Mitigating CO₂ emissions from energy use in the world's buildings

Abstract

An overview of climate change mitigation opportunities in the world's buildings is presented, based on the key building-specific findings of the Fourth Assessment Report from the Intergovernmental Panel of Climate Change. Buildings and the building stock can play a major role in mitigating climate change in the short- to medium-term, since substantial reductions in CO₂ emissions from their energy use can be achieved over the coming years. A significant portion of these savings can be achieved in ways that reduce life cycle costs, thus providing reductions in CO₂ emissions that have a net negative cost. There are indications that the building stock has the highest share of negative- and low-cost greenhouse gas reduction potential among all sectors. Based on 80 collected national or regional studies estimating CO₂ mitigation potential in five continents, the global potential for CO₂ reductions through buildings is analysed and estimated. The co-benefits associated with the implementation of these measures are also substantial, helping policy-makers justify actions even in the absence of a strong climate commitment. Since the barriers to unlocking the high potentials in the residential and commercial sectors are especially strong, no single instrument can make a large impact. Instead, portfolios of targeted policies tailored to local conditions, combined with strong compliance and enforcement regimes, are needed.

Cet article présente une vue générale des possibilités d'atténuation du changement climatique dans le monde en ce qui concerne le secteur du bâtiment; il repose sur les résultats propres à ce secteur et exposés dans le Quatrième rapport d'évaluation du Groupe d'experts intergouvernemental sur l'évolution du climat (GIEC). Les bâtiments et les parcs de bâtiments peuvent jouer un rôle majeur dans l'atténuation du changement climatique à court et à moyen termes puisqu'au cours des années à venir on pourra réduire sensiblement les émissions de CO₂ issues de l'utilisation de l'énergie. Une partie non négligeable de ces économies peut être réalisée de façon à réduire les coûts des cycles de vie, ce qui permet d'obtenir des réductions des émissions de CO₂ ayant un coût négatif net. Certains signes indiquent que parmi tous les secteurs industriels, les parcs de bâtiments offrent la proportion la plus élevée de possibilités de réduction des gaz à effet de serre pour un coût négatif ou faible. S'appuyant sur 80 études nationales ou régionales consacrées à l'estimation des possibilités d'atténuation du CO₂ sur les cinq continents, cet article analyse et évalue les possibilités qu'offrent les bâtiments en matière de réduction des émissions de CO₂ dans le monde. Les avantages connexes associés à l'application de ces mesures sont également substantiels, ce qui aide les décideurs à justifier les mesures qu'ils prennent même lorsqu'ils ne font pas preuve d'un fort engagement envers les questions climatiques. Les obstacles au déblocage des possibilités de réduction de ces émissions dans les secteurs des immeubles d'habitation et des bâtiments commerciaux étant particulièrement robustes, aucune mesure prise isolément ne peut avoir un impact important. En revanche, il faut une panoplie de mesures ciblées, élaborées en fonction des conditions locales et associées à des règles fortes de conformité et d'application.

Mots-clés: parc de bâtiments changement climatique réduction du CO₂ conception efficacité énergétique atténuation moyens

Keywords:

• building stock
• climate change
• CO₂ reduction
• design
• energy efficiency
• mitigation
• policies

Acknowledgements

The authors are indebted to all those who have contributed to the intellectual work behind Chapter 6 of AR4, and therefore to the outcomes of this paper. These include, but are not limited to: Kornelis Blok, Luis Geng, Siwei Lang, Geoffrey Levermore, Anthony Mongameli Mehlwana, Hiroshi Yoshino, Jacques Rilling, Paolo Bertoldi, Brenda Boardman, Suzanne Joosen, Phillipe Haves, Jeff Harris, Aleksandra Novikova, Marilyn Brown, Mithra Moezzi and Eberhard Jochem. In addition, this paper and the background work could not have been made possible without the sponsors of the AR4 Chapter 6 work for the IPCC, including, but not limited to, the World Meteorological Organisation and Yehuda Elkana of the Central European University.

Notes

¹The IPCC was established by the United Nations in 1988, in affiliation with the United Nations Environment Program and the World Meteorological Organization, to provide periodic comprehensive scientific reviews of the state of knowledge concerning the science of human-induced climatic change (commonly referred to as global warming), concerning potential impacts and the response options from technical, economic and policy points of view. The first three assessments were published in 1990, 1995 and 2001. AR4 is due to be released in autumn 2007, in time to serve as input to the negotiations concerning future steps in emission reduction. Like previous assessments, AR4 consists of three working group reports, divided this time as follows: WG1 on the background science, WG2 on impacts, vulnerability and adaptation, and WG3 on mitigation options. The material summarized in this paper is taken largely from the buildings chapter of the WG3 report.

²Readers interested in recent advances in the background science are urged to consult the IPCC Working Group 1 (WG1) AR4 report when it is released (particularly Chapter 3 on recent trends in temperature, Chapter 6 on past climates, and Chapter 9 on the attribution of observed changes).

³Particularly pertinent are WG2 Chapter 4 (Ecosystems, their Properties, Goods, and Services), especially Table 4.2, WG2 Chapter 5 (Food, Fibre, and Forest Products), and Chapter 19 (Key Vulnerabilities).

⁴In this paper the residential, commercial and service sectors (or tertiary, as they are classified to in some countries) are referred to in short as the ‘buildings’ sector.

⁵Ratio of light output (lumens) to input power (watts).

⁶To extrapolate the potential as a percentage of the baseline into the future (i.e. to estimate the potential for 2020 from a given value for 2010 assuming 2000 as the starting year), the following formula was used: [Potential₂₀₂₀ = 1 – (1 – Potential₂₀₁₀)^(20/10)]. The implementation of this formula results to approximately 78% CO₂ savings in 2020.

⁷This corresponds to an approximate 22% potential in 2020 if the suggested extrapolation formula is used.

⁸This corresponds to an approximate 38% in 2020 if the suggested extrapolation formula is applied to derive the intermediate potential.

⁹Conversely, many residents find higher indoor temperatures acceptable in winter than in summer.