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.

Drawing Roofs

There are many options for drawing roofs in the Tas3D modeller. This short guide explains when each option may be the best choice and clears up some common questions.

Option 1: Set Wall Height
Pros: A very quick solution for simple sloped roofs with a level ridge.
Cons: Unsuitable for any other type of roof.

Option 2: Set Space Height
Pros: A very quick solution for stepped flat roofs.
Cons: Unsuitable for sloped roofs.

Option 3: Set Point Height (Select Join)
Pros: Allows quick modelling of curved roofs and intersecting slopes.
Cons: Can be time-consuming with roofs that cannot be triangulated easily. Not suitable when there is an abrupt change in roof level.

Option 4: Use 3D Planes
Pros: Can be applied to any sloping roof situation. Plane can be used for multiple roof areas at once. Intersection line between two planes can be calculated automatically. Reduces risk of errors arising from incorrect wall and point heights.
Cons: Creating the planes can be more time-consuming than the other methods.


How would three different roofs be modelled most effectively on this simple building?

With this roof there is a sudden change in roof level, and the “Set Point Height” option cannot be used. We can see why if we consider one of the points used by both sloping roofs (highlighted in lower image) which would need to have two different roof heights at the same time; in this example it would need to be 4.5m for the left-hand roof and 5.5m for the right-hand roof.

We need to use 3D Planes here.

With this example we have a sudden change in roof level, meaning that once again we have points which would need to have two different heights at once; we cannot use the “Set Point Height” option.

In this case we would need to use 3D Planes for the left-hand roof. For the right-hand roof we can simply use the “Set Space Height” option.

This roof rises to a single point and there is no step or sudden change in roof level. The roof can be achieved easily by using the “Set Point Height” option.

What about a situation where the roof itself is very simple, but there are several internal walls underneath it?

The answer depends on whether or not the roof is on a separate storey. In the case where the internal walls extend upwards to meet the underside of the sloping roof, the best option is to use 3D Planes. But if there is a separate roof space and the internal walls only extend to the underside of a flat ceiling, we should model the roof on a separate storey and the “Set Point Height Option” can be used.

What about “gaps” in the roof where internal walls or null lines are exposed?

When you create the analysis model, Tas3D creates a new building element for the exposed parts of internal walls, null walls, etc. These new elements, which will have a name ending in “-exposed” can be changed by the user to represent external walls (or, depending on your building, you may want to set these up to represent, e.g., glazing). When you refresh the analysis model you will see that your roof “gaps” have been filled. Be sure to assign an appropriate construction to these building elements in the TBD.

Overview of a 90.1 Appendix G Project in Tas

This blog post gives a brief overview of the methods recommended in Tas to carry out an ASHRAE 90.1 Appendix G analysis. Please note that the emphasis here is on the Tas methods, rather than interpretation of the regulations; as Tas files allow editing, a wide range of different interpretations can be allowed for. Moreover, the exact requirements for results or methods can vary from project to project. The steps explained here are designed to make carrying out a 90.1 project as quick and accurate as possible.

First step: Create the Proposed Tas3D file

When zoning the model, consider space use and conditioning so that each area can receive the correct internal condition and HVAC. Also consider perimeter zoning rules for the version of 90.1 you are using.

Create the Proposed TBD file

The Proposed TBD file represents the building fabric and space use of the designed building (with some important exceptions), and is used as the basis for the Baseline buildings.
Depending on the requirements of your project, may have to consider the following:
Blinds or shades that are controlled automatically or which are permanent features may be included in the Proposed building. Manually controlled blinds or shades cannot be included in the Proposed building.
The building is required to be mechanically ventilated for the purposes of the 90.1 project, so apertures for naturally ventilated areas should be removed even if they are part of the design.
The solar reflectance of roof constructions should be set as 0.30.
Automatic lighting controls may be included, but manual lighting controls may not.
If the lighting system has been designed then you should use these values. If not then the Proposed building should be set based on the building area method for the appropriate building type (more on this later).
EDSL recommend that the fresh air ventilation rate is set correctly in the internal conditions (or at least close to the correct rate) in order to ensure accurate results in TPD.

Add Proposed files to the NPO Studio

The 90.1 Studio allows organisation of the files associated with the project, and has built-in tools to speed up the project work.

Create the Baseline buildings

The 90.1 Studio creates the geometry for the four Baseline buildings; this includes rotating the building and applying new constructions in line with 90.1 versions 2007, 2010, 2013, and 2016. Constructions will be applied to the Baseline according to the surface type which the user assigns to the building elements from the proposed TBD file, according to the space use types (also assigned by the user), and according to the climate zone.

Adjust Baseline lighting

The 90.1 Studio adjusts the lighting level in the Baseline TBD files to comply with 90.1 2007, 2010, 2013, or 2016. If the Proposed building uses the building area method (because the lighting system has not been fully designed) then so should the Baseline building. In other cases, use the space-by-space method to assign the lighting gains to the Baseline building.
Lighting controls are not allowed in the Baseline building, and are automatically removed by the lighting wizard.

Simulate the TBD files

The TSD files created by these simulations will be automatically stored within the 90.1 project structure.

Create the Proposed systems file

In the Proposed building, if an area of the building has a fully designed mechanical ventilation system which provides both heating and cooling, then you should model the designed system. In all other cases (for example if the area is intended only to be heated, or it is intended to have heating and cooling but the system has not been designed) you must use the appropriate Baseline system.
When modelling the designed system, you should try to replicate the design as closely as possible. In most cases a close equivalent can be found in the wizard and edited later if necessary. Baseline systems can be created in the wizard.
See the Tas documentation for more information on Tas Systems:
If Baseline systems are used, the user should follow the guidelines below, and ensure that they run the 90.1 airside and plant efficiency tools in the Proposed TPD:
When the Proposed TPD is complete, save and add it to the 90.1 Studio.

Complete a sizing run for the Proposed TPD

This is needed so that the zone fresh air rates can be sized (if applicable) and copied to the Baseline TPD files. Save the Proposed TPD after the sizing run.

Create the Baseline 000 TPD file

We only need to create systems for one Baseline building. The TPD files for the three remaining orientations will be generated from this file.
See the guide “Tas Systems Project Wizard and 90.1 Baseline Systems” for details of Baseline system selection and setup:
Tas can generate Baseline systems for 90.1 versions 2007, 2010, 2013, 2016, or 2019.
When the Baseline TPD is complete, save and add it to the 90.1 Studio.

Create the other Baseline TPD files

Select the Baseline 000 TPD file. Select the “Use for Baseline Systems” option.

Copy fresh air rate values

Located in the 90.1 Studio under Tools -> Copy Fresh Air Rate Values.

Simulate TPD files

Final Step: Re-runs and reports

The “Generate Documentation” button in the 90.1 Studio creates several reports, including a summary of unmet hours in the Proposed and Baseline buildings. Depending on the 90.1 version and the requirements of your project, a large number of unmet hours may require you to make changes to your system sizing.

A large number of unmet hours could mean zones have been grouped together incorrectly, e.g. zones with very different schedules or gains. It could also indicate airside schedule issues, for example a radiator which is turned off during unoccupied hours and cannot provide out-of-hours heating.

Many 90.1 project submissions are assisted by providing supporting documentation to explain the project inputs. A great deal of this information can be extracted from the systems files, using the “Create Report” button in TPD and by copying data from the 90.1 efficiency tools.

Approved Document O

Overheating: Approved Document O

Approved Document O, commonly referred to as “Part O”,  relates to assessing overheating in domestic properties and came into force on the 15th June 2022.

Its purpose is to reduce the occurence of high indoor temperatures to protect the health and welfare of occupants.

TM59 vs Approved Document O?

When it comes to dynamic thermal modelling, the methodology is based on TM59 – the main differences relate to openings. The following opening controls should be familiar:

  • During the day (8am to 11pm), openings should start to open at 22°C and be fully open at 26°C
  • The openings should start to close when the temperature falls below 26°C and be fully closed at 22°C
In addition to the above, Approved Document O states that, at night (11pm to 8am), inaccessible openings should:
  • Be fully open if the internal temperature exceeds 23°C at 11pm and stay open until 8am

This does not apply to ground floor windows or openings which pose a security risk.

Demonstrating Complaince in Tas

In Tas version 9.5.4 we have introduced a new aperture function specifically for Approved Document O.

Simply set up your models as you would for TM59 and apply the above aperture function to openings which are safe to open at night.

The day operation of the function will reflect the input settings, and at night the apertures will automatically stay open if the temperature exceeds 23°C at 11pm.

Then run through the TM59 wizard as normal.

Part O Aperture Function in Tas.

What else is new?

In addition to the new aperture function for part O, Tas v9.5.4 also allows you to model the effect of ceiling fans and other means of reliably generating air movement:

TM59 wizard screenshot showing wind speed column

Increased air movement can help reduce the temperature a person experiences when there are warm radiant surfaces present.

This functionality has also been added to our TM52 Adaptive Overheating report.

Where can I find more information about TM59 and Approved Document O?

In addition to the official TM59 document and the offical Approved Document O document, please see our TM59 documentation for more information about Approved Document O and TM59 in Tas.

Tas and EnergyPlus

EDSL Tas can both import and export EnergyPlus IDF files.

EnergyPlus IDF files generally contain good quality data and a comprehensive set of inputs, making IDF import a reliable and convenient way to get data into EDSL Tas quickly.

IDF import to Tas3D:

Create a new Tas 3D model from an IDF file. In Tas3D you can create feature shading systems and edit windows. The file can be used for daylighting calculations and Climate Based Daylighting Modelling using Tas3D’s built-in daylighting engine.


IDF import to TBD:

Create a new, ready-to-simulate model from an IDF file. Geometry, room assignments, opaque and glazed constructions, gains, thermostats, and humidistats are all imported. Surface shading can optionally be imported.


IDF import to Tas3D and TBD:

Combines all the advantages of the import types mentioned above, simultaneously creating new Tas3D and TBD files. Enables the user to, e.g., import the IDF and immediately carry out daylighting calculations on the geometry, then export to TBD and find all the construction and internal condition data already assigned and the TBD ready to simulate or to import into a Tas Studio.


IDF export from TBD:

Any TBD that is ready to simulate can be used to create an IDF file which is ready to simulate in EnergyPlus (for room loads only).


The IDF Import and IDF Export features make it easy for current EnergyPlus users to get started with EDSL Tas.


Validation of Tas against BS EN ISO Standards

The BS EN ISO Standards 13791, 13792, 15255, and 15265 are used to validate a building simulation software’s results against expected results; compliance with these standards demonstrates the integrity of the simulation engine as the results are concerned with the solar, heat flow, and room load calculations which underpin the annual simulation.

Models were set up in Tas to the requirements specified in the standards. In each case Tas results fell within the standards’ specified margin of the expected results.

BS EN ISO 13791 tests heat conduction, long-wave radiation, surface sunlit factors, and operative temperatures resulting from different geometry, constructions, and ventilation methods.

BS EN ISO 13792 tests surface sunlit factors, and operative temperatures resulting from different geometry, constructions, and ventilation methods.

BS EN ISO 15255 tests operative temperatures and cooling loads resulting from different constructions, gains, ventilation methods, and cooling systems.

BS EN ISO 15265 tests heating and cooling loads resulting from different geometry, constructions, gains, and system schedules.

The Tas software’s compliance with these standards means users can have confidence in the accuracy of the TBD simulation engine.

To read the full compliance reports or download the Tas models, click here: https://www.edsl.net/validation/

Migrating from Hevacomp to Tas

Migrating from Hevacomp to Tas

Are you a Hevacomp user in need of a new tool for your building load and energy calculations? If so, in this post, we’ll look at how you can perform heat sizing and cooling sizing load calculations in Tas. 

You can also see an example heat sizing report and an example cooling sizing report from Tas. 

New Projects: Create the geometry

Creating new projects in Tas is a lot like Hevacomp. Start with the geometry, generate a building simulator file and provide constructions and weather details. 

You can create geometry by importing a DWG file and tracing around it. Label the spaces by assigning a zone, then export to the Building Simulator to assign constructions, weather & internal conditions. 

For existing projects, you can import IDF files from Hevacomp or use our gbXML import. 

New Projects: Select Weather & Assign Constructions

You can import an EPW weather file directly into the building simulator, use CIBSE weather or create your own weather file. 

You can assign constructions to your Building Simulator file from one of our databases bundled with the software, or you can create your own constructions by building up the material layers.

Calculating Loads using the Design Day Wizard

Once you’ve created a building simulator file with appropriate weather and constructions, you can launch the Design Day Wizard via: Tools > Design Day Wizard.

This wizard will guide you through performing heating & cooling load calculations. For heating loads, enter the heating setpoint and infiltration rate and the wizard will generate the heat loss report. 

The heat loss report is generated for each of the zones selected in the wizard showing the breakdown through the building fabric. You can easily re-run the wizard to make amendments and generate a new report. 

Admittance Calculations & Pipe/Duct Sizing

For pipe & duct sizing, Tas integrates with MEPWorx, (formally Cymap). Data is transferred from your detailed HVAC simulation models. 

Importing Hevacomp files into Tas

Tas can import both gbXML and IDF files; the best way to import existing Hevacomp projects into Tas is with our IDF import wizard:

Using the IDF Import wizard, you can automatically create a Tas3D file to perform daylight calculations on. The wizard will also create a building simulator file with internal gains, construction information and create a weather file for you either using an EPW or a native Tas TWD file.

You can find the IDF wizard in the Utilities folder of the Tas Manager

Improve Efficiency with Dynamic Simulation

So far we’ve examined how you can calculate heating and cooling loads using Tas using the steady state method. As Tas is a dynamic simulation package, you can also simulate a full year and determine peak loads that are more representative of the actual demand for heating and cooling, therefore preventing oversizing and undersizing, and leading to far more efficient building operation.

This can save energy, money and reduces the carbon footprint of the building. 

Ready to try it?

If you’re an existing Hevacomp user and wish to try Tas Engineering, you can download a free trial. To get started quickly, try using the IDF wizard to import an existing project of yours so you can explore the Design Day Wizard. If you have lots of users who would like a trial or have any specific questions, contact us

If you wish to create new projects in Tas, sign up for our free online e-trianing

Learn to Code with Tas and Excel Lesson 4- Tas3D Zone Writer pt 3

Learn to Code with Tas and Excel Lesson 4- Tas3D Zone Writer pt 3

In the last lesson, we modified our zone writer macro to:

  • Check for duplicate zone names
  • Check for existing zone groups and add zones to groups if they already exist

In this lesson, we’ll take a look at performance. So far, our macro works very well for adding a small number of zones to a model but as our model and the number of zones gets bigger, it can take a very long time to run!

Do I really need to worry about performance?

Usually, the time to start worrying about performance is when we try and use our macro and it takes a long time to run. After all, the whole point of writing these macros is to save time! 

Getting a feel for the difference between fast code and slow code is quite useful though, as it you’ll intuitively write fast code from the start and develop an intuition for how to keep things snappy. 

Lets time our macro

Lets modify our existing macro so we can time how long it takes to run. First, lets add a new subroutine called TimeAddZoneNames. We’ll use this function to call our existing function, AddZoneNames, and time how long it took to run:

					Sub TimeAddZoneNames()
    'Declare some variables to keep track of when we started timing and how much time has elapsed
    Dim StartTime As Double
    Dim SecondsElapsed As Double
    'Use the built in 'Timer' function to get the current number of seconds since midnight
    StartTime = Timer
    'Call our macro that adds zones to our model
    'Call timer again, and calculate the difference in seconds
    SecondsElapsed = Round(Timer - StartTime, 2)
    'Display a message showing the time it took to run
    MsgBox "This code ran successfully in " & SecondsElapsed & " seconds", vbInformation
End Sub

We’ll also need to modify our AddZoneNames subroutine to remove the ‘finished’ messagebox at the end. 

Think about it

Why do we need to remove the finished message box from AddZoneNames?


If we didnt remove the message box, our timer would time how long it takes us to press OK to the Finished message box. We're interested in timing how long it takes to add zones to the 3D modeller file, not how quickly we can press Finished!

Last but not least, we’ll need to change the button we use to run our macro to call our TimeAddZoneNames subroutine:

To do this, right click on the button and press Assign Macro

How long does it take to run?

Using the above modifications, i’ve timed how long it takes to run our macro when we’re adding a variable number of zones to the model. Results below. 

When we’re only adding 30 zones, the macro takes 3.5 seconds to run. Pretty good.

When we want to add 200 zones, it takes over a minute. Maybe that’s ok, we can usually spare a minute.

When we want to add 500 zones, it takes over 12 minutes!! This is not good. What if we make a mistake and need to re-run it? that’s almost half an hour of wasted time!

These times are from a fast 4GHz processor – take a moment to see how long it takes to add 200 zones on your machine and see how the times compare. 

Why does it take so long to run?

You might be wondering why this macro takes so long to run when computers can perform billions of calculations every second. Lets time how long a simple operation such as an addition takes:

					Sub addMillionTimes()
    Dim i As Long
    i = 0
    While i < 1000000
        i = i + 1
End Sub

I timed calling this function, which adds 1 to a variable 1 million times, to see how long it would take to execute. Even with declaring the variable and assigning space for it in the computer RAM, this macro took 0.01 seconds to run!

Now lets compare it to a function which retrieves the building name in a file:

					Sub getBuildingNameMillionTimes(doc As TAS3D.T3DDocument)
    Dim i As Long
    Dim name As String
    i = 0
    While i < 1000000
        name = doc.Building.name
        i = i + 1
End Sub

This subroutine takes a jaw dropping 46 minutes to run! Why? Because when we use a type library to control another application, the Windows operating system has to perform many security checks each time we call a function belonging to that library. Therefore, if we want to write fast macros, we need to reduce any unnecessary type library function calls.

In the case of our existing macro, every time we add a zone to the file we need to check every single zone in the file to see if it already exists. If we have 10 zones in the file and we want to add another, we have to check 10 zones before we can add a new one. A checking operation involves getting a reference to a Zone object then reading its name (3 operations). 

If we have 499 zones in our file, we have to check 499 zones names before we can add another one. 

But what if we could check each of the zone names once and remember the result, so that next time we want to add one we can save a lot of time? 


Fortunately, we can use an object called a Dictionary in order to create a lookup table in the computers memory of zone names and zone references. 

Before we start adding zones to our file, we can read all the zones in the 3D modeller file once and add them to our lookup table. 

					Function CreateZoneDictionary(doc As TAS3D.T3DDocument) As Scripting.Dictionary
    Dim lookup As Dictionary
    Set lookup = New Scripting.Dictionary
    Dim curZone As TAS3D.Zone
    Dim curZoneIndex As Integer
    curZoneIndex = 0
    While Not doc.Building.GetZone(curZoneIndex) Is Nothing
        'Get a reference variable for the current zone
        Set curZone = doc.Building.GetZone(curZoneIndex)
        lookup.Add curZone.name, curZone
        'incremenet the zone index so we look at the next one in the file when the loop repeats
        curZoneIndex = curZoneIndex + 1
    Set CreateZoneDictionary = lookup
End Function

Note that in order to use Dictionaries, you need to reference the Microsoft Scripting Runtime via Tools > References.

This function creates a dictionary on line 3, and then iterates over every zone in the file. On line 15, it stores the zone name as the dictionary key and a reference to the zone as the value in the dictionary. 

We can therefore use the dictionary to very quickly retrieve a reference to a zone using its name. Using this dictionary, we can re-write our ZoneExists function:

					Function ZoneExists(name As String, lookup As Scripting.Dictionary) As Boolean
  ZoneExists = lookup.Exists(name)
End Function

Looking up a value in a dictionary based on its key is extremely fast, as no type library function calls are required. 

Putting it all together

The complete macro, with the changes highlighted, can be seen below. I have also created a dictionary for zoneSets in order to speed up checking of zone sets exist already, and adding zones to them. 

					Sub TimeAddZoneNames()
    Dim StartTime As Double
    Dim SecondsElapsed As Double
    StartTime = Timer

    SecondsElapsed = Round(Timer - StartTime, 2)
    MsgBox "This code ran successfully in " & SecondsElapsed & " seconds", vbInformation
End Sub

Sub AddZoneNames()
    'Read the file path from the spreadsheet
    Dim filePath As String
    filePath = Cells(1, 5)

    'Open the 3D modeller
    Dim t3dApp As TAS3D.T3DDocument
    Set t3dApp = New TAS3D.T3DDocument

    'Declare a variable for checking if operations were successful
    Dim ok As Boolean

    'Try to open the existing file
    ok = t3dApp.Open(filePath)

    'Check if it did open successfully
    If Not ok Then
        MsgBox "Couldnt open the file; is it in use?"
        Exit Sub
    End If

    'Define our loop variables
    Dim rowIndex As Integer
    Dim zoneName As String
    Dim zoneSetName As String
    Dim newZone As TAS3D.Zone
    Dim zoneSet As TAS3D.zoneSet

    'Set the starting rowIndex
    rowIndex = 2
    Dim zoneLookup As Dictionary
    Dim zoneSetLookup As Dictionary
    Set zoneLookup = CreateZoneDictionary(t3dApp)
    Set zoneSetLookup = CreateZoneSetDictionary(t3dApp)

    'Check each zone name cell to see if it contains something
    While Not IsEmpty(Cells(rowIndex, 1))

        'Read the zone name from excel
        zoneName = Cells(rowIndex, 1)
        'Read the zone set name from excel
        zoneSetName = Cells(rowIndex, 2)

        'Check that the zone name isnt already in use
        If ZoneExists(zoneName, zoneLookup) Then
            Cells(rowIndex, 3) = "Skipped"
            'Check to see if there is a zone set already in the file with the right name
            Set zoneSet = GetZoneSet(zoneSetName, zoneSetLookup)
            'If it doesnt exist, make a zone set wtih that name
            If zoneSet Is Nothing Then
                Set zoneSet = t3dApp.Building.AddZoneSet(zoneSetName, "", 0)
                'Add it to the dictionary
                zoneSetLookup.Add zoneSetName, zoneSet
            End If
            'Add a zone to the zone set
            Set newZone = zoneSet.AddZone()
            'Change the name of the zone we just added
            newZone.name = zoneName
            'Add it to the dictionary
            zoneLookup.Add zoneName, newZone
            'Note the addition was a success
            Cells(rowIndex, 3) = "added"
        End If

        'Increment the row index (so we read the next cell down)
        rowIndex = rowIndex + 1


    'Save the file and check the save was successful
    ok = t3dApp.Save(filePath)

    If Not ok Then
        MsgBox "Couldn't save the file!"
        Exit Sub
    End If

    'Close the file

    'Close the 3D modeller
    Set t3dAppp = Nothing

End Sub

Function CreateZoneDictionary(doc As TAS3D.T3DDocument) As Scripting.Dictionary
    Dim lookup As Dictionary
    Set lookup = New Scripting.Dictionary
    Dim curZone As TAS3D.Zone
    Dim curZoneIndex As Integer
    curZoneIndex = 0
    While Not doc.Building.GetZone(curZoneIndex) Is Nothing
        'Get a reference variable for the current zone
        Set curZone = doc.Building.GetZone(curZoneIndex)
        'Add the zone to the dictionary, using its name as the key
        lookup.Add curZone.name, curZone
        'incremenet the zone index so we look at the next one in the file when the loop repeats
        curZoneIndex = curZoneIndex + 1
    Set CreateZoneDictionary = lookup
End Function

Function CreateZoneSetDictionary(doc As TAS3D.T3DDocument) As Scripting.Dictionary
    Dim lookup As Dictionary
    Set lookup = New Scripting.Dictionary
    Dim curSet As TAS3D.zoneSet
    Dim curZoneSetIndex As Integer
    curZoneSetIndex = 0
    While Not doc.Building.GetZone(curZoneSetIndex) Is Nothing
        'Get a reference variable for the current zone
        Set curSet = doc.Building.GetZoneSet(curZoneIndex)
        'Add the current zone set to the dictionary, using its name as the key
        lookup.Add curSet.name, curSet
        'incremenet the zone index so we look at the next one in the file when the loop repeats
        curZoneSetIndex = curZoneSetIndex + 1
    Set CreateZoneSetDictionary = lookup
End Function

Function ZoneExists(name As String, lookup As Scripting.Dictionary) As Boolean
  ZoneExists = lookup.Exists(name)
End Function

Function GetZoneSet(name As String, lookup As Scripting.Dictionary) As TAS3D.zoneSet
    If lookup.Exists(name) Then
        Set GetZoneSet = lookup(name)
        Set GetZoneSet = Nothing
    End If
End Function


As we have already discussed how dictionaries work, we wont go through this macro line by line – hopefully the comments will be enough to explain what’s going on, along with your experience from the lessons so far. 

How much time did we save?

The amount of time we saved by using dictionaries might shock you. 

To add 1,000 new zones using dictionaries took only 2.16 seconds. With the old version, it took over 12 minutes to add half that number!

Details: Dictionaries

Dictionaries are common in most programming languages, but sometimes they go by other names such as ‘Hash Maps’. A dictionary is an object that can store a number of pairs of items. These pairs consist of a Key and a Value.

The Key can be of any type, as can the Value

Each key in a dictionary must be unique — that is, you cant have the same key in there multiple times!

If you’re still unsure what a dictionary is, you can think of it as a kind of lookup table. Imagine you had a table of council tax bands and the prices you’d pay for each band:

Band Price
A £20,000
B £30,000
C £43,000
D £51,000

Here, the band is the key and the price is the value. If you wanted to find out the price for being in a band, you’d look it up in the table. 

Dictionaries have functions that allow you to:

  • See if there is an entry in a dictionary for a key already (dictionary.exists)
  • Add items (dictionary.add)
  • Remove items (dictionary.remove)

For more information about dictionaries, see the Excel Macro Mastery topic on the subject. 

Next Lesson

In this lesson we’ve learned something very important – that we should try to call certain type libraries functions as infrequently as possible in order to write fast macros. We’ve also looked at one way in which we can achieve this – by calling these functions once and storing the result to use later, so we don’t have to check again.

In the next lesson, we’ll move on from our zone writer macro and write one to perform some daylight calculations in the 3D modeller. We’ll also learn how to read the lux values for each point and write them to our spreadsheet. 

Smart Glass

What is Smart Glass and is it the future of glazing?

‘Smart Glass’ is glazing that has changeable light and solar transmission values, there are a number of different types of Smart Glass that use different types of technology to alter these properties such as electrochromic, thermochromic and photochromic glazing.

Electrochromic glazing has its light and solar transmission altered when a voltage is applied to the glazing.

Thermochromic glazing has its light and solar transmission altered when heat is applied to the glazing.

Photochromic glazing has its light and solar transmission altered when electro-magnetic radiation is applied to the glazing.

When used in building design, Smart Glass can adapt to the varying climate experienced throughout the year and can create a responsive building envelope. 

Diagram from Heliotrope Technologies Inc., showing how electrochromic glazing can allow different amounts of light and solar energy into a space depending on which ‘state’ the glazing is in, not only can light and solar be controlled but they can be so in an independent way.

There are numerous potential advantages to utilising Smart Glass in building design such as:

  • Allowing more daylight into the building during winter months when there is less available, whilst also being able to reduce the amount of daylight entering the building during the summer months when excessive levels and glare are more likely to be experienced.
  • Prevent the need for external shade systems that may require higher maintenance costs, obscure occupant’s views or even be considered an eyesore.
  • Reduce heating demands in the winter and cooling demands in the summer by varying the solar energy allowed into the building.
  • Smart Glass can be used for privacy, reducing the light transmittance of the glazing of an occupied room so people can no longer see in.
  • Prevent the need for internal blinds that can lead to high glass and blind surface temperatures when there is not sufficient ventilation between the blind and the glass, leading to high radiant temperatures in the space and therefore poor occupant comfort.
  • The fact that the glazing parameters can alter means that architects have more flexibility, they can design buildings with a higher proportion of glazed façade with less risk of overheating, glare and high cooling demands. 

Photograph of public restrooms in Japan that utilise the adjustable light transmission of Smart Glass to become opaque when occupied.

So is Smart Glass the future of building design and will we see it replace conventional glazing systems? It definitely has its applications and can be of great use for designing buildings in areas that have highly variable climates but with a higher cost and the need for its benefits to be considered at early design stage it may not be for everyone.  As production costs start to drop however we could expect to see it installed more regularly, particularly in markets like high end domestic, hotels, and retrofits of buildings currently struggling with the increasing effects of climate change, experiencing high cooling demands and/or occupant discomfort.

Modelling Smart Glass with Dynamic Simulation Modelling (DSM)

Modelling the effects of Smart Glass is obviously much more complicated than modelling standard glazing as the glazing specifications are not static for the yearlong simulation. At EDSL we recently carried out an investigation into how Heliotrope’s electrochromic glazing performed in comparison to more conventional glazing options for a number of different climates. The electrochromic glazing has variable transmission, with extremes called the “bright” state and the “dark” state. Transitions between these two extreme states are changed by applying a voltage across the glass.

The “bright” state was modelled with the following parameters:

The “dark” state was modelled with the following parameters:

As you can see from the light transmittance and G values the dark state of the glazing allows significantly less light and solar energy into the space. 

Each EC glazing system has its own solar gain sensor that controls the hourly variation of the panel between ‘bright’ and ‘dark’ states. The optimal control curve (to continuously control to a target average lux level on the working plane) is non-linear and depends on both model geometry and location. Deriving these control curves requires multiple annual daylight simulations, similar to CBDM, which are non-trivial and can be time consuming. The shape of the control curve is obviously important, but the solar gain sensor value at which the EC unit starts to dim is also critical. This whole process of optimising EC control would be intractable without using the multiple cores/threads of modern processors.

Graph of the incident solar gain on the windows and the average lux in the space when using the calculated control curve to control the ‘state’ of the Smart Glass, as you can see the lux levels are held below a value of 2000 lux even when higher solar gain levels are incident. Without the control curve and with the glazing always in its ‘bright state’ lux levels reached an average of up to 14000 lux at some points through the year!

As new technologies become available for building design, thermal modelling software tools must be developed so that the effects of these can be investigated at the design stage. Modelling Smart Glass is no trivial task, at EDSL we are continuing to develop the software to make the modelling of Smart Glass a completely seamless experience for the user. 

If you’d like to find out more about Heliotrope’s electrochromic glazing check out their website Heliotrope Technologies – The Next Generation in IGU Evolution

If you have your own Smart Glass or innovative technology project you would like assistance with contact our consultancy department 

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