bluuebunny/crossref_metadata_2025 huggingface dataset:
Employment Inequality Revisited
Authors: Doren Bonnie , Benz Michael R.
Published: December 2008

Young women with disabilities are more likely to experience poorer postschool employment outcomes than young men with disabilities. This study explores factors associated with better employment outcomes for both young women and young men with disabilities, and factors associated uniquely with better outcomes for young women. Findings indicate that two factors predict better outcomes for both young women and young men with disabilities: having two or more job experiences while in high school, and having used the self-family-friend network to find their postschool job. Females who came from a family with a low household annual income, who had low self-esteem at the time of exit from high school, and who fit both of these characteristics were much less likely to be competitively employed out of school than females who did not fit these characteristics. These variables did not affect the employment status of males in the study. Implications for both practice and research are discussed.
To Teach Me is to Know Me
Authors: Kea Cathy D. , Utley Cheryl A.
Published: December 2008

Many students do not succeed in school because their cultural, social, and/or linguistic characteristics are unrecognized, misunderstood, or devalued. The continuing problem of disproportionate representation of multicultural students in special education programs is controversial. We believe that for teacher educators and practitioners to reach and teach multicultural students with and without disabilities, they must first know them. We propose three solutions to address the problem of disproportionate representation: (a) training of culturally and linguistically diverse teachers in teacher preparation programs, (b) the inclusion of multicultural education perspectives in special education, and (c) the implementation of culturally responsive instruction in classroom settings. These three solutions are key components to increasing the cultural competence of practitioners in special education teacher preparation programs.
Study of Amino Functional Polysiloxane Film on Regenerated Cellulose Substrates by Atomic Force Microscopy and X-ray Photoelectron Microscopy
Authors: Qiufeng An  , Qianjin Wang  , Linsheng Li  , Liangxian Huang
Published: December 2008

Film morphology, surface compositions and hydrophobic properties of N-β-aminoethyl-γ-aminopropyl polysiloxane (ASO-1) coated on regenerated cellulose (cel) substrate surface (ASO-1/cel) were investigated and studied by atomic force microscopy, X-ray photoelectron spectroscopy and other techniques. Influenced by the irregularities of cel substrate, ASO-1/cel showed a very similar microscopic morphology to the cel. In addition, the ASO-1/cel surface was hydrophobic. There were strongly hydrogen-bonded linkages at the interface between ASO-1 and cel. All the data indicate that ASO-1 molecules interact with the regenerated cellulose in such a way that the hydrophobic silicon methyl (Si-CH3) groups are oriented towards the air, while the Si—O dipole bonds as well as the polar amino groups are aligned towards the interface of the cellulose substrate.
Low Water and Energy Saving Process for Cotton Pretreatment
Authors: Preša Polonca , Forte Tavčer Petra
Published: December 2008

Cotton fabric was alkaline scoured with sodium hydroxide and bioscoured with acid or alkaline pectinases. In addition, the scoured fabrics were bleached with hydrogen peroxide (HP) or peracetic acid (PAA). The cotton fabric was treated simultaneously with pectinases and PAA in a one-bath process. The CIE whiteness, water absorbency, weight loss, tenacity at maximum load, and dyeability with a reactive dye were evaluated on differently pretreated samples. The remaining scouring and bleaching baths were analyzed for ecological parameters including pH, total organic carbon (TOC), chemical oxygen demand (COD), and biological oxygen demand (BOD5). The quantity of water and energy used for different processes was estimated. The water absorbency of all scoured fabrics was satisfactory. The degree of whiteness of all bleached fabrics was improved. The highest degrees of whiteness were from HP bleached samples. Less whiteness was achieved in PAA bleached samples. The whiteness was greater in the alkaline scoured fabrics relative to the enzymatic scoured fabrics. One-bath processes produced whiteness values comparable to alkaline scouring and bleaching with PAA. Neither of the processes had little effect on the tenacity at maximum load. All samples were evenly dyed with reactive dye. There was a remarkable color difference between samples that were alkaline or enzymatically scoured before dyeing and between differently bleached samples. On the other hand, there was no noticeable color difference between samples that were scoured and bleached in two-bath or one-bath processes before dyeing. In comparison to conventional pretreatment, less energy and water is used in enzymatic and/or PAA treatments since they proceed at 60°C and at a pH between 6 and 8. Therefore, neutralization is unnecessary. The remaining baths are biodegradable. During the one-bath scouring/bleaching process, the consumption of water and energy was even lower and the production time was shorter.
Delicate Engagement
Authors: Bambara Cynthia S. , Harbour Clifford P. , Davies Timothy Gray , Athey Susan
Published: December 2008

This article reports the findings of a phenomenological study that examined the lived experience of community college students enrolled in high-risk online courses (HRCs) at a community college in the American Southeast. HRCs were defined as college courses with withdrawal or failure rates of 30% or more. In-depth interviews were conducted with 13 students enrolled in four different HRCs. Isolation, academic challenge, ownership, and acquiescence emerged as structural themes that framed the experience of participants. These structural themes intermingled in discrete ways that led to the survival or surrender of these HRC participants and formed the essence of the phenomenon that is referred to as delicate engagement, which speaks to the vulnerable threads of academic and social involvement that permeated the HRC student experience.
Review of possible implications of an airtightness standard for new dwellings in the UK
Authors: Lowe R. , Johnston D. , Bell M.
Published: December 2008

The central purpose of this paper is to develop and test a case for compulsory pressurisation testing for new dwellings. The authors have argued elsewhere in favour of such a policy. The paper reviews the available information on airtightness in the UK housing stock, the impact of airtightness on ventilation and fabric heat losses, the information that is available on the costs of making houses airtight and the logistics of pressurisation testing. The authors use this information to explore the costs and benefits that might accrue at the national level from the introduction of such a policy. While a number of areas of uncertainty are apparent, the analysis shows a modest but apparently robust economic case for the introduction of pressurisation testing of new housing.
Detergency in soil and vent pipe (SVP) systems
Authors: Campbell D.P. , MacLeod KD
Published: December 2008

Current soil and vent pipe (SVP) system design guides aim to produce ventilated drainage networks, which protect attached water trap seals from unwanted air pressure effects that cause failure of trap seals. The ventilation design guides are based on steady-state experiments utilising cold clean water as a test medium. However, most 'grey' and 'black' water sources are dosed with detergent, and are often warm, which significantly alters the behaviour when compared to the use of clean water. Thus, current design standards provide only approximations of SVP system response. This paper quantifies the effect of detergents in SVP systems in terms of observed air entrainment rates and previously published research on the factors that contribute to air entrainment.
Robust control of HVAC plant II: controller design
Authors: Underwood C.P.
Published: December 2008

A linear time-invariant model has been fitted to simulated results from the nonlinear air heating plant described in Part I. The model describes the plant well subject to uncertainty in two of its parameters. These uncertainties have been used to derive an uncertainty weight that, together with a performance weight, have led to an augmented plant description. The resulting augmented plant model was used to develop a robust controller that minimises the H--notm of the closed-loop plant based upon the solution of two algebraic Riccati equations. The resulting controller is of the same order as the augmented (fifth-order) plant. Simulation results of the robust controller compare very favourably with a locally-optimised PID controller developed in Part I. The main advantage of the robust controller is that it merely requires a knowledge of the uncertainty limits of a simple linear model of the plant, whereas a PID controller of comparable performance would need extensive parameter tuning in practice.
Mechanistic model of centrifugal chillers for HVAC system dynamics simulation
Authors: Wang S. , Wang J. , Burnett J.
Published: December 2008

A chiller model is developed to simulate the operational performance of centrifugal chillers based on the performance data from site measurement. The model is developed on the basis of basic mechanistic principles of chillers to ensure the reliability and accuracy of the model in a wide working range using the parameters identified using limited performance data. A pre-processor identifies the parameters of chillers using chiller performance data to ensure convenience of application. This paper presents the model, the strategy for model parameter identification, and the applications and validation of the model on an existing multiple chilling system in a building and on a chiller using manufacturer's catalogue data.
Building services component reuse: A response to the need for adaptability
Authors: Webb R.S. , Thomson D.S. , Kelly J.R.
Published: December 2008

As businesses become more dynamic, their need for supporting buildings providing flexibly usable space is growing. While such space can readily be constructed, its servicing remains problematic. Continued use of existing practice to alter services installations with increasing frequency is predicted to have detrimental whole-life cost and environmental consequences. The reuse of functionally obsolete services components has been proposed as a new, more adaptable, method of servicing buildings. Such component reuse will implement the proposal of the UK government, proposed in one of its 'Technology Foresight' reports, that standardised components be reused to increase the competitiveness of the UK construction industry. This paper summarises models developed by a recently completed pilot study to assess the technical and economic feasibility of component reuse. These models identify the potential viability of component reuse but also identified a number of issues requiring further, more detailed, investigation.
Ground heat transfer: Some further insights into the influence of three-dimensional effects
Authors: Rees S.W. , Thomas H.R. , Zhou Z.
Published: December 2008

The results of a numerical investigation of three-dimensional ground heat transfer are presented. In particular, the influence of varying floor slab geometry has been considered within an assessment of the importance of maintaining full three-dimensionality in the analysis of heat losses to the ground. A comparison is made between three-dimensional (3D) and two-dimensional (2D) representation of a particular series of test problems. The results obtained, for the specific problems analysed, suggest that two-dimensional simplification can lead to heat flux calculations that differ by at least 45% from the three-dimensional analysis of the problem. An analysis of the results is presented that can be used to aid the choice of analysis to be performed, estimate 3D behaviour from 2D analyses; and estimate the relative errors associated with 2D and 3D heat and flux calculations. The results achieved also help substantiate earlier findings that suggest that equations used to estimate heat flux should include reference to the area/perimeter ratio and not simply to the perimeter. One practical equation of this kind is suggested. Further work is required before more general conclusions can be made.
Energy cost reduction in industry†
Authors: Winch G.R. , Tuxford A.F.
Published: December 2008

The article describes the value and method of studies of energy usage in factories by means of case studies in milk processing, cheese manufacture, beer brewing and safety glass manufacture. The financial results of energy cost reduction surveys are emphasised. The technical aspects of the measures required to secure the savings in annual operating costs are described.
Interstitial condensation: Applicability of conventional vapour permeability values
Authors: McLean R.C. , Mashrae Mcibse , Galbraith G.H.
Published: December 2008

Condensation is now one of the greatest building problems of this decade, and it is essential that the mistakes of the past are not repeated in the future. Accurate predictive techniques for interstitial condensation are now being used widely, but calculations are only as accurate as the input vapour permeability data. Although a considerable quantity of data are available, much of these are shown to be of limited use, only applying to the conditions under which the material was originally tested. The vapour permeability of plasterboard and plywood is investigated and a new approach to the presentation of vapour permeability data is suggested.
Plate recuperators used with air/air heat pumps in building ventilation systems
Authors: Olsen H.R.
Published: December 2008

The economic viability of stand-alone heat pumps for space heating is limited by the achievable coefficient of performance. By combining the heat pump with a plate recuperator in full fresh air systems the average heating season efficiency can be increased to the equivalent of a COP of 6. The system works both as a heating and cooling system and will provide over 90% of annual energy requirement, making the use of central heating plant for back-up heating uneconomical. The resulting capital cost saving can be used to offset in part or in full the extra capital cost of the heat pump equipment.
Thermal bridging: Significance in U-value calculation
Authors: Siviour J.B. , Mould A.E.
Published: December 2008

Thermal bridging by, for example, structural timber and mortar joints, is far too often neglected in U-value calculation. This is the case even with Building Regulations 'deemed to satisfy' constructions. Such bad practice is unnecessary because the CIBSE Guide Section A3 provides a method of calculation. This Note illustrates numerically the effects of thermal bridging in some typical building elements. The U-values are calculated by the CIBSE method allowing for thermal bridging, and compared with values calculated ignoring it.
Longitudinal ventilation analysis for the Limehouse Link Tunnel with slip roads
Authors: Leung K.M. , Wood D.W.
Published: December 2008

The paper addresses the ventilation system design and analysis for the Limehouse Link Tunnel, a 1.6 km dual carriageway vehicular tunnel with an incoming slip road on the south carriageway and an outgoing slip road on the north carriageway. The road cross-section varies to accommodate speed change lanes. The tunnel complex is represented mathematically by a series of flow paths with nodes. The paper describes the design features, the major system components and the technique used in analysing the system.
Olf and decipol: New units for perceived air quality
Authors: Fanger P.O.
Published: December 2008

In many offices, schools, dwellings and other non-industrial buildings the air is often perceived as annoying, unpleasant, stale, and stuffy. In many cases it has not been possible to identify the causes of these complaints by chemical analysis of the air. Therefore, two new units, the olf and the decipol, have been introduced to quantify how air is perceived by human beings. Olf is a unit which quantifies the source strength of air pollution; decipol is a unit quantifying perceived air pollution. Humans perceive the air by their olfactory and chemical sense, being sensitive to odorants and irritants in the air.
Domestic ventilation unit with heat exchanger and heat pump
Authors: McIntyre D.A.
Published: December 2008

A ventilation heat recovery unit was installed in an Electricity Council Research Centre test house. The unit consists of a cross flow heat exchanger augmented by a small heat pump. It supplies warm air to all inhabited rooms, while extracting air from kitchen and bathroom. Trials were run during the winter of 1986/87. The unit provided a ventilation air flow of 180 m 3 h-1, and a gross heat input to the house of 1.7 kW; this figure is averaged over time, and includes the effect of defrost periods. An overall coefficent of performance of 3 was achieved. Such a system can provide the greater part of the heating requirement of a low-energy house, and has its own advantages over other heating systems.
Variable compressor speed control: Economic evaluation
Authors: Wong A K H
Published: December 2008

The capital and annual energy consumption costs of an air conditioning system were evaluated to assess the economic application of variable compressor speed for refrigeration system capacity control. This system was compared with two other capacity control systems, hot gas bypass and cylinder unloading, for both continuous and intermittent operation. It was concluded that variable compressor speed control is only economically viable when used for continuous operation.
Condensation avoidance in layered structures: Synfihesis of designs
Authors: Letherman K.M.
Published: December 2008

The standard prediction method for assessing the risk of condensation in layered structures in the steady state is discussed, and it is pointed out that this is essentially an analysis method for a case which has to be pre-defined. Designers may prefer to have methods of synthesising a construction which avoids condensation under given humidity and temperature conditions, or of finding the limiting conditions for condensation to be avoided with a given construction. Equations are presented for the calculation of the necessary thermal and vapour properties of layers added to existing designs in order to eliminate condensation risk and permit a chosen safety margin, and for calculation of the limits on humidity for elimination of condensation in a given construction. Examples are given to illustrate the use of the equations.
Thermal response of temporary school buildings: II Summertime overheating
Authors: Penman J.M. , Murdoch N.
Published: December 2008

A simplified dynamic thermal response model has been used to study summertime overheating in temporary school buildings as a function of thermal insulation thickness, building orientation, external colour, shading, occupancy and ventilation rate. Practical advice on ameliorative strategies is given, and the provision of ventilation under buoyancy-driven flow discussed in some detail. It is suggested that dynamic thermal modelling could usefully be combined with the stack effect equation for the design of natural ventilation in buildings.
Air flows between two zones: Accuracy of single-tracer gas measurements for estimation
Authors: Riffat S.B.
Published: December 2008

This paper examines the accuracy of various theoretical methods for the analysis of experimental data on interzone air movement obtained using a single tracer gas technique. Two types of data were examined; (a) well conditioned data obtained in the laboratory from measurements of air movement between two chambers and (b) less well conditioned measurements made in houses. Errors in calculated flow rates were found to be in the range -8 to 33% for well-conditioned measurements. For less well-conditioned data the estimated values of air flow rates were spread over a wide range and it was not possible to establish the errors in these values as the real flow rates were unknown.
Ventilation and the leakage characteristics of dwellings
Authors: Galbraith G.H. , McLean R.C. , Stephen R.
Published: December 2008

As fabric heat losses decrease with improved thermal insulation, ventilation heat losses, as a fraction of the total, become relatively more important. Thus, further effective energy savings may best be achieved by reducing energy losses associated with excessive ventilation. However, a means of measuring ventilation levels, or the magnitude of the air leakage paths through which ventilation takes place, is required to ensure that sealing of some openings does not result in unacceptably low ventilation rates and the accompanying risks of condensation, mould and poor indoor air quality. The fan-pressurisation technique does not measure ventilation rate directly, but air leakage data may be used for comparisons between houses and to predict ventilation rates which would occur under natural conditions. Air leakage data for a sample of 32 traditionally constructed Scottish dwellings are presented and discussed. The mean air leakage rate in these dwellings was found to be 60% higher than that found in a sample of 100 dwellings throughout the UK. It is concluded that there is considerable scope for reducing air leakage rates, and therefore ventilation heat loss, in many Scottish dwellings.
Science and Engineering Research Council research reports
Authors: Building Serc
Published: December 2008

The article reports research carried out into ventilation, air movement and heat transfer within large spaces. The work has many facets ranging from energy consumption to ventilation requirements. Practitioners interested in current developments should contact SERC direct† for a full list of sponsored projects.
Building heat loss calculations: Choice of internal temperature and of heat exchange coefficient hi
Authors: Uyttenbroeck J.
Published: December 2008

In most European countries transmission heat losses through external building elements have been calculated for many years on the basis of an ill-defined internal temperature, but with constant heat exchange coefficients at the inner side of the building elements. The paper concludes that constant heat exchange coefficients are satisfactory if dry resultant temperature is taken as the internal temperature. The advantage of this usage is that in most cases the dry resultant temperature is known a priori because it corresponds for practical purposes with the derived confort temperature in the rooms.
Mean radiant temperature in the CIBSE Guide
Authors: Davies M.G.
Published: December 2008

The term 'mean radiant temperature' is used in Section A1 of the CIBSE Guide in connection with thermal comfort, and in Section A5 in connection with the thermal response of an enclosure. With one amendment, the argument of Section A1 is correct but those of Section A5 are flawed and incomplete. This Note draws attention to the need for three separate measures of radiant temperature in a room: the local value Trp (potentially observable), its space-averaged value ( Trv), and the radiant star temperature Trs. ('Mean radiant temperature' might refer to any of these.) A study of room radiant exchange requires explicit consideration of the role of surface emissivity, and of the effect of long-wave energy flow from an internal heat source. It is pointed out that the conductances associated with this exchange (and also the convective exchange) are 'large', while the radiant and convective conductances associated with comfort temperature are 'small'.
Internal long-wave radiation exchange in buildings: Comparison of calculation methods: II Testing of algorithms
Authors: Stefanizzi P. , Wilson A. , Pinney A.
Published: December 2008

The pair of papers of which this is the second presents some of the commonest methods for calculating long-wave radiation heat exchange in a room. Paper I covered the theory behind the various methods. These vary in complexity from accurate calculation of view factors with multiple inter-reflections between surfaces to simple, non-geometric methods using fixed heat transfer coefficients. This paper (Paper II) presents the results of a set of tests which were developed to compare the performance of these algorithms with an analytically exact method. The main conclusion is that in many cases it is possible to use a non-geometric model without significant loss of accuracy. A more accurate method is required in cases of low surface emissivity or large temperature differences between surfaces. The importance of internal long-wave radiation for the overall energy balance of typical houses was tested, and the results are presented here. If no account is taken of long-wave exchange (disabling exchanges by setting all internal emissivities to zero), predicted energy requirements change by up to -11% in the type of house and heating system tested. Greater changes could arise in different house types or those with a larger radiant output from the heating system. The results also showed the importance of modelling long-wave exchange to and from windows explicitly.
Empirical and theoretical optimum start algorithms
Authors: Murdoch N. , Penman J.M. , Levermore G.J.
Published: December 2008

Optimum start algorithms are evaluated using a dynamic simulation model. The performance of empirical algorithms, based on an assumed preheat curve, is compared with theoretical algorithms which rely on a building model. These algorithms are tested for variations in plant sizing ratio and building thermal mass. The parameters used in the empirical algorithms are approximately related to the plant sizing and thermal mass and it is suggested they could be used as concise building monitoring indices. An improved first-order theoretical algorithm is introduced and it is shown how its parameters may be extracted from the building thermal time series. Its performance is comparable with a reliable log (time) empirical algorithm which monitors external as well as internal temperature.
Thermal comfort studies and applications for Dhaka
Authors: Ahmed Z.N. , Howarth A.T. , Zunde J.M.
Published: December 2008

In countries with hot climates, thermal comfort always depends on the acquired tolerance of people to the prevailing conditions, and from this stems their perceived comfort level indoors. Comfort evaluation must allow for acclimatisation if economic environmental control systems are to be specified. Previous comfort studies are critically evaluated for application to the Bangladesh climate. The most appropriate findings are summarised and considered in the context of local vernacular design and social requirements.
Outbreak of Legionnaires' disease at Stafford District General Hospital
Authors: Brundtett G.W.
Published: December 2008

In April 1985 175 patients were admitted to the District or Kingsmead Stafford Hospitals with chest infection or pneumonia. 28 died. The medical diagnosis showed that this was Legionnaires' disease and the immediate epidemiological investigation traced the source of the infection to the air-conditioning cooling lower on the roof of the Stafford District Hospital. A Government Inquiry was set up to investigate how the infection occurred and why it became Britain's largest epidemic of Legionnaires' disease. This paper describes the case history of events. The infection was linked to one small zone in the hospital, the outpatients department. The initial investigation searched for engineering reasons to explain why this particular zone was the risk area. More detailed and wider epidemiological surveys subsequently showed that staff working in the whole area supplied with fresh air taken adjacent to the tower, had antibodies to the disease. The outpatients department was unique in having a very large transient population of susceptible individuals either receiving treatment or accompanying friends. The implications of this case are important to all practising engineers. The speed of such epidemics is frightening: The whole cycle of the outbreak started suddenly and was over before the investigations began.
Availability of monitored hourly building performance data for validating dynamic thermal models of buildings
Authors: Lomas K.J.
Published: December 2008

As part of the SERC/BRE sponsored exercise to develop tools for validating dynamic thermal models, Leicester Polytechnic undertook a review and evaluation of monitored structures to identify data sets suitable as the basis for empirical validation tools. Over 580 monitored buildings located throughout the world were classified and assessed; all had produced hourly building performance data and had associated weather data. Data from only 18 structures, located at six sites in Europe and the USA, were deemed to be of high enough quality that they could be used for validating a wide range of complex dynamic and simpler thermal models. This Note gives an overview of the evaluation procedure, the types of data available and the major conclusions of the research.
Pressure-driven flows around doors
Authors: Howarth A.T. , Taylor-Firth A.
Published: December 2008

A major occupancy-controlled parameter affecting inter-zonal air movements is the internal door. Pressure-driven flows around an internal door in closed and partly open positions are measured. For closed doors, the strong influence of under-door clearance is observed and the crack flow regime is dominant. Even for small openings of doors, the transition to orifice flow is observed, giving a discharge coefficient of around 0.6.
Airflow between two zones: Comparison of experimental results with the MULTIC computer program
Authors: Riffat S.B. , Abdalla W.E.
Published: December 2008

A tracer-gas technique is used to measure airflow between two zones of a house and experimental results are compared with airflow rates predicted by the MULTIC computer program. Tracer gas measurements were generally found to be in good agreement with values predicted by the computer program.
Domestic radiators: Performance at lower mass flow rates and lower temperature differentials than those specified in standard performance tests
Authors: Ward I.C.
Published: December 2008

The heat output from conventional hot water radiators falls as the return temperature and the mass flow rate are reduced. This paper presents the results of an experimental investigation into the output of some commonly available British pressed steel domestic radiators when operating at conditions of low mass flow rate or higher temperature differentials across the radiator. It also addresses the problems encountered at mass flow rates less than 20% of the design flow rate and lower temperature differentials.
U-values of uninsulated ground floors: Relationship with floor dimensions
Authors: Anderson B.R.
Published: December 2008

The paper examines the calculation of U-values of uninsulated ground floors, and proposes a method based on the area and perimeter of the floor. The method gives values consistent with the procedure in the current CIBSE Guide and is a more flexible alternative, especially for irregular shapes of floor. It is proposed to incorporate this new basis in the revision of the material in Section A3 of the current Guide.
Room heat needs in relation to comfort temperature: Example using the rad-air model
Authors: Davies M.G.
Published: December 2008

Following the methods developed in an earlier paper, an example is given to illustrate the calculation of room heat needs using the rad-air model.
HVAC optimisation studies: Steady-state fan model
Authors: Wright J.A.
Published: December 2008

Heating, ventilating and air conditioning (HVAC) system simulation and optimisation studies require large component product databases; the quantity of data required to model any one component should therefore be kept to a minimum. This paper describes a steady-state model for ducted fans that compacts the quantity of data required to model a range of fans. The model also allows any initial form of data and incomplete characteristics to be modelled. Submodels for performance, energy, constraints and cost are described. An example model and simulation are given. The model is flexible and accurate enough to be used in general simulation and optimisation studies.
Review Paper: Building simulation and building representation: Overview of current developments
Authors: Wright A.J. , Bloomfield D. , Wiltshire T.J.
Published: December 2008

This paper reviews the current state of thermal modelling for buildings, and describes developments in data modelling, object-oriented programming and specific research projects which indicate the likely course of future developments. The limitations of the data structures and processes of current programs are described, in the context of the forces which drive development. Emerging international data exchange standards, which are likely to be a major influence on future engineering software, are examined in the context of building modelling. The applicability of object-oriented programming to building simulation is explained. Finally, a number of research projects are described; some aim to facilitate the production of new simulation programs, while others aim to integrate a set of design tools sharing a common building description.
Thermal conductivity of concrete: Effect of moisture
Authors: Tinker J.A. , Cabrera J.G. , Ganjian E.
Published: December 2008

The thermal conductivity λ of eight concrete specimens, containing Pellite, limestone or quartz aggregate with and without air entraining agent, varying in density from 1550 to 2350 kg m-3, have been measured at several moisture contents between 0.04 and 15.5 per cent by volume. Although λ increased with increasing moisture content, the change was much less than that predicted by the Jakob factors. In general, the moisture factors were found to be density dependent and to increase with decreasing density. A general expression has been derived relating the moisture factor to both density and moisture content by volume over the range 0-5%.
Ice storage: Design study of the factors affecting installations
Authors: Beggs C.B. , Ward I.C.
Published: December 2008

The extent to which ice thermal storage is adopted depends very much on its commercial viability. To establish fully the economic viability of such systems, it is necessary to examine the factors which affect their operation over a complete cooling season. This paper examines the factors affecting the economic performance of ice storage systems, and investigates the impact of variations within these factors on ice storage systems. An investigation is made of systems controlled by both chiller priority and store priority operating strategies. The figures quoted in the text are the results of an ice storage computer program developed by the authors.
Heat loss: A comparison of four European calculation methods
Authors: Simmonds P.
Published: December 2008

With the advent of 1992 European building services engineers will be looking at the possibilities of 'spreading their wings' and working in other countries. Calculation methods will come under close scrutiny. This paper shows how the heat losses for a reference room are calculated in four European countries. The basis of these calculations was the German DIN 4701 from 1959. This has been improved slowly over the years by Germany, the Netherlands and Belgium. The CIBSE method was the fourth method to be compared. The results do not differ greatly but the approach is different for each method. The first conclusion is that it wil take a great deal of discussion before a uniform European code can be produced.
Harmonics due to non-linear loads: Investigation in high-rise commercial buildings
Authors: Lai E C C
Published: December 2008

Nowadays, non-linear electrical loads are commonly found in domestic, commercial and industrial buildings. These loads draw a distorted current from the supply system and thus cause harmonic distortion. In this paper, various harmonic generating loads in high-rise commercial buidings are identified and their harmful effects are analysed. Site measurements on harmonic currents were taken and associated problems were studied. Guidelines on the minimisation of harmonics and their associated effects in distribution systems in buildings are given.
Conduction in dynamic thermal models: Analytical tests for validation
Authors: Bland B.H.
Published: December 2008

Analytical tests are based on physically simple cases for which the exact solution is known. A set of recommended analytical tests is described for the validation of conduction calculations in dynamic thermal models of buildings. They are one product of a collaborative research project on model validation. The principal advance is the explicit recognition of the need to design tests differently for (a) verification and debugging, in which not more than one source of error should contribute to the difference observed between model predictions and exact solution, and (b) tests to estimate the likely accuracy in use, in which ultimately all sources of error should be active in the way that they would be in a normal building simulation. The chief obstacles to creating such clear-cut tests are the discretisation errors arising from input sampling and reconstruction, and other deliberate approximations used in the modelling. It is shown that it is possible to construct tests that have all the necessary properties, without having recourse to tests of isolated sub-models. It is strongly recommended that analytical tests be made available as a software facility accessible to users, and be applied: (i) to programs by their authors, both when new, and as part of routine software maintenance, (ii) to established programs by independent validators.
Moisture movement and extractor fans : Experimental study
Authors: Saiz N. , Kolokotroni M. , Littler J.
Published: December 2008

This paper describes an experimental study of moisture migration in a small dwelling. Experiments were carried out to measure the migration of moisture from the kitchen and bathroom to the rest of the house. Extractor fans and a cooker hood were operated to reduce the migration, and their effectiveness was measured. The tracer gas step-up method was also used to measure the air movement. The transfer index was used to characterise the migration. The results show the relative effectiveness of the fans running at various speeds. They also show how much moisture and tracer gas migrates into each room.
Interstitial condensation in building structures: Revised model for identifying problem material combinations
Authors: Taylor B.E.
Published: December 2008

The computation of interstitial condensation risk, in particular the rate of condensation, has increased in importance in assessing the acceptability of building details, especially those incorporating insulation or vapour-resisting materials. This Note details a model which incorporates effects currently omitted from the present methods; in particular, the effect of the presence of the saturated water film, the absorption of water by the materials and the latent heat flow resulting from the condensation or drying out process. It is shown that in some simple example cases these effects can considerably alter the conclusions that might be drawn concerning the acceptability or otherwise of a combination of materials and environmental conditions.
Vapour permeability: Suitability and consistency of current test procedures
Authors: Galbraith G.H. , McLean R.C. , Tao Z.
Published: December 2008

The avoidance of condensation problems in the future depends on designers having available accurate and reliable vapour permeability values. The emergence of free trade within the European Community requires the transferability of measurement data between countries, as well as between individual laboratories. This paper describes a recent European intercomparison carried out to assess the comparability of existing permeability measurement techniques, and to provide the information required to enable future international standards to be properly formulated. Identical samples of two materials were tested by eleven laboratories covering thirteen European countries. At the beginning of the project detailed instructions were issued on all aspects of the test procedure. Even with such an approach, many of the participants failed to comply with all of the test requirements, and the data produced exhibited unacceptably large variations between laboratories. The major contributory factors for this are discussed, and recommendations on a possible approach to the development and implementation of a future international test standard presented.
Controlled background ventilation for large commercial buildings†
Authors: Perera M D A E S , Marshall S.G. , Solomon E.W.
Published: December 2008

A preliminary study was carried out on a naturally ventilated office built as a low-energy building. The study uses a multi-zoned prediction program to determine a ventilation strategy to provide controlled background ventilation. Full-scale, whole-building pressurisation measurements are used to provide envelope leakage characteristics. The surface wind pressure coefficient data are provided through measurements carried out in the Building Research Establishment's Environmental Wind Tunnel. This study assessed the effectiveness of permanent but controllable background ventilators in naturally ventilated office-type buildings with various envelope tightnesses. Preliminary results show that, during the heating season, it is possible to provide adequate background ventilation for occupant comfort by incorporating commercially viable, manually controllable trickle ventilators within each room. Recommendations for possible consideration may be that 4000 mm2 open-area ventilators could be used in rooms with floor areas less than 10 m2, and 400 mm2 per m 2 (of floor areas) for those which are larger.
Modelling water vapour conditions in buildings
Authors: Jones R.
Published: December 2008

This paper proposes a 'moisture admittance' model which accounts for the moisture absorption and desorption processes for predicting humidity levels in buildings. The experimental method whereby the required coefficients were derived is described and some examples of the results are given. The approaches to real buildings, as opposed to test rooms, and possible modifications to BREDEM are briefly discussed.
HVAC simulation studies: Solution by successive approximation
Authors: Wright J.A.
Published: December 2008

Large-scale system simulations are efficient in solving large equation sets. However, where the simulation is restricted to a single component or subsystem; however, it is often more efficient to solve the equation set by a simple iteration. This paper describes the use of a successive approximation algorithm in solving equations for small-scale steady-state HVAC system simulations. The algorithm is shown to be robust and easily implemented.
Variable-volume-flow secondary water system: Best location for differential pressure sensing and control
Authors: Lau K.K.
Published: December 2008

A simple analysis is presented which calculates the best location of differential pressure sensing and control for large variable-votume-flow secondary water systems. The condition addressed is when the pressure drop across the coils at full load is very small compared with the pressure drops across the supply and return mains. The purpose of putting the sensor at the best location is to make valve authorities of control valves as high as possible, and the associated benefit is a reduced pumping head.
Rotary absorption - recompression heat pump
Authors: Riffat S.B. , Shankland N.J. , Wong C.W.
Published: December 2008

This Note describes a rotary-absorption heat pump combined with a vapour recompression system. The absorption heat pump employs process intensification which exploits centrifugal fields. The heat pump has been analysed thermodynamically using H2O/LiBr and H2O/NaOH-KOH-CsOH combinations.
Intelligent rapid-response water heater for supplementing outputs from a domestic hot water store
Authors: Newborough M. , Probert D.
Published: December 2008

A modification to a conventional domestic hot water system is proposed, in order to reduce wastages of heated water and provide a more convenient means for consumers to obtain hot water at the temperature they require. A laboratory simulation of the behaviour of such an all-electric hot water supply, for a four-person single-family dwelling, reduced the proportion of hot water wasted from 32% to 8% of the amount required and yielded daily energy savings of 11%. The associated financial savings depend mainly upon the price per litre of water and the hot water temperature requirements of individuals.
Multivariate stochastic modelling of a full-scale office zone and air conditioning plant: The potential for BEMS
Authors: Loveday D.L. , Virk G.S. , Cheung J Y M
Published: December 2008

In facilities management, mathematical models have the potential to improve system management, to enhance control, and to maintain healthy conditions for occupants of buildings. Various model types and implementation methods exist, and to date these have chiefly been investigated using simulation and/or laboratory small-scale set-ups. In this paper, the application of the identification technique to full-scale system modelling is demonstrated. Multivariable stochastic models are identified which describe the thermal and moisture behaviour of air in a full-scale unfurnished office zone serviced by a dedicated air-conditioning plant. The models are used to forecast values af air temperature and relative humidity, and are validated by comparing their short-term (10-20 min) and long-term (several days) forecasts with measured data. Short-term prediction accuracies were found to be well within ±0.25°C in 19°C and ±0.6% RH in 53% RH, while corresponding long-term values were to within ±0.8 °C and ± 1.3% RH, respectively. The results show that good quality models are obtainable for full-scale systems, while comparisons with a simple piece-wise constant approximation (next value = current value) further demonstrated the superiority of the model-based approach. The implications for the future development of bems are also discussed.
Ice thermal storage: Application to demand-side management in the United Kingdom†
Authors: Beggs C.B. , Roberts L.
Published: December 2008

The paper investigates the use of ice storage technology as a demand side management tool. A theoretical study of a dairy application is described in which the costs of running an ice storage installation under a traditional maximum demand tariff are compared with those under a pool-based contract. The paper also describes a new dynamic ice slurry system currently under development.
Coupling of thermal and airflow calculation programs offering simultaneous thermal and airflow analysis
Authors: Kafetzopoulos M.G. , Suen K.O.
Published: December 2008

This paper assesses the feasibility of coupling a thermal simulation sofware (Apache†) with a multi-zone airflow software (Swifib†). The simultaneous multi-zone airflow and thermal analysis is particularly important in large enclosure buildings, such as atria. The study highlights the need for such analysis and shows that a new generation of combined thermal and airflow software can be produced by coupling the currently available thermal and airflow simulation software together. The combined software provides the design engineers with a fast, effective and computationally less demanding tool for analysing the performance of the built environment.