AM 11 Document - Bentley Communities
Contents
1. Comments The software uses AutoCAD DXF files as a template for inputting data B1 8 Associated databases Thermophysical properties Yes M No O Basic material properties Yes M No E Properties of complete construction Yes MW No O Transmission of windows Yes M No O Comment Weather data Yes M No O Worldwide Yes M No O Number of sites 7900 Comment Other databases Check that the modules are available and working consult vendors about likely future releases Ask how many entries are in each database ask to see some of their contents 5 of 14 75 pce AM 11 Document B1 9 User support Manuals User manual Ys M No O Hard copy Ys OH No M On line Yes M No O Date of the latest copy May 2011 Does it include example problems with the expected answers Yes M No O Do the problems exercise all program modules Ys O No M Does it explain how to use every module Ys M No O Comments Technical manual Yess M No O Hard copy Ys O No M On line Yes M No d On line help Yes M No O Comments Case studies Vendor s case study examples obtained Ys M No O Case studies of others obtained Yes O No Vv Hotline Hotline support Ys M No O Turn round Instant O 1day MW gt 1 day O 10 r tyes Ask to see the manual Ensure that it contains all the useful features and that it is up to date 6 of 14 75 cade AM 11 Document Software Updates provided Ys M No O Media for dissemination Floppy dik O CD WM Interet M2. Training Courses provided Ys M No O Cost from 350 Length Details available Frequency Details available B1 10 User base Numbers Users in UK 10 500 Users worldwide 11 800 Sites in UK 1 500 Sites worldwide 1 630 UK building services engineers UK architects UK builders UK others 10 500 Is there a user club Yes O No M Contacts Name Support and Sales Address Bentley Systems UK Ltd The Portergate 257 Ecclesall Road Sheffield S11 8NX Tel 0808 101 9247 Fax E mail via www Bentley com 7 of 14 z enue AM 11 Document B1 11 Cost Software and associated databases Core program on request on request Modules Name Name Name Databases Name Name First year user licence fee Total software and data Computer Name Annual recurring licence fee after first year of use Typical training course fees per year B1 12 Accuracy Has the program been evaluated Yes M No O Does the vendor exercise routine in house quality testing Yes M No O Complete the table below to document the validation history Independently i Date tested or by vendor v Type of test A C E Source of information Comments on the results Aug 07 i E CLG Part L Accreditation test Nov 07 i A ASHRAE HVAC Tests Nov 07 i A ASHRAE Fabric tests Nov 07 i A ASHRAE 120 Nov 07 G A BESTest July 09 i ACE CLG Part L Accreditation A Analytical verificatio
3. al convection note whether a fixed coefficient is used or a more detailed algorithm which may account for wind speed direction and surface orientation is used Although a rigorous approach is theoretically preferable wind speeds and directions close to surfaces are difficult to calculate 3 Longwave heat loss to surroundings has a significant impact on the temperature of external surfaces and for glazed surfaces and other poorly insulated areas the temperature of the interior spaces This has a significant impact on the comfort conditions and perhaps the demands for heating in highly glazed spaces such as atria The exchange may be modelled by a single coefficient or a detailed algorithm may be adopted The algorithm may calculate exchange to both the sky and surrounding surfaces ground and buildings or to just the sky The method of calculating the sky temperature should be noted 4 Heat input from plant and casual sources people lights and equipment may have fixed radiant and convective components or the user may be able to specify these The ability to specify will be important if for example a highly radiant source is used or if highly radiant sources are combined with convective sources The ability to specify the latent proportion of casual heat gains may be similarly important particularly regarding cooking equipment Some programs use detailed models e g which incorporate a time delay and an exponential temperature rise so that hea
4. ces can be very important for modelling e g conservatories or atria note the treatment of this effect 10 of 14 z penteu AM 11 Document B2 3 Surface heat exchange Internal surfaces Combined convection and Separate convection and radiation coefficient O radiation networks Vv Internal combined coefficients Fixed user defined C Program calculated once O Calculated at each time step O Notes Not applicable Internal convection coefficients Fixed user defined MO Program calculated once O Calculated at each time step MI Notes Internal longwave exchange Star network E IntersuArface exchange Vv Notes External surfaces Combined convection and Separate radiation and radiation coefficient O convection networks M Some programs calculate heat exchange between surfaces and the enclosed air using a coefficient which describes both the convective and longwave effects With such an approach the calculated space temperature is not a true air temperature it is often termed the enclosure temperature The true effects of highly asymmetric radiant environments e g a radiant ceiling panel are poorly predicted The approach is however adequate for most spaces and where long term energy use predictions are required Note whether the approach used for glazing is the same as that used for opaque surfaces Ignore if separate convective and radiant exchange networks are employed Ignore if combined coefficients use
5. d In reality coefficients vary depending on the surface to air temperature difference surface length or height roughness etc Note the algorithm used to describe these effects Ignore if combined coefficient used A star network balances radiation exchange at a fictitious central node Radiation actually occurs by intersurface exchange A view factor calculation is needed to describe the intersurface visibility Note whether exact or approximate view factors are used and whether the program calculates these The heat exchange at external surfaces may be calculated using a simple combined surface heat transfer coefficient or by separating out convection and radiation and modelling each of these in detail Note whether the approach used for glazing is the same as that used for opaque surfaces 11 of 14 z penteu AM 11 Document External combined coefficients Fixed user defined O Program calculated once E Calculated at each time step MI External convection coefficients Fixed user defined O Program calculated once O Calculated at each time step MI Notes External longwave exchange User or program calculated coefficient O Detailed algorithm Vv Notes B2 4 Heating cooling and casual gains Heat input Combined radiant and Separate fixed radiant and convective E convective components vi Notes Cooling Sensible cooling only O Sensible and latent cooling M Notes If a separate treatment is adopted for extern
6. es B1 4 Modelling methods The Design Simulation program uses the EnergyPlus simulation engine B1 5 Input interface Type of interface GUI Mi Menu driven O Command line O Other Digital data file Program produces accessible and human readable digital data files Yes M No O Legibility of digital file Good M Poor O Bad O Is entire problem definition contained Yes M No O Are all simulation parameters included Yes M No E Data checking Does program check for consistency and plausibility of input Ys M No O Interfaces may generate files e g binary files which cannot be read by people but only by the program interface These are much less useful and old binary files may cease to be readable by new versions of the interface Check that all the data are included e g geometry construction and occupancy data and that the weather file used is noted Check that all the simulation control information such as time step length length of preconditioning and convergence criteria is given 4 of 14 z enue AM 11 Document B1 6 Output interface Type of interface GUI Me Tabular O Digital O Digital data Is digital output accessible Yes M No E Legibility of digital file Good M Poor O Bad O Is all output contained Yes M No O Are algorithm level outputs accessible Yes M No O B1 7 Linked modules CAD input Yes O No Vv Vendor s own interface Yes M No O Other cad system s name AutoCAD DXF files
7. f radiation Considered M Not considered O Diffuse radiation sky model Isotropic E Anisotropic mi Notes Window transmission direct User specified mi Program calculated mi Other notes Window transmission diffuse User specified mi Program calculated Vv Other notes Internal solar distribution User specified fixed to Calculated once by one or more surfaces O program O Calculated at each time step Vv Notes Solar radiation and its reflection are best calculated if the direct and diffuse radiation components are separated 3 A P Ground reflection must be calculated especially for more highly glazed spaces such as atria Anistropic diffuse solar radiation models are generally considered superior gt Window transmission may be calculated by the program or the user may specify incidence angle dependent values For direct solar radiation incidence angle dependent transmission and reflection or absorption properties are necessary a single value is often used for diffuse radiation Correct specification for direct radiation is most important Software is available to calculate incidence angle dependent values if programs require users to specify these and databases are inadequate The distribution of internal solar radiation is usually important only where glazed areas are large surfaces have very different thermal mass or a number of surfaces are glazed The retransmission through other glazed surfa
8. ity to schedule heating and cooling plant and the occurrence of internal heat gains is important Some programs are very flexible enabling minute by minute variations others are less flexible 13 of 14 Z pct AM 11 Document B2 5 Observations 28 segs Record here any other general observations about the capabilities of the program which have not been covered elsewhere For example some programs impose geometric description limits on the maximum numbers of zones surfaces per zone or windows per surface 14 of 14
9. n C Intermodel comparison E Empirical validation 8 of 14 z enue AM 11 Document B2 Thermal simulation programs theoretical basis B2 1 Conduction and thermal storage Solution method Explicit finite difference Implicit finite difference vI Respnse factor vi Weighting factors Other OO Time step length User specified Vv Calculated by program E Opaque surface conduction model One dimensional Mi Three dimensional O Opaque layers node placement Fixed at number vi User specified O O Not applicable Other Glazing conduction model Resistance or U value E Multi layer with nodes vi Other Air gaps User specified resistance O Program calculated resistance Other Initial node temperature User specified E Program calculated mi Notes Preconditioning time User specified O Program recommended Vv 11 gis is Gora i z Validation work indicates that conduction and thermal storage are well modelled in the programs studied Alternative approaches generally have little impact on results and a small impact on program run times The ability to conduct three dimensional analyses is rarely needed For modelling a large area of glass especially heat absorbing glass windows are best modelled as multi layer constructions 9 of 14 z penteu AM 11 Document B2 2 Solar radiation External solar radiation Direct and diffuse Separate treatment of combined O direct and diffuse M Ground reflection o
10. on will help in the understanding of published literature especially about validation studies 2 of 14 z enue AM 11 Document B1 2 Computer specification Platform and operating system PC Yes VI No d MS dos Ol Windows 3 x d Windows 95 O Windows nt v Windows XP v Windows Vista Vv Windows 7 v ps2 os2 Unix Yes O No Mi Apple Macintosh Yes O No vi Comments Can be run from either the PC or the Server Machine with Control from a License Manager run from a server machine or online Processor storage and peripherals Processor speed 3 GHz recommended quad core Minimum RAM 2 GB recommended 4 gig Minimum disk space 10 GB Other devices Floppy disk Yes O No mi CD rom drive Yes M No O Printer Yes Mi No O Plotter Yes M No O Digitising table Yes O No mi Other Plotter is optional A LAN connection is required Other requirements Screen resolution gt 800x600 Internet connection required for update patches network or Internet connection required for license manager Suitable machines Most modern PCs will have no trouble running the software 3 F Consider screen size video RAM Internet connection local area network connection etc List types of machine known to be suitable 3 of 14 z enue AM 11 Document B1 3 Program code Type of code Compiled code only Yes W No O Source code available Yes O No Vv Extra for source code Yes O No vi Programming language Fortran mi C C Not
11. ting plant can be more accurately modelled This is less important for long term energy calculations than for short term temperature predictions gt An ability to calculate the latent cooling load will be particularly important in humid environments The ability to do this implies that the moisture content of the air is tracked by the program few programs do this 12 of 14 75 pce AM 11 Document Controlling plant Free float Ys M No O Idealised control Ys M No O Ideal preheat cool Ys M No O Fixed heat injection Ys M No O On off thermostat Ys M No O Accelerator Ys M No O Proportional Yes M No O Proportional plus integral Yes M No O Proportional plus integral plus derivative Yes M No O Advanced e g fuzzy logic adaptive self tuning neural network Yes OFF No M Other Schedules Repeated daily schedule Ys M No O Repeated hourly schedule Yes M No O Seasonal variations Ys M No O Flexible hourly schedule Yese M No O Notes Sensor types Sensing air temperature Yes M No O Mixed radiation and convection sensing Yes M No O Surface temperature sensing Yes O No Vv Intraconstruction sensing Yes O No Vv Notes 9 Most programs assume perfect control is possible i e that a specified set point can be quickly achieved provided plant capacities are sufficient this is usually adequate for long term energy calculations In some programs the impact on temperature of alternative forms of control can be explored The abil
12. z enue AM 11 Document Introduction Bentley Hevacomps AM 11 document can be found below Please note that AM 11 is a statement about simulation software and is not an accredited item Appendix B Checklist for choosing BEEM software This checklist complements section 4 of the CIBSE Applications Manual AM11 1998 Building Energy and Environmental Modelling B1 General B1 1 Program description Name vendor origins Program name Design Simulation Version V8i Date of current release Feb 2010 Vendor s name Bentley Systems UK Ltd Contact name Stephen Brown Vendor s address The Portergate 257 Ecclesall Road Sheffield S11 8NX Tel 0808 101 9247 Fax E mail via www Bentley com Program type Thermal analysis Load calculation Vv Plant and controls mi Energy simulation MJ Lighting and visualisation Electric lighting Vv Daylighting mi Combined mi Air movement Vv Specialist tool vi Further description The classification of programs is explained in Section 2 A program may have a number of listed capabilities Space is provided to elucidate the description 1of14 75 cade AM 11 Document Program history Description Design simulation was first produced in 2007 and incorporates Hevacomp CAD input The simulation engine is EnergyPlus List previous names by which program known significant advances in functionality and dates of these changes of platform and changes of vendors This informati
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