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DesignBuilder CFD

What is CFD?

cfd4.jpgComputational Fluid Dynamics (CFD) analysis is used by building environmental designers to calculate the temperature, velocity and other fluid properties through a 3-D domain. CFD is used to answer design questions such as:

  • What sort of temperature distribution could I expect in an atrium under clear sky summer conditions?
  • Will the arrangement of supply diffusers provide adequate air movement?
  • Is the location of the radiators going to provide good comfort conditions?
  • Will natural ventilation provide occupants with adequate comfort in the summer?
  • What effect will the shape of the building have on local wind velocity?
  • Are there any regions of stale air inside the building?
  • Which layout in a hot/cold isle server centre design give most effective cooling of equipment?

DesignBuilder 3-D CFD

DesignBuilder CFD has been especially designed to provide data on airflow and temperature distribution in and around buildings using the same methods as the general purpose pure CFD packages, but at a fraction of the cost and without the need for specialist knowledge.

Using conventional CFD packages for building airflow analysis can be a time consuming task requiring very careful attention to setting up the correct geometry and boundary conditions. Using CFD in DesignBuilder simplifies this process hugely by automatically providing the geometry and boundary conditions. Temperatures, heat flows and flow rates previously calculated by EnergyPlus can be seamlessly used to provide boundary conditions simply by specifying the time/date of the CFD analysis.



The CFD interface has been designed to enable virtual ‘push-button’ CFD analysis from automatically generated rule-based default data, with options to allow more experienced or interested users to modify this data as required. Adopting this approach enables users to obtain realistic 3-D results without having any specialist CFD knowledge.

Some of the key DesignBuilder CFD features:

  • 3-D CFD grids are generated automatically from model geometry and boundary conditions to promote optimal solution convergence.
  • The CFD engine has been developed around the SIMPLER algorithm, which belongs to one of the most widely used families of CFD solution methods. Turbulence can be modelled using the widely researched and documented k-e model and there are plans to introduce additional models for specific applications.
  • The interface incorporates tools to enable a wide range of boundary conditions such as supply diffusers, extracts, temperature patches, etc. to be assigned to room surfaces. A component library is also provided to enable radiators, fan-coil units, furniture, occupants, etc. to be located anywhere within the model and automatically incorporated within the analysis.
  • Boundary conditions can be automatically assigned from a previous EnergyPlus simulation.
  • 3-D CFD results are displayed using the DesignBuilder OpenGL graphics engine providing impressive, easy-to-interpret images of velocity vectors, temperature contours, iso-surfaces etc.
  • The CFD simulation is based on the full 3-D DesignBuilder model taking into account the zone wall and floor thickness, so the domain is correctly generated without additional modification being required.

The high quality output provided by DesignBuilder CFD will help you to communicate your results to clients in a clear visual way that they can really understand.



DesignBuilder CFD has been independently tested against Pheonics, one of the most powerful and widely respected general purpose CFD packages available. The validation work, carried out by Northumbria University, shows that DesignBuilder is able to reproduce the same results as Pheonics given the same input data. This adds to confidence in the results produced by DesignBuilder CFD.

Download the validation report

CFD Demonstrations

You can view recorded demonstrations of the DesignBuilder CFD software on the Webinars page. These show how DesignBuilder EnergyPlus surface temperature and airflows results can be fed into CFD as boundary conditions and also how DesignBuilder CFD for can be used as part of the HVAC design process.


DesignBuilder CFD can be purchased either as a standalone module or as part of the Advanced Simulation package.The CFD module can be purchased from the bottom of the main purchase page .


Latest News

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