bluuebunny/crossref_metadata_2025 huggingface dataset:
Simple model for an optimiser
Authors: Levermore G.J.
Published: December 2008

A simple model of a building is developed to analyse the preheating curve for optimised heating. The model considers an effective thermal mass of the building so that internal air temperature can be used rather than a mean fabric temperature. With this model a curve similar to that of Birtles and John is derived. At low outside temperatures and with small heating plant this curve is found to bend over. The model results can be explained in terms of a time constant and a plant size ratio. Variable heat emitter output is also considered and the characteristic curve retains the same form. Birtles and John's empirical constants are related to building parameters of the simple model. The response factor for a building as used in the CIBSE Energy Code is found to relate approximately to the model. It is pointed out, however, that the CIBSE admittance method used in deriving the response factor is slightly erroneous. A number of other points relating to optimiser performance are explained by the model.
Condensation risk prediction: Addition of a condensation model to BREDEM
Authors: Boyd D. , Cooper P. , Oreszczyn T.
Published: December 2008

The paper describes a design tool for assessing condensation risk in dwellings and the effect of remedial measures thereon. The BREDEM energy model is augmented by a moisture model to determine mean internal relative humidity (MIRH). This measure of condensation risk is calculated for two zones in a dwelling from mean internal temperatures, moisture generation and ventilation rates. Primary input data relate to occupancy (fuel expenditure and moisture production) and dwelling characteristics (thermal and ventilation). MIRH results are presented as a function of space heating input in example dwellings with remedial measures applied (insulation, draught stripping and extract fans). The constraints imposed by household income and the implications for condensation risk are discussed.
Daylight in dynamic thermal modelling programs: Case study
Authors: Haves P. , Littlefair P.J.
Published: December 2008

Heating, cooling and lighting energy consumptions in buildings are inter-related, and a model which treats thermal performance and lighting simultaneously is required in order to evaluate the full benefits of daylighting in buildings. A lighting facility has been included in a dynamic building simulation program (SERI-RES) used in the Department of Energy's passive solar programme. Interior daylight illuminance is calculated using an extension of the daylight factor method. The lighting usage of various lighting systems is predicted from the daylight illuminance, and the thermal consequences of that lighting use included in the thermal simulation of the building. The applicability of the method described in this paper is not limited to SERI-RES. The method could be incorporated in any building energy analysis program intended for the UK or similar climates.
Review paper: Sick building syndrome
Authors: Sykes J.M.
Published: December 2008

This paper reviews published information on 'sick building syndrome', the cause of a reputedly high incidence of sickness among occupants of sealed, mechanically ventilated buildings. It discusses symptoms, common features of 'sick buildings' and postulates possible causes. On the basis of reported cases, there appears to be no single cause but a series of contributing factors.
HVAC optimisation studies: Component modelling methodology
Authors: Hanby V.I. , Wright J.A.
Published: December 2008

Significant changes in the way HVAC systems are designed would be made possible by the application of optimal search techniques to find the 'best' design for any given criterion. A suite of programs has been developed which implements this type of optimisation; it was necessary to develop HVAC component models which are more extensive than the conventional performance or energy models used in contemporary system simulation. The paper describes the development of component models which: reproduce the characteristics of ranges of manufactured products; execute quickly when linked to form system models; and model on three levels: performance, economics and constraints. An example is given of the use of the models in the optimisation of a heat pump system for minimum energy consumption.
Fire-induced convective flow inside an enclosure before flashover: Numerical experiments
Authors: Chow W.K. , Leung W.M.
Published: December 2008

This paper reports how the technique of field modelling can be applied to simulate the 'fire environment' in an enclosure at the preflashover stage. The theory behind it is to solve a system of partial differential equations describing momentum and heat transfer with turbulent effects. By specifying the geometric configurations of the enclosure, location, size and thermal power of the fire, it is possible to predict the three-dimensional flow, temperature and smoke fields induced by a fire plume. These results are very useful for assessing the fire responses of different types of enclosures such as offices, trains, compartments, aircraft cabins, atria and tunnels at the preeashover stage. Appropriate fire services systems can then be designed to control fire during its early stages.
Thermal response of temporary school buildings: I Heating
Authors: Penman J.M. , Murdoch N.
Published: December 2008

Space heating requirements in thermally lightweight temporary school buildings with between 25 mm and 60 mm thermal insulation have been estimated using a simplified dynamic thermal response model. The results suggest that, compared with thermally heavyweight school buildings, lightweight temporary classrooms, even down to 25 mm insulation thickness, should be operable in a reasonably energy-efficient manner under the highly intermittent school occupation pattern. This is because lightweight construction confers a generic advantage for space heating provision under intermittent occupancy. However, this advantage will not be realised unless care is taken about heating plant control (start-up times, occupation and frost protection setpoint temperatures) and the ventilation regime. The penalties for poor performance in these areas are quantified in a practical fashion.
Rad-air temperature: The global temperature in an enclosure
Authors: Davies M.G.
Published: December 2008

It is first established that heat losses from an enclosure must be based on a global index temperature, rather than on any observable value. Environmental temperature is such an index temperature but it and its associated model are ill-conceived and unsuitable as a general method of handling radiative and convective exchange in merged form in a room. Rather, one should use the binary star model if one wishes to keep these processes separate, or the rad-air model if they are to be merged. The rad-air temperature is the true global temperature in a room and is exactly equivalent for indoor use to the well established sol-air temperature (which relates to an outer surface.) Holmes has recently presented a comparison of computational methods in which he has demonstrated that the binary star method has no advantages in estimating surface temperatures over the environmental temperature method as set out in the 1970 IHVE Guide. With Holmes's choice of surface emissivities and convection coefficients, this result is to be expected; his results support the use of the rad-air model in connection with the rooms he analyses. The exact equivalence of the rad-air and sol-air concepts is established. It is demonstrated that the Guide method of arriving at environmental temperature amounts to a delta-to-star transformation of the real enclosure conductances; and this proves to be invalid. The scaling factor which is needed in handling radiation is treated through an equivalence theorem. The 'surface factor' technique in the Guide is shown to underestimate certain enclosure temperatures.
Intelligent controls for building services
Authors: John R.W. , Dexter A.L.
Published: December 2008

The paper reviews the 'state of the art' in the design and application of adaptive and self-tuning controls. Their role in the hierarchy of control loops needed to operate modern building services is described, and an introduction to adaptive and self-tuning control techniques is given. The performance of a self-adaptive optimum-start controller, a rule-based selforganising regulator for three-port valves and a self-tuning control scheme for cooling coils are discussed in detail. The case studies are used to demonstrate the potential advantages and practical problems associated with the implementation of intelligent controls. The authors conclude that future control strategies are most likely to be based on a combination of 'rule-based' and analytical techniques.
Fluid flow and heat transfer in pipework systems: I Mathematical model for dynamic modular simulation
Authors: Ip K C W , Day B. , Richardson D.
Published: December 2008

A general-purpose simulation software package ('Bristol') is used for the simulation of variable fluid flow pipework systems. The simulation solves the fluid pressure and mass flow in pipe networks and in addition computes the non-steady state heat transfer through the pipe wall to the environment. The simulation package is intended to assist engineers or designers to solve design problems, and an example is included to illustrate how it could be used in the design of a hot water supply system. The program not only takes up the task of tedious arithmetic but also gives information that cannot be obtained from conventional design calculations. The potential and drawbacks of modular simulation systems for design in general are also discussed. This paper (Paper I) describes the mathematical models of pipework components and nodes followed by an introductory example of a pipe network. Paper II will continue with a design example together with conclusions and discussion on future work.
Thermal conductivity of porous materials: II Theoretical treatment of radiative heat transfer
Authors: Simpson A. , Stuckest Audrey D
Published: December 2008

A theoretical background relating to radiative heat transfer in porous materials, and the effect on thermal conductivity, is presented. Simplified models are considered as well as a more rigorous analysis provided by the Hamaker two-flux model which takes into account both radiation scattering and absorption. Conventional equations derived from Hamaker assume radiation scattering only, and predict that the radiative conductivity increases with thickness to a limiting value—the 'thickness effect'. A modified expression for radiative conductivity, which includes absorption, has been derived from the Hamaker model. This might be expected to apply to insulants where absorption effects are small compared with those of scattering and which are subject to temperature conditions normally found in the built environment. The radiative conductivity still increases with increasing thickness of insulant. However as the amount of absorption is increased the radiative conductivity is reduced and the limiting value occurs at smaller thicknesses.
Turbulent flow in a duct: Measurement by a tracer gas technique
Authors: Riffat S.B. , Lee S.F.
Published: December 2008

We describe the use of the constant injection tracer gas technique to study turbulent flow in a rectangular duct. A comparison between tracer gas measurements and measurements made using a hot-wire anemometer and a pitot tube is presented. Tracer gas concentration, air velocity and pressure distribution were measured at various distances from the duct wall and inlet. The Reynolds number based on the hydraulic diameter and the bulk velocity was varied between 7.5 x 103 and 18.6 x 103. An empirical equation for the entrance length required for fully developed turbulent flow was obtained and this was compared with experimental results.
Lift traffic analysis: Formulae for the general case
Authors: Peters R.D.
Published: December 2008

Lift or elevator passenger traffic analysis is generally based on an up peak calculation. Various authors have considered other specific passenger flows for down peak, two-way and interfloor traffic. This paper gives formulae for the general case. The formulae are based on a Poisson approximation of passenger arrivals at a lift landing station. The probable number of stops and probable reversal floors are calculated, allowing the round-trip time, waiting interval and capacity factor to be determined. The number of calculations is such that a computer is needed to implement the formulae, though the final result may be checked by hand.
Solar radiation: Further evaluation of the Muneer model
Authors: Muneer T.
Published: December 2008

The performance of Muneer's slope solar radiation model is evaluated against one-year, hourly vertical and horizontal surface solar irradiation measurements at Cranfield, UK. It is demonstrated that if only the global horizontal irradiation data are available, the slope irradiation consisting of the beam, sky-diffuse and ground-reflected components may be estimated with satisfactory accuracy.
Internal long-wave radiation exchange in buildings: Comparison of calculation methods: I Review of algorithms
Authors: Stefanizzi P. , Wilson A. , Pinney A.
Published: December 2008

The pair of papers of which this is the first presents some of the commonest methods for calculating long-wave radiation heat exchange in a room. Paper I covers the theory behind the various methods. These vary in complexity from accurate calculation of view factors with multiple inter-reflections between surfaces to simple, non-geometric methods using fixed heat transfer coefficients. Paper II presents a set of tests which were developed to allow a comparison of the performance of these algorithms with an analytically exact method. The results of these tests are shown, the main conclusion being that in many cases it is possible to use a non-geometric model without significant loss of accuracy. A more accurate method is required in cases of low surface emissivity or large temperature differences between surfaces. The importance of internal long-wave radiation to the overall energy balance of typical houses was tested, and the results presented in Paper II. If no account is taken of long-wave exchange (disabling exchanges by setting all internal emissivities to zero), predicted energy requirements changed by up to -11% in the type of house and heating system tested: greater changes could arise in different house types or in those with a larger radiant output from the heating system. The results also showed the importance of modelling long-wave exchange to and from windows explicitly.
Fluid flow and heat transfer in pipework systems: II Design example
Authors: Ip K C W , Day B. , Richardson D.
Published: December 2008

A general-purpose simulation software package ('Bristol') is used for the simulation of variable fluid flow pipework systems. The simulation solves the fluid pressure and mass flow in pipe networks and in addition computes the non-steady state heat transfer through the pipewall to the environment. The simulation package is intended to assist engineers or designers to solve design problems, and an example is included to illustrate how it could be used in the design of a hot water supply system. The program not only takes up the task of tedious arithmetic but also gives information that cannot be obtained from conventional design calculations. The potential and drawbacks of modular simulation systems for design in general are also discussed. Paper I of this pair describes the mathematical models of pipework components and nodes followed by an introductory example of a pipe network. This paper (Paper II) continues with a design example together with conclusions and discussion on future work.
Multiple liquid chillers: Intelligent control
Authors: Wong A K H , James R.W.
Published: December 2008

A validated model of a liquid chilling plant has been adapted for an investigation into the control of multiple liquid chilling plants incorporating reciprocating compressors. Problems of set point accuracy, system stability and energy efficiency are analysed and a new intelligent controller has been developed. The controller has three sequencing schedules and is superior to PID systems considering first safety, then set point accuracy and finally energy efficiency; however, further development work is required.
Room heat needs in relation to comfort temperature: Simplified calculation methods
Authors: Davies M.G.
Published: December 2008

Definitions are set up of local and space-averaged air and radiant temperatures and certain derived temperatures, together with the conductances that are needed to estimate building heat needs. Expressions are derived for the radiant and convective heat inputs Qr and Qa which are needed to establish a particular value of comfort temperature; they are given for each of three models for room internal heat exchange. They are easy to derive and simple to state. The method currently advanced in the CIBSE Guide (Section A5) to compute these needs is summarised: quite apart from the fundamental flaws in its basis, its exposition is more protracted and convoluted than is necessary.
Solar heated and daylit offices: Design study
Authors: Muneer T.
Published: December 2008

A design study has been undertaken to determine the perfomance of solar heated and daylit office buildings under the climate of the United Kingdom. The simulation study used data from three years which consisted of hourly horizontal global and diffuse irradiation, ambient temperature and wind speed for four sites. The sites considered were Easthampstead (England), Aberporth (Wales), Eskdalemuir (Scotland) and Aldergrove (Northern Ireland). The simulation procedure utilises the latest available models for vertical surface solar irradiation, daylight, wind-conductance, comfort, energy-exchange and energy-saving measures. The study shows that 50-60 per cent savings may be achieved in the primary electrical consumption by exploiting daylight potential. The solar gains in conjunction with the occupancy and equipment gains were found to be adequate for most of the space heating requirements. The study also quantifies the significant reductions in electric lighting consumption by proper design and the use of dimming controls over simple time-based controls.
Dynamic thermal simulation models of buildings: New method for empirical validation
Authors: Lomas K.J.
Published: December 2008

A new empirical validation methodology for dynamic thermal models has been devised and illustrated using the three models ESP, SERIRES and HTB2, and a simple data set collected from the Polytechnic of Central London test cells. The method hinges on making an initial base case prediction and then taking account of the errors and uncertainties in a systematic way. The method proved capable of revealing internal errors in thermal models. The relationship of this method to other validation techniques is discussed.
Displacement air flow in a printing plant measured with a rapid response tracer gas system
Authors: Breum N.O. , Skotte J.
Published: December 2008

A multipoint (8 channel) single tracer-gas measuring unit is described. Using a gas chromatograph for the tracer (SF6) analysis a 9 s sampling interval was achieved. The detection limit was 0.03 ppb. The workshop (9700 m 3) was ventilated using the displacement design principle. The air supply rate by mechanical ventilation was 7.7 m3s-1 and infiltration was added to this at a rate of 6.3 m3 s-1. The displacement air flow created two different flow regions in the workshop. Heat and air pollutants accumulated in an upper region giving acceptable working conditions in the lower region (the zone of occupancy). Consequently, displacement ventilation has potential for improving air quality in high-ceiling workshops with a heat load.
Self-syphonage in plumbing drainage systems: Effects of surface tension and viscosity
Authors: Adesanya D.A.
Published: December 2008

Self-syphonage is a major problem in plumbing design and so has been addressed in various codes by building services experts. This paper reports the results of experimental investigations carried out to determine the effect of viscosity and surface tension on the formation of vortices and eddies on flow characteristics within the trap and pipe, and most especially on trap seals. Within the range of the experimental results, viscosity and surface tension are insignificant factors for self-syphonage and residual seal depth analysis.
Underground district heating mains: Causes of failure
Authors: Duffy P.F.
Published: December 2008

This report highlights the principal causes of failure of underground district heating pipelines installed in the UK over the last 20 years. Standard UK practice is to use prefabricated pipe in pipe conduit systems. Both steel and plastic cased systems have suffered from penetration of the outer conduit, especially at the location of the main joints. This has enabled moisture to enter the systems and corrode the hot steel carrier pipes within. An improvement in site supervision and the introduction of a registered training scheme for completing conduit closures could increase the reliability of future installations. This is vital if the UK is to benefit from the potential energy savings of city-wide CHP schemes.
Dynamic thermal models: Reliability for domestic building design
Authors: Lomas K.J. , Bloomfield D.P. , Cole A. , Parand F. , Pinney A.A.
Published: December 2008

This paper describes a three year UK initiative—Applicability Study 1-to enhance the usability and credibility of detailed thermal simulation programs with particular reference. to the design of passive solar dwellings. Researchers at Leicester Polytechnic and the Building Research Establishment are working with ESP, HTB2 and SERIRES. The aims are to identify the problems for which these programs can be used reliably and those for which they cannot, to provide guidance on the best modelling techniques, indicate the uncertainty inherent in predictions, identify the attributes of programs which are necessary to obtain reliable results, and indicate areas in which additional theoretical or experimental research is needed. The results to date show that good agreement in some design trends can be obtained provided a high level of quality control is exercised and program users have a good understanding of the theoretical basis of the programs. There were, however, some situations in which the programs still predicted significant differences in the trends in energy consumption as the building design changed. These may be explained by the different algorithms employed by the detailed thermal simulation programs and errors in them.
Mechanical and electrical services for the Limehouse Link road tunnel
Authors: Ghent S.W. , Wood D.W.
Published: December 2008

This paper briefly describes the main mechanical and electrical services which will be provided for the Limehouse Link road tunnel. These services include 11 kV electrical distribution, lighting, ventilation, drainage, fire protection, closed-circuit television (CCTV), traffic management, radio communications, supervisory control and data acquisition (SCADA), uninterrupted power supply (UPS) and services in the tunnel services buildings.
HVAC system simulation: Use of condensed input data
Authors: Hanby V.I. , Round M.
Published: December 2008

Many applications of HVAC system simulation require results obtained over a long period, which can mean a long computation time. A method is described for producing multivariable binned data which reduces the computation time needed. The accuracy of the method is illustrated by comparing the results obtained in an example simulation using the condensed input data with those obtained from hourly time series values.
Air flows between predominantly naturally ventilated rooms through partly open doors
Authors: Howarth A.T. , Jennett I.L.
Published: December 2008

Flows around doors in partly open positions are measured in full-scale laboratory chambers and in site tests. Flows which are primarily temperature driven are measured using tracer gas techniques. Also investigated are the superimposed effects of mechanical ventilation in the laboratory tests and of wind and stack effects in the site tests. At small door opening positions, conventional buoyancy theory can be applied to estimate the two-way flow generated by temperature difference. Combined temperature and pressure driven flows can be analysed within ±20% by superimposing the respective theories. Room air movement plays an important part, giving rise to relatively high superimposed flows. For this reason, back-flow is almost inevitable when the door is not properly closed.
Air infiltration through background cracks due to temperature difference
Authors: Shao L. , Howarth A.T.
Published: December 2008

Despite its practical importance, there has been a general lack of information on air infiltration through building background cracks, especially when induced by temperature differences. This paper describes experimental work in which it was found that the rate of air infiltration due to temperature differences through cracks is proportional to the temperature difference between two adjoining rooms (or a building and the atmosphere) which the cracks connect. This finding agrees with theoretical predictions. The experimental results also confirm that the infiltration rate increases with increasing vertical distance between cracks.
Solar-assisted heat pump systems: Assessment of an example using profiled steel cladding
Authors: Loveday D.L.
Published: December 2008

Correlation equations are presented which describe the in-situ performance of an air-source heat pump installed in a UK domestic residence. The equations are used for assessing the effect on overall system performance of heat pump solar assistance provided by profiled steel cladding acting as an air preheater. Results are compared with those for the cases of conventional tile roof preheating, and no preheating at all, and the assessment procedure is validated with reference to measured data for the tile roof case. It is shown that system performance can be enhanced by use of the cladding. However, the effects of fan power and defrost cycling are shown to be important, and it is concluded that a full investigation of the cost effectiveness of such a system is warranted before application on a larger scale.
Moisture movement: A study using tracer gas techniques and CFD modelling
Authors: Kolokotroni M. , Saiz N. , Littler J.
Published: December 2008

The moisture distribution within a space and the degree to which moisture movement can be modelled using tracer gas techniques and computational fluid dynamics (CFD) models are examined. The validity of these methods to study moisture migration is examined experimentally in an environmental two-zone test chamber. It is found that molecular diffusion plays a very small role in airborne moisture movement. Thus airborne moisture migration is primarily affected by air movement. The major influences are the shape of the buoyant plume and the position of air supply and extract in relation to the moisture source location.
Thermal stratification in intermittently heated heavyweight buildings (Churches)
Authors: Bemrose C.R. , Smith I.E.
Published: December 2008

Vertical temperature gradients have been monitored hourly during the winter heating period in two mediaeval churches with typical usage once or twice per week. Little stratification was found except during periods of solar gain, and temperature inversion often occurred because of heat loss through uninsulated roofs. Correlations between vertical temperature gradient and ambient temperature have shown the effect of roof heat loss, and this has been confirmed by dynamic thermal modelling using measured temperatures. Modelling of buoyancy-driven convection in one church has demonstrated the internal airflow patterns and verified the lack of hot air at roof level. Where roofs are uninsulated and heating systems low-powered, it should not automatically be assumed that air at high level will necessarily be hot, or destratification fans beneficial.
Evaluation of condensing boiler performance and space heating in a sheltered housing scheme
Authors: Underwood C.P.
Published: December 2008

As part of the Energy Efficiency Office's condensing boiler demonstration programme, Newcastle Polytechnic were responsible for a project in the North of England, consisting of a 30-unit sheltered housing scheme. This involved central condensing boilers for space heating and independent gas fired generators for domestic hot water. Data on various aspects of the heating installation performance were collected during a two year period in the late 1980s. The dual condensing boilers were under direct external temperature compensation control, and were oversized to make provision for stand-by capacity. At light load, expected high efficiency operation was not always achieved due to the effect of low load factor. Condensing operation was found to be sporadic, though during significant loads, dry mode efficiency was high; generally around 86-88%. The use of a low flow temperature compensation range set during commissioning was identified as the main reason for restricted condensing operation.
l'AICVF/CIBSE Comparative Study: Interim report
Authors: Dale K.W.
Published: December 2008

In June 1990 at Deauville, members of l'AICVF (Association des Ingenieurs en Climatique, Ventilation et Froid) and CIBSE (the Chartered Institution of Building Services Engineers) agreed to work together to make a comparative study of each other's Building Regulations' thermal requirements. For this purpose, the design of a dwelling which could be built in England or Northern France was agreed upon.
Flaws in the environmental temperature model
Authors: Davies M.G.
Published: December 2008

The paper summarises the arguments which led to the establishment of 'environmental temperature' as a room index temperature and its attendant model for discussion of room internal heat exchange. The model leads to some logically absurd conclusions. The index proves to be flawed since it was defined in terms of air and mean surface temperature but interpreted as a mix of air and mean radiant temperature. The series of defects implicit in the setting up of the model are presented: the principle upon which environmental temperature was arrived at is invalid; the use of the global mean surface temperature is invalid; radiant exchange in a room was mishandled and the status of dry resultant temperature was misrepresented. Quite apart from errors of principle, the exposition of the model in the 1986 CIBSE Guide is unnecessarily complicated.
Hygrothermal microclimate: New system for evaluation of non-uniformity
Authors: Jokl M.V.
Published: December 2008

The non-uniformity of the hygrothermal constituent of the environment (NUN) causes problems not only in hot workplaces in industry, but also in light buildings, in air-conditioned and even in ventilated buildings. It is almost impossible to avoid cold draughts, unilateral thermal radiation etc. in such situations. The theory of NUN in space and in time and climatic NUN (convective, radiant, perspiratory) and conductive NUN is presented, as well as its estimation by a new instrument, the stereothermometer.
Review paper: Thermal energy storage
Authors: Tahat M.A. , Babus'Haq R.F. , O'Callaghan P.W.
Published: December 2008

Energy storage not only plays an important role in conserving energy but also improves the performance and reliability of a wide range of energy systems. It can be expected to continue as a cost-saving technology as utility companies struggle to meet consumer energy needs without constructing new power plants. An up-to-date comprehensive overview of the role of thermal energy storage is presented in the context of achieving a more rational use of energy and in particular its contribution towards satisfying the future requirement. A summary of thermal energy storage theory is given and its concepts are discussed. The energy density and the economic viability for several storage media are also presented.
Aerodynamic protection of hangars against cold ingress through apertures
Authors: Strongin A.S.
Published: December 2008

Aerodynamic protection of apertures in buildings effectively counteracts cold ingress while doors are open. Aerodynamic protection systems are classified as full or partial. Full systems are characterised by virtually complete localisation of the aperture and elimination of its influence on the air-heat regime (AHR) of the premises. The air curtain and infiltration protection systems are full systems. Partial aerodynamic protection systems (SAP) are used where full protection systems are technically impossible or economically inexpedient to implement. SAP reduces the quantity of external air entering the premises, but does not remove the influence of the aperture on the AHR. The physical-mathematical model of AHR of premises with large apertures is developed in terms of microclimatic variables. The resulting algorithm determines the current air temperature, the temperatures of surfaces of gates and plant, the optimal capacity of the peak heating system and SAP, and the time taken to re-establish steady-state microclimatic conditions. The application of the program is illustrated by an example of calculation for a hangar building.
Design of true half-round roof eaves gutters
Authors: Anderson J.A.
Published: December 2008

In this paper the design of true half-round roof eaves gutters is based on a complete solution of the governing unsteady flow equations for open-channel flow. The predicted flow capacity for a short horizontal gutter of any diameter is compared with previously obtained equations which were based solely on experimental data. Reduction factors applicable to this equation are obtained for long horizontal gutters. In addition, the flow capacities of gutters laid to standard falls of 1 in 600 and 1 in 350 are determined, showing that for gutters laid to a fall of I in 600 the capacity is almost constant irrespective of its length, and for gutters laid to a steeper fall the capacity increases slightly with increasing length of gutter.
Tracer gas mixing with air
Authors: Shao L. , Sharples S. , Ward I.C.
Published: December 2008

The tracer gas method is one of the most widely used methods for measuring flow rates for building air infiltration and ventilation. The accuracy of this method depends vitally on the spatial uniformity of the tracer/air mixing. However, information on this critical problem has been scarce, largely due to the practical difficulty in experimentally obtaining data. In the last decade a new tool for building research has emerged, namely computational fluid dynamics or CFD. A study of tracer/air mixing has been carried out using a time dependent CFD method, supported by conceptual/dimensional analysis. In this study, 12 cases of tracer/air mixing in simulated tracer decay tests were computed. Each case had a different zonal volume or other boundary or initial conditions. By comparing these results, it was found that there were many factors affecting tracer/air mixing and, contrary to a previous report, there does not exist a universal critical value of air change rate below which satisfactory mixing is guaranteed, although lower air change rates are generally beneficial to mixing. In addition, it has been demonstrated that smaller building zones and higher inlet air flow velocities have positive effects on tracer/air mixing while the initial tracer concentration level has no effect. Finally a statistical parameter of concentration spread coefficient for assessing tracer mixing has been introduced.
Chilled water production : Storage priority control strategy
Authors: Simmonds P.
Published: December 2008

The production of chilled water in ice-based thermal storage systems presents unique operational considerations. The parameters controlling the generation and utilisation of chilled water are functions of the intended strategy for the production and use of the chilled water, the physical arrangement of the components, and the amount of storage available for heat rejection. The storage priority strategy investigated in this study involves limiting the storage capacity of the installation so that it meets the predicted (or actual) load to such a capacity that it is fully depleted at the end of the occupation period. As cooling load and chilled-water return temperatures vary, the temperature of the water leaving the heat exchanger of the storage system is controlled at a constant temperature to balance the load between the storage and series chiller to ensure optimal depletion of the thermal store. Load-limiting control optimises the plant's electrical power use. By using the integrated load profile produced from the simulation results it is possible to use a predictive control strategy that minimises the cooling plant loads.
Performance charts for convective heat exchangers
Authors: Brinkworth B.J. , Tough M.C.
Published: December 2008

Methods are given for the preparation and use of charts which present the thermal performance of convective heat exchangers for HVAC applications. Performance is expressed by the relationship between three parameters: the air-side and water-side effectivenesses and a design parameter representing the heat-transfer characteristics. These incorporate the effect of varying air velocity on the rate of heat transfer. Typical charts are illustrated for counterflow heat exchangers with one, two or three tube rows. Examples are given showing the utility of the charts as a practical aid to design and to the development of heat exchangers for novel operating conditions.
Heat loss from a solid floor: A new formula
Authors: Davies M.G.
Published: December 2008

It is pointed out that Macey's formula, used in the CIBSE Guide to calculate the heat loss from a solid uninsulated ground floor slab, is unsymmetrical in its handling of the floor length and breadth L and B, and further that it implies the existence of a volume of perfectly insulating material embedded in the base of the wall (thickness W). Both flaws are avoided in a simple expression for heat loss which involves the floor dimensions grouped as LB/W( L + B). The expression provides an excellent approximation to an exact expression for heat loss due to Delsante, Stokes and Walsh.
Air-conditioning control strategies : Computer simulation for a commercial building in Hong Kong
Authors: Ho W.F. , Li Fu Hui
Published: December 2008

This paper presents a transient simulation method for simulating an air-conditioning (AC) system in a commercial building. Using the simulation program, a typical air-water cooling system in a commercial building was simulated with real data from Hong Kong. The impacts of several different control strategies (start/stop, continuous, start/stop with night ventilation, economiser) on energy saving were computed and the energy consumptions were compared. The effects on energy saving of the control mode before the occupied period and the chilled water outlet temperature from the chillers were also simulated. The computational results show that the control strategy has a significant effect on the energy consumption of an air-conditioning system and that there is an optimal range of chilled water outlet temperature within which the system energy consumption is a minimum.
Ice thermal storage: Theoretical study of the implications of the deregulated electricity market in England and Wales
Authors: Beggs C.B.
Published: December 2008

The forthcoming expansion of the electricity contract market in England and Wales in April 1994 will have far-reaching consequences on energy usage in buildings. This paper examines the effect of the expansion on the utilisation of ice thermal storage within the England and Wales. Electricity pool selling prices are analysed, and a cost study is carried out to compare ice storage operating costs under a pool based contract with those incurred while running under a maximum-demand tariff.
Domestic ducted forced-air heating: Duct system leakage and heating energy use
Authors: Babawale Z.A. , Serive-Mattei L. , Littler J.
Published: December 2008

A residential ducted forced-air heating system was investigated to assess the impact of duct system leakage. Ductwork pressurisation and tracer gas techniques were used to quantify leakage in the heating duct system, and added infiltration to the house caused by duct leaks. Determination of leakage fraction by pressurisation tests showed a distribution loss of 23% in supply ductwork and 3% for the return duct during normal operation of the air heater's circulation fan. Tracer gas tests showed that the house infiltration is affected by the duct system leakage: infiltration increased from 0.1 ac h-1 for no ducting, to 0.21 and 0.5 ac h-1 with heating ductwork when the circulation fan is off and on respectively. A direct calculation shows the heat loss due to duct leakage to be about 45% of the house peak winter load. Hourly simulation of the space heating requirements indicates an annual increase of 35% in heating load due to heating duct leakage and transmission losses.
Extract fan flow rates resulting in spillage
Authors: Shepherd T.A.
Published: December 2008

Experiments were carried out on open-flued gas and oil boilers in a test house at the Building Research Establishment, Garston, to find out what parameters affect combustion gas spillage. The experimentation consisted of testing the pressure difference and extract fan flow rate at which spillage occurred. The results showed that in a large number of cases spillage will result if an open-flued gas appliance and air extract fan are running concurrently. Spillage was not encountered with the oil boiler which had a pressure jet burner. Any fan installed in the same room as an open flued gas appliance or an oil fired appliance with a vaporising plate burner should have a maximum capacity of 201 s-1, and fan and appliance should pass a suitable spillage test
New building air flow simulation model: Theoretical basis
Authors: Tuomaala P.
Published: December 2008

A new method for modelling multi-zone air infiltration and ventilation simulation and a simple test case are described. The network approach was used, and the solution was based on a fully implicit formulation of the flow equations. In the present version of the building simulation model (BUS version 2.1), the thermal behaviour of a building is neglected, and constant and uniform air temperatures are assumed. Convergence of the program was tested by test runs. The simulated steady-state mass flow rates and pressures were checked by analytical calculations. The results are found to satisfy both mass balance equations for every node and momentum equations for each flow element when a simple test case is simulated.
Building services and building finishing works: A model for analysing problems in construction
Authors: Baldwin A.N. , Chan Y.K.
Published: December 2008

During construction it is commonplace for conflicts to occur between building services systems and the finishing works. These have three main causes, design, co-ordination or procedural. This paper presents a co-ordination cube model for classifying design and co-ordination problems. The model may be used at both project level and corporate levels to monitor problems and to assist in the prevention of future conflicts. Its flexibility allows for the easy extension and breakdown of information to the level of detail required by management. The model has been used to analyse data from a major design-and-build firm.
Occupants' assessments of indoor environments: Questionnaire and rating score method
Authors: Levermore G.J.
Published: December 2008

This Technical Note briefly outlines a questionnaire that can be used to assess both occupants' liking of their indoor environment and also the importance to them of the relevant factors that they are questioned about. Both liking and importance are measured on seven-point scales. From these scales an overall rating for the indoor environment of a building can be calculated. A normalised rating can be produced between +100 and -100, the positive scale increasing with liking and importance and the negative scale showing disliking and unimportance. The questionnaire demonstrated relates to offices, but it can be modified for other buildings and the scoring system retained. This 'liking' score may be a useful indicator of occupants' perceptions of a building, especially of its indoor environment. Other questions are included in the questionnaire for supplementary information, but are not included in the scoring.
Neural network control of a non-linear heater battery
Authors: Hepworth S.J. , Dexter A.L. , Willis S T P
Published: December 2008

The unsatisfactory performance of conventional building services controls is frequently due to poor commissioning, and to the inability of conventional controllers to deal with non-linearities and to adapt to long-term changes in the behaviour of the plant. The paper describes a hybrid neural control scheme which is capable of compensating for plant static non-linearities and of adapting on-line to degradation in the plant, but avoids the instability problems that can arise when neural networks are introduced into the feedback control loop. The hybrid controller uses a neural network, which learns the non-linear static characteristics of the plant, to generate feed-forward control action, and a conventional proportional controller, acting as a feedback trimmer, to deal with unmeasured disturbances. Results of a detailed computer simulation of a heater battery are presented; these show that the hybrid scheme can produce more consistent control, and is less sensitive than a conventional PI algorithm to initial tuning and to variations in the temperature of the water supplied by the boilers.
Building fabric thermal storage: Use of computational fluid dynamics for modelling
Authors: Winwood R. , Benstead R. , Edwards R. , Letherman K.M.
Published: December 2008

The paper describes work towards the construction and validation of an accurate and detailed computer model of a commercially available thermal storage system. The model is constructed with the aid of a computational fluid dynamics package, using a minimum of fitted data. The paper also includes a discussion of the reasons for current interest in fabric energy storage (FES), the mechanisms by which it may operate and summaries of operational experience with FES buildings and current research in this field. Some preliminary results from the computer model are presented and the plans for future work are outlined.
STEP technology for building services projects
Authors: Griffin C.R. , Evans F.J.
Published: December 2008

The paper describes the development and demonstration of a STEP-compatible prototype system for product modelling, and the transfer of engineering information transfer, from design to commissioning, in building services projects. Product modelling tools are described on the basis of an interactive graphics interface, and the population of the databases generated using an enhancement of a commercial CAD system. The automatic generation of wiring diagrams and commissioning schedules from higher-level design schematics produced on a remote computer is also demonstrated. It is claimed that the principles successfully established can form the basis for substantial reduction of project costs in the future.