The implications of some technical options for decarbonizing the UK domestic sector are explored. The main focus is on interactions between dwellings and the energy supply and conversion systems that support them, rather than on the detail of the dwelling stock. Synergies between the electricity supply system, intermediate energy-conversion systems and the dwelling envelope make it possible to achieve 60–70% reductions in CO₂ emissions with plausible combinations of existing and/or emerging technologies. Sensitivity analysis shows that a halving of the carbon intensity of the UK electricity system, plausible improvements to dwelling envelopes, and extensive use of second law energy-conversion systems (typified by, but not restricted to, heat pumps and combined heat and power) to supply space and water heating render total CO₂ emissions insensitive to demolition rates. As a result, increased demolition rates may be unnecessary to achieve deep cuts in carbon emissions from dwellings. Additional insights from this study are the strategic importance of decarbonizing the electricity system and the importance, in developing policy for this sector, of synergies between all components of the energy supply, distribution, conversion and end-use system. L'étude décrit les implications de plusieurs options techniques de décarbonisation du secteur intérieur britannique. Elle insiste davantage sur les interactions entre la fourniture d'énergie, les unités d'habitation et les systèmes de conversion dont elles sont équipées, que sur les caractéristiques des enveloppes des bâtiments. Des synergies entre le système de fourniture en électricité, les systèmes intermédiaires de conversion de l'énergie et le parc résidentiel permettraient d'atteindre entre 60 et 70% de réduction des émissions de CO₂ grâce à des combinaisons plausibles de technologies existantes ou émergentes. L'analyse de sensibilité montre qu'en diminuant de moitié l'intensité carbone du système électrique du Royaume-uni, des améliorations plausibles apportées aux enveloppes des bâtiments et l'utilisation extensive de systèmes de conversion obéissant au deuxième principe de la thermodynamique – les pompes à chaleur et les systèmes de cogénération de chaleur et d'électricité en sont des exemples types, mais non exclusifs – pour assurer le chauffage des locaux et la génération d'eau chaude, rendraient le total des émissions de CO₂ indépendant des taux de démolition. En conséquence, l'accélération des démolitions pourrait ne pas être nécessaire pour réduire de manière significative les émissions de carbone du parc résidentiel. Parmi les autres constatations de cette étude, citons l'importance stratégique de la décarbonisation du système de génération d'électricité et l'importance, pour l'élaboration des politiques de ce secteur, de synergies entre toutes les composantes de la fourniture, de la distribution, de la conversion et des systèmes d'utilisation finale de l'énergie. Mots clés: parc résidentiel, intensité carbone, changement climatique, réduction des émissions de CO₂, décarbonisation, démolition, énergie, logement

This commentary reflects on a series of strategic questions facing the energy and buildings research community and research funding bodies in the UK. These include the problems of research capacity and funding, the need to find a new balance between competition and cooperation between research groups, and a need for a renewed focus on the empirical performance of buildings. The authors argue that conventional distinctions between research, development and the deployment of technologies are inappropriate for the built environment. A wider range of approaches to research is needed to enable researchers to engage more effectively with stakeholders throughout the research, development, and deployment process, to reduce the distinction between research and knowledge transfer, and to reduce the length of learning cycles. Without such developments, there is a risk that the energy and buildings research community will be reduced to commenting on accelerating developments in the real world and, at the same time, an increased risk that the massive investments currently being envisaged in the refurbishment and decarbonization of the built environment will underperform. Ce commentaire réfléchit sur une série de questions stratégiques auxquelles se trouvent confrontés la communauté des chercheurs dans le domaine de l'énergie et des bâtiments et les organismes qui financent la recherche au Royaume-Uni. Figurent au nombre de ces questions les problèmes des capacités de recherche et du financement de la recherche, la nécessité de trouver un nouvel équilibre entre la concurrence et la coopération entre les groupes de recherche, et la nécessité d'un recentrage renouvelé sur les performances empiriques des bâtiments. Les auteurs soutiennent que les distinctions classiques entre la recherche, le développement et le déploiement des technologies ne sont pas adaptées à l'environnement bâti. Un éventail d'approches de la recherche plus large est nécessaire pour permettre aux chercheurs de travailler plus efficacement avec les parties prenantes tout au long du processus de recherche, de développement et de déploiement, pour réduire la distinction entre recherche et transfert de connaissances, et pour réduire la longueur des cycles d'apprentissage. Sans de telles évolutions, il existe un risque que la communauté des chercheurs dans le domaine de l'énergie et des bâtiments se retrouve réduite à commenter les développements qui s'accélèrent dans la réalité et, dans le même temps, un risque accru que les investissements massifs actuellement prévus pour la rénovation et la décarbonisation de l'environnement bâti se révèlent insuffisamment performants. Mots clés: bâtiments changement climatique décarbonisation énergie transfert de connaissances politiques publiques politique de recherche tendances

From publicly available data, two simple models are developed to help identify the trajectory of total delivered energy to UK households and provide benchmarks for the UK domestic sector. Both models can help to inform policy-makers and the public whether delivered energy in the domestic sector is on track and whether the reductions correspond with the expected impact of a more efficient domestic sector. The annual delivered energy, price, and temperature (ADEPT) model uses multiple linear regression to fit consumption data since 1970 (R ² = 0.76). Findings indicate that with typical recent heating season temperatures of 7°C and at 2005 energy prices, average household delivered energy is estimated at 21.7 MWh (95% confidence interval = 20.8, 22.6). For every 1°C increase in heating season temperature, average household delivered energy drops by approximately 1 MWh/year. Energy price elasticity is estimated at –0.2, so that a 50% rise in energy prices corresponds to an approximate 10% decline in energy demand. To fit quarterly delivered energy data since 1998, a seasonal temperature energy price (STEP) model is also developed using polynomial multiple regression (R ² > 0.99). At 2005 energy prices, the average household has a minimum power demand of 1.2 kW (including approximately 0.4 kW electricity) at about 16°C, which rises as external temperatures drop to 5°C, where it begins to plateau at approximately 3.8 kW. The average heat loss coefficient is estimated at 240–320 W/°C. Both models find no evidence to date to indicate that changes in delivered energy are beyond those expected due to variations in external temperature and energy price. The seasonal model also provides benchmarks for delivered energy as a response to external temperature and energy price that will be useful for a comparison of building performance evaluations with the national stock, without requiring data for a whole year. Deux modèles simples sont développés à partir des données publiquement accessibles afin d'aider à identifier la trajectoire de l'énergie totale fournie aux foyers britanniques et de fournir des données de référence pour le secteur résidentiel britannique. Ces deux modèles peuvent aider les responsables politiques comme le public à savoir si l'énergie fournie dans le secteur résidentiel évolue dans le bon sens et si les réductions correspondent aux effets attendus d'un secteur résidentiel plus performant. Le modèle ADEPT qui prend en compte l'énergie annuelle fournie, le prix et la température utilise une régression linéaire multiple permettant un ajustement des données de la consommation depuis 1970 (R ² = 0.76). Les résultats indiquent que pour des températures types récentes en période de chauffe de 7°C et aux prix 2005 de l'énergie, l'énergie résidentielle moyenne fournie est estimée à 21,7 MWh (intervalle de confiance de 95% = 20,8, 22,6). Pour chaque augmentation de 1°C de la température en période de chauffe, l'énergie résidentielle moyenne fournie baisse d'environ 1 MWh/an. L'élasticité du prix de l'énergie est estimée à - 0,2, de sorte qu'une hausse de 50% des prix de l'énergie correspond à une baisse d'environ 10% de la demande énergétique. Pour permettre un ajustement des données trimestrielles relatives à l'énergie fournie depuis 1998, un modèle des prix de l'énergie en fonction de la température saisonnière (STEP) est également développé en utilisant une régression multiple polynomiale (R ² > 0.99). Aux prix 2005 de l'énergie, le foyer moyen a une demande énergétique minimale de 1,2 kW (dont environ 0,4 kW d'électricité) à environ 16°C, qui augmente au fur et à mesure que les températures extérieures descendent jusqu'à 5°C, température à laquelle la demande commence à se stabiliser autour de 3,8 kW. Le coefficient moyen de perte de chaleur est estimé à 240-320 W/°C. Les deux modèles n'ont constaté à ce jour aucun élément probant pouvant indiquer que les évolutions de l'énergie fournie dépassent celles prévues, dues aux variations de la température extérieure et du prix de l'énergie. Ce modèle saisonnier fournit également des données de référence concernant l'énergie fournie en réponse à la température extérieure et au prix de l'énergie, données qui seront utiles pour comparer les évaluations des performances des bâtiments avec celles du parc bâti national, sans qu'il soit nécessaire de disposer de données pour une année entière. Mots clés: parc bâti parc bâti résidentiel demande énergétique rendement énergétique performance énergétique logement modèles

This paper brings together a rapid evidence assessment of impacts of elevated CO ₂ concentrations on human cognition with IPCC projections of atmospheric CO ₂ concentration by the end of the present century, and an analysis of potential consequences of increased atmospheric CO ₂ concentrations for ventilation systems in buildings and other enclosed spaces. Whilst only limited research has been done on the effect of CO ₂ on cognition (as opposed to air quality in general), half of the studies reviewed indicate that human cognitive performance declines with increasing CO ₂ concentrations. Hence, given the likelihood of increasing atmospheric CO ₂ concentration by the end of the 21st century, direct impacts of anthropogenic CO ₂ emissions on human cognitive performance may be unavoidable. Attempts to minimise these direct impacts are likely to result in significant indirect impacts on the engineering of ventilation systems and associated energy use in all enclosed spaces including buildings and transport systems. Practical application: This paper concerns what may well be one of the most important long-term drivers of the design, management, operation and regulation of ventilation systems over the remainder of the 21st century. It will be relevant to professionals, particularly at senior levels in the building industry.

Raymond J. Cole’s body of work, spanning sustainable design, system complexity and human agency, has encouraged researchers to reconceptualize the notions of comfort and building performance. However, methods for predicting energy use and assessing environmental performance have remained predominantly within a reductionist approach common to physics and engineering. The recognition that building performance is characterized by interactive adaptivity and co-evolution of the physical with the social has not been matched by the generation of new methods. Although social practice theories that articulate the socio-technical nature of the built environment have been increasingly appropriated to understand occupants’ role in performance, the challenge of studying buildings as complex socio-technical systems remains. This methodological paper discusses the application of the case study method (CSM) to the study of 10 retrofit projects selected from the Retrofit for the Future (RfF) Programme in UK between 2011 and 2012. Guided by Greene’s framework for methodological discourse, the epistemic regime is articulated under four headings: philosophical assumptions, investigative logics, guidelines for practice and contribution to system perspective. The discussion of these domains highlights the fecundity of CSM in providing a more nuanced understanding of the interaction between social and technical systems in performance.

This paper presents empirical evidence and analysis that supports the existence of a significant heat loss mechanism resulting from air movement through cavities in party walls in masonry construction. A range of heat loss experiments were undertaken as part of the Stamford Brook housing field trial in Altrincham in the United Kingdom. Co-heating tests showed a large discrepancy between the predicted and measured whole house heat loss coefficients. Analysis of the co-heating results, along with internal temperature data, thermal imaging and a theoretical analysis indicated that the most likely explanation for the discrepancy was bypassing of the thermal insulation via the uninsulated party wall cavities. The data show that such a bypass mechanism is potentially the largest single contributor to heat loss in terraced dwellings built to the 2006 revision of the Building Regulations. A comparable convective heat bypass associated with masonry party walls was identified in the late 1970s during the course of the Twin Rivers Project in the United States, albeit in a somewhat different construction from that used at Stamford Brook. A similar effect was also reported in the United Kingdom in the mid 1990s. However, it appears that no action was taken at that time either to confirm the results, to develop any technical solutions, or to amend standards for calculating heat losses from buildings. Current conventions for heat loss calculations in the United Kingdom do not take account of heat losses associated with party walls and it is suggested by the authors that such conventions may need to be updated to take account of the effect described in this paper. In the final part of the paper, the authors propose straightforward solutions to prevent bypassing of roof insulation via party walls by for example filling the cavity of the party wall with mineral fibre insulation, or by inserting a cavity closer across the cavity in the plane of the roof insulation. Practical application: The heat bypass mechanism described in this paper is believed by the authors to contribute to a significant proportion of heat loss from buildings in the UK constructed with clear cavities such as those found in separating walls between cavity masonry dwellings. It is proposed that relatively simple design changes could be undertaken to eliminate such heat loss pathways from new buildings. In addition, simple and cost effective measures are envisaged that could be used to minimise or eliminate the bypass from existing buildings. Such an approach could give rise to a significant reduction in carbon emissions from UK housing. ^a The Department for Communities and Local Government, previously the Office of the Deputy Prime Minister, ODPM. References produced before the change of name are listed under ODPM. ^b Difficulties in the recruitment of households have delayed the long term monitoring programme to 2007 but, fortuitously, this has provided the capacity for a more detailed investigation of the party wall heat loss issues discussed in this paper with further co-heating tests (incorporating a more detailed measurements) planned for the winter of 2006/07. ^c A co-heating test involves electrically heating the inside of a house to a constant temperature over a period of several weeks. Correlation of the measured electrical heat input with external temperature and solar insolation then allows an estimation of the total dwelling heat loss coefficient. ^d House A is an end-of-terrace house with one adjacent house. House E is a mid-terrace house with two adjacent houses, D and F. ^e In the UK, the regulations consist of a broadly framed, performance based, legal requirement supported by detailed technical guidance on compliance. Such guidance is provided by a system of approved documents issued by the Secretary of State. The current methodology for dwelling heat loss calculations is contained in the Standard Assessment Procedure 2005 ¹² which is invoked by regulation 17A and Approved Document L1A. ^{2 f} The Building Regulations do limit the leakage of air from within each dwelling into the cavity through an overall limit on dwelling permeability. ^g The higher-than-normal inside-outside temperature difference during the co-heating tests implies that background ventilation rates and ventilation heat loss coefficients during these tests are likely to have exceeded those in the table. Calculations based on a semi-analytical model of air flow ¹⁴ suggest that the increase is of the order of 3 WK ^—1 (10%) for the two-storey house A and 15 WK ^—1 (27%) for the three-storey house E. ^h Note that the correction is only used to improve the graphical presentation of the data. The heat loss coefficient is calculated directly from multiple regression of heating power against ΔT and S.