The impact of climate change on the distribution of rural income in Ethiopia

Recent evidence suggests that global climate change is likely to increase the incidence of environmental disasters, as well as the frequency of extreme weather events. As a result, it is generally recognized that climate and weather variability has negative impacts on households’ welfare relying mainly on agriculture. In Ethiopia, 95% of the population depends on rain-fed agriculture and consequently the economic impact of climate change is crucial for small-scale farmers’ food security and welfare. The objective of this study is to provide a comprehensive analysis of the impact of climate change on rural households’ welfare in Ethiopia by using a Quantile Regression (QR) analysis. The main econometric results show that the elasticity of crop income with respect to rainfall varies across quantiles. It is confirmed that there is a non-linear relationship between climatic variables and income.     

深层搅拌水泥土基底加固层的三维随机有限元分析

在软土基坑开挖过程中,围护结构的最大侧向位移往往出现在开挖面以下。常用的防范方法是采用深层搅拌法对设计深度以下2~3 m的软土层进行水泥加固处理,形成水泥土加固层以减少围护结构的侧向位移。由于水泥土的强度具有显著的空间变异性,工程设计中通常采用较为保守的整体强度设计值。考虑深层搅拌桩形成过程中的两种主要不确定性因素:桩身位置不确定性和桩身内部水泥土强度不均匀性,将水泥土加固层的强度模拟为随机场,且将其作为材料变量结合有限元仿真模拟进行受力分析。分析结果表明水泥土加固层的设计强度可表示为钻心取样强度平均值减去t倍标准差,对系数t进行了详细探讨,所得结果可为今后类似工程设计提供参考依据。     

A flood risk assessment to municipal infrastructure due to changing climate part II: case study

Flooding often has devastating consequences. It is important to understand the evolution of these risks as climate changes. Municipal infrastructure is designed using historical data that no longer accurately represents current climate conditions, indicating infrastructure may underperform. The purpose of this study is to apply a new methodology for the assessment of climate change caused flood risk by Bowering et al. (2013) to the City of London, Ontario, Canada. Floodplain maps derived from climate, hydrologic and hydraulic analyses provide direct input into risk assessment procedure. Inundated infrastructure and high risk areas are identified in tables and maps for two climate and two hydraulic scenarios. Results indicate the most critical flood scenario is the 100 year climate change upper bound and high risk is driven by expensive infrastructure located in the floodplains. Results of the study are used as the support for climate change adaptation policy development and emergency management.     

Statistical evaluation on storm sewer design criteria under climate change in Seoul,South Korea

This study conducted statistical analysis under both stationary and non-stationary climate using rainfall data measured in Seoul, South Korea. The 50 year annual maximum rainfall data were analysed with generalised extreme value distribution and Gumbel distribution. Possible rainfall changes were predicted with nonstationary forms of the two distributions, considering time variable location parameters. The current storm sewer design criteria were assessed by reflecting climate change implications and expected lifetime performance. Expected return periods were reduced to 4.67, 8.66, 19.16 and 23.53 years for the current 10 min - 5, 10, 30 and 50 years. The newly suggested design criteria of 5, 10, 30 and 50 yr return period storm events were 5.3, 12, 48 and 107 years for the 10 min duration for a 50 year lifetime expectancy.     

Sensitivity analysis of municipal drinking water distribution system energy use to system properties

Municipal Drinking Water Distribution Systems (MDWDSs) consume a significant quantity of energy to transport water, thereby exacerbating greenhouse gas emissions and global climate change. The current study is a sensitivity analysis that uses a network solver to quantify energy savings due to the alteration of three system properties—system-wide water demand, storage tank parameters (maximum water level, diameter, elevation), and pumping stations (horsepower, number of boosters, and their locations) of seven diverse MDWDSs. It was found that a 50% reduction in water demand, main pump horsepower, and booster horsepower resulted in an average energy savings of 47, 41, and 9.5% respectively, for the seven systems analyzed. Other properties examined showed insignificant savings. Even though an individual system analysis is more conclusive, this sensitivity analysis can guide optimization studies to focus on the most sensitive properties.     

Regional loss estimation due to hurricane wind and hurricane-induced surge considering climate variability

This paper presents a framework to assess the potential hurricane damage risks to residential construction. Studies show that hurricane wind, frequency and/or hurricane-induced surge may change as a result of climate change; therefore, hurricane risk assessments should be capable of accounting for the impacts climate change. The framework includes a hurricane wind field model, hurricane-induced surge height model and hurricane vulnerability models. Three case study locations (Miami-Dade County, FL; New Hanover County, NC and Galveston County, TX) are presented for two types of analyses: annual regional loss estimation and event-based regional loss estimation. Demographic information, such as median house value and changes in house numbers, and distribution of houses for different exposures, is used to estimate the time-dependent probability of damage with or without possible climate change-induced change in wind speed, frequency and/or surge height. Through both analyses, it was found that climate change may have a significant impact on regional hurricane damage losses.     

Design strategy for low-energy ventilation and cooling within an urban heat island

Natural ventilation is a proven strategy for maintaining thermal comfort in non-domestic buildings in the UK. The energy consumption and thus the carbon dioxide emissions that contribute to global warming are lower than in conventional air-conditioned buildings. However, the ambient temperatures in the UK have risen over the last decade and new climatic data for use in the design of naturally ventilated buildings has been published. Using these data and dynamic thermal modelling, it is shown that passive stack ventilation alone was unlikely to maintain summertime comfort in a proposed University College London building within an urban heat island. The stack ventilation strategy was evolved by the introduction of passive downdraught cooling. This low-energy technique enables cooled air to be distributed throughout the building without mechanical assistance. The underlying principles of the technique were explored using physical models and the anticipated performance predicted using thermal modelling. The architectural integration is illustrated and the control strategy described. The resulting building is believed to be the first large-scale application of the passive downdraught cooling technique; construction began in late 2003.     

Evaluating design strategies,performance and occupant satisfaction: a low carbon office refurbishment

Existing buildings present the best opportunity for reducing greenhouse gas emissions in developed economies, given that only 2–3% of the building stock is newly built each year. Insights from a post-occupancy evaluation of a large-scale refurbishment project of a head office building in Sydney, Australia, are presented to inform future refurbishment strategies. The study evaluates occupant satisfaction and energy performance, and elicits influencing factors arising from the design process and interventions, ongoing building management, and operational performance. Occupants returned a high level of satisfaction across the range of environmental variables for overall comfort, temperature, lighting, and air quality as well as perceived productivity and health. These outcomes highlight the importance of improving indoor environmental quality for occupants particularly through increased fresh air, daylight, glare control, access to views, and noise management. The positive results reinforce the value of an integrated and user-responsive approach that was adopted for building design, development, and management. The reduction in operational energy (in this project, coupled with carbon reduction) as a consequence of refurbishment and positive user feedback demonstrates the potential to future-proof existing buildings in the context of climate change.

Les bâtiments existants offrent la meilleure possibilité de réduction des émissions de gaz à effet de serre dans les économies développées, étant donné que les constructions neuves ne représentent chaque année que 2 à 3% du parc bâti. Les enseignements retirés d'une évaluation après occupation d'une opération de rénovation à grande échelle réalisée dans l'immeuble d'un siège social de Sydney, en Australie, sont présentés afin d'infléchir les futures stratégies en matière de rénovation. L'étude évalue la satisfaction des occupants et les performances énergétiques, et met au jour les facteurs d'influence qui découlent du processus de conception et des interventions réalisées, de la gestion en cours du bâtiment et des performances de fonctionnement. Les occupants ont exprimé un degré de satisfaction élevé sur l'ensemble des variables environnementales concernant le confort global, la température, l'éclairage et la qualité de l'air, aussi bien que la productivité et la santé telles qu'ils les ont perçues. Ces résultats mettent en évidence le fait qu'il est important d'améliorer la qualité environnementale intérieure pour les occupants, tout particulièrement en apportant davantage d'air frais et de lumière du jour, un plus grand contrôle de l'éblouissement, un accès accru à des panoramas et une gestion renforcée du bruit. Ces résultats positifs renforcent l'utilité d'une approche intégrée et sensible aux besoins des utilisateurs, telle qu'elle a été adoptée pour concevoir, aménager et gérer ce bâtiment. La réduction de l'énergie de fonctionnement (dans cette opération, conjointement avec la réduction du carbone) en conséquence de la rénovation et du feedback positif des utilisateurs démontre le potentiel de cette approche pour permettre aux bâtiments existants de bien affronter l'avenir dans le contexte du changement climatique.

Mots clés: adaptation, changement climatique, confort, énergie, qualité environnementale intérieure, conception intégrée, occupants, évaluation après occupation, rénovation     

Introducing the prebound effect: the gap between performance and actual energy consumption

German regulations for the thermal renovation of existing homes demand high thermal standards, which the government claims are technically and economically feasible. This paper examines existing data on 3400 German homes; their calculated energy performance ratings (EPR) are then plotted against the actual measured consumption. The results indicate that occupants consume, on average, 30% less heating energy than the calculated rating. This phenomenon is identified as the ‘prebound’ effect and increases with the calculated rating. The opposite phenomenon, the rebound effect, tends to occur for low-energy dwellings, where occupants consume more than the rating. A similar phenomenon has been recognized in recent Dutch, Belgian, French and UK studies, suggesting policy implications in two directions. Firstly, using a dwelling's energy rating to predict fuel and CO₂ savings through retrofits tends to overestimate savings, underestimate the payback time and possibly discourage cost-effective, incremental improvements. Secondly, the potential fuel and CO₂ savings through non-technical measures such as occupant behaviour may well be far larger than is generally assumed in policies so policy-makers need a better understanding of what drives or inhibits occupants' decisions.

La réglementation allemande relative à la rénovation thermique des logements existants exige des normes thermiques élevées, que le gouvernement prétend être techniquement et économiquement applicables. Cet article examine les données existantes sur 3400 logements allemands; leurs classes d'efficacité énergétique (CEE) calculées sont ensuite comparées à la consommation réelle mesurée. Les résultats indiquent que les occupants consomment, en moyenne, 30 % d'énergie de chauffage en moins que la classe calculée. Ce phénomène est identifié en raison de l'accroissement de l'effet de « pré-bond » avec la classe calculée. Le phénomène opposé, l'effet de rebond, tend à se produire dans les logements à basse consommation d'énergie, dans lesquels les occupants ont une consommation supérieure à la classe. Un phénomène similaire a été reconnu dans des études récentes néerlandaises, belges, françaises et britanniques, suggérant des implications en termes de politiques dans deux directions. En premier lieu, l'utilisation de la classe énergétique d'un logement pour prévoir les économies de combustible et de CO₂ pouvant être obtenues grâce à des rénovations a tendance à surestimer les économies, à sous-estimer le délai d'amortissement et éventuellement à dissuader d'effectuer des améliorations incrémentielles rentables. En second lieu, les économies potentielles de combustible et de CO₂ pouvant être obtenues par des mesures non techniques telles que le comportement des occupants peuvent se révéler être bien plus importantes que cela n'est supposé en règle générale dans les politiques, de sorte que les décideurs ont besoin de mieux comprendre ce qui motive ou empêche les décisions des occupants.

Mots clés: performance des bâtiments, rénovations thermiques, politique climatique, classe énergétique, politique énergétique, comportement de consommation énergétique     

Resilience to increasing temperatures: residential building stock adaptation through codes and standards

The resilience of the current Spanish residential building stock to increased temperatures is modelled. Homogenized daily temperature data recorded at 50 Spanish meteorological stations for the periods 1950–1979 and 1981–2010 were used to investigate anticipated climate warming on the Spanish residential building stock by means of the degree-day method. Impacts on residential buildings were investigated for three different future time periods (2011–2040, 2041–2070 and 2071–2100) for three representative Spanish provincial capitals. Future climate change scenarios comprising two statistical downscaling methods, three general circulation models and two carbon emission scenarios were used to project local climate. Results show that 72% of current residential building stock in Spain is thermally unprotected. In addition, the energy demand for heating the building sector in Spain is expected to decrease by between 30% (Barcelona, B2 scenario) and 36% (Valencia, A2 scenario) by 2100, while the respective energy demand for cooling could increase by between 107% (Valencia, B2 scenario) and 296% (Madrid, A2 scenario) by 2100. To increase resilience to higher winter and summer temperatures, strategies for modifying the built environment are needed, particularly for the role of building codes and standards.

La résilience du parc bâti résidentiel espagnol actuel face à l'augmentation des températures est modélisée. Les données homogénéisées des température journalières enregistrées dans 50 stations météorologiques espagnoles pour les périodes 1950–1979 et 1981–2010 ont été utilisées pour étudier le réchauffement climatique prévu sur le parc bâti résidentiel espagnol en utilisant la méthode des degrés-jours. Les répercussions sur les immeubles résidentiels ont été étudiées pour trois périodes futures différentes (2011–2040, 2041–2070 et 2071–2100) et pour trois capitales provinciales espagnoles représentatives. Il a été utilisé des scénarios de changement climatique futur comprenant deux méthodes de réduction d'échelle statistique, trois modèles de circulation générale et deux scénarios d'émission de carbone pour prévoir le climat local. Les résultats montrent que 72 % du parc bâti résidentiel actuel de l'Espagne est dépourvu de protection thermique. Il est en outre prévu que la demande énergétique liée au chauffage dans le secteur du logement en Espagne diminue de 30 % (Barcelone, scénario B2) à 36 % (Valence, scénario A2) d'ici à 2100, tandis que la demande énergétique respective liée à la climatisation pourrait augmenter de 107 % (Valence, scénario B2) à 296 % (Madrid, scénario A2) d'ici à 2100. Afin d'augmenter la résilience face à des températures hivernales et estivales plus élevées, il est nécessaire de disposer de stratégies de modification du cadre bâti, concernant en particulier le rôle des codes et des normes du bâtiment.

Mots clés: stratégies d'adaptation, performances des bâtiments, réglementation du bâtiment, parc bâti, changement climatique, degrés-jours, surchauffe, confort thermique, vulnérabilité, Espagne