Regulations and robust low-carbon buildings

Building regulations and associated calculation methods have been rapidly evolving, driven in Europe by the European Union Energy Performance of Buildings Directive. As an example, the current UK regulations are explored in relation to buildings that are naturally ventilated, mechanically ventilated, or mechanically ventilated and cooled. The UK regulatory energy and carbon calculation methods are investigated using a standard office design with typical, best practice, and advanced building fabric and systems applied. The criteria and calculations for demonstrating avoidance of excessive temperatures in buildings that have no mechanical cooling are also explored. Observations are made on how the regulations may influence future adoption of mechanical cooling. Current regulatory methods can be subjective and limited in scope. For example, they do not include adaptive comfort criteria or uncertainties in parameters such as occupant behaviour, climate, internal gains from equipment, etc. A design methodology is proposed that addresses these issues and provides a capability parameter to quantify robustness. This capability parameter allows comparison of design options and provides an indication to building users of the limitations to a building's use beyond which mitigating action would have to be taken for performance to be maintained

Simulation and BIM in building design, commissioning and operation: a comparison with the microelectronics industry

Analogy between the Microelectronics and Building industries is explored with the focus on design, commissioning and operation processes. Some issues found in the realisation of low energy buildings are highlighted and techniques gleaned from microelectronics proposed as possible solutions. Opportunities identified include: adoption of a more integrated process, use of standard cells, inclusion of controls and operational code in the design, generation of building commissioning tests from simulation, generation of building operational control code (including self-test) from simulation, inclusion of variation and uncertainties in the design process, use of quality processes such as indices to represent design robustness and formal continuous improvement methods. The possible integration of these techniques within a building information model (BIM) flow is discussed and some examples of enabling technologies given

Dietary-based gut flora modulation against Clostridium difficile onset

Clostridium difficile infection is a frequent complication of antibiotic therapy in hospitalised patients, which today is attracting more attention than ever and has led to its classification as a 'superbug'. Disruption of the composition of the intestinal microflora following antibiotic treatment is an important prerequisite for overgrowth of C. difficile and the subsequent development of an infection. Treatment options for antibiotic-associated diarrhoea and C. difficile-induced colitis include administration of specific antibiotics (e.g. vancomycin), which often leads to high relapse rates. More importantly, both the rate and severity of C. difficile-associated diseases are increasing, with new epidemic strains of C. difficile often implicated. For the prevention and treatment of antibiotic-associated diarrhoea and C. difficile infection, several probiotic bacteria such as selected strains of lactobacilli (especially Lactobacillus rhamnosus GG), Bifidobacterium longum, and Enterococcus faecium and the non-pathogenic yeast Saccharomyces boulardii have been used. Controlled trials indicate a benefit of S. boulardii and L. rhamnosus GG as therapeutic agents when used as adjuncts to antibiotics. However, the need for more well designed controlled trials with probiotics is explicit

Thermal mass, insulation and ventilation in sustainable housing - An investigation across climate and occupancy

Sustainable housing standards are reviewed including the UK 2005 building regulations, the UK Advanced Standard and EU Passive-house Standard. Conflicts between the standards are highlighted. The significance of insulation, orientation, ventilation, thermal mass, occupancy, gains, shading and climate on predicted energy performance is illustrated. An ESP-r model is then used to investigate these factors across a range of climates and occupancy / gains scenarios. The investigation covers both heating and cooling energy requirements. The relative importance of key factors is quantified and a matrix of results presented with conclusions. The role of simulation in informing design decisions is demonstrated as well as the importance of considering climate and occupancy/ gains patterns

Embracing variations in patterns of use, pre and post design phase, to improve tenant energy performance

This paper elaborates a new energy performance benchmarking method to support green tenancy agreements and other energy performance contracts. The existing national energy reporting method does not categorise systemic variations in patterns of use. Results of a case study monitoring operational data of a multi-tenanted office building are presented. The data reveals the actual designed spectrum of occupant density accounts for a 44% increase in tenant energy demand per square meter and a 112% increase in tenant energy demand per full time employees [FTE], dramatically affecting the buildings internal gains, heating and cooling requirements. The study highlights how low levels of occupancy and extended operational hours can give a false representation of energy efficiency

Why advanced buildings don't work?

The intent of policy is to achieve robust comfortable low energy buildings. However there are obvious policy disconnects and, where there is evidence, it appears that in general advanced buildings do not achieve their intended performance. There are many industry and policy initiatives aimed at improving industry processes such as: Soft Landings, BREEAM, LEED, Green Star, AGBR and BIM. In this paper the performance of buildings likely to be promoted by current policy is investigated and a number of significant and recurring problems identified. The possibility that these problems will be resolved by current initiatives is discussed and it is concluded that important gaps remain to be addressed

Carbon and energy performance of housing : a model and toolset for policy development applied to a local authority housing stock

The area of strategy formulation for energy and carbon performance of housing is coming under increasing focus. A model has been developed based on simulation results aligned with knowledge of the housing stock which can be used to calculate energy, carbon and cost results from a reduced number of input parameters. The context of the model can be varied to reflect different climates and patterns of use. The model is embedded in a user friendly java tool which can be used to give results for a dwelling or the housing stock of an organisation, region or country. It is possible to investigate the effect of housing upgrade options, future building regulations, climates, patterns of use, renewable energy systems etc. and support formulation of future policy. In this paper the tool is briefly described and an example given showing its application to a local authority rented housing stock

Thermal performance of a naturally ventilated building using a combined algorithm of probabilistic occupant behaviour and deterministic heat and mass balance models

This study explores the role of occupant behaviour in relation to natural ventilation and its effects on summer thermal performance of naturally ventillated buildings. We develop a behavioural algorithm (the Yun algorithm) representing probablistic occupant behaviour and implement this within a dynamic energy simulation tool. A core of this algorithm is the use of Markov chain and Monte Carlo methods in order to integrate probablistic window use models into dynamic energy simulation procedures. The comparison between predicted and monitored window use patterns shows good agreement. Performance of the Yn algorithm is demonstrated for active, medium and passive window users and a range of office constructions. Results indicate, for example, that in some cases, the temperature of an office occupied by the active window user in summer is up to 2.6ºC lower than that for the passive window user. A comparison is made with results from an alernative bahavioural algorithm developed by Humphreys [H.B. Rijal, P. Tuohy, M.A. Humphreys, J.F. Nicol, A. Samual, J. Clarke, Using results from field surveys to predict the effect of open windows on thermal comfort and energy use in buildings, Energy and Buildings 39(7)(2007) 823-836.]. In general, the two algorithms lead to similar predictions, but the results suggest that the Yun algorithm better reflects the observed time of day effects on window use (i.e. the increased probability of action on arrival)

Project management under uncertainty

Morris' (1986) analysis of the factors affecting project success and failure is considered in relation to the psychology of judgement under uncertainty. A model is proposed whereby project managers may identify the specific circumstances in which human decision-making is prone to systematic error, and hence may apply a number of de-biasing techniques

Performance assessment of tariff-based air source heat pump load shifting in a UK detached dwelling featuring phase change-enhanced buffering

Using a detailed building simulation model, the amount of thermal buffering, with and without phase change material (PCM), needed to time-shift an air source heat pump's operation to off-peak periods, as defined by the UK 'Economy 10' tariff, was investigated for a typical UK detached dwelling. The performance of the buffered system was compared to the case with no load shifting and with no thermal buffering. Additionally, the load shifting of a population of buffered heat pumps to off-peak periods was simulated and the resulting change in the peak demand on the electricity network was assessed. The results from this study indicate that 1000 L of hot water buffering or 500 L of PCM-enhanced hot water buffering was required to move the operation of the heat pump fully to off-peak periods, without adversely affecting the provision of space heating and hot water for the end user. The work also highlights that buffering and load shifting increased the heat pump's electrical demand by over 60% leading to increased cost to the end user and increased CO2 emissions (depending on the electricity tariff applied and time varying CO2 intensity of the electricity generation mix, respectively). The study also highlights that the load-shifting of populations of buffered heat pumps wholly to off-peak periods using crude instruments such as tariffs increased the peak loading on the electrical network by over 50% rather than reducing it and that careful consideration is needed as to how the load shifting of a group of heat pumps is orchestrated