bluuebunny/crossref_metadata_2025 huggingface dataset:
Reduction of window design risk in 'passive solar' houses: A proposed simple calculation method
Authors: Warren B.F.
Published: December 2008

The selection of inappropriate combinations of wall and window designs by the 'passive solar' designer may lead to a seasonal auxiliary energy penalty instead of the expected advantage. When window areas are increased beyond those necessary for adequate daylight and view out there is a greater risk of overheating and increasing auxiliary energy use. Computer performance assessments are usually based on a fixed operational scenario and do not take account of the different operational regimes which may apply over the lifetime of a house. It is necessary to use average seasonal values. A simple method is proposed whereby a designer may check the average efficacy of different combinations of window and wall designs for different orientations and so reduce the risk of incurring an energy penalty.
Hydraulic design of roof drainage gutters
Authors: Anderson J.A.
Published: December 2008

In this Note the design of roof gutters is based on a solution of the gradually varied flow equation with uniform lateral inflow entering the gutter at right angles to the flow. The flow capacities of standard valley, boundary wall, northlight, box and rectangular eaves gutters were determined for a full range of lengths and for typical gradients of zero, 1 in 600 and 1 in 350. It is shown that BS 6367 is somewhat conservative in predicting capacities for short horizontal channels. For gutters laid to a fall of 1 in 600 the capacity usually increases slightly with increasing length except for gutters of small cross-section, and for gutters laid to a steeper fall the capacity increases with increasing length of gutter.
Energy monitoring and its effect on energy consumption at the University of Wales, College of Cardiff (UWCC)
Authors: Knight IP
Published: December 2008

A 20-month old energy monitoring scheme has achieved a 14% reduction in gas energy consumption and costs at Cardiff University. This paper reviews the implementation of the energy monitoring scheme, briefly noting the main details including the data gathering techniques used and the main obstacles encountered. It also notes the total energy and cost benefits achieved to date along with measures proposed to maintain and improve the savings achieved.
Air-conditioning and mechanical ventilation design for queuing enclosures in a bus terminus
Authors: Yik F W H , Yiu J. , Burnett J.
Published: December 2008

Summaty Passengers have complained about poor air quality inside several semi-enclosed bus termini in Hong Kong, but analysis of measured contaminant concentrations revealed that the levels were rather low. This implies that 'poor' air quality may not be the only cause of such complaints - the thermal stress experienced by the passengers is likely to be a major factor. For sheltering passengers from the contaminated environment inside a bus terminus, and to provide an acceptable thermal environment, a fundamental solution is to provide air-conditioned queuing enclosures. The method for establishing appropriate indoor environmental design criteria and the ventilation and cooling requirements for queuing enclosures in a bus terminus are discussed. Energy expenditure for ventilating and air-conditioning the queuing enclosure is also considered.
Heat capacity of building materials: New test method
Authors: Yang H.X. , Marshall R.H. , Brinkworth B.J.
Published: December 2008

A new test method is described for determining the heat capacity of building materials. The test method is a combination of a finite-difference calculation procedure and a parameter identification technique. The measurement of heat capacity is deduced from temperature measurements taken under transient conditions which can be achieved in a calibrated hot box or guarded hot box. The surface temperature and the ambient temperatures on both sides of the sample must be varied. Compared with a conventional electrical method or a ralorimetric method, this new approach can easily be used for testing large samples, and samples integrated in building facades under real-time transient conditions. The test results for two typical samples are presented; first for a window sample and then for an insulation sample. The results using this new method are presented and compared with the heat capacity given in a materials handbook. The comparisons show that this new test method is accurate and can be conveniently used as a software package.
Performance lines and energy signatures: Analysis with reference to the CIBSE Building Energy Code
Authors: Levermore G.J.
Published: December 2008

With the increasing use of building energy management systems (BEMS) and serially interfacable utility meters, performance lines and energy signatures can be very useful management tools. This paper proposes models of intermittent heating, taken from the CIBSE Building Energy Code, boiler efficiency and compensator control to give a better understanding of energy signatures, the heating plant and its control. Using these models the seasonal efficiency of the boiler is determined as 57%, that for the compensator as 70%, and the intermittent heating saving 17% for an example two-storey open-plan office building.
Ventilation design: Use of computational fluid dynamics as a study tool
Authors: Chow W.K.
Published: December 2008

The technique of computational fluid dynamics (CFD) is applied to simulate indoor air flow induced by air distribution devices and thermal sources in large enclosures. The CFD package FLOVENT is used as the simulation tool. Examples taken to illustrate the capability of the technique are the air movement in four large waiting halls and the associated air conditioning design. The air flow in a large car park is also adopted as an example for a critical review of the performance of the mechanical ventilation system. To validate the package, numerical simulations are performed with experimental data for air-conditioned spaces reported by Sakamoto and Matsuo, Murakami and Kato and Chow and Wong. Further, the use of the model to calculate the mixing factor for a displacement ventilation system is illustrated.
Importance of multi-dimensional conductive heat flows in and around buildings
Authors: Davies M. , Tindale A. , Littler J.
Published: December 2008

The modelling of certain structures in a manner consistent with current practice can lead to significant errors as a result of the non-treatment of multi-dimensional conductive heat flows. A series of multi-dimensional simulations using a modified whole building thermal simulation model have been performed in order to highlight this problem. As a result, it is suggested that all building thermal simulation models should offer a facility to model certain conductive heat flows in more than one dimension. In the case where a one-dimensional simulation is the only available option, sugggestions are offered on how to achieve improved simulations.
'Passive solar' house performance: Derivation from simulation results
Authors: Newton M.N. , Warren B.F.
Published: December 2008

In the House Design Studies commissioned by the Energy Technology Support Unit of the UK Department of Trade and Industry, the thermal performance of forty-three different house designs, incorporating passive solar features, was simulated for comparison with the simulated performance of selected 'reference' and 'upgraded reference' houses. The simulations were not performed by the authors of this paper. An overview of this project, also carried out by others, provided a qualitative indication of the relative solar performance of the designs and references, but no quantitative analysis of the data. This paper seeks to redress this omission by analysing the data from the project to determine the relative energy savings due to insulation and solar gains. Taking the simulations at face value, the results indicate that in most cases the savings in auxiliary energy were largely due to the effects of insulation, with only very small savings arising from the incorporation of 'passive solar' design features.
Review paper: Indoor humidity calculation procedures
Authors: Jones R.
Published: December 2008

Recently the results from a number of studies of the absorption and desorption of moisture by building materials have been published. Working independently, various groups have evolved their own theories and experimental methods. Afodelling water vapour conditions in buildings(1) was such a report which gave an account of the progress so far at BRE. This paper sets out the common basic theory, then reviews seven methods including those of BRE, EDF and CSTB of France and IEA Annex 14 of Belgium. What emerges is that all the work is at some interim stage and nobody offers definitive correct answers. The suitability of any particular theory depends on aligning it to the desired accuracy. Also, harmonisation of terminology and nomenclature, if it were possible, would be a tremendous advantage.
Flow characteristics in circuits using three-port modulating control valves
Authors: Underwood C.P. , Edge J.S.
Published: December 2008

This work has sought to identify the nature of the total flow characteristic in circuits controlled by three-port modulating valves. A theoretical model has been developed and compared with a small family of three-port control valves. The influence of valve signal/flow hysteresis error has been quantified, though no account was taken of valve wear. Good potential for the use of control valves as passive flow monitors has been identified, though further work is required to evolve a practical solution for this. The agreement between experimental data and theoretical results is encouraging, suggesting that a model has potential for use where measurements of valve performance are unavailable. The influence of signal/flow hysteresis was found to be insignificant.
Indoor aerosol particle deposition and distribution: Numerical analysis for a one-zone ventilation system
Authors: Lu W. , Howarth A.T.
Published: December 2008

This paper describes a numerical analysis model for simulating airflow patterns and aerosol particle deposition and distribution in a ventilated room. The deposition and concentration of aerosol particles are largely influenced by the particle properties, air movement patterns and ventilation conditions. Indoor pollutants are mainly composed of small particles.
Wall parameters by time domain methods : Part 2—The conduction transfer coefficients a, b, c and d
Authors: Davies M.G.
Published: December 2008

It is shown that the heat transfer behaviour of a wall subjected to random excitation can be expressed by four series of coefficients, ao, a 1, ..., aN, and similar series bn, c n and dn. The number N of such coefficients, typically 4, depends upon the thickness and weight of the wall. The values of dn derive from the first few values of the wall decay times together with the choice of a time interval, typically one hour. an values depend further upon the series of response factors ϕ eeJ, bn on ϕre j and cn on ϕrr j. Values of the wall cyclic transmittance and admittance such as are used in the CIBSE Guide can readily be found from the transfer coefficients. The example given in Part 1 is extended to provide these values.
Speedy comfort assessment using ISO 7730
Authors: Francis J. , Edwards R.E.
Published: December 2008

ISO 7730 (1984) Annex E provides 'look-up' tables of the predicted mean vote at 50% relative humidity for a range of operative temperatures, mean air velocities, activity levels and clothing resistance values. The suitability of Annex E for speedy assessment of comfort conditions is discussed with the aid of examples. The dangers of its injudicious use are illustrated, particularly with reference to discrepancies between ISO 7730 and Fanger's comfort equations, and to the assignment of M (met) and CL (clo) values for given real-life situations.
Thermal performance lines of chiller plants of two institutional buildings in Hong Kong
Authors: Yik F W H , Burnett J. , Chang H.L.
Published: December 2008

Chiller plant electricity consumption of two institutional buildings have been audited and to identify potential problem areas and establish a basis for assessing improvement measures, thermal performance lines for the two plants were derived using multiple linear regression methods. Stepping regression methods and variance inflation factor analysis were used to select the significant weather parameters for use as the independent variables in the performance line models. This yielded models that cannot be used for inter-building comparison because different combinations of independent variables and coefficients are involved in the models for the two plants. Another model equation with a single independent variable, the product of daily mean outdoor temperature and humidity ratio, was found applicable to both plants. Adequacy of the models was verified by examining the residuals and validity of the models verified by data splitting method. Comparing the regression statistics with observations made in the energy audits shows that a thermal performance line may be used as a diagnostics tool on the quality of control and operation of a chiller plant.
Stochastic modelling of building heating and cooling systems
Authors: Hanby V.I. , Dil A.J.
Published: December 2008

Computer simulations, which can model the operation of the heating, ventilation and air conditioning plant in buildings, generally have lengthy execution times when they are used to generate long-term measures of performance. This investigation has established the feasibility of using a stochastic model, based on Markov chains, wich preserves the dynamic nature of the problem but offers reduced execution time. There is a trade-off between reduction in execution time and the accuracy of the simulation. A simulation enabled a simple combined building/plant model to be run in both Markov and conventional (time-series) modes, thus permitting a direct performance comparison. It was found possible to obtain significant reduction in execution times by running a Markov model without incurring unacceptable inaccuracies. The technique was considered to be worthy of further development in the context of plant simulation.
Elimination of air conditioning in existing buildings through fabric thermal storage: Theoretical study
Authors: Beggs C.B. , Warwicke B. , Howarth A.T.
Published: December 2008

Designers are being encouraged towards passive cooling and natural ventilation in buildings. This will promote heavyweight buildings which utilise both fabric thermal storage and night venting techniques. In terms of energy consumption and carbon dioxide emissions, the new build sector is of relatively minor importance compared with the existing stock of high energy consumption buildings, many of which already contain air conditioning. This paper describes a new technique whereby new and existing buildings can be fitted with a low energy air movement system, which significantly increases the fabric thermal storage capacity of the building. This should eliminate the need for air conditioning whilst still enabling occupants to remain comfortable in summer.
Monetary, energy and environmental implications for infill gases used in high-performance windows
Authors: Fernie D. , Muneer T.
Published: December 2008

The energy, monetary and environmental implications of using inert gases as cavity infill in sealed multiple glazed windows were examined using recent energy consumption data. It was found that the embodied energy and subsequent atmospheric emissions attributable to the inert gas production easily offset the energy savings achieved as a result of the reduced space heating demand.
AC pressurisation: Fourier analysis and the effect of compressibility of air
Authors: Dewsbury J.
Published: December 2008

The AC pressurisation method of measuring the airtightness of buildings is briefly described. Using a simplified model, the leakage characteristics of the enclosure may be found by Fourier analysis of the pressure signal if the effects of compressibility and flexing are neglected. These effects become small at low frequency, but the frequency required to make them negligible may be too low for the available instruments (low-frequency microphones) and the resulting pressure signal may be smaller than appropriate for building airtightness measurements. The conditions under which the other approximations in the model may be justified are not yet known.
Energy model usage in building design: A qualitative assessment
Authors: Robinson D.
Published: December 2008

This qualitative study of energy model usage is a response to the poor uptake of models in practice and to the disparity of views which exists as to which type is most appropriate: simplified or detailed. To better understand this situation, past research on this topic has been reviewed and the results from returns of a detailed questionnaire analysed. It is concluded that (i) users perceive simplified models to have greater efficacy than detailed models, by a factor of three. (ii) users of the spectrum of energy models require improved user interfaces, and this issue grows in urgency with increased model complexity (supporting the previous conclusion). Model developers should respond by enhancing interfaces, this will also reduce the effort of utilisation. Examples of current innovative interface developments are presented as tentative exemplars.
Aural environment survey in air-conditioned open-plan offices
Authors: Tang S.K. , Burnett J. , Poon C.M.
Published: December 2008

In this study, a field survey of the indoor aural environment was carried out in thirty air conditioned open-plan commercial offices in Hong Kong, with over a thousand office workers were interviewed. Subjective responses of the office workers towards their aural environments were collected using questionnaires. Physical noise measurements were performed in an attempt to establish a suitable noise criterion for aural comfort. In addition, the nature of the noise from air conditioning systems is discussed. Results show that the equivalent sound pressure level and noise criterion are better criteria than noise rating when correlated with subjective responses.
A method for estimating the time-of-day carbon dioxide emissions per kWh of delivered electrical energy in England and Wales
Authors: Beggs C.B.
Published: December 2008

The privatisation of the etectricity supply industry in the UK has had far reaching environmental consequences. This paper discusses the environmental impact of the changes that have taken place in the generating sector, and presents a model for the prediction of carbon dioxide emissions per kWh of delivered electrical energy in England and Wales, on a time of day basis.
BREDEM: Testing monthly and seasonal versions against measurements and against detailed simulation models
Authors: Dickson C.M. , Dunster J.E. , Lafferty S.Z. , Shorrock L.D.
Published: December 2008

This paper presents the results of testing BREDEM-8 and BREDEM-12 against measurements in real dwellings and against detailed simulation models. BREDEM-8 is a monthly calculation whereas BREDEM-12 works on a nominal heating season of 8 months. The BREDEM-8 results have been presented before but it is instructive to present them here again because this highlights the performance of the two versions of BREDEM relative to one another. Often all that is required of an energy calculation is a prediction of annual energy use. The results obtained indicate that in this respect the two versions of BREDEM are as good as the detailed simulation models. Both versions of BREDEM perform well in both types of test, and the predictions from the simpler seasonal calculation are as good as those from the more complex monthly calculation. This suggests that for many purposes, and in particular for those where a hand calculation option needs to be available, a seasonal calculation is quite adequate. For example, there is no point in basing an energy label such as the Standard Assessment Procedure on anything more complicated than a seasonal calculation. In situations where a computer would always be used to do the calculations, either a seasonal or a monthly calculation could be employed. The amount of data input is not significantly different in the two cases but the monthly calculation has the advantage that information on seasonal variations is available and this can be important, particularly for passive solar and low energy design purposes.
Differential pressure, bypass chilled water systems: Capacity ratios between on-off and modulating units
Authors: Lau K.K.
Published: December 2008

An analysis is presented concerning the relative proportion betwen the sums of rated capacities of on-off controlled and modulating controlled terminal units in differential-pressure-bypass type chilled water distribution systems. In these systems, there is the chance that differential temperature across the supply and return mains at system part-load conditions could be lower than the system design value. The ratio of the sum of rated capacities of on-off controlled terminal units to the sum of the rated capacities of all terminal units should be smaller than the smallest value of the ratios of the pressure difference across the mains at the distribution end (when all the connected terminal units are receiving their rated water flows) to the constant supply differential pressure for all distribution circuits. This excludes units designed for precooling intake outdoor air to or above the design room air temperature.
Multiple glazed windows: Design charts
Authors: Muneer T. , Han B.
Published: December 2008

Thermal resistance, noise reduction, daylight and solar energy admittance are some of the expected duties of a window. A window manufacturer or a building services engineer employed to select windows for optimum performance does not necessarily need to know the intricate details of the thermal, sound, daylight and solar transmission characteristics of multiple glazed windows. Rather, they require broadly based information on critical design parameters and their influence on window performance. This paper presens charts which enable appropriate design of windows for any given duty and set of constraints.
Advanced fabric energy storage III: Theoretical analysis and whole-building simulation
Authors: Winwood R. , Benstead R. , Edwards R.
Published: December 2008

The paper is the third in a series of four which describe a three-year research project into advanced fabric-energy-storage (FES) systems. It presents the derivation of a theoretical relation for the heat transfer (storage efficiency) within a FES-slab which is used to construct a simple model of the slab. The model is then validated against experimental data and incorporated into the full building simulation, ESP-r. An investigation of the summer time overheating risk in an office equipped with FEs-slabs demonstrates the application of the model.
Variable-air-volume air-conditioning system under reduced static pressure control
Authors: Tung Dennis S L , Deng Shiming
Published: December 2008

A field experimental study on the performance of a VAV system having a variable speed drive for fan motor under reduced static pressure control has been carried out. Direct-digital-control VAV boxes and network communication technology were applied in the study. The supply fan speed was adjusted to its lowest possible level using summation of airflow passing each VAV box as the control signal. The results confirmed that more fan energy can be saved if duct static pressure is allowed to be reduced as compared to the requirements of fixed static pressure control algorithms, and when a VAV system is operated in lighter load condition under reduced static pressure control.
Humidity levels in buildings with variable moisture sources, ventilation rates and environmental conditions
Authors: Taylor Eurlng B E
Published: December 2008

The paper outlines a derivation of a fundamental equation of humidity for any enclosed space or set of spaces exchanging air with each other and with the external environment. The solution enables the humidity levels to be predicted for any arbitrarily changing set of conditions. A number of simpler solutions for room humidity levels are given and discussed. A program to allow users to evaluate different hypothetical effects in the general case easily is cited. A brief discussion, using some specific examples, is made of the various factors contributing to the resultant room humidity and the effectiveness of ventilation. The analytical form of the solution given to the equations allows a user to assemble a model of the humidity response of a building to any degree of complexity using simple calculations.
Passively cooled and ventilated learning resource centre: Performance appraisal
Authors: Robinson Darren
Published: December 2008

A quasi-automatic system has been developed to monitor the energy and environmental performance of a new university learning resource centre. The centre is a THERMIE demonstration project. Monitoring has concentrated on global performance indicators, to describe envelope and environmental provision effectiveness; Micro-performance indicators, to describe performance at the zonal level and ancillary performance indicators, to describe the performance of parameters which cannot be sensed automatically. The effectiveness of the building in reducing energy consumption and providing a pleasant internal environment has been quantified in both physical and psychological terms. Results suggest that, when designing similar buildings in future, greater attention should be paid to humidifcation, distributing daylight, and the provision and thorough commissioning of appropriate automatic and manual occupant controls.
Ventilation and house air tightness: Effect on indoor temperature and humidity in Southampton, UK
Authors: Stephen F.R. , McIntyre D.A. , Lane A. , Raw G.J. , Wiech C.R. , Frederick J.
Published: December 2008

Continuous mechanical ventilation with heat recovery (MVHR) has been advocated as a means of controlling house dust mite. 40 houses in the Southampton area, UK, were chosen for study. 20 were fitted with MVHR systems and the remainder acting as controls. Temperatures and humidities were measured in asthmatic patients' bedrooms for a period of over one year. Measurements were also made of mite and allergen levels, indoor air pollutants and clinical changes. Analysis of these variables will be reported separately. Over the winter months the mechanically ventilated (MV) bedrooms had a mean absolute humidity of 6.75 g kg-1 as against 7.53 g kg-1 for the controls (P < 0.001). The World Health Organisation has suggested 7 g kg-1 as a value below which mites fail to thrive. 15 of the mechanically ventilated houses had a mean winter humidity below 7 g kg-1, compared with only 3 of the control houses. Humidities were lower in leakier homes, but this was significant in the mechanically ventilated group only.
Thermoeconomic life-cycle costs of absorption chillers
Authors: Tozer R. , James R.
Published: December 2008

Thermoeconomics, which is a blend of thermodynamic and economic analysis, can be used to determine life-cycle equipment costs. This paper deals with the application of thermoeconomic theory to absorption chillers. Both initial and operating costs are considered. The best chiller selections for specific operating conditions are identified.
Ice thermal storage: Theoretical study of environmental benefits
Authors: Beggs C.B. , Howarth A.T.
Published: December 2008

This paper is the last of three dealing with 'real time' electricity use and ice storage. The paper investigates the ability of ice thermal storage to reduce carbon dioxide emissions through the use of night-time electrical power. Time-related carbon dioxide emission data are used to analyse the potential environmental benefits of ice thermal storage.
Trickle ventilators: Field measurements in refurbished offices
Authors: Kolokotroni M. , White M.K. , Perera M D A E S
Published: December 2008

Sununary This paper describes field measurements to assess the effectiveness of trickle ventilators in providing adequate and controlled background ventilation in office buildings during the heating season. The tests were at full-scale in two multi-storey office buildings. Both are located within a built-up area and recently refurbished. Carbon dioxide, air ventilation rates, temperatures and relative humidity were monitored for two weeks in one open-plan office in both buildings. It was concluded that resultant internal airspeeds are low, thus minimising the possibility of cold draughts. Metabolic carbon dioxide levels are not excessive and adequate ventilation is provided. It was also found that occupants use trickle ventilators regularly to control their environment once they are familiar with their operation.
Moisture permeability data: Mathematical presentation
Authors: Galbraith G.H. , McLean R.C. , Guo Jiansong
Published: December 2008

The successful application of moisture transport models to building envelopes requires accurate values of moisture permeability. Unfortunately, although a considerable amount of information is available, much of this is in a form which is of limited use to a designer. This paper examines the presentation of permeability data in terms of the concept of differential permeability. This allows permeability values to be predicted accurately for the humidity conditions to which materials are exposed in practice. Several suggested mathematical forms of the permeability-humidity functions have been compared by applying them to experimentally determined permeabilities for four representative building materials. From this comparison the functional form which would provide the most appropriate basis for a standardised system of data presentation has been identified.
Natural ventilation: Airflow measurements in a lightweight test room
Authors: Eftekhari M.M. , Pinnock D.J.
Published: December 2008

The airflow distribution inside a naturally ventilated lightweight test room is investigated. The room is situated in a relatively sheltered location and is ventilated through adjustable louvres. Indoor air temperature and velocity are measured at four locations and at six different levels for various sizes of opening. The outside local temperature, wind velocity and direction are also monitored. The collected data are used to predict thermal comfort parameters across the test room. The experimental results demonstrate that a displacement mode of ventilation is maintained in the space when the wind comes from behind the test room. When the wind impinges on the louvre bulkhead the displacement flow into the room is reduced. Predicted mean votes (PMV) for thermal comfort indicate that values in the afternoon are significantly improved with a higher internal air velocity.
Review paper: Validation of building thermal and energy models
Authors: Ahmad Q.T.
Published: December 2008

A literature review is presented on the validation of thermal and energy models up to 1994. Over 65 different studies are reported here. The existing validation methodologies are reviewed. The validation process began in the early 1970s. However, there was little distinct validation methodology or procedure. Only a few high-quality, well documented data sets are available. It is concluded that much work is needed on detailed data collection, as in most of studies reported here, such data were not available. Many values had to be assumed, resulting in uncertainties in the reported comparisons.
Airborne particles in a ventilated room: Prediction and measurement
Authors: Lu Weizhen , Howarth Andrew T , Adam Nor , Riffat Saffa B
Published: December 2008

A study of air movement and aerosol particle distribution and migration in a ventilated two-zone chamber is presented. The comparisons of average particle concentration decay between numerical results and measured data are generally satisfactory and acceptable. It can be concluded that the particle distribution and migration are mainly influenced by the airflow pattern and ventilation rates.
Fire safety codes for Hong Kong: Inadequacy for atrium design
Authors: Chow W.K. , Wong L.T.
Published: December 2008

The fire safety codes for buildings in Hong Kong are reviewed in terms of building type, building interior layout, construction materials, occupancy levels, circulation patterns, access and escape routes, fire detection and firefighting systems. The fire safety codes are valid only for traditional buildings in Hong Kong. Following these codes in modem buildings might lead to 'over-design' or to providing safety systems which are not workable in case of fire. The prescriptive approach is found to be insufficient to design fire safety for an atrium. It is timely to review the fire codes, to identify and revise those parts which are not workable. The possibility of implementing engineering performance-based fire codes is discussed. The fire safety requirements in atria are taken as an illustrative example. An engineering approach to designing fire safety is strongly advocated.
Fire alarm bell audibility in a housing block in Hong Kong
Authors: Mak C.M. , Chao Christopher Y H
Published: December 2008

A case study on fire alarm bell audibility in a government housing block in Hong Kong is presented. A sound survey included sound pressure level measurement, and a questionnairehas been administered. The results highlight a typical problem in the audibility of fire alarm bell in residential buildings in Hong Kong. Improvement to the fire alarm bell system is suggested. A performance-based approach to fire safety provision in building design is proposed.
Variable-air-volume terminal units II: Dynamic model
Authors: Khoo I. , Levermore G.J. , Letherman K.M.
Published: December 2008

Variable-air-volume (VAV) air conditioning systems are used extensively in air-conditioned buildings. This paper extends the steady-state measurements described in a previously paper to obtain a dynamic model of one of the pressure-independent terminal units. These have sometimes been difficult to tune due to interaction with other VAV equipment, e.g. the supply fan or other terminal units. Hence validated, dynamic pressure-independent terminal unit models are essential for future investigations of plant interaction. This paper describes the derivation of a representative dynamic model based on a commercially manufactured European terminal unit including the integral flow controller and actuator gear common in Europe. The dynamic terminal unit model contains detailed sub-modules for the flow controller, variable-speed actuator, damper linkages with hysteresis, damper, fan and velocity sensor. The sub-modules are assembled on a readily available simulation platform. Using them, accurate validated results have been obtained, showing that instability can occur. The modules will be useful to simulators wishing to model real VAV systems.
Seasonal energy flow across façades: An estimation approach for house designers
Authors: Harper N.C.
Published: December 2008

House designers are concerned with potential energy savings during the lifetime of the dwelling. The average seasonal heating energy savings due to solar gains in houses at a particular location depend on the wall insulation, the type and size of windows, their orientation and the seasonal mean temperature difference across the façade under consideration. A simple approach is proposed to determine whether it is beneficial, in terms of energy saving, to increase window areas, and to estimate potential savings at an early design stage. This enables an assessment of the cost effectiveness of any changes to be made. The method is suitable for both new design and refurbishment. No attempt has been made to provide guidance on potential summer overheating problems if windows are oversized.
Intermittent heating: Equations in CIBSE Building Energy Code Part 2(a)
Authors: Harrington-Lynn J.
Published: December 2008

The CIBSE Building Energy Code Part 2(a) which was first published in 1981 contains equations, which provide a link between the daily mean internal temperature, the control temperature during the occupied period and the thermal response of an intermittently heated building. The derivation of these equations has never been published. As a revised version of the Code containing similar equations is due to be published shortly it is timely that the following derivation is produced.
Air-conditioning with underfloor air supply: Comfort in non-uniform thermal environment
Authors: Kawahara Y. , Emura K. , Nabeshima M. , Bougaki K. , Kadoya M.
Published: December 2008

The effect of a non-uniform thermal environment on subjects is studied using an air-conditioned chamber with underfloor air supply and radiator panels. The mean equivalent temperature Teq around sitting subjects is intentionally varied, and boards placed at waist level allow various combinations of upper and lower Teq to be realised. Thermal sensation and comfort votes are analysed for the whole body, the upper body and the lower body. In winter, female subjects tolerated cold over the lower body. In summer, experiment, subjects generally felt comfortable over the whole body whenever the upper Teq was 26°C and the difference between upper and lower Teq was within 3°C.
Hospital energy performance: New indicators for UK National Health Service estate
Authors: Williams J.M. , Knight I.P. , Griffiths A.J.
Published: December 2008

In 1991 the UK Audit Commission produced energy performance indicators for hospitals based on the type of care provided. However, an analysis of over 100 hospitals throughout the United Kingdom has found the type of care provided to have relatively little effect on the energy performance of hospitals. Although other factors influenced energy use to some degree, the major factor affecting performance was found to be the plan of the hospital, as this influenced the amount of mechanical ventilation required. Modem mechanically ventilated hospitals were found to typically use 40% of their total electricity consumption in fan power, equating to 80 kWh m-2 purely due to fans. This paper presents a suggested set of new performance indicators based on the percentage of floor area which is ventilated mechanically.
Air quality and ventilation rates in school classrooms I: Air quality monitoring
Authors: Lugg Andrew B , Batty William J
Published: December 2008

Indoor air quality was monitored at two schools in Essex, UK (located on the same site) during the week 3-7 November 1997. The objective was to determine whether the ventilation rates within the buildings were adequate to provide acceptable air quality to the occupants. Airborne carbon dioxide concentration was determined using continuous infrared detectors. A class base in each school was monitored for a two-day period. Occupancy patterns and window/door opening were observed during the first day of each period. Air temperature was also recorded. Indoor carbon dioxide levels exceeded those recommended for acceptable indoor air quality for a large proportion of the occupied period. Fresh air ventilation rates were below recommended guidelines.
Cooling tower packing: Effect of configuration on performance
Authors: Goshayshi H.R. , Missenden J.F. , Tozer R.
Published: December 2008

The effect of form of corrugated packing on heat transfer and pressure drop characteristics in atmospheric cooling towers has been studied experimentally. Heat transfer coefficient decreased with increasing packing pitch and with increasing ratio of rib pitch to rib height. Friction factors were expressed by a dimensional equation, which included pitch and distance between the packings, for both smooth and rough surfaces. The relationship between packing heat transfer coefficient and pressure drop is deduced.
Calcuiation of heating degree-days for Pakistan
Authors: Samo S.R. , Letherman K.M.
Published: December 2008

Heating degree-days for various locations in Pakistan — Karachi, Hyderabad, Lahore, Multan, Islamabad, Peshawar and Quetta — from 1987 to 1996, are calculated from the available meteorological data. The method to calculate the degree-days, which may be the first attempt for Pakistan, is briefly described. This study shows that the average heating degree-days in Quetta are about ten times more than the degree-days in Karachi and are double the number in Islamabad and Peshawar. In Lahore the heating degree-days are about one quarter of those at Quetta. In Pakistan in the month of January Quetta needed maximum heating and Karachi required minimum heating as compared with the other regions of Pakistan. Heating degree-days in Peshawar and Islamabad were approximately equal over the ten years 1987-1996. The heating requirement in Quetta region starts about two months earlier in the year than in the other regions of Pakistan.
Evaluation of passive solar calculations in SAP
Authors: Silver Elizabeth , Parand Foroutan
Published: December 2008

The Government's Standard Assessment Procedure (SAP) for the energy rating of dwellings, in the Building Regulations, is compared with detailed simulations using SERI-RES. The emphasis here is on the passive solar contribution to heating load. In this context the aspects of SAP being questioned are: the fact that solar gain and heating load refer to a single location (Sheffield); the fact that solar fluxes refer to October to April for a heating season of October to May; the limited window transmission coefficients; fixed percentage of frame; and neglect of solar gain on the walls and roof. Other aspects of SAP are: nonlinearity of heating load with heat loss, and neglect of uninsulated roof space. SAP is meant to be a rating system but the above points should be noted when values of solar gain or heating load are required.
Numerical modelling of the priming of a siphonic rainwater drainage system
Authors: Arthur S. , Swaffield J.A.
Published: December 2008

The operation of siphonic rainwater systems, and in particular their priming action, is described. Current industry recognised design procedures are discussed. The initial priming of a test facility developed to replicate current design practice is described in detail, and related to the expected performance of systems installed in the field. The impartance, hydraulically, of several specific elements of the system operation are emphasised in terms of the priming action. Additionally, problems encountered at start-up, due to air in both the system and the inflow, are highlighted. A numerical model is discussed that represents system priming, and conclusions are drawn regarding the data presented here and how they relate to the siphonic roof drainage industry as a whole.
Effectiveness of simple ventilation strategies and partitioning in mitigating the effects of passive smoking
Authors: Kolokotroni M. , Perera M D A E S , Palmer J. , Currie J. , Capper G. , Watkins R.
Published: December 2008

Pubs, bars and restaurants are places where smoking policy is still left to the discretion of the manager and where smoking is often permitted. However, there is demand to take measures to eliminate or reduce the effects of environmental tobacco smoke (ETS) to non-smoking occupants. This paper reports the results of a field study in which ETS markers and air flow patterns were monitored in a number of occupied spaces. The measurements included CO concentrations as a marker of ETS, CO2 concentrations as a general indoor air quality (IAQ) indicator and air flow measurements to estimate ventilation and infiltration rates. The findings indicate that shared-space smoking needs action beyond that of simple ventilation, segregation of occupants or simple partitioning to minimise the potentially harmful effects of ETS to both staff and customers.
An investigation into the use of a supply air window as a heat reclaim device
Authors: Baker P.H. , McEvoy M.E.
Published: December 2008

An 'airflow' window can be considered both as a passive solar and as a heat reclaim device. 'Supply air' airflow windows are of renewed interest given the increased volume of air needed for background ventilation in houses as stipulated in the 1995 amendment to the Building Regulations. This study was carried out using the test cells at BRE Scotlab; it sought to establish the effect of climatic conditions on the operation of a Scandinavian 'double' window that was converted for use as a supply air window. A clear correlation was established between intensity of incident solar energy and the temperature gradient within the window. It was also evident that the window acted at night as a heat reclaim device. During the period of the test, the problem of reverse flow was encountered (similar to that found in 'passive stack vent' systems), and the influence of wind speed was investigated. Comparison was made between test cell measurements of the U-value of the standard (unventilated) triple glazed window and those derived from the program FRAME. By reference to recent work on ventilated photovoltaic glazing systems it was possible to derive a simulation method for predicting the temperature rise within the window.
Identification of the uncertainties in degree-day-based energy estimates
Authors: Day A.R. , Karayiannis T.G.
Published: December 2008

A formal method has been developed for quantifying the uncertainties in degree-day-based energy estimates in buildings. Different interpretations of base temperature as a means of describing the building energy balance were investigated, with the result of an improved degree-day model that does not require the use of correction factors. This model has been tested using high-quality data from building simulations, and the outputs have been subjected to statistical uncertainty analysis. The results show that degree-day uncertainties diminish with longer time frames. The uncertainties also impact on regression techniques used in monitoring and targeting of building performance, and these uncertainties may exceed typical targets for energy efficiency improvements.
A new degree-day model for estimating energy demand in buildings
Authors: Day A.R. , Karayiannis T.G.
Published: December 2008

A new degree-day model for estimating energy consumption in buildings has been developed that removes the need for correction factors and allows the user more control over the inputs. The proposed method incorporates a model for determining mean internal temperatures of buildings. The model has been tested for accuracy and sensitivity to input variations. It has also been possible to quantify the uncertainty in the model, which allows the user to determine the usefulness of a result to a particular application.
Dynamic insulation in multistorey buildings
Authors: Taylor B.J. , Imbabi M.S.
Published: December 2008

Dynamic insulation permits the movement of air and moisture through the external walls of a building to reduce heat loss and achieve high indoor air quality. The present paper details a pilot study carried out to examine the influence of fire safety requirements and external wind on the performance of naturally ventilated multistorey buildings in which the external envelope is dynamically insulated. The theoretical foundation is outlined for a spreadsheet model used to simulate prototype 3-, 4-, 5- and 10-storey buildings all sharing the same rectangular floor plan, with fresh air drawn into the building through the envelope by depressurisation using a fan-driven, ducted extract system. From the analysis, the effects of wall porosity, depressurisation level, extract system deployment, occupant density and distribution, and building orientation have been quantified, confirming the practical feasibility of such a system.