Rhino to Tas: How to with Honeybee

Creating Tas models with Rhino & Honeybee

Rhinoceros, otherwise known as Rhino3D, is a freeform surface modeller that is gaining popularity amongst energy modellers and architects for its ease of use in creating complex geometries. Not only that, but Rhino has a diverse range of plugins which make it possible to perform building energy analysis using interoperability with simulation engines such as Tas. In this blog post, we’ll walk through using the Honeybee plugin by Ladybug tools to link Rhino and Tas. 

What are Grasshopper, Ladybug Tools & Honeybee?

Ladybug tools is a collection of applications that support environmental design founded in 2012. These applications are opensource, and are free to use. 

One of these tools is called Honeybee, and this tool is a plugin for Grasshopper, a parametric modelling tool which is part of Rhino. 

Honeybee can be used to perform daylight simulations using Radiance, and simulate energy models using OpenStudio and EnergyPlus. Honeybee can also be used to produce IDF and gbXML files, both of which provide a route into Tas. 

gbXML? IDF? What's the difference?

Both gbXML and IDF are industry standard formats that are designed to allow building design software to share and communicate data. Whilst most building design packages can export gbXML, very few produce gbXML files that contain more than just geometry.

Fortunately, IDF files often contain both geometry and the data required to perform a full building simulation. IDF files produced using Honeybee contain geometry, internal conditions, construction information, design conditions and more, so we recommend using IDF files unless you’re only interested in importing Rhino geometry into Tas. 

How do I get started?

In order to get started with Rhino and Honeybee, you’ll first need to download and install Rhino. At the time of writing, you can get an 90 day trial if you do not have a license. 

Next, you’ll need to download and install Ladybug tools from Food4Rhino. This is a zip file, so unzip it and start Rhino. Then launch Grasshopper, and open the installer.gh file within Grasshopper:


After running the installation script and restarting Rhino, you should see the Ladybug tools appear in Grasshopper.

Note that you will also need to install OpenStudio if you want to generate IDF files. 

Creating Rhino Geometry

Now we’re ready to create some simple geometry in Rhino, to get ready for export. Let’s start by drawing a two zone model with a couple of windows – this way we can check that our adiabatic links are created correctly, and we’ll be able to see the principles behind marking surfaces as windows. Note that there are several ways to achieve the same outcome in Rhino, so feel free to experiment!

In the video below, I demonstrate how to:

  • Set the Rhino units
  • Draw two connected cuboids
  • Draw surfaces where the windows will be

It is important to remember that two touching faces must have the same dimensions in order to form an adiabatic link when using Honeybee. 

Setting up Honeybee in Grasshopper

Now that we’ve installed Honeybee and created some geometry in Rhino, we can start setting up our Grasshopper document. In the below video, I demonstrate how to produce a gbXML and an IDF file. I also demonstrate how to modify one of the Honeybee components to produce the IDF file without simulating the OpenStudio project..which saves a lot of time!

To skip running the open studio project and copy the IDF file to a directory of our choice, we can find the line containing run_idf and comment it out using a # at the start of the line. 

					import shutil
        elif run_ in (1, 3):  # run the resulting idf throught EnergyPlus
            #sql, zsz, rdd, html, err = run_idf(idf, _epw_file, silent=silent)

    # parse the error log and report any warnings
#    if run_ in (1, 3) and err is not None:
#        err_obj = Err(err)
#        print(err_obj.file_contents)
#        for warn in err_obj.severe_errors:
#            give_warning(ghenv.Component, warn)
#        for error in err_obj.fatal_errors:
#            raise Exception(error)


We have also used shutil.copyfile to copy the IDF file to the path of our choosing using the _idfPathOut parameter we added to the ModelToOSM component. For full details, see the video above.

Commenting out the end of the script stops any error messages appearing when we attempt to run the component. 

Importing the IDF into Tas

Once we’ve created our IDF file, we can import it into Tas using the IDF tool. We can optionally create a Tas3D model for shading calculations, import constructions & geometry and even specify the weather we want to use to simulate. In other words, the model is ready to go!

Rhino to Tas Workflow Summary

Below is a labelled Grasshopper diagram showing the key steps in creating gbXML and IDF files from Rhino. Remember, this is just one way to do it! Some of the components can be linked together in a different order, and some can be omitted. If you wanted to model % glazing, for example, you could add the apertures straight to the HoneyBee model and skip specifying and combining them. 

As the Rhino files are saved separately to the Grasshopper files, you can save the Grasshopper files and re-use them on future projects just by updating the geometry components each time. 

What else is Possible with Tas & Rhino?

As Grasshopper provides a visual programming interface to Rhino and Tas has a programming interface, the two can be linked to achieve endless outcomes – from parametric runs to performing full energy simulations and visualising the results in Rhino. 

You can create your own Tas Grasshopper code modules via python scripts:

					import win32com.client

#open the building simulator and then open a file
tbdDoc = win32com.client.Dispatch("TBD.Document")
tbdDoc.openReadOnly("C:\\Users\\hilmya\\Desktop\\tas house.tbd")

i = 0
while(tbdDoc.Building.getZone(i) is not None):
    #print each zone name to console
    i = i+1

Better yet, you can create C# modules in Grasshopper which have the advantage of code completion:

In order to use the Tas automation interface with a c# script component in Grasshopper, right click on the component and click Manage Assemblies. Then reference the appropriate dll, for example, for TBD you would reference Interop.TBD.dll from the Tas installation directory. 

You can do the same with the Visual basic (VB script) component. 

Ben Abel shares how Hilson Moran use the Tas API

Ben Abel shares how Hilson Moran use the Tas API

Ben Abel is a Director and Head of Research and Development at Hilson Moran, and we recently spoke to him to learn how Hilson Moran use the Tas Application Programming Interface to be one of the most advanced cutting edge designers of the built environment.

Hilson Moran have been using Tas for 25 years

HM has been a long-time user (25 years) of advanced computer modelling techniques in the built environment. EDSL TAS has been the preferred dynamic thermal modelling (DTM) tool of choice over that period and has been used on many iconic and significant projects in the business from 30 St. Mary Axe (The Gherkin) in London, to three of the stadia for the Qatar 2022 World Cup and many others in-between.

Noticing Trends: Coding

The recent upturn and interest in coding by users to create custom interfaces has become increasingly important to improve productivity and allow the outputs to meet the end user/client requirements.

TAS was an early adopter of allowing access to the underlying functions in the software through the Application Programming Interface (API). HM has used this feature extensively to create a range of tools to improve both functionality and productivity.

The types of tools range from bespoke interfaces, for areas such as thermal comfort, HVAC plant modelling and dynamic façade control, and interoperability in using the software through applications such as Grasshopper to allow the DTM information to interact with other outputs from a variety of software.

TM59 Parametric Tool & the CIBSE Building Simulation Group Awards

The HM creation of a TM59 parametric tool, using the TAS API, resulted in the tool being a CIBSE Building Simulation Group Awards finalist at the event at Build2Perform in November 2022.

The tool was used to test and inform the values which were used in the simplified method of the new Building Regulation Part O. The tool allowed hundreds of models to be tested against the overheating criteria to ensure the glazed and ventilations areas presented in the simplified method were in line with the full dynamic methodology.

This task would have been excessively time consuming to achieve manually and at risk of human error.

HM will continue to explore and develop the use of TAS through the API as the benefits it brings are immense due to the efficiencies of automation and the wider sharing and integration of data.