Accounting for refrigeration heat exchange in energy performance simulations of large food retail buildings

Heat exchange between chilled food storage and conditioned spaces in large food retail stores is not currently required as part of design stage regulatory compliance energy performance models. Existing work has identified that this exchange has a significant impact on store energy demand and subsequently leads to unrealistic assessment of building performance. Research presented in this article uses whole building dynamic thermal simulation models that are calibrated against real store performance data, quantifying the impact of the refrigeration driven heat exchange. Proxy refrigerated units are used to simulate the impact of these units for the sales floor areas. A methodology is presented that allows these models to be simplified with the aim of calculating a realistic process heat exchange for refrigeration and including this in thermal simulation models; a protocol for the measurement of chilled sales areas and their inclusion in the building models is also proposed. It is intended that this modelling approach and the calculated process heat exchange inputs can be used to improve the dynamic thermal simulation of large food retail stores, reduce gaps between predicted and actual performance and provide more representative inputs for design stage and regulatory compliance energy calculations

London's urban heat island: Impact on current and future energy consumption in office buildings

This article is available open access and shared under a Creative Commons license: (http://creativecommons.org/licenses/by/3.0/). Copyright @ 2011 Elsevier B.V.This paper presents the results of a computational study on the energy consumption and related CO2 emissions for heating and cooling of an office building within the Urban Heat Island of London, currently and in the future. The study developed twenty weather files in an East-West axis through London; the weather files were constructed according to future climate change scenario for 2050 suitable for the UK which have been modified to represent specific locations within the London UHI based on measurements and predictions from a program developed for this purpose (LSSAT). The study simulated an office with typical construction, heat gains and operational patterns with an advanced thermal simulation program (IESVE). The predictions confirm that heating load decreases, cooling load and overheating hours increase as the office location moves from rural to urban sites and from present to future years. It is shown that internal heat gains are an important factor affecting energy performance and that night cooling using natural ventilation will have a beneficial effect at rural and city locations. As overheating will increase in the future, more buildings will use cooling; it is shown that this might lead to a five-fold increase of CO2 emission for city centre offices in London in 2050. The paper presents detailed results of the typical office placed on the East-West axis of the city, arguing the necessity to consider using weather files based on climate projections and urbanheat island for the design of currentbuildings to safeguard their efficiency in the future.EPSR

Evaluation of the Workplace Environment in the UK, and the Impact on Users’ Levels of Stimulation

The purpose of this study is to evaluate a number of recently completed workplaces in the UK. The first aim is to assess the impact of various aspects of the workplace environment on users’ levels of stimulation. The body of previous research undertaken into the workplace environment, identified the aspects to be investigated. Samples of employees from the sixteen businesses were surveyed to determine their perceptions of the workplaces. The results were entered into a regression analysis, and the most significant predictors of perceived stimulation identified. The data also revealed a dramatic reduction in staff arousal levels from mornings to afternoons. Thus, there is a second aim to determine whether changes to significant aspects of the workplace environment during the day can counteract the reduction in users’ stimulation. Two further workplaces were studied to enable changes to be made over a 12-week period. A sample of employees completed questionnaires, and semi-structured interviews revealed the reasons behind the results. It was found that provision of artwork, personal control of temperature and ventilation and regular breaks were the most significant contributions to increasing stimulation after lunch; while user choice of layout, and design and décor of workspaces and break areas, were the most significant aspects at design stage

Dynamic thermal simulation of advanced natural ventilation in buildings : current and future usage, UK exemplar

This paper evaluates the use of advanced natural ventilation (ANV) strategies in a range of climatic conditions from four cities in the UK. A prototype ANV system was proposed to determine the most effective case in mitigating overheating. The case was then assessed under identical simulation conditions for all four ANV strategies. The overheating criteria used in the research include the single temperature criterion from CIBSE Guide A and the adaptive thermal comfort overheating criteria from BS EN 15251. Both the current and future ‘Design Summer Year (DSY)’ weather data were used to examine the thermal performances of the proposed design. The findings show that shading, night cooling and heavy weight structures (ceiling) were all useful in mitigating overheating, with night cooling being identified as the most effective measure. The work assessed the use of ANV in both current and future scenarios to quantify the limits of outdoor environmental conditions under which natural ventilation is an effective strategy for achieving thermal comfort. The adaptive thermal comfort overheating criteria were proved to be easier to meet compared with the CIBSE single temperature criterion. With the adaptive overheating criteria, the given design is predicted to not overheat until 2050 in London Heathrow; and for other places evaluated in the UK (Edinburgh, Manchester & Birmingham), the design passes these criteria. The Centre-in ANV strategies proved to be more effective than the Edge-in strategies for space cooling due to the extended structure thermal mass

Thermal responses of single zone offices on existing near-extreme summer weather data

There have been a number of attempts in the past to define “near extreme” weather for facilitating overheating analysis in free running buildings. The most recently efforts include CIBSE latest release of Design Summer Year (DSY) weather using multiple complete weather years and a newly proposed composite DSY. This research aims to assess how various single zone offices respond to these new definitions of near extreme weathers. Parametric studies were carried out on single zone offices through which four sampling sets of models were employed to examine the thermal responses of dry bulb temperature, global solar radiation & wind speed collectively. London weather data from 1976 to 1995 were used and the overheating assessments were made based on CIBSE Guide A & BS EN 15251. The research discovers that solar radiation and wind both influence the predicted indoor warmth with solar radiation has obvious stronger impacts than wind. No perfect correlation was found from observation and Spearman’s rank order analysis on the ranks between the weather warmth and the predicted indoor warmth. The ranks made using multiple weather parameters show better correlation than some of the dry bulb temperature only metrics. The research also discovers that the Test Reference Year weather behaves warmer than expected. It is also found that a single complete year can not represent the near-extreme consistently and there is no evidence a composite DSY is better statistically. These findings support the notion of using multiple complete warm weather years for overheating assessments

Bridging the gap between energy and comfort: Post-occupancy evaluation of two higher-education buildings in Sheffield

Recent technical guidance has suggested that comfort and energy efficiency should not be seen as mutually exclusive [CIBSE, “TM54: Evaluating operational energy performance of buildings at the design stage”, 2013]. Currently, however, there is a lack of comprehensive understanding of energy use during building operation and how it influences user comfort. Through comparison of the complex relationships between energy, thermal comfort, and environmental strategy in two flexible highereducation buildings in Sheffield, this paper demonstrates how designers can utilise aspects of active and passive design to deliver more comfortable, lower-energy workspaces. Analysis of the authors’ post-occupancy evaluation of each case study examines what lessons might be learnt and applied to other institutional buildings in order to save energy without compromising occupant comfort. The findings illustrate how perceptions of comfort can be improved by increasing the degree of environmental control occupants have without necessarily increasing energy consumption. The paper highlights the significance of occupancy patterns to a complete understanding of energy efficiency and comfort, and speculates that the prediction and assessment of energy per occupant may have an important future role to play in bridging the gap between energy performance and comfort

Impact of Emerging Interaction Techniques on Energy Use in the UK Social Housing

End use energy efficiency and fuel poverty is one of the major issues in the UK social housing sector. It is estimated that about 10% of English households live in fuel poverty. During 2015 UK greenhouse gas emission final figures show that the net CO2 emission was reduced by 4.1% between 2014 and 2015. This shows that the UK is on course to attain its second carbon budget with annual 2013–2015 emissions that are each below the estimated level for the period. However, the housing sector lags with a 4% increase in emissions over the same period. More work needs to be done in this sector. Householders can adopt more efficient energy use approaches and make better lifestyle choices to save money and have a safer environment. This research addresses government priorities to reduce energy demand, meet CO2 reduction targets, and reduce domestic reliance on fossil fuels, offering protection from price risks and fuel poverty as well as providing more affordable and comfortable domestic environments. The proposed research paper deals with novel interaction methods on energy use in social housing and how the aforesaid issues can be reflected on. A detailed background study on existing interaction methods and ongoing development of a serious game trialled in 19 households has been carried out. It has been noted that displaying real-time utility use and indoor environmental conditions to householders increased awareness and impacted how energy is being consumed. Furthermore, the proposed paper will investigate end use energy profile pattern changes due to novel interaction methods

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

Overheating in English dwellings: comparing modelled and monitored large-scale datasets

Monitoring and modelling studies of the indoor environment indicate that there are often discrepancies between simulation results and measurements. The availability of large monitoring datasets of domestic buildings allows for more rigorous validation of the performance of building simulation models derived from limited building information, backed by statistical significance tests and goodness-of-fit metrics. These datasets also offer the opportunity to test modelling assumptions. This paper investigates the performance of domestic housing models using EnergyPlus software to predict maximum daily indoor temperatures over the summer of 2011. Monitored maximum daily indoor temperatures from the English Housing Survey's (EHS) Energy Follow-Up Survey (EFUS) for 823 nationally representative dwellings are compared against predictions made by EnergyPlus simulations. Due to lack of information on the characteristics of individual dwellings, the models struggle to predict maximum temperatures in individual dwellings and performance was worse on days when the outdoor maximum temperatures were high. This research indicates that unknown factors such as building characteristics, occupant behaviour and local environment makes the validation of models for individual dwellings a challenging task. The models did, however, provide an improved estimate of temperature exposure when aggregated over dwellings within a particular region

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