• Energy Research

Traditionnellement, les bâtiments des vallées himalayennes intérieures du Bhoutan étaient construits à partir de terre battue dans les régions occidentales et de pierre de carrière dans les régions centrales et orientales. Bien que les éléments de conception architecturale de base aient été conservés, les méthodes de construction ont toutefois changé au cours des dernières décennies parallèlement aux attentes en matière de confort thermique intérieur. Néanmoins, malgré le besoin de chauffage des locaux, les performances thermiques des bâtiments restent largement inconnues. En outre, aucune donnée climatique dédiée n'est disponible pour les évaluations de la performance des bâtiments. Cet article établit de telles informations climatologiques pour la capitale Thimphu et présente une enquête sur les propriétés physiques des bâtiments de types traditionnels et contemporains. Dans une étude de terrain d'un mois, 10 bâtiments ont été étudiés, en examinant l'étanchéité à l'air du bâtiment, le climat intérieur, les valeurs U des murs et l'absorption d'eau des matériaux de construction de murs typiques. Les résultats mettent en évidence des valeurs U de paroi comparativement élevées de 1,0 à 1,5 W/m²K pour les constructions actuelles et historiques. En outre, les tests d'étanchéité à l'air montrent que, en raison de joints mal scellés entre les éléments de construction, les fenêtres et les portes, de nombreux bâtiments ont des taux d'infiltration élevés, atteignant jusqu'à 5 changements d'air par heure. Cependant, les résultats indiquent également un effet modérateur du climat intérieur des techniques de construction en terre plus traditionnelles. Sur la base de ces résultats d'enquête, des améliorations de base sont suggérées. Tradicionalmente, los edificios en los valles del Himalaya Interior de Bután se construían con tierra apisonada en las regiones occidentales y piedra de cantera en las regiones central y oriental. Si bien se han conservado los elementos básicos de diseño arquitectónico, los métodos de construcción han cambiado en las últimas décadas junto con las expectativas de confort térmico interior. Sin embargo, a pesar de la necesidad de calefacción, el rendimiento térmico de los edificios sigue siendo en gran medida desconocido. Además, no se dispone de datos climáticos específicos para las evaluaciones de rendimiento de los edificios. Este documento establece dicha información climatológica para la capital, Thimphu, y presenta una investigación de las propiedades físicas de la construcción de los tipos de edificios tradicionales y contemporáneos. En un estudio de campo de un mes, se encuestaron 10 edificios, analizando la estanqueidad del aire del edificio, el clima interior, los valores U de la pared y la absorción de agua de los materiales de construcción típicos de la pared. Los hallazgos destacan valores U de pared comparativamente altos de 1.0 a 1.5 W/m²K para construcciones actuales e históricas. Además, las pruebas de estanqueidad muestran que, debido a las juntas mal selladas entre los elementos de construcción, ventanas y puertas, muchos edificios tienen altas tasas de infiltración, alcanzando hasta 5 cambios de aire por hora. Sin embargo, los resultados también indican un efecto moderador del clima interior de las técnicas de construcción de tierra más tradicionales. Sobre la base de estos resultados de la encuesta, se sugieren mejoras básicas. Traditionally, buildings in the Inner Himalayan valleys of Bhutan were constructed from rammed earth in the western regions and quarry stone in the central and eastern regions. Whilst basic architectural design elements have been retained, the construction methods have however changed over recent decades alongside expectations for indoor thermal comfort. Nevertheless, despite the need for space heating, thermal building performance remains largely unknown. Furthermore, no dedicated climate data is available for building performance assessments. This paper establishes such climatological information for the capital Thimphu and presents an investigation of building physics properties of traditional and contemporary building types. In a one month field study 10 buildings were surveyed, looking at building air tightness, indoor climate, wall U-values and water absorption of typical wall construction materials. The findings highlight comparably high wall U-values of 1.0 to 1.5 W/m²K for both current and historic constructions. Furthermore, air tightness tests show that, due to poorly sealed joints between construction elements, windows and doors, many buildings have high infiltration rates, reaching up to 5 air changes per hour. However, the results also indicate an indoor climate moderating effect of more traditional earth construction techniques. Based on these survey findings basic improvements are being suggested. تقليديا، شيدت المباني في الوديان الداخلية لجبال الهيمالايا في بوتان من الأرض المدك في المناطق الغربية وحجر المحجر في المناطق الوسطى والشرقية. في حين تم الاحتفاظ بعناصر التصميم المعماري الأساسية، فقد تغيرت أساليب البناء على مدى العقود الأخيرة إلى جانب توقعات الراحة الحرارية الداخلية. ومع ذلك، على الرغم من الحاجة إلى تدفئة المكان، لا يزال أداء المبنى الحراري غير معروف إلى حد كبير. علاوة على ذلك، لا تتوفر بيانات مناخية مخصصة لبناء تقييمات الأداء. تحدد هذه الورقة مثل هذه المعلومات المناخية للعاصمة تيمفو وتقدم تحقيقًا في خصائص فيزياء البناء لأنواع المباني التقليدية والمعاصرة. في دراسة ميدانية مدتها شهر واحد، تم مسح 10 مبانٍ، بالنظر إلى ضيق هواء المبنى، والمناخ الداخلي، وقيم الجدار على شكل حرف U وامتصاص الماء لمواد بناء الجدار النموذجية. تسلط النتائج الضوء على قيم U للجدار المرتفعة نسبيًا من 1.0 إلى 1.5 واط/مترمربع لكل من الإنشاءات الحالية والتاريخية. علاوة على ذلك، تُظهر اختبارات إحكام الهواء أنه بسبب الوصلات محكمة الإغلاق بين عناصر البناء والنوافذ والأبواب، فإن العديد من المباني لديها معدلات تسرب عالية، تصل إلى 5 تغييرات في الهواء في الساعة. ومع ذلك، تشير النتائج أيضًا إلى تأثير معتدل للمناخ الداخلي لتقنيات بناء الأرض الأكثر تقليدية. وبناءً على نتائج هذه الدراسة الاستقصائية، تُقترح تحسينات أساسية.

Simulation packages for predicting building performance in terms of energy and comfort are becoming increasingly important in the planning process. However, current industry standard weather files for building simulation are not suited to the assessment of the potential impacts of a changing climate, in particular summer overheating risks. In addition, no bespoke climate change weather files are readily available that can be loaded directly into environmental simulation software. This paper describes the integration of future UK climate scenarios into the widely used Typical Meteorological Year (TMY2) and EnergyPlus/ESP-r Weather (EPW) file formats and demonstrates the importance of climate change analysis through a case study example. The ‘morphing’ methodology published by the Chartered Institution of Building Services Engineers (CIBSE) is utilised as a baseline for transforming current CIBSE Test Reference Years (TRY) and Design Summer Years (DSY) into climate change weather years. A tool is presented that allows generation of TMY2/EPW files from this ‘morphed’ data and addresses the requirements related to solar irradiation, temperature, humidity and daylighting beyond the parameters provided by CIBSE weather years. Simulations of a case study building highlight the potential impact of climate change on future summer overheating hours inside naturally ventilated buildings.

Abstract Building integration of photovoltaics (PV) has long been acknowledged as a key application for PV in developed countries. The avoided use of comparably priced alternatives such as polished or cut stone in commercial facades enables PV to be applied often at little or no additional cost. The use of semi-transparent PV modules within commercial atria represents an interesting application in this respect as they can be used to replace traditional shading solutions which often have a high maintenance burden. However, compared to standard double glazing, an element incorporating either mono or poly crystalline PV cells in a glass–glass construction comes at a cost premium. To justify such an application there must be significant added value in the PV solution. This paper critically appraises a semi-transparent PV atrium which links two administration buildings at the University of Southampton, enclosing the main campus reception desk. Choosing PV laminates for the atrium roof has multiple benefits for the building users and the wider University, such as electricity generation, solar shading, environmental and technology statements, enhanced comfort and prestigious office workspace. This paper compares alternative shading solutions for the atrium and discusses user perception of the building and the atrium’s impact on their personal workspace. It is shown that PV in commercial atria does not always have to be considered as a ‘luxury’ option. With appropriate consideration of added value factors its selection can be justified in terms of both cost and carbon footprint.

Building performance and solar energy system simulations are typically undertaken with standardised weather files which do not generally consider future climate predictions. This paper investigates the generation of climate change adapted simulation weather data for locations worldwide from readily available data sets. An approach is presented for ‘morphing’ existing EnergyPlus/ESP-r Weather (EPW) data with UK Met Office Hadley Centre general circulation model (GCM) predictions for a ‘medium–high’ emissions scenario (A2). It was found that, for the United Kingdom (UK), the GCM ‘morphed’ data shows a smoothing effect relative to data generated from the corresponding regional climate model (RCM) outputs. This is confirmed by building performance simulations of a naturally ventilated UK office building which highlight a consistent temperature distribution profile between GCM and RCM ‘morphed’ data, yet with a shift in the distribution. It is demonstrated that, until more detailed RCM data becomes available globally, ‘morphing’ with GCM data can be considered as a viable interim approach to generating climate change adapted weather data.

In order to improve the sustainability of buildings one of the challenges is to address the role of the building envelope as the key climate moderator between the internal and external environments. The envelope is exposed to the elements and needs to control air exchange as well as sunlight and sound passing through to the occupants. Therefore, it has a major impact not only on the energy utilisation within the space it controls but also on the quality of comfort. However, inside highly glazed modern buildings, achieving good comfort is often at the cost of high-energy consumption. Therefore, in the light of ever increasing energy costs, improved facade design can contribute to a reduction of operational costs. The aim of this paper is to explore technical, economic, environmental and indoor comfort implications of emerging glazing technologies for energy control of highly glazed buildings in arid Middle Eastern climates, which is one of the harshest climates for this building type. The work includes predictions through thermal simulation of the impact of electrochromic glazing, holographic optical elements (HOE), aerogel glazing and thin film photovoltaics on two example buildings. Potential reductions in cooling demand are assessed.

Abstract The increasing need for energy conservation has led to the development of a range of energy models for assessing energy demand in the residential sector of a country. Even though such models deliver a principal solution for forecasting energy demand and assessing the impact of future energy saving measures, collecting the required baseline data is fraught with difficulties such as a complete lack of data, missing data within a dataset and a lack in coherence between different datasets in terms of detail, data collection method, baseline assumptions and sample size. This paper analyses the transferability and accuracy of twelve energy models (MAED-2, FfE-Gebaudemodell, CDEM, REM, CREEM, ECCABS, REEPS, BREHOMES, LEAP, DECM, CHM, BSM), taking Germany as case study example. Furthermore, a sensitivity analysis is conducted for each model to analyze the significance of the input variables for the overall modelling outcome, highlighting the most influential variables. It is shown that models with a high level of disaggregation do not necessarily guarantee more accurate results. Adjustments are proposed to improve the transferability of the models to the case study country Germany.

Current thermal comfort models are based on studies with adult subjects, mainly in offices. There is no assurance however that these models apply to children. This paper presents findings from thermal comfort surveys and measurements of indoor environmental variables in naturally ventilated classrooms in Hampshire, England. School children aged 7-11 were surveyed regarding their thermal sensation and preference in repeated survey runs outside the heating season, gathering about 1300 responses in total. The results were compared to predictions achieved with the two common approaches used in existing comfort standards, the heat balance and the adaptive comfort model. The heat balance model indices PMV (predicted mean vote) and PPD (predicted percentage of dissatisfied) were calculated for the survey periods, using the measured physical parameters, estimated values for clothing insulation and four different approaches for determining the metabolic rate. The applicability of the adaptive comfort model was investigated by comparing the comfort temperature equation derived from the survey with the equation used in the European Standard EN 15251. The results suggest that children are more sensitive to higher temperatures than adults with the comfort temperatures being about 4 °C and 2 °C lower than the PMV and the EN 15251 adaptive comfort model predictions respectively. © 2012 Elsevier B.V.

© 2014 Elsevier Ltd. Recent thermal comfort research in a light-weight junior school building showed that children were more sensitive to higher temperatures than adults and subsequently that current thermal comfort standards were not appropriate for the assessment of their thermal environment. This paper presents a comparison of these survey results to those from a survey conducted in a medium-weight school building, in order to evaluate the role of the construction type on the results. Both surveys followed the same methodology, including thermal comfort questionnaires and measurements of indoor environmental variables. A total of 2990 responses were gathered. The buildings had an average difference in air temperature of 2.7°C during occupied hours in the period of investigation (June and July 2012), with the medium-weight building being cooler than the light-weight building. However, the different construction type and the cooler overall thermal environment in the medium-weight school building had little impact on the pupils' overall thermal sensitivity. The comparison showed a general agreement on the pupils' warm thermal sensation trends, interpersonal variation and undeveloped adaptive behaviour. The results further support the finding that current thermal comfort criteria lead to an underestimation of pupils' thermal sensation during summer.

Since October 2008, Energy Performance Certificates (EPCs) have been a mandatory requirement for all dwellings sold or rented in England and Wales. Having now been in place for some time, it is of interest to assess the scheme’s impact and effectiveness. This paper presents the results of a questionnaire survey, targeted at almost 2000 homeowners in Southampton on the South coast of England, who bought their home within the first year of the scheme’s introduction. The survey had a response rate of 17% and established homeowner awareness of EPCs, but highlighted that they had little impact on decision-making or price negotiation. Where retrofitting measures have been undertaken, results are inconclusive as to whether retrofitting was done as a result of EPCs. Energy efficiency was not found to be a priority for homebuyers. Practical applications: The survey presented in this paper highlights that further refinement of EPCs and the certification process appear to be needed, in order for the scheme to become a widespread success in the domestic sector. Whilst there is an awareness of the scheme in general, there appears to be limited recognition of its potential. This poses a challenge for the building industry and certification bodies, which need to seek ways to better communicate the benefits of the scheme, in order to instigate the refurbishment works that are required to meet the national carbon emissions reduction targets in the UK.