of equipment types used and their increased owner-

ship and use (robust evidence, high agreement). [9.2, 9.3]

Strong barriers hinder the market uptake of these cost-effec-

tive opportunities, and large potentials will remain untapped

without adequate policies (robust evidence, high agreement). These

barriers include imperfect information, split incentives, lack of aware-

ness, transaction costs, inadequate access to ﬁnancing, and industry

fragmentation. In developing countries, corruption, inadequate service

levels, subsidized energy prices, and high discount rates are additional

barriers. Market forces alone are not likely to achieve the necessary

transformation without external stimuli. Policy intervention addressing

all stages of the building and appliance lifecycle and use, plus new

business and ﬁnancial models are essential. [9.8, 9.10]

There is a broad portfolio of effective policy instruments avail-

able to remove these barriers, some of them being implemented

also in developing countries, thus saving emissions at large

negative costs (robust evidence, high agreement). Overall, the his-

tory of energy efﬁciency programmes in buildings shows that 25 – 30 %

efﬁciency improvements have been available at costs substantially

lower than marginal supply. Dynamic developments in building-related

policies in some developed countries have demonstrated the effec-

tiveness of such instruments, as total building energy use has started

to decrease while accommodating continued economic, and in some

cases, population growth. Building codes and appliance standards with

strong energy efﬁciency requirements that are well enforced, tightened

over time, and made appropriate to local climate and other conditions

have been among the most environmentally and cost-effective. Net

zero energy buildings are technically demonstrated, but may not always

be the most cost- and environmentally effective solutions. Experience

shows that pricing is less effective than programmes and regulation

(medium evidence, medium agreement). Financing instruments, poli-

cies, and other opportunities are available to improve energy efﬁciency

in buildings, but the results obtained to date are still insufﬁcient to

deliver the full potential (medium evidence, medium agreement). Com-

bined and enhanced, these approaches could provide signiﬁcant further

improvements in terms of both enhanced energy access and energy

efﬁciency. Delivering low-carbon options raises major challenges for

data, research, education, capacity building, and training. [9.10]

Due to the very long lifespans of buildings and retroﬁts there is

a very signiﬁcant lock-in risk pointing to the urgency of ambi-

tious and immediate measures (robust evidence, medium agree-

ment). Even if the most ambitious of currently planned policies are

implemented, approximately 80 % of 2005 energy use in buildings

globally will be ‘locked in’ by 2050 for decades, compared to a sce-

nario where today’s best practice buildings become the standard in

new building construction and existing building retroﬁt. As a result,

the urgent adoption of state-of-the-art performance standards, in both

new and retroﬁt buildings, avoids locking-in carbon intensive options

for several decades. [9.4]

In addition to technologies and architecture, behaviour, life-

style, and culture have a major effect on buildings’ energy use;

three- to ﬁve-fold difference in energy use has been shown for

provision of similar building-related energy service levels (limited

evidence, high agreement). In developed countries, evidence indicates

that behaviours informed by awareness of energy and climate issues can

reduce demand by up to 20 % in the short term and 50 % of present

levels by 2050. Alternative development pathways exist that can moder-

ate the growth of energy use in developing countries through the pro-

vision of high levels of building services at much lower energy inputs,

incorporating certain elements of traditional lifestyles and architecture,

and can avoid such trends. In developed countries, the concept of ‘suf-

676676

Buildings

Chapter 9

ﬁciency’ has also been emerging, going beyond pure ‘efﬁciency’. Reduc-

ing energy demand includes rationally meeting ﬂoor space needs. [9.3]

Beyond energy cost savings, most mitigation options in this

sector have other signiﬁcant and diverse co-beneﬁts (robust evi-

dence, high agreement). Taken together, the monetizable co-beneﬁts of

many energy efﬁciency measures alone often substantially exceed the

energy cost savings and possibly the climate beneﬁts (medium evidence,

medium agreement), with the non-monetizable beneﬁts often also

being signiﬁcant (robust evidence, high agreement). These beneﬁts offer

attractive entry points for action into policy-making, even in countries or

jurisdictions where ﬁnancial resources for mitigation are limited (robust

evidence, high agreement). These entry points include, but are not lim-

ited to, energy security; lower need for energy subsidies; health (due to

Table 9�1 | Summary of chapter’s main ﬁndings organized by major mitigation strategies (identities)

Carbon efﬁciency Energy efﬁciency of technology System / (infrastructure) efﬁciency

Service demand

reduction

Mitigation

options

Building integrated RES

(BiRES, BiPV). Fuel switching

to low-carbon fuels such as

electricity (9.4.1.2). Use of

natural refrigerants to reduce

halocarbon emissions (9.3.6).

Advanced biomass stoves (9.3.8).

High-performance building envelope (HPE).

Efﬁcient appliances (EA). Efﬁcient lighting (EL).

Efﬁcient Heating, Ventilation, and Air-Conditioning

systems (eHVAC). Building automation and control

systems (BACS). Daylighting, heat pumps, indirect

evaporative cooling to replace chillers in dry

climates, advances in digital building automation

and control systems, smart meters and grids (9.3.2).

Solar-powered desiccant dehumidiﬁcation.

Passive House standard (PH). Nearly / net zero and

energy plus energy buildings (NZEB) (9.3.3.3).

Integrated Design Process (IDP). Urban planning

(UP), (9.4.1). District heating / cooling (DH / C).

Commissioning (C). Advanced building control

systems (9.3.3.2). High efﬁciency distributed

energy systems, co-generation, trigeneration,

load levelling, diurnal thermal storage,

advanced management (9.4.1.1). ‘Smart-grids’

(9.4.1.2). Utilization of waste heat (9.4.1.1)

Behavioural change

(BC). Lifestyle

change (LSC). Smart

metering (9.4.1.2)

Potential

reductions

of energy

use / emissions

(versus

baseline BAU)

Solar electricity generation

through buildings’ roof-top

photo voltaic (PV) installations:

energy savings – 15 to – 58 %

relative to BAU (Table 9.4)

– 9.5 % to – 68 % energy savings relative to

BAU (Table 9.4). Energy savings from advanced

appliances: Ovens: – 45 %; Microwave ovens:

– 75 %; Dishwashers: up to – 45 %; Clothes washers:

– 28 % (by 2030, globally); Clothes dryers: factor

of 2 reduction; Air-conditioners: – 50 to – 75 %;

Ceiling fans: – 50 to – 57 %; Ofﬁce computers/

monitors: – 40 %; Circulation pumps for hydronic

heating / cooling: – 40 % (by 2020, EU); Residential

water heaters: factor of 4 improvement (Table

9.3); Fuel savings: – 30 to – 60 %; Indoor air

pollution levels from advanced biomass stoves (as

compared to open ﬁres): – 80 to – 90 % (9.3.8).

– 30 to – 70 % CO2 of BAU. PH & NZEB (new

versus conventional building): – 83 % (residential

heating energy) and – 50 % (commercial heating &

cooling energy); Deep retroﬁts (DR): – 40 to – 80 %

(residential, Europe); IDP: up to – 70 % (ﬁnal energy

by 2050; Table 9.4); Potential global building ﬁnal

energy demand reduction: – 5 % to – 27 % (IAMs ),

– 14 % to – 75 % (bottom up models) (Fig. 9.21).

Energy savings by building type: (i) Detached

single-family homes: – 50 – 75 % (total energy use);

(ii) Multi-family housing: – 80 to – 90 % (space

heating requirements); (iii) Multi-family housing

in developing countries: – 30 % (cooling energy

use), – 60 % (heating energy); (iv) Commercial

buildings: – 25 % to – 50 % (total HVAC), – 30

to – 60 % (lighting retroﬁts) (9.3.4.1).

– 20 to – 40 % of

BAU. LSC about

– 40 % electricity

use (Table 9.4).

Cost-

effectiveness

– Retroﬁt of separate measures: CCE: 0.01 – 0.10

USD

2010

/ kWh (Fig. 9.13). Efﬁcient Appliances:

CCE: – 0.09 USD

2010

/ kWh / yr (9.3.4.2)

PH & NZEB (new, EU&USA): CCE: 0.2 – 0.7

USD

2010

/ kWh (Figure 9.11, 9.12); DR

(with energy savings of 60 – 75 %): CCE:

0.05 – 0.25 USD

2010

/ kWh (Fig. 9.13)

Co-beneﬁts

(CB),

adverse side

effects (AE)

CB: Energy security; lower need for energy subsidies; health and environmental beneﬁts

CB: Employment impact;

enhanced asset value of buildings;

energy / fuel poverty alleviation.

AE: Energy access / fuel poverty

CB: Employment; energy / fuel poverty alleviation;

improved productivity / competitiveness;

asset value of buildings; improved quality

of life. AE: rebound and lock-in effects

CB: Employment impact; improved productivity

and competitiveness; enhanced asset values of

buildings; improved quality of life. AE: Rebound

effect, lower lifecycle energy use of low-energy

buildings in comparison to the conventional (9.3.9)

Key barriers Suboptimal measures, subsidies

to conventional fuels

Transaction costs, access to ﬁnancing, principal

agent problems, fragmented market and

institutional structures, poor feedback

Energy and infrastructure lock-in (9.4.2),

path-dependency (9.4.2) fragmented

market and institutional structures,

poor enforcement of regulations

Imperfect information,

risk aversion, cognitive

and behavioural

patterns, lack of

awareness, poor

personnel qualiﬁcation

Key policies Carbon tax, feed-in tariffs

extended for small capacity; soft

loans for renewable technologies

Public procurement, appliance standards,

tax exemptions, soft loans

Building codes, preferential loans, subsidised

ﬁnancing schemes, ESCOs, EPCs, suppliers‘

obligations, white certiﬁcates, IDP into Urban

Planning, Importance of policy packages

rather than single instruments (9.10.1.2)

Awareness raising,

education, energy

audits, energy labelling,

building certiﬁcates

& ratings, energy or

carbon tax, personal

carbon allowance

677677

Buildings

Chapter 9

reduced indoor and outdoor air pollution as well as fuel poverty alle-

viation) and environmental beneﬁts; productivity and net employment

gains; alleviated energy and fuel poverties as well as reduced energy

expenditures; increased value for building infrastructure; improved

comfort and services (medium evidence, high agreement). However,

these are rarely internalized by policies, while a number of tools and

approaches are available to quantify and monetize co-beneﬁts that can

help this integration (medium evidence, medium agreement). [9.7]

In summary, buildings represent a critical piece of a low-carbon

future and a global challenge for integration with sustainable

development (robust evidence, high agreement). Buildings embody

the biggest unmet need for basic energy services, especially in develop-

ing countries, while much existing energy use in buildings in developed

countries is very wasteful and inefﬁcient. Existing and future buildings

will determine a large proportion of global energy demand. Current

trends indicate the potential for massive increases in energy demand

and associated emissions. However, this chapter shows that build-

ings offer immediately available, highly cost-effective opportunities

to reduce (growth in) energy demand, while contributing to meeting

other key sustainable development goals including poverty alleviation,

energy security, and improved employment. This potential is more fully

represented in sectoral models than in many integrated models, as

the latter do not represent any or all of the options to cost-effectively

reduce building energy use. Realizing these opportunities requires

aggressive and sustained policies and action to address every aspect

of the design, construction, and operation of buildings and their equip-

ment around the world. The signiﬁcant advances in building codes and

appliance standards in some jurisdictions over the last decade already

demonstrated that they were able to reverse total building energy use

trends in developed countries to its stagnation or reduction. However,

in order to reach ambitious climate goals, these standards need to be

substantially strengthened and adopted for further jurisdictions, build-

ing types, and vintages. [9.6, 9.9, 9.10] Table 9.1 summarizes some

main ﬁndings of the chapter by key mitigation strategy.

9.1 Introduction

This chapter aims to update the knowledge on the building sector

since the Intergovernmental Panel on Climate Change (IPCC) Fourth

Assessment Report (AR4) from a mitigation perspective. Buildings and

activities in buildings are responsible for a signiﬁcant share of GHG

emissions, but they are also the key to mitigation strategies. In 2010,

the building sector accounted for approximately 117 Exajoules (EJ) or

32 % of global ﬁnal energy consumption and 19 % of energy-related

emissions; and 51 % of global electricity consumption. Buildings

contribute to a signiﬁcant amount of F-gas emissions , with large differ-

ences in reported ﬁgures due to differing accounting conventions, rang-

ing from around an eighth to a third of all such emissions (9.3.6). The

chapter argues that beyond a large emission role, mitigation opportuni-

ties in this sector are also signiﬁcant, often very cost-effective, and are

in many times associated with signiﬁcant co-beneﬁts that can exceed

the direct beneﬁts by orders of magnitude. The sector has signiﬁcant

mitigation potentials at low or even negative costs. Nevertheless, with-

out strong actions emissions are likely to grow considerably — and they

may even double by mid-century — due to several drivers. The chapter

points out that certain policies have proven to be very effective and

several new ones are emerging. As a result, building energy use trends

have been reversed to stagnation or even reduction in some jurisdic-

tions in recent years, despite the increases in afﬂuence and population.

The chapter uses a novel conceptual framework, in line with the gen-

eral analytical framework of the contribution of Working Group III

(WGIII) to the IPCC Fifth Assessment Report (AR5), which focuses on

identities as an organizing principle. This section describes the iden-

tity decomposition Chapter 9 chooses to apply for assessing the litera-

ture, resting on the general identity framework described in Chapter 6.

Building-related emissions and mitigation strategies have been decom-

posed by different identity logics. Commonly used decompositions use

factors such as CO

intensity, energy intensity, structural changes, and

economic activity (Isaac and Van Vuuren, 2009; Zhang etal., 2009), as

well as the IPAT (Income-Population-Afﬂuence-Technology) approach

(MacKellar etal., 1995; O’ Mahony etal., 2012). In this assessment, the

review focuses on the main decomposition logic described in Chapter

6, adopted and further decomposed into four identities key to driving

building sector emissions:

C O

= CI·TEI·SEI·A

where CO

is the emissions from the building sector; (Identity 1) CI is the

carbon intensity; (Identity 2) TEI is the technological energy intensity;

(Identity 3) SEI is the structural\systemic energy intensity and (Identity

4) A is the activity. For a more precise interpretation of the factors, the

following conceptual equation demonstrates the different components:

C O

UsefulE

pop

·pop ≈ CI·TEI·SEI·

pop

·pop

in which FE is the ﬁnal energy; UsefulE is the useful energy for a par-

ticular energy service (ES), as occurring in the energy conversion chain,

and pop is population. Instead of population in the residential sector

the Gross Domestic Product (GDP) is often used as the main decompo-

sition factor for commercial building emissions. Because ES is often dif-

ﬁcult to rigorously deﬁne and measure, and UsefulE and ES are either

difﬁcult to measure or little data are available, this chapter does not

attempt a systematic quantitative decomposition, but rather focuses

on the main strategic categories for mitigation based on the relation-

ship established in the previous equation:

C O

mitigation ≈ C

Eff

· T

Eff

·S I

Eff

·DR

whereby (1) C

Eff

, or carbon efﬁciency, entails fuel switch to low-carbon

fuels, building-integrated renewable energy sources, and other supply-

side decarbonization; (2) T

Eff

, or technological efﬁciency, focuses on

678678

Buildings

Chapter 9

the efﬁciency improvement of individual energy-using devices; (3)

Eff

, or systemic / infrastructural efﬁciency, encompass all efﬁciency

improvements whereby several energy-using devices are involved, i. e.,

systemic efﬁciency gains are made, or energy use reductions due to

architectural, infrastructural, and systemic measures; and ﬁnally (4) DR,

or demand reduction, composes all measures that are beyond tech-

nological efﬁciency and decarbonization measures, such as impacts

on ﬂoor space, service levels, behaviour, lifestyle, use, and penetration

of different appliances. The four main emission drivers and mitigation

strategies can be further decomposed into more distinct sub-strategies,

but due to the limited space in this report and in order to maintain

a structure that supports convenient comparison between different

sectoral chapters, we focus on these four main identities during the

assessment of literature in this chapter and use this decomposition as

the main organizing / conceptual framework.

9.2 New developments

in emission trends

and drivers

9�2�1 Energy and GHG emissions from

buildings

Greenhouse gas (GHG) emissions from the building sector have more

than doubled since 1970 to reach 9.18 GtCO

eq in 2010 (Figure 9.1),

representing 25 % of total emissions without the Agriculture, Forestry,

and Land Use (AFOLU) sector; and 19 % of all global 2010 GHG emis-

sions (IEA, 2012a; JRC / PBL, 2013; see Annex II.8). Furthermore, they

account for approximately one-third of black carbon emissions (GEA,

2012), and one-eighth to one-third of F-gas emissions, depending par-

tially on the accounting convention used (UNEP, 2011a; EEA, 2013; US

EPA, 2013; JRC / PBL, 2013; IEA, 2012a; see Annex II.8).

Most of GHG emissions (6.02 Gt) are indirect CO

emissions from elec-

tricity use in buildings, and these have shown dynamic growth in the

studied period in contrast to direct emissions, which have roughly stag-

nated during these four decades (Figure 9.1). For instance, residential

indirect emissions quintupled and commercial emissions quadrupled.

Figure 9.2 shows the regional trends in building-related GHG emissions.

Organisation for Economic Co-operation Development (OECD) coun-

tries have the highest emissions, but the growth in this region between

1970 and 2010 was moderate. For least developed countries, the emis-

sions are low with little growth. The largest growth has taken place in

Asia where emissions in 1970 were similar to those in other developing

regions, but by today they are closing in on those of OECD countries.

Due to the high share of indirect emissions in the sector, actual emission

values very strongly depend on emission factors — mainly that of electric-

ity production — that are beyond the scope of this chapter. Therefore, the

rest of this chapter focuses on ﬁnal energy use (rather than emissions)

that is determined largely by activities and measures within the sector.

In 2010 buildings accounted for 32 % (24 % for residential and 8 % for

commercial) of total global ﬁnal energy use (IEA, 2013), or 32.4 PWh,

being one of the largest end-use sectors worldwide. Space heating rep-

Figure 9�1 | Direct and indirect emissions (from electricity and heat production) in the building subsectors (IEA, 2012a; JRC / PBL, 2013; see Annex II.9).

Commercial

Residential

O Emissions (Indirect)

Others

Commercial

Residential

Direct

Indirect

GHG Emissions [GtCO

eq/yr]

0.48

1.32

2.52

Total Direct and Indirect 3.8

(Total Direct 2.5)

Total Direct and Indirect 6.3

(Total Direct 2.9)

Total Direct

and Indirect 9.2

(Total Direct 3.2)

0.80

2.11

3.50

0.81

0.77

0.84

1.72

2.13

2.18

0.01

0.01 0.13

1970 1975 1980 1985 1990 1995 2000 2005

2010

Figure 9�2 | Regional direct and indirect emissions in the building subsectors (IEA, 2012a; JRC / PBL, 2013; see Annex II.9).

GHG Emissions [GtCO

eq/yr]

1970 1980 1990 2000 2010

GHG Emissions [GtCO

eq/yr]

GHG Emissions [GtCO

eq/yr]

GHG Emissions [GtCO

eq/yr]

Non-OECD Asia

Total Direct + Indirect: 2.6

Total Direct: 0.86

(2010)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

OECD-1990 Countries

Total Direct + Indirect: 4.3

Total Direct: 1.5

(2010)

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.0

0.2

0.4

0.6

0.8

1.0

Africa and Middle East

Total Direct + Indirect: 0.92

Total Direct: 0.28

(2010)

0.0

0.3

0.6

0.9

1.2

1.5

GHG Emissions [GtCO

eq/yr]

Economies in Transition

Total Direct + Indirect: 1.1

Total Direct: 0.39

(2010)

Latin America and Caribbean

Total Direct + Indirect: 0.28

Total Direct: 0.11

(2010)

Commercial

Indirect

Residential

Commercial

Direct

Residential

O Emissions (Indirect)

Others

679679