bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal simulation models: Comparison with monitored data for houses with large areas of advanced glazing
Authors: Robinson P. , Littler J.
Published: December 2008

This paper presents measured results from a 'superglazed' and an otherwise identical double-glazed house, and compares the monitored data with predictions from a dynamic hour-by-hour simulation model (SERI-RES) and a degree-day model (DESIGNER). The 'superglazing' has a measured U-value of 0.8 ± 0.1 W m-2 K-1, and the double glazing of 2.8 ± 0.1 W m-2 K-1. Five superglazed and three double-glazed houses at Milton Keynes were monitored for two years. SERI-RES was driven with weather data measured on site, and the observed schedules of casual gains. Agreement between measurements and predictions is very good over the whole heating season and fairly good on a month-by-month basis. Internal temperatures are underpredicted, and solar gains and building heat loss overpredieted, during the summer. In DESIGNER the weather conditions are represented as monitored degree-days. The annual consumption figures compare well with those measured; but there is little scope for examining the performance of each building component in relationship to energy use.
Corrosion of refrigerator condensers cooled with estuarine water
Authors: Eames I.W. , Edyvean R. , Brook R.
Published: December 2008

The failure of a cupro-nickel tubed condenser unit is described. The unit was part of a ship's air conditioning system and coolant was estuarine water. Failure occurred four months after the system was commissioned. The condensers were found to be corroded at the end sheets and in the tubes. There was a considerable amount of deposit in the tubes and it is thought that localised attack enhanced by bacterial activity under debris was the cause of tube failure.
Condensation, heat transfer and ventilation processes in flat timber-frame cold roofs
Authors: Simpson A. , Castles G. , O'Connor D.E.
Published: December 2008

An experimental study of the heat and moisture transfer processes in an insulated flat timber cold roof, 4.4 m long x 2 m wide, has been carried out under controlled steady state winter conditions and wind speeds up to 5 m s-1. The experiments were performed with intact, perforated and absent vapour barriers on the ceiling. The cavity between the insulation and plywood roof deck was ventilated via openings of various sizes at the ends of the roof. Cavity air speed, relative humidity and vapour pressure were measured, as well as moisture content in the timbers and the heat flow, temperatures and thermal properties of the roof. In accordance with current standards the roof was designed to have a 50 mm clear cavity, but in practice this was effectively 10 mm, thus restricting ventilation. The results show that vapour barriers and ventilation are of paramount importance if the airspace is to be prevented from reaching saturation conditions, resulting in dangerous levels of moisture in the timber deck and support elements. The minimum requirement for ventilation slot area was found to be an insufficient safeguard at low wind speeds, particularly in roofs without vapour barrier protection. At high wind speeds substantial heat losses from the cavity, accompanied by consequent increases in the thermal transmittance of the roof, were measured. Predictive models are given for the vapour pressure distribution and heat losses from the cavity.
Hot water service using high-efficiency gas-fired appliances†
Authors: Moore N.G. , Gibson N.M. , Wright G.F.
Published: December 2008

Smnmary Research on boilers used for heating systems has been extensive but less attention has been paid in the past to hot water appliances. Improved boiler performance, higher insulation of buildings and increased adventitious gains have meant that energy use for the supply of hot water has become more significant. Field and laboratory studies have therefore been carried out to investigate the performance of recently available high-efficiency gas-fired water heaters. A field study of a plate heat exchanger used in conjunction with a high-efficiency boiler was also undertaken to gain some knowledge of an alternative method of supplying hot water. The results obtained show that changes to the existing system at the field trial site reduced running costs considerably and improved control of the delivered water temperature. Gas-fired appliances with heat transfer efficiencies of up to 94% are now available for the supply of hot water to commercial premises.
Advanced control for BEMS: A model-based predictive approach
Authors: Loveday D.L. , Virk G.S. , Cheung J.M.
Published: December 2008

Control may be carried out using compact mathematical models which describe the thermal behaviour of building systems. In this paper, the performance of advanced stochastic model-based control algorithms for use in building energy management systems (BEMS) is compared with that of the conventional control techniques currently employed in such systems. Test cell experiments show that model-based predictive on/off control is an improvement over standard on/off control, giving an energy saving of 11%. Based on a simulation approach, further comparisons show that the standard proportional-integral-derivative (PID) and minimum variance predictive control methodologies give comparable performances but that both are superior to the on/off cases. It is pointed out, however, that the minimum variance method can be improved so as to out-perform the PID technique. The modelling technique is then applied to a full-scale occupied zone, the model derived giving excellent agreement with measured data. The work demonstrates the potential of advanced techniques for building environmental control.
Single-sided natural ventilation—How deep an office?†
Authors: Walker R.R. , White M.K.
Published: December 2008

Renewed interest is being shown in designing for natural ventilation, as a means of avoiding the need for air conditioning. This has come about as a result of concern about local and global environmental issues related to air conditioned buildings. On the local level there is, for example, the risk of health-related problems such as 'sick building syndrome'. Global issues concern the depletion of the ozone layer and the atmospheric greenhouse effect. It is generally acknowledged that, in operation, ozone depleting gases are released from refrigeration plant of most air conditioned buildings; they consume more primary energy, with an associated greater production of carbon dioxide. To provide adequate ventilation for cooling in summer, traditional guidance recommends cross-ventilation for naturally ventilated offices deeper than 6 m, but this is often not practicable in many modern designs for office buildings. There is little guidance on designing for single-sided ventilation, which may be an option in some cases. This report describes tracer gas measurements of the local mean age of air at different locations within an office room 10 m deep, ventilated through single-sided ventilation. These results show that fresh air is generally distributed over the whole depth, suggesting that if effectiveness of ventilation is the main criterion, natural ventilation may be incorporated into deep open-plan style rooms and wider buildings than is implied by the present limit. The adequacy of the total supply of single-sided ventilation to avoid overheating in summer was assessed using BRE and CIBSE design guidance calculations, and this indicated that comfortable temperatures can be maintained.
Ventilation and air quality in a library building
Authors: Cheong K.W. , Riffat S.B.
Published: December 2008

Measurements of air flow were carried out in a library building. The constant-injection and pulse-injection tracer-gas techniques were used to measure air flow in air handling units and to estimate flow rates supplied to each floor. Tracer-gas measurements were compared with measurements made using a Pitot-static tube. Air exchange rate, ventilation efficiency and age of air were examined. The concentrations of carbon dioxide (CO2), carbon monoxide (CO), formaldehyde (HCHO) and dust particles were monitored. In addition, a questionnaire was completed by library staff and users in order to provide a subjective assessment of indoor air quality.
Natural and forced convection in an auditorium
Authors: Vazquez B. , Yianneskis M.
Published: December 2008

A numerical study of natural and forced convection inside an auditorium of the National University of Mexico was performed. Two-dimensional steady-state simulations of the heat transfer and fluid flow processes within a cross-section of the auditorium were carried out using a CFD program. The boundary conditions were varied to obtain Rayleigh numbers in the range 103 to 1.85 X 1010 for natural convection and Reynolds numbers of 10 3 to 105 for the forced convection flows. The κ-ε model of turbulence was employed to predict turbulent forced convection. The aim of the study was to determine the air flow patterns and temperature field and their effect on thermal comfort conditions inside the auditorium.
Ice thermal storage: Impact on United Kingdom carbon dioxide emissions
Authors: Beggs C.B.
Published: December 2008

Air conditioning makes a significant contribution to UK carbon dioxide emissions. This paper investigates the impact that ice thermal storage might make on carbon dioxide emissions. Carbon dioxide emissions from English and Welsh generating plant are also analysed in detail.
Feed-forward control for a DX air cooling plant: Model simulation of a new system
Authors: Deng S.M. , James R.W.
Published: December 2008

A new feed-forward control concept for a Dx air cooling plant has been developed by mathematical modelling. This control system manipulates the compressor speed using the evaporator superheat signal and additionally adjusts the refrigeration duty by metering the required quantity of refrigerant into the evaporator. The simulation results are promising and indicate that further research work should be undertaken on this new control system.
Experimental U-values of some house walls
Authors: Siviour J.B.
Published: December 2008

Experimental U-values based on measured heat flows through the walls of some houses have been found to be significantly higher than predicted by conventional calculation procedures. The work was carried out in ordinary occupied houses, and included measurements on party, internal and external walls. There are a number of possible reasons for the differences including thermal bridging, high thermal conductivities and excessive air movement in the wall cavities and behind plasterboard dry lining.
Review Paper: Solar-assisted heat pump research and development
Authors: Day A.R. , Karayiannis T.G.
Published: December 2008

The main findings of a detailed literature search on solar-assisted heat pumps (SAHP) are presented. The various system types are described and the relevant performance criteria by which systems can be assessed are defined. Where possible different system performances are compared and specific conclusions drawn. While most work in the literature has focused on series systems there is no evidence that these can compete with parallel systems, either in non-purchased energy delivery or, more significantly, in cost. Efforts to improve control strategies for series systems are unable to achieve better performance. Technology is sufficiently advanced to exploit the best of these systems if the economic climate becomes favourable. Some suggestions are advanced as to where future research effort can make a useful contribution.
Solar chimney for promoting cooling ventilation in southern Algeria
Authors: Bouchair A.
Published: December 2008

In hot climates ventilation can be a useful means of cooling dwellings, if the outside air is cooler than that inside the dwelling. Often, in hot regions the outside air is so hot during the day that cooling by ventilation is of no benefit until the evening when the outside air cools. Ventilation can then be beneficial, and can be promoted by a sun-warmed cavity or 'solar chimney' added to a building on the sunward side. The cavity may be of any material of high thermal capacity. Heat from the sun is stored within the walls and heats the air within. The cavity is closed at the top and bottom by dampers. These, when opened in the evening, allow the buoyant hot air contained within to rise, drawing cooler outside air into the building. This process continues until the stored energy is consumed. The performance of a typical cavity in inducing ventilation into a house is studied experimentally and theoretically. The measurements are made on a full-scale model under steady-state conditions. Cavity width and air inlet area are important parameters in this study. Measurements are made on the temperature and velocity of the air. Observations on air flow patterns in the room and the cavity are made. A dynamic model is developed based on a finite-difference technique, and used to examine the performance of the cavity in various circumstances. The results show that air movement can be produced by a sun-warmed cavity if the dimensions of inlet and cavity width are kept to certain values, and that thermal comfort can be improved.
Airtightness in masonry dwellings: Laboratory and field experience†
Authors: Lowe R.J. , Curwell S.R. , Bell M. , Ahmad A.
Published: December 2008

Considerable attention has been paid to airtightness in timber-framed dwellings over the last 15 years. As a result it is now possible routinely to construct timber framed houses with air leakages below 3 ac h-I at 50 Pa. Less attention has been paid to airtightness in masonry dwellings, particularly in the UK. This paper presents results of laboratory work whcih confirms the very high airtightness of wet-plastered masonry, and identifies a significant weakness in the construction of conventional load-bearing masonry dwellings. Field experience with airtightness in masonry dwellings is described, including the construction of a new detached house with a leakage of less than 3 ac h-I at 50 Pa.
Building energy analysis simulation: Experience of three programs in use
Authors: Chow W.K. , Chan K.T. , Yik F W H , Wu A P W , Ho C.M. , Leung S.L.
Published: December 2008

This paper reports an experience of using three building energy analysis programs- BLAST-3.0, DOE-2.1D and ESP version 7 release 2b. The programs are validated and their results compared for the subtropical climate of Hong Kong. Two occupied buildings have been studied to evaluate the programs; a ten-storey office building and a Polytechnic lecturer's office. The indoor conditions and the energy consumptions of the two buildings were measured. The predicted energy performance is compared with the measured energy consumption for the two buildings. Discrepancies between the simulated results and the measured performance, and likely problems in the application of these programs by practicing engineers, are discussed. The applicability of the three programs is further demonstrated by simulating the energy performance of a hypothetical test building, where the programs' predictions of building load imposed on the air conditioning plant are compared.
Smoke filling and extraction in atria: Time constant
Authors: Chow W.K.
Published: December 2008

Whether a smoke extraction system has to be installed for an atrium building in Hong Kong is currendy determined by its volume. This is not a satisfactory criterion, since the smoke filling times in atria of the same volume but different shapes are very different. A time constant is proposed as an appropriate parameter to replace the atrium volume. This paper reports an evaluation of this quantity using the zone model FIRST developed at the Building and Fire Research Laboratory, NIST, USA. Simulation by this model of smoke extraction effects in different types of atria is studied, and the results are compared with experimental results on smoke filling from the literature. In addition, a crude analysis without thermal effects was carried out. Closed-form expressions on the time required to fill 80% of the atrium height with smoke were derived. Lastly, a'design fire' is proposed to calculate the time constant of the atrium.
Timber frame wall: Hygrothermal properties and vapour barrier damage
Authors: Simpson A. , O'Connor D.E.
Published: December 2008

A study of moisture distribution in plywood sheathing, and the heat transfer processes, in an experimental timber frame wall (unvented), has been carried out under steady state simulated winter conditions of 20°C indoors, and 0°C outdoors. The experiments were performed with intact and perforated vapour check/plasterboard inner linings, under 'dry' (25% RH), and 'wet' indoor conditions (60% RH). In the absence of a vapour check, 'wet' conditions would cause condensation on the plywood sheathing. Under these conditions, sheathing moisture content is increased when the inner lining is perforated, the strongest concentrations occuring opposite the holes. With two 20 mm perforations, inducing moist air circulation effects, the sheathing moisture opposite the holes was found to be significantly more than that for one 20 mm perforation, approaching levels necessary to sustain decay. Small changes of 7% in the thermal transmittance of the wall, were measured under 'wet' conditions and with the lining perforated. An apparent reduction in the transmittance was observed when the wall contained two perforations, due to vertical transfer of heat resulting from air movement through the insulation.
A review of CIBSE psychrometry
Authors: Jones W.P.
Published: December 2008

The equations and procedures used to calculate the psychrometric properties of air-water vapour mixtures in the current CIBSE Guide are reviewed. The psychrometric data determined in this way are considered in the light of recent work on the subject and compared with similar psychrometric properties published in the ASHRAE Handbook: Fundamentals (1989). It is concluded that there is little to be gained by extensive revision to the current data in the CIBSE Guide and it is recommended that these data be retained but that the descriptive pages preceding the data should be updated and corrected where necessary.
Estimation of design ventilation rates for buildings
Authors: Galbraith G.H. , McLean R.C. , Emsfie S.V.
Published: December 2008

Building fabric heat loads have decreased in recent years as standards of thermal insulation have improved. This in turn has led to an increase in the relative importance of the infiltration component of the total heat loss. The quantification of this component requires the accurate assessment of air infiltration rates under relevant environmental design conditions. Unfortunately, techniques for such assessments are much less well developed than those for calculating fabric heat loss and in many cases building services designers still rely upon the use of empirical estimates which are often unrealistic. This paper presents a case study in which a combined measurement and modelling procedure is applied to provide the designer with a more realistic estimate of air infiltration rates for an existing building. The basis of this work involves the use of the fan pressurisation measurement technique to determine actual leakage characteristics for the building envelope. This information provides real input data for a nodal airflow computer model, the results of which can then be used to estimate appropriate design ventilation rates. The case study involves application of the technique to a large secondary school undergoing refurbishment, and shows clearly that empirical estimates could have led to the installation of a severely undersized heating system. The measurements, in fact, highlighted a problem of excessive infiltration rates which required remedial action. The effectiveness of this remedial action was then confirmed by further measurements and remodelling was carried out to establish the final infiltration rates to be applied by the design engineers.
Transition test method: New approach to determining thermal properties
Authors: Yang H.X. , Marshall R.H. , Brinkworth B.J.
Published: December 2008

A transition test method is developed for determining the thermal properties of building materials using a guarded hot box apparatus. The model is presented and the results of the tests are analysed. The results are compared with the results from the standard guarded hot box test method (GHB). They are accurate and time saving. Compared with the conventional test method, this new approach can reduce the test time from 24 hours to within only 2 hours. For determining the temperature-dependent thermal conductance (equivalent value) of a sample of transparent insulation materials, several days can be saved. The method can be also used to measure the insulation properties of materials with low thermal conductance, to which the conventional method cannot be applied with a GHB.
The CIBSE Building Energy Code Part 2(a) as an educational tool
Authors: Day A.R. , Levermore G.J.
Published: December 2008

The CIBSE Building Energy Code Part 2(a) was devised as a method of assessing the energy performance of designs for heated and naturally ventilated buildings. This paper presents the authors' experience in teaching the use of the Code, primarily to building services undergraduates, and the value of developing this into an educational tool to raise students' awareness of energy issues in buildings. There are a number of other significant educational benefits. Projects along these lines could be adapted to suit other professions in the building industry. Some example results are presented, together with some broad conclusions drawn by both students and the authors on the validity of the Code as a general tool. Its strengths and weaknesses are discussed and further work suggested.
Boiler efficiency and gas consumption: Effects of cycling and pump speed
Authors: Rayment R.
Published: December 2008

This brief note sets down some results on the effects of decoupling the room thermostat and cylinder thermostat from the pump and boiler in a 'wet' domestic gas-fired central heating system. Decoupling means that the boiler and pump operate continuously, as opposed to coupled control in which the control thermostats switch off the pump and boiler when no heat is required. The results showed that, for decoupled control, the boiler cycling rates were increased by 62%, the mean boiler efficiency was reduced from 68% to 62% and the gas consumption was increased by about 3% across the 1990/91 winter season. In mild weather the deterioration was much worse and it is important that the controls be properly coupled in these conditions. Lower pump speeds also increase boiler cycling and slow down the heating-up rates for space and hot water heating.
Sensor location for variable-volume-flow control at the secondary chilled-water distribution loop
Authors: Yik F W H
Published: December 2008

A method to determine the 'best' differential pressure sensor location for pump speed control in a variable-volume-flow chilled water distribution system has been presented by Lau. In this Note, Lau's method is reviewed and alternative expressions for determining the sensor location and pumping requirement are derived, which include the effects of water pressure drop across the chilled water coils. Neglecting this will lead to overestimation of the improvement on the valve authority and the reduction in pumping pressure. Issues related to this method of control, including pump energy saving and water balancing are discussed
Energy simulation of displacement ventilation in offices
Authors: Hensen J L M , Hamelinck M J H
Published: December 2008

Modelling and simulation of heating, ventilating, and air-conditioning systems in the context of building performance evaluation is rapidly gaining more and more interest. The objective of the case study described in this paper is to evaluate the performance of displacement systems in offices (i.e. an environment with a low air pollution load) in terms of thermal energy.The paper describes the modelling, how the model is verified, and summarises the simulation results. The main conclusion of this case study is that — from an thermal energy point of view — application of a displacement system in typical offices is only recommended when the casual gains are relatively low (i.e. up to 30 W m-2).
Direct-gain dwellings: Accuracy of short reference years for predicting thermal performance
Authors: Waide P.A. , Norton B.
Published: December 2008

Ten 'short reference year' weather data sets were compared with three full weather sets. Using the SERI-RES building thermal analysis program, comparative simulations were performed on range of buildings. Graphs illustrating the efficacy of the short reference years when used to predict a range of parameters are presented. Short reference years comprising five days per month provide the best composite accuracy.
Degree-hour steady-state temperature index
Authors: Waide P.A. , Norton B.
Published: December 2008

The rationale for introducing an alternative steady-state temperature index dubbed 'degree-hours' is given. The degree-hour approach is much more accurate than the degree-day method as it facilitates treatment of diurnal variation in HVAC set points. The index's behaviour has been investigated for 29 European locations and a method for compressing dramatically the volume of stored data is devised based upon a commonality of behaviour among a wide range of tested locations. A compact Western European degree-hours database has been composed, covering all likely intemal building set point temperatures with a data compression factor of 30.
Characteristics of buoyancy-driven interzonal airflow via horizontal openings
Authors: Riffat S.B. , Shao L.
Published: December 2008

Airflow through horizontal openings in buildings, e.g. stairwells, ventilation shafts, service shafts and chimneys, has important implications for building energy consumption, thermal comfort, contaminant control and fire safety. However, little information is available regarding the characteristics and mechanism of air exchange through horizontal openings, especially that driven by buoyancy. This paper presents a study of buoyancy-driven flow through horizontal openings using time-dependent computational fluid dynamics (CFD). The results reveal that flow patterns in the zones as well as in horizontal openings are highly transient and that the dominant mode of air exchange through openings is that of intermittent pulses. This character of instability and oscillation should be adequately represented in multizone airflow models to improve their prediction accuracy.
Wall parameters by time domain methods: Part 1—Response factors
Authors: Davies M.G.
Published: December 2008

The sequences of wall response factors permit calculation of the wall response to hourly meteorological data over a long period. It is shown here that they can be computed using time-domain methods, through superposition of the response to a steadily maintained rise in temperature, together with a transient solution. As applied to multi-layer walls, this process entails the use of layer transmission matrices for both steady-progressive and transient excitation, multiplication of which enables the overall wall properties to be found. The matching of the solutions follows from the result that the energy distributions throughout the wall for any two transient eigenfunction temperature distributions are independent of each other. An example is given.
Natural ventilation in the United Kingdom: Design issues for commercial and public buildings
Authors: Perera M D A E S , Gilham A.V. , Clements-Croome T D J
Published: December 2008

The principle of good design for natural ventilation is to 'build tight — ventilate right'. A building cannot be 'too tight', but it may be under-ventilated. There is considerable scope for making UK buildings tighter. However, simpler techniques need to be developed (especially in large non-domestic buildings) to identify envelope tightness and associated leakage paths. Also, guidance needs to be provided on constructing tighter envelopes. Studies necessary to assess the implication of tighter buildings are described. Sufficient information is available on ventilation requirements necessary to satisfy safety and health criteria. However, criteria relating to comfort, especially those associated with odour, metabolic CO2 and summer overheating need to be investigated. The paper also discusses minimising the effects of tobacco smoke and controlling other internally generated pollutants. Guidelines for natural ventilation design may conflict with other design or climate-responsive strategies; future work should address this, and address issues such as ventilation openings (to provide both 'background' and 'rapid' ventilation) and design for deeper, naturally ventilated buildings.
HVAC optimisation studies: Sizing by genetic algorithm
Authors: Wright J.A.
Published: December 2008

Previous research into the optimum sizing of hvac systems has focused on the use of direct search optimisation methods. Although these methods can find a solution, it is difficult for them to move discrete variables along nonlinear constraint boundaries and they often fail as a result. This paper describes the performance of a simple genetic algorithm search method when applied to such a problem. The formulation of the problem is described together with the operation of the algorithm. It is concluded that the algorithm exhibits rapid initial progress but that final convergence is slow due to the highly constrained nature of the optimisation problem. It is suggested that a more effective use of the constraint functions could improve the convergence and robustness of the algorithm. The performance of the algorithm is also sensitive to the problem formulation.
BEMS control strategies: Evaluation of realistic performance by computer simulation
Authors: Wang S. , Burnett J.
Published: December 2008

The numerical simulation method is implemented to test and evaluate the realistic performances (e.g. energy, control and indoor environment) of building HVAC systems controlled by bems. The paper presents the simulation method, modelling, test results and validation.
Interstitial condensation in building structures : Dynamic model for predicting the amount of condensation
Authors: Stevens E B H , Fordham M.
Published: December 2008

The traditional approach to the calculation of condensation makes many assumptions and completely disregards certain physical properties. This note details a model which was developed for use on PC-type computers using finite element analysis, and a year's recorded weather data to predict the amount of condensation which will occur in the roofspace in a typical year. This model also incorporates the heating produced by the act of condensation, the effect of radiation to the atmosphere at night, and re-evaporation of any condensation.
Ventilation for humidity control: Measurements in a ventilation test house
Authors: Palin S.L. , McIntyre D.A. , Edwards R.E.
Published: December 2008

Three ventilation systems were installed in a recently refurbished test house: full house mechanical ventilation with heat recovery (MHVR), passive stack ventilation (PSV) and extract fans in kitchen and bathroom. Humidifiers were installed to simulate normal occupancy and behaviour of the ventilation was monitored over the winter of 1993/94. The test house has a low leakage rate of 3 ac h-1 at 50 Pa pressure difference; this low rate was maintained over the duration of the tests. A comparison of ventilation rates provided by the three systems is given. MHVR was the most effective in maintaining low humidity.
Charging a thermal (ice) store: Results of a theoretical and experimental study
Authors: Eames I.W. , Adref K.
Published: December 2008

This paper presents the results of a theoretical and experimental investigation into ice growth and energy removal rates from spherical ice storage capsules. Results from mathematical model of the freezing process of phase change material (PCM) water within spherical enclosures are compared with experimental results. From this model of simple elements, an encapsulated ice thermal storage unit model is developed. Predicted results from this model discussed are compared with experimental data.
Ventilation and air quality in an office building
Authors: Cheong K.W.
Published: December 2008

The aim of this study is to assess the performance of the mechanical ventilation system and air quality in an office building. The perfluorocarbon tracer (PFT) technique was used to measure air flow in an air handling unit and to estimate flow rates supplied to the office. In order to validate the PFT technique as a viable means of measuring air flow in the mechanical ventilation system, the PFT measurements were compared with measurements made using a pitot-static tube. Air exchange range, ventilation effectiveness and age of air were examined. The concentrations of carbon dioxide (CO2), carbon monoxide (CO), formaldehyde (HCHO) and dust particles were monitored. In addition, a questionnaire was completed by the staff in order to provide a subjective assessment of indoor air quality.
Active noise control: Evaluation in ventilation systems
Authors: Au Yeung Y.N. , Yiu Philip C H , Chow W.K.
Published: December 2008

Rapid advances in adaptive signal processing are making active noise control products a practicable proposition. One unit available in the industry was chosen in this study to evaluate its application and effectiveness in controlling noise in ventilation systems. Its performance with aerodynamic and static noises was evaluated against the conventional duct lining approach. Experimental results indicate that the system is applicable in air-conditioning systems despite the existence of some constraints that have to be taken care of. It is proposed to use the equipment to supplement the traditional dissipative silencer for noise level control and for the achievement of spectrum balance.
Reduction of window design risk in houses: Testing a simple calculation method
Authors: Harper N.C. , Warren B.F.
Published: December 2008

A previous paper by the author showed that the selection of inappropriate combinations of wall and window designs by the 'passive solar' designer could lead to a seasonal auxiliary energy penalty instead of the expected advantage. A simple method was proposed whereby a designer could calculate a 'critical house temperature difference' which would enable the average efficacy of different combinations of window and wll designs for different orientations to be evaluated over a heating season and so reduce the risk of incurring an energy penalty. The proposed method has now been tested using DEMON, a program derived from BREDEM 8, and shown to be effective for the cases used. This paper describes the testing of the proposed calculation method.
Advanced fabric energy storage I: Review
Authors: Winwood R. , Benstead R. , Edwards R.
Published: December 2008

This is the first of a series of four papers which describe a three-year research project into 'advanced fabric energy storage', which is defined to be the subgroup of fabric-energy-storage systems which pass ventilation air through a structural mass element for the purpose of heat exchange. The technique can reduce or eliminate a building's requirement for mechanical cooling and allow the heating requirement to be demand-shifted to the night-time cheap electricity tariff. The paper presents a literature survey of advanced fabric-energy-storage systems and describes the historical development of the 'FES-slab' - the leading commercial system. Subsequent papers describe the investigation of the slab with a computational-fluid-dynamics model, the theoretical analysis of the cfd results and the incorporation of a slab model into a full-building simulation and, finally, results from experimental monitoring of the first uk building to apply the FES-slab.
Advanced fabric energy storage II: Computational fluid dynamics modelling
Authors: winwood R. , Benstead R. , Edwards R.
Published: December 2008

The paper is the second in a series of four which describe a three-year research project into advanced fabric-energy-storage (FES) systems. It presents the construction and validation of a computational-fluid-dynamics (CFD) model of the 'FES-slab' which is subsequently used to investigate the slab's behaviour under a variety of boundary conditions and with modified air paths. Similar models are used to compare the FES-slab with the competing 'generic slab' and 'hollow-core screed' advanced FES systems.
Advanced fabric energy storage IV: Experimental monitoring
Authors: Winwood R. , Benstead R. , Edwards R.
Published: December 2008

The paper is the last in a series of four which describe a three-year research project into advanced fabric-energy-storage (FES) systems. It presents experimental monitoring of the first uk building to put the FES-slab into practice, showing the building's thermal performance and energy consumption during 1995. The results are discussed and recommendations made to improve the building's operation during 1996.
Legionella: Impact of risk on building services systems in Hong Kong
Authors: Liu Yanmin , Chao Christopher Y H , Chan Daniel W T , Burnett John
Published: December 2008

This paper summarises the modes of contamination of Legionnaires' Disease (LD) so as to allay fears and misconceptions on LD. Isolation of Legionella in a typical hotel and a summary of LD cases in Hong Kong demonstrate the potential risks of LD infection in building services in such a semi-tropical climate. The Hong Kong Code of Practice is compared with other codes. It is postulated that the key to maintaining water services so as to minimise risk is to reconcile environmental effectiveness with cost-effectiveness. The optimum operational range of cooling water temperature in cooling towers illustrates this reconciliation.
1996 UK Research Assessment Exercise, and CIBSE research projects in progress
Authors: Harfington-Lynn John
Published: December 2008

Articles on the state of the art of developments in building services engineering Welcome to the 'Blue Pages'. This is where guest editors from the Editorial Advisory Panel for Building Services Engineering Research and Technology address current developments in building services engineering practice and research. The articles are very short, on one theme of current interest, and do not go through the longer refereeing process for conventional research papers. This is to encourage consultants and contractors to discuss their latest developments in a non-commercial manner. Academics will also be asked to outline current research areas in universities and colleges. Without the constraint of full refereeing there is scope in the articles to provoke interest and to raise issues for discussion. Consequently the Editor of BSER&T is happy to receive and publish letters furthering the discussion of 'Blue Pages' articles. If you have a suggestion for an article or topic you would like to see included in the 'Blue Pages' pleasc inform the Editor, Barry Copping. Comments on the 'Blue Pages' are also welcome. 'Blue Pages' will only succeed if readers of the journal wish the feature to succeed and contribute to its success.
Energy efficiency of buildings: Simple appraisal method
Authors: Birtles A.B. , Grigg P.
Published: December 2008

A new method is proposed to appraise the relative energy efficiency of designs for new or refurbished buildings. Based on the development of an energy efficiency index, it is simple to use and understand, and requires no particular expertise. The method offers a straightforward determination of likely energy performance. It addresses the total power rating of plant installed to achieve specified indoor environmental conditions, and the monitoring and control equipment which manages that capacity. Potential applications include appraising performance against established or proposed standards of good practice, testing compliance with energy performance specifications and ranking alternative design choices, either overall or at various stages of design. Inverted, the method offers targets for plant sizing. The strategy offers services designers a more authoritative argument for plant room space early in the design. Despite its simplicity the method promises good field performance. Limited data from six fully air-conditioned buildings reveal a perhaps surprisingly good correlation between the energy efficiency index and observed performance. Once performance data for a wider range of buildings are available, the method can be developed fully for widespread practical application.
Low-emissivity coatings in high-performance double-glazed windows: Energy, monetary and environmental costs
Authors: Weir G. , Muneer T.
Published: December 2008

An energy, monetary and environmental cost analysis of low-emissivty (low- e) coatings on double-glazed window designs is presented. The energy associated with the manufacture and use of windows over their life cycle, and the resulting carbon dioxide, sulphur oxide and nitrous oxide emissions are evaluated. This note considers the additional cost of applying low-emissivity coatings, and evaluates the savings to the consumer.
Two-dimensional heat transfer beneath a modern commercial building: Comparison of numerical prediction with field measurement
Authors: Rees S.W. , Thomas H.R.
Published: December 2008

A numerical analysis of two-dimensional transient heat transfer through the ground floor slab of a modem commercial building is presented. A finite-element model of heat conduction is applied to the thermal performance of a concrete slab of normal weight. The relevant experimental data and material properties are also briefly described. The results show a very good correlation between numerically simulated and field-measured thermal responses. A practical approach for the determination of a representative initial temperature distribution is illustrated. A relatively versatile modelling approach appears necessary to accommodate the interaction of a number of different material types. Furthermore, the variation of climauc boundary conditions with time and space needs to be included correctly in the analysis. The work is viewed as a contribution to the overall validation of ground heat transfer models via the direct comparison of simulated results with high-quality in-situ experimental data.
Moisture within a porous layer in a building envelope
Authors: Qigao Chen , Mingfang Tang
Published: December 2008

The paper is a study of the effect of air infiltration on temperature and water vapour pressure distributions within a porous layer. A theoretical formula describing these is proposed. The paper concludes with some new recommendations to the designer.
Low-pressure ejectors: Prediction of performance by computational fluid dynamics
Authors: Smith S.J. , Riffat S.B. , Wu S. , Eames I.
Published: December 2008

Computational fluid dynamics (CFD) is applied to predict the performance of low-pressure ejectors. Its accuracy is compared with predetermined experimental results. This Note shows that low-pressure ejectors depend strongly on geometry. CFD can predict their performance good accurately whether there is good positive entrainment or back pressure resulting in negative entrainment. It is concluded that CFD is a useful tool for designing low-pressure ejectors.
Cooling load dynamics of rooms with cooled ceilings
Authors: Niu J. , Kooi J v.d. , Ree H v.d.
Published: December 2008

Radiant cooling technologies are emerging in the European market. The dynamic building thermal analysis program ACCURACY has therefore been enhanced so as to calculate cooling loads and analyse annual energy consumption for rooms with cooled-ceiling climate systems. The program addresses the radiant effects of the ceiling panels on thermal comfort and cooling load dynamics. The program was validated against the measured dynamic response of a test room to step heating and step cooling. The underlying principles of the program are given. It is used to calculate the cooling load for an office room. This demonstrates the applicability and significance of the new method.
Collector sizing for solar heating of indoor swimming pools
Authors: Brinkworth B.J.
Published: December 2008

A procedure is set out for calculating the area of solar collectors required to provide an optimum contribution to the heating of indoor swimming pools. The procedure draws on the recent appearance of International Organisartion for Standardisation Technical Report TR 12586, taken together with the British Standard Code of Prartice BS 6785. It is hoped that a procedure referenced to public documentation might displace some of the empiricism that has had to be employed in collector sizing hitherto.
Buoyancy-driven displacement ventilation flows: Evaluation of two eddy viscosity turbulence models for prediction
Authors: Cook M.J. , Lomas K.J.
Published: December 2008

A computational fluid dynamics code has been used to model buoyancy-driven displacement ventilation flows. The results of using two eddy viscosity turbulence models are compared with those of mathematical theory and salt bath experiments carried out at the University of Cambridge. The work highlights some of the difficulties involved in modelling buoyancy-driven flows and identifies a preferable turbulence model for predicting such flows.
Outside surface resistance: Proposed new value for building design
Authors: Loveday D.L. , Taki A.H.
Published: December 2008

This paper presents a critique of the design guidance currently offered by the Chartered Institution of Building Services Engineers (CIBSE) and by the American Society of Heating, Refrigeration and Air-conditioning Engineers (ASHRAE) with respect to external convection heat transfer at building façades. Their guidance to date is based on wind tunnel studies. Values are deduced for the convection heat transfer coefficients that form the basis of current advice. Deductions are compared with the findings of outdoor full-scale experimental studies. It is shown that these experimentally measured values for the convection coefficient are significantly higher than the values assumed in current design guidance. Based on this evidence, an expression derived from four full-scale investigations is presented for use by designers and building thermal modellers for correlating the external convection coefficient with surface windspeed. Using the expression, a modified design value of 0.04m2K W -1 for the external surface resistance Rso is proposed for the condition of 'normal' exposure (based on a design surface windspeed of 2 m s-1 as defined by CIBSE) to replace the current value of 0.06 m2 K W-1. As a result, it is recommended that the corresponding U-value for single glazing be raised to 6.3 W m -2K-1 from its currently accepted value of 5.6W m-2 K-1. A summary of results is also presented, showing the effect of window framework on external convection heat transfer.
The consequences of lightweight buildings on sound transmission
Authors: Craik Robert J M
Published: December 2008

Changes in building practise have led to an increased use of lightweight components in modem buildings. Lightweight walls and floors do not rely on mass to prevent sound transmission but on the way in which the various components with different material properties are combined. This requires a knowledge of both the materials used and the details of construction. The traditional approach to design is to compare the proposed construction with measured data from similar systems. However, the possible range of lightweight designs makes this impractical. Theoretical models offer an alternative approach to design and are becoming increasingly important for sound transmission in buildings.