Glazing daylighting performance and Trombe wall thermal performance of a modular façade system in four different Portuguese cities

This paper reports on a new façade system that uses passive solutions in the search for energy efficiency. The differentials are the versatility and flexibility of the modules, which are important advantages of the system. The thermal performance of Trombe walls and glazings and the daylighting performance of glazing were the key aspects analyzed in the results. Computational simulations were accomplished for the thermal performance of different arrangements of the modules with DesignBuilder software. The glazing daylighting performance was studied by means of Ecotect and Desktop Radiance programs and compared with the transmittance curves of glazings. Occupancy profile and internal gains were fixed according to the Portuguese reality for both studies. The main characteristics considered in this research were the use of two double glazings, four different climates in Portugal and one and two Trombe walls in the façade. The results show an important reduction in the energy consumption with the use of Trombe walls and double self-cleaning glazing in the façade, which also presented better daylighting performance.Author Helenice M Sacht benefited from a scholarship granted by Erasmus Mundus ISAC - Improving Skills Across Continents to perform her research work at University of Minho, from which resulted this article

Thermal and sound insulation performance assessment of vacuum insulated composite insulation panels for building façades

Composite insulation panels (CIPs) currently used in building façades require significant design changes e.g. increased thickness to realise higher thermal and sound insulation performance. This study deals with the manufacturing and characterisation of smart façade panels for achieving higher thermal and sound insulation dual characteristics in one panel without a significant increase in thickness. Prototype panels were manufactured using vacuum insulation core (VIC) combined with mass loaded vinyl (MLV) layers. Thermal transmission and weighted sound reduction index (R_w) was experimentally measured in the laboratory. The results were compared with a control panel made with extruded polystyrene (XPS) core. The VIC panel showed a 51% improvement in the centre of panel U-value compared to control XPS core panel of the same thickness. Integrating the two MLV layers inside of aluminium skins either side of the vacuum insulation panel led to 3dB improvement in R_w from 32 dB to 35 dB which could be further improved by optimising the MLV layer positioning in the CIP and better bonding between the MLV and the vacuum insulation panel. This shows that vacuum insulation core panels combined with MLV offers a solution to achieve smart building façade with excellent thermal and sound insulation performance

Bridging the domestic building fabric performance gap

It is recognized that there is often a discrepancy between the measured fabric thermal performance of dwellings as built and the predicted performance of the same dwellings and that the magnitude of this difference in performance can be quite large. This paper presents the results of a number of in-depth building fabric thermal performance tests undertaken on three case study dwellings located on two separate Passivhaus developments in the UK: one masonry cavity and the other two timber-frame. The results from the tests revealed that all the case study dwellings performed very close to that predicted. This is in contrast with other work that has been undertaken regarding the performance of the building fabric, which indicates that a very wide range of performance exists in new-build dwellings in the UK, and that the difference between the measured and predicted fabric performance can be greater than 100%. Despite the small non-random size of the sample, the results suggest that careful design coupled with the implementation of appropriate quality control systems, such as those required to attain Passivhaus Certification, may be conducive to delivering dwellings that begin to ‘bridge the gap’ between measured and predicted fabric performance

Energy and economic analysis of Vacuum Insulation Panels (VIPs) used in non-domestic buildings

The potential savings in space heating energy from the installation of Fumed Silica (FS) and Glass Fibre (GF) Vacuum Insulation Panels (VIPs) were compared to conventional expanded polystyrene (EPS) insulation for three different non-domestic buildings situated in London (UK). A discounted payback period analysis was used to determine the time taken for the capital cost of installing the insulation to be recovered. VIP materials were ranked using cost and density indexes. The methodology of the Payback analysis carried out considered the time dependency of VIP thermal performance, fuel prices and rental income from buildings. These calculations show that VIP insulation reduced the annual space heating energy demand and carbon dioxide (CO2) emissions by approximately 10.2%, 41.3% and 26.7% for a six storey office building, a two floor retail unit building and a four storey office building respectively. FS VIPs had the shortest payback period among the insulation materials studied, ranging from 2.5 years to 17 years, depending upon the rental income of the building. For GF VIPs the calculated payback period was considerably longer and in the case of the typical 4 storey office building studied its cost could not be recovered over the life time of the building. For EPS insulation the calculated payback period was longer than its useful life time for all three buildings. FS VIPs were found to be economically viable for installation onto non-domestic buildings in high rental value locations assuming a lifespan of up to 60 years

Summertime temperatures and thermal comfort in UK homes

This is an Author's Accepted Manuscript of an article published in Building Research and Information [copyright Taylor & Francis], available online at: http://www.tandfonline.com/10.1080/09613218.2013.757886Internal summertime temperatures measured in 268 homes in the UK city of Leicester are reported. The hourly data was collected from living rooms and bedrooms during the summer of 2009, which was generally cool but with a short hot spell. Some household interviews were conducted. The sample of homes is statistically representative of the socio-technical characteristics of the city’s housing stock. The data provides insight into the influence of house construction, energy system usage and occupant characteristics on the incidence of elevated temperatures and thermal discomfort. The warmest homes were amongst the 13% that were heated. Significantly more of these were occupied by those over 70 who are particularly vulnerable to high temperatures. The national heatwave plan might usefully caution against summertime heating. Temperatures in the 230 free-running homes were analysed using both static criteria and criteria associated with the BSEN15251 adaptive thermal comfort model. These indicated that that flats tended to be significantly warmer than other house types. Solid wall homes and detached houses tended to be significantly cooler. It is argued that adaptive criteria provide a valuable and credible framework for assessing internal temperatures in free-running UK homes. However, the temperatures in the Leicester homes were much lower than anticipated by the BSEN15251 model. Numerous possible reasons for this discrepancy are discussed

Turkish D-light : accentuating heritage values with daylight

Historic buildings have their own cultural identity, which is often related to their aesthetic qualities such as period characteristics (geometry, size, colour, form and shape), materials and construction. Daylight is one of the primary elements contributing to the distinctiveness of the visual environment of many historic buildings, but is rarely considered as one of the components that shape the character of a building when adaptive preservation schemes of historical buildings are planned. Many historic buildings were originally designed to accommodate activities different to their new use and preserving the quality of daylight that originally contributed to their visual identity is a challenging task. Maintaining the ‘day-lit appearance’ of a building can be particularly problematic if the building is to be used as a museum or a gallery owing to the artefacts’ conservation requirements. This work investigated the opportunities of maintaining the original ambient conditions of renovated historical buildings while meeting the required daylight levels of the proposed new use. The study utilised an annual daylight simulation method and hourly weather data to preserve daylight conditions in renovated historic buildings. The model was piloted in a Turkish bathhouse situated in Bursa, Turkey, that is currently under renovation. The simulation model produces 4483 hourly values of daylight illuminance for a period of a whole year using the computer program Radiance. It is concluded that daylight characteristics should be taken into account when developing a renovation scheme. With increasing pressure on valuing historic buildings in many parts of the world, the work reported here should be beneficial to those concerned with the conservation and adaptive reuse of historic buildings. The study findings could also be useful to those interested in predicting potential energy savings by combining daylighting and electric lighting in historic buildings

Temperature in housing: stratification and contextual factors

Overheating in new and retrofit low carbon dioxide homes is a growing issue in the UK due to climate change and other factors, with 99% of existing housing predicted to be at medium to high risk if summer temperatures become 1·4°C warmer. A year-long field study in two residential developments in the north of England monitored housing at three different scales: two-storey houses and three- and ten-storey blocks of flats. This revealed significant temperature stratification in the staircase zone, which allows a stack effect, as well as temperature differences between dwellings depending on their location in the building, both for summer and winter conditions even in the low-rise housing. Further investigation revealed that albedo and east–west orientation also contributed to non-linear overheating. Analyses of inhabitants’ thermal comfort and security practices as well as occupancy patterns also challenge the regulatory modelling used to predict building performance. It is suggested that these additional physical as well as user factors in residential developments need further investigation and should now be considered in relation to thermal comfort modelling

Building a better future: An exploration of beliefs about climate change and perceived need for adaptation within the building industry

Copyright © 2011 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in Building and Environment . Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Building and Environment Vol. 46 (2011), DOI: 10.1016/j.buildenv.2010.12.007The present research explored beliefs about climate change among an important yet relatively understudied population: representatives of the building industry. We also assessed the perceived adequacy of current climate-related actions within the industry and the perceived need for developing new practices. The results of a survey administered within a large engineering firm suggest a fairly high level of concern about climate issues within this sector: participants perceived climate change to be an important issue, current practices to be inadequate, and a need to develop new ways of addressing climate change. Despite this, there was notable and consequential variability in how participants thought about climate change. Higher levels of seniority were associated with greater satisfaction with current practices, and the belief that climate change was a natural rather than man-made phenomena was associated with a reduced support for the idea that changes to current practices were necessary. In addition, when thinking about climate relevant actions (whether current practices or the alternatives) participants focussed almost exclusively on mitigation rather than adaptation. The implications of these patterns for innovation around climate change within the building industry are discussed.EPSR

An experimental study on the effect of visual tasks on discomfort due to peripheral glare

This article concerns discomfort due to sources of glare in the peripheral visual field. A visual task is needed to maintain foveal fixation at a known location and in past studies the tasks have ranged from a simple fixation mark to a task requiring greater cognitive attention such as reading. It was hypothesized that these different approaches to control visual attention would influence the evaluation of discomfort. This article reports an experiment which compared evaluations of discomfort when using the two visual tasks, a simple circle and a pseudo-text reading task, and two procedures, category rating and luminance adjustment. The results from both procedures confirmed the hypothesis: a lower degree of discomfort was expressed in the pseudo-text trials than in trials with the circular fixation mark