CoDyBa - Dynamical Behaviour for Buildings

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What CoDyBa is CoDyBa is a design tool on classical PC for buildings dynamic performance simulation.
It's aimed for design offices, teaching and research organisms.
The new CoDyBa version is called KoZiBu : a prototype is available by download for free.
What CoDyBa is designed for CoDyBa is a software used to analyze dynamic hygrothermal performance of building elements when subjected to any kind of climate conditions. The tool is aimed to conduct studies of heating and cooling strategy, air conditioning or ventilation options, insulating materials to be installed. The main objective of CoDyBa is to forecast the energy consumption, and temperature and humidity evolution range.

It permits to estimate the instant heating or cooling powers needed to maintain a given set-point, or to calculate the indoor temperatures when the heating or cooling system is insufficient. Humidity is treated in the same way.

CoDyBa can be used to investigate the energy performance of buildings of almost any type and size. In addition to performing peak load calculations necessary for mechanical equipment design, CoDyBa also estimates the annual energy performance of the building.

For more details, see the presented samples.
How does it work CoDyBa is based on simply bricks assembled to form a complex building with its equipment. Through the graphical interface, users construct a model of the building's geometry using basic elements (air volumes, walls, windows). With the interface users can add internal loads and HVAC-systems into the created model of the building and perform thermal calculations.

Building screenThe building main screen is like the Windows Explorer.

The building have to be described accurately : the building description is given by the use of a graphical interface, which includes a building tree, similar to Windows Explorer. The building tree is used to describe the general building structure. Users can choose to display different hierarchies of information, zone level, etc. Within the interface, each "entity" is associated to a graphical representation, that permits to manipulate it by operations of "copy", "paste", "drag-and-drop" type. The explorer makes it possible to reach and to edit each entity.

The input entities are those currently utilised by the professionals, while the calculation models are treated in a transparent manner.

CoDyBa has no limit in air volumes number (thermal zones) : it can simulate building of any size. The only real limit is the time used to input data.
Screen shots SEE FURTHER.
Samples Traditional house (1 level, 10 volumes).
Office building (7 floors, 79 volumes).
Audience Engineers, researchers, architects, energy consultants (architecture/engineering firms, utilities, equipement manufacturers).
Students of engineering and architecture.
Expertise required Understanding of thermal-physical processes in buildings is desirable but not absolutely necessary.
Engineering background is helpful to analyze calculations results.
One day of training is desirable but not necessary for those familiar with building modeling (no training courses are required).
CoDyBa is designed for people not being experts on simulation methods, but has an advanced level appreciated by simulation experts.
Availability The single-zone version is free (free download) and can be used as demo version.
Special price for Department of Education and training organisms : * Base price.
Partnership Partners are required to continue the development of CoDyBa (please contact Jean NOEL) :
- softwares developers : for links with CAD softwares (reading of building geometry to avoid tedious inputs).
- researchers and manufacturers : for the developement of new functionalities and the introduction of more sophisticated materials.

Platform PC-compatible, Windows 95 or higher, Pentium processor with 20 Mo of RAM is recommended
Languages CoDyBa is available in french and in english (at present the help is only in french). Texts are in separated files and the translation of the software in an other language may be quick.
The software has been built in an Object-Oriented Programming language : C++ (use of an hierarchy of classes to represent the building).
Users Over 50 (in France and other countries).
History CoDyBa was initially created by J.-J. ROUX, researcher at the University. The version multi-zones under Windows and the extra functionalities were carried out by Jean NOEL.
Keywords Energy simulation, energy efficiency, building performance, renewable energy, comfort, thermal analysis, indoor air temperature, dynamic simulation.
Other softwares You can compare CoDyBa with other software of the market, for example : DOE2, TRNSYS, IDA-ICE, APACHE, ESP-r, PLEIADES-COMFIE. The points of comparison can be the size of the treated geometries, the scientific tests carried out and published, the treatment of humidity, the number of output graphs, and the price.

Input The basic data are the building geometry and constitution : air volumes, walls (with the materials of layers and the surface parameters), windows (possibility for solar masks). The main parameters are : the climate (several meteorological files for different french cities are supplied), internal loads (from lighting, persons, equipments), regulators (powers and set-points for temperature, humidity and ventilation).
Virtually everything is defaulted but modifiable. The user adjusts descriptions using fill-in menus.
Output A number of result graphs may be viewed and printed. These graphs can compare selected alternatives and/or selected hourly variables to provide information on energy use. All result graphs can be exported to other packages such as Microsoft Excel or Word for customised report generation. The user chooses desired graphical output for each entity or for the whole building.
Following graphical output are available (as hourly time function) :
- building : sensible and latent powers (sum of all air volumes powers).
- air volumes : sensible and latent powers, indoor air temperature, resultant temperature (average of air and walls temperatures), air relative humidity.
- surfaces : absorbed direct and diffuse solar fluxes, surface temperature (useful for thermal comfort evaluation).
- windows : transmitted direct and diffuse solar fluxes, sunlit fraction, direct and diffuse transmission coefficient, global transmission coefficient g.
- regulators : power.
CoDyBa produces input summary reports that may viewed on-screen or stored as rtf files.
Physical models Numerical algorithms of CoDyBa are specific, but the physical models of CoDyBa are those commonly admitted :

Each air volume can contain an unspecified number of temperature regulators (heating/cooling) with their own power and set-point. Power, set-point and activity are given hourly, per day or by week. Humidity is treated in the same way. In the absence of regulation, the temperature and humidity evolve freely. Regulators have a perfect efficiency.
Taking into account of the mean radiant temperature.
R2C wall model. Wall data is layers (material and thickness), azimuth, tilt, etc.
Calculation of each temperature of surface (wall or window), what allows an evaluation of thermal comfort (otherwise very simplified).
The room occupancy is included.
Internal loads and regulators can have power or control parameters as time dependent functions.
Taking into account of the absorption coefficients and of emission for each wall.
Taking into account of the far masks and shading devices.
Hour-by-hour weather data is used.
At present ventilation with outside (in commercial versions).
Shading devices (venetian blinds, etc.) : a modeling was developed and was tested. A version of CoDyBa includes this modeling. The results are ready to be published, and a preliminary report (in english) is available.

A whole series of functionalities were developed without being integrated into commercial version (for an use of these functionalities or for specific studies, consult Jean NOEL) :

Comfort indices, PPD and PMV (FANGER methods).
Forced aeraulic (flow between air volumes).
A reading of the files of software TRNSYS was developed and will be later integrated.
Validation The BESTEST benchmark (International Energy Agency) was passed successfully (see report in pdf format). This benchmark is the most precise and the most reliable which exists. Then CoDyBa can simulate the performance of 155 buildings in the BESTEST protocol and in almost all the cases matched the performance of other reference energy programs.
Strengths No limitation in the numbers of air volumes (thermal zones, see sample 1), simplicity of use, ease of input data, multi-zones calculation, computational speed.
Weaknesses Equipment is modelled very simple (maximum power, set point, activity). Lack of global input of building data.

CoDyBa Screen Shots

Materials A predefined materials library exists :

Materials screen
Surfaces The screens of walls and windows are :

Wall screenWall.

Window screenWindow.
Regulators The screens of reagulator and internal loads are :

Heating screenCooling.

Lighting screenLighting.
Results The results are provided in the form of curves in function of time (the output time step is choosen by the user).
An integrated tracer makes it possible to visualize them quickly, and an exportation in the Excel format is possible.

Tracer screen
Weather data The software is provided with the weather files of 10 french cities (Agen, Ajaccio, Carpentras, LaRochelle, Limoges, Macon, Millau, Nancy, Rennes, Trappes).
A tool makes it possible to define specific weather :

Weather screen
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