Section One
General
description of ESP-r
and its
associated documentation
This first section of the User Guide gives a general overview of ESP-r (Environmental Systems Performance; r for "research"); a computing environment for building and/or plant energy simulation. The application potential of ESP-r is outlined by citing some typical design questions which the model has been used to answer. Then, the program modules which comprise the system are outlined, along with the essential hardware environment. Finally, some further information sources are indicated.
ESP-r is the outcome of model development projects funded over the years by the UK Science and Engineering Research Council (now EPSRC) and the European Commission’s DGXII. Significant contributions have also been made by many individuals as outlined in the Development history and acknowledgements section.
ESP-r is free software. It is released under the GNU General Public License.
ESP-r is a transient energy simulation system which is capable of modelling the energy and fluid flows within combined building and plant systems when constrained to conform to control action. The package comprises a number of interrelating program modules addressing project management, simulation, results recovery and display, database management and report writing.
One or more zones within a building are defined in terms of geometry, construction and usage profiles. These zones are then inter-locked to form a building, in whole or in part, and, optionally, the leakage distribution is defined to enable air flow simulation. The plant network is then defined by connecting individual components. And, finally, the multi-zone building and multi-component plant are connected and subjected to simulation processing against user-defined control. The entire data preparation exercise is achieved interactively, and with the aid of pre-existing databases which contain standard (or user-defined) constructions, event profiles and plant components. Additional modules exist to permit an increase in simulation rigour if the related data is available.
A central Project Manager allows importing/ exporting of building geometry from/ to CAD packages and other specialised simulation environments such as Radiance for lighting simulation.
ESP-r is equally applicable to existing buildings and new designs, with or without advanced technological features. The system offers sophisticated input/output facilities which enable the user to answer such design questions as
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What, and when, are the peak building or plant loads and what are the rank-ordered causal energy flows? | |
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What will be the effect of some design change, such as increasing wall insulation, altering the window shape and size, changing the glazing type or distribution, introducing daylight control devices, re-zoning the building, re-configuring the plant or changing the heating/ cooling control regime? | |
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What is the optimum plant start time or the most effective algorithm for weather anticipation? | |
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How will comfort levels vary throughout the building? | |
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What benefits can be expected from the different possible lighting control strategies? | |
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What are the relative merits of different heating and cooling systems and their associated controls? | |
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How will temperature stratification, in terms of zone sensor and terminal unit location, affect energy consumption and comfort control? | |
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What contribution does building infiltration and zone-coupled air flow make to the total boiler or chiller load and how can this be minimised? | |
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How do suggested design alterations affect air flow and fresh air distribution (i.e. indoor air quality) within the building? | |
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What is the effect of special glazings (such as thermotropic, holographic, low-e or electrochromic glazing) on summer overheating? | |
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Which are the benefits from architectural building features such as atria, sunspaces, courtyards, etc? | |
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What is the contribution (in terms of energy saving and thermal comfort) of a range of passive solar (heating or cooling) features? | |
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What is the optimum arrangement of constructional elements to encourage good load levelling and hence efficient plant operation? | |
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What are the energy consequences of non-compliance with prescriptive energy regulations or, conversely, how should a design be modified to come within some deemed-to-satisfy performance target? | |
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Which heat recovery system performs best under a range of typical operating conditions? |
and so on. This allows the user to understand better the interrelation between design and performance parameters, to then identify potential problem areas, and so implement and test appropriate building, plant and/or control modifications. The design to result is more energy conscious with better comfort levels attained throughout.
Figure 1.1 Structure of ESP-r
Figure 1.1 shows the relationship between the program and database modules which form the simulation environment. In this User Guide only the Users-side of the environment will be addressed.
The Project Manager allows the interactive definition of some building and plant configuration which is to be subjected to some weather influence and simulated over time. The complete description of the building and plant configuration is called the product model. All data items, as input, are subjected to strict range and legality checks before being directed to disk file for later recall. To ease the input burden, the user is given access to standard databases so that constructions, event profiles and plant components can be accessed by name or simple code number reference. Also, many input items have a corresponding default value so that typed responses can vary as a function of the design information to hand at any time during a design’s evolution. The Project Manager also controls user access to the other ESP-r programs such as the Simulator for simulation and the Results Analyser for analysing the time-series of state variables as generated by the Simulator. The Tutorial Module is linked to the tutorial material now held as Web pages. The content of the tutorial pages ranges from a general introduction to information on how to use ESP-r in a real world design context. The on-line tutorial mechanism is very powerful since it allows a user to look something up quickly when actually using ESP-r. Since they are in-built, the tutorials are much more easily kept up-to-date than this User Guide.
The Event Profiles Database Management Module manages a number of standard or project-specific profiles which define the time dependent variations in zone occupancy, lighting, plant control and miscellaneous appliance usage. These profiles can then be accessed by the Project Manager to define zone and plant behaviour.
The Plant Components Database Management Module manages a plant components database. For each plant component, a summary description is held, along with the data required by the Simulator to allow the time dependent generation of the coefficients of the differential equations which represent component heat and mass balance. Component matrix template data is also held to dictate the whole-system matrix building undertaken at each simulation time-step. The database is then accessed from the Project Manager to enable plant network formulation by component interconnection.
The Climate Database Management Module manages and analyses climatic data collections. A climate collection spans any period from one day to one year and contains hourly values of dry bulb temperature, direct normal or total horizontal solar intensity, diffuse horizontal solar intensity, wind speed, wind direction and relative humidity. The climate management module offers solar radiation prediction, curve fitting to daily maximum and minimum data, statistical analysis, graphical and tabular display and general data management. The climate data is required by the Simulator to generate the time dependent boundary conditions for the building and plant configuration.
The Simulator is the building and plant simulation engine which predicts building and plant energy/ fluid flows by a rigorous numerical method. The building/ plant network is divided into a large number of finite volumes. Then, at each time-step as a simulation proceeds, an energy and mass balance is applied for all volumes, giving rise to a differential matrix for the entire system. This is then solved by custom matrix processing software in terms of any user-imposed control objectives.
The Results Analysis Module operates on the simulation results located in a database by the Simulator. A variety of output options are available: perspective visualisations, results interrogation, statistical analysis, graphical display, tabulations, frequency binning and 3D plotting.
The Insolation and Shading Module is a support module which predicts the time-series shading of external zone surfaces (opaque and transparent) as caused by facade and site obstructions and/or the time-series insolation of internal zone surfaces (opaque and transparent) as caused by solar penetration through windows. The predictions for any surface can, optionally, be archived in a shading/insolation database for access and use within a simulation.
The View Factors Module computes the black body view factors between each zone surface pairing for use by the Simulator to evaluate internal longwave radiative exchanges. It also evaluates zone comfort level variations.
Building/ plant fluid flow simulation can be performed by the Simulator in tandem with the heat balance calculations. In this case full account will be taken of buoyancy driven air movements between outside and inside and between internal zones. If pressure driven air flow dominates, it is possible to use the Flows Simulation Module in stand-alone mode to predict infiltration and zone-coupled air flow. Buoyancy effects are still included but correspond to fixed zone temperatures assigned by the user.
The Construction Data Management Module manages (creates, modifies, edits and lists) primitive and composite constructions databases. The materials database contains the thermophysical properties of conductivity, density, specific heat, solar absorptivity and emissivity for a number of standard homogeneous elements. Diffusion resistance factors are also held as required by ESP-r’s interstitial condensation computations. A second, project-related database can also be created to hold multilayered constructions formed from elements extracted from the materials’ database. Both databases can then be accessed from the Project Manager as required.
A number of ESP-r modules create and/or manipulate random access, binary disk files such as the constructions databases, the event profiles database, and the simulation results database. They also allow for the transformation of ESP-r’s binary files to ASCII format and vice versa. This permits the transmission of binary databases to other computer sites (via tape for example) and, if a user is experienced, direct file editing.
In normal use, the three main modules, the Project Manager, the Simulator and the Results Analyser, are used to investigate building and/or plant performance and, by iteration, to assess the consequences of any change to system design or control. The database modules help to reduce the input burden and the support modules exist to allow the subsystem they address to be treated with greater rigour, if this can be justified by the design objectives and data to hand.
The theories underlying ESP-r and the validity of the Simulator are summarised in Section 5 and presented, in detail, in the following references:
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Clarke J A Energy Simulation in Building Design, 2nd Edition, Butterworth-Heinemann, Oxford, 2001. | |
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Tang D Modelling of Heating and Air-Conditioning Systems, PhD Thesis, University of Strathclyde, 1985. | |
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Hensen J L M On the Thermal Interaction of Building Structure and Heating and Ventilating System, PhD Thesis, University of Eindhoven, 1991. | |
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Aasem E O Practical Simulation of Buildings and AIr-Conditioning Systems in the Transient Domain, PhD Thesis, University of Strathclyde, 1993. | |
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Negrao C O R Conflation of Computational Fluid Dynamics and Building Thermal Simulation, PhD Thesis, University of Strathclyde, 1995. | |
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Nakhi A E Adaptive Construction Modelling Within Whole Building Dynamic Simulation, PhD Thesis, University of Strathclyde, 1995. | |
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Chow T T Air-Conditioning Plant Component Taxonomy by Primitive Parts, PhD Thesis, University of Strathclyde, 1995. | |
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MacQueen J The Modelling and Simulation of Energy Management Control Systems, PhD Thesis, University of Strathclyde, 1997. | |
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Kelly N J Towards a Design Environment for Building-Integrated Energy Systems: The Integration of Electrical Power Flow Modelling with Building Simulation, PhD Thesis, University of Strathclyde, 1998. | |
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Hand J W Removing Barriers to the Use of Simulation in the Building Design Professions, PhD Thesis University of Strathclyde, 1998. | |
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Beausoleil-Morrison I The Adaptive Coupling of Heat and Air Flow Modelling Within Dynamic Whole-Building Simulation PhD Thesis, University of Strathclyde, 2000. |
ESP-r requires the following hardware and software:
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A UNIX TM or LINUX workstation# offering X-Windows and with at least 128 MBytes RAM. Implementations exist for SUN, Silicon Graphics and Linux (PC and Mac) platforms. | |
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A disk capacity to store the executables, manuals, tutorials, training examples (~25 MBytes), perhaps source code (~20 MBytes) and simulation results (~2 MBytes per zone-year at a one hour time step). | |
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Fortran77 and C compilers. | |
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A laser writer for graphical hard copy. |
In terms of usage, this User Guide and the web-based tutorial facilities of ESP-r are the main sources of documentation. In addition, a number of papers concerning ESP-r development and application can be found in the literature. A full list of publications can be found on the ESRU web site.
As indicated in the Table of Contents, the User Guide has a number of appendices. These are available from our FTP server: they can be automatically downloaded by accessing ESRU’s publication list on the WWW (http://www.esru.strath.ac.uk/) or by direct ftp (file transfer protocol) transfer. In the latter case, ftp to ftp.strath.ac.uk and login as anonymous with your email address as the password. The documents will be found in directory Esru_public/documents.
Papers and technical reports cover issues such as:
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How to add new entities such as climate data, project-specific construction databases and plant components. | |
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A list of training assignments enabling an instructor to assess whether the training material is absorbed properly, and enabling the trainee to check whether the training material is understood. | |
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Good practice guidelines for researchers interested in developing or expanding parts of ESP-r. | |
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A bibliography describing much of ESP-r’s technical detail and philosophy. This list includes books, journal articles, conference papers and internal ESRU reports. In some cases PostScript or pdf versions of these publications are available. | |
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A summary of the tasks to be undertaken when implementing ESP-r at a particular site. | |
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A summary of ESP-r’s underlying data model. | |
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Some step-by-step worked examples of simulation projects. |
ESP-r is released under the terms of the GNU General Public License. It can be used for commercial or non-commercial work subject to the terms of this open source licence agreement.
Although ESP-r can be used for free, it is often the case that a new ESP-r site will incur a nominal expense. For example it may be appropriate to send someone to one of the ESP-r courses which we organise regularly at ESRU (the cost is approximately £500 per person). We strongly recommend this course of action for all new users to ensure that the learning process is as short and painless as possible. Dates of forthcoming courses are listed on the ESRU web site. In addtion, ESRU offer a range of options for supporting the use of ESP-r in organisations. Contact ESRU for details.
ESP-r can be downloaded from the web site http://www.esru.strath.ac.uk by following the appropriate links to the software. Note that, because ESP-r is under active development at a growing number of sites, there are frequent updates and revisions.
ESP-r is a building and plant energy simulation environment which is under development at various research centres throughout Europe and elsewhere. These developments involve both enhancements and new developments to the existing system as well as validation activities and application related research.
The people working with ESP-r keep in contact via an electronic communication platform. The purpose of this is to keep each other informed about ongoing and planned developments, system related publications, new results, emerged problems, upcoming releases, etc. To join, simply email the string "subscribe esp-r <your email address" to majordomo@strath.ac.uk. After your name has been registered, you can communicate with other subscribers by sending messages to esp-r@strath.ac.uk. Please note that any e-mail messages received by the virtual user esp-r@strath.ac.uk will be forwarded unmoderated to all people currently subscribed.
Further technical, operational or commercial details on ESP-r may be obtained from ESRU at the address on the front of this User Guide. Alternatively, you may want to browse through our web pages, which can be accessed from http://www.esru.strath.ac.uk.
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