In case you’re just joining us on the Thermal Bridging Simulation Adventure, here’s post 0, post 1, post 2, and post 3.

We’re hitting the Start Simulation Button!

Finally. Doing so gives us two results which we can subsequently place as images on our detail. Here’s what my simulation generates after I place the two potential images in the detail window:


I also get this numeric information (which I assume the documentation that comes with EcoDesigner STAR will eventually explain):


In a sense we could stop here. We now have some pretty images that we can show the client and brag about around the office. And I’m sure without really understanding what they mean, we could use them to make all sorts of arguments. We can see where the freezing point in the walls is: where the color goes from red to blue (the white zone) in the first image. I know that’s not a good location, but this wall will also never see zero degrees Fahrenheit. In the second image we can see where the weak parts are in the flow of energy, i.e., where heat is escaping or entering the easiest (the red zones in the second image). By just reading the images graphically we get some utility out of them. And with this basic sense of where the weak points are, we know what we have to focus on if we want to make design changes. But with my limited knowledge, changes would all be gut instinct. Or semi-educated assumptions. It’d be nice to understand more. In other words, we need some external knowledge to be able to use the results as a sophisticated design tool. And here’s where I’m a bit conflicted. Do I really need to understand more? Yes and no.

Here’s the NO argument:

I’m using Thermal Bridging Simulation as a low-level energy modeling design tool. I can read the visuals well enough to know roughly if my detail is good or bad (just not the DEGREE of goodness or badness). I can run a few iterations of the detail, adding or subtracting insulation, changing the materials, etc. and then compare the results—at least visually. I can take that knowledge and then have a more intelligent conversation with someone who has a better understanding of building science. I can focus on learning the tool and let someone else help me understand what to do with the output. I’m assuming that if I do this a few times, I’ll learn the important bits through a combination of osmosis and working with an expert. I like that. It saves me from having to do copious amounts of research in a near vacuum. And from the start of this exploration, this was about introducing myself to the tool, not mastering it.

Here’s the YES argument:

EcoDesigner STAR is a powerful tool and if I don’t research in depth what the data means, I’m not getting enough value out of it. I’m wasting my time; I’m just a dabbler. If I don’t understand all the details, I won’t really integrate it into my design methods. It’ll always just be secondary and something to skip if it gets too complicated. If I’m serious about designing with Building Energy Models (BEM), then I need to really learn what BTU/Square Foot/Hour and all the other numbers mean. And how they all relate to the bigger picture. And… death spiral of in action.

Next Steps

So maybe I’m not so conflicted after all. My answer to “Do I really need to understand more?” is “Short term: No. Long term: Yes.” Right now I just need to raise awareness. I need to remember to keep exploring more of EcoDesigner STAR and BEM. It’s enough for now to get something out of the images and also do a few pieces of research, to focus on the parts that excite me. This is a marathon, not a sprint. This is a huge evolution in how I think about my relationship to the design process. I won’t master this all in a few blog posts. I need to apply it to a real project and take baby steps. So perhaps the next step is running a few variations and then talking to an expert.

A future step is getting this data integrated into the larger energy model. I saw the EcoDesigner STAR introduction webinar (which you can rewatch from the beta site) and I know that the data from the Thermal Bridging Analysis can be fed back into the Energy Model to make the overall energy simulation more accurate, but I am not there yet. Nowhere near that point. So we’ll come back to that aspect later. That’s actually another answer to my Yes/No conundrum: I can do the next step with the results of the Thermal Bridging Analysis data without going down a long research path. I can get to the BIG model, see those results, learn what they mean, and then figure out which little parts I need to tweak to change the bigger picture. I assume? Again this is the (fun?) of blogging during exploration and not at the end. I have to live with unanswered questions and only a vague understanding of the endgame. I can live with that. And I hope these posts are inspiring you to take some early steps towards BEM as well.

Further Reading

This AIA document (An Architect’s Guide to Integrating Energy Modeling in the Design Process)  from the second half of 2012 doesn’t mention ArchiCAD’s built in energy evaluation and obviously not EcoDesigner STAR (so it’s analysis of available tools is a bit out of date, no surprise since any list of tools would be out of date by the time the PDF is created). But it’s worth a look at for some bigger picture energy modeling issues. I’ll be honest: I’ve only skimmed it. I would like to find the time to read it all the way through, but it’s 86 pages. And well… little kids. My excuses aside, it looks like this document will fill in some of the bigger picture items and help us focus in on what’s important to research now and what can wait until later.

The ArchiCAD help documents are also worth a read. Here’s the one from ArchiCAD 16 as it pertains to many of the numbers we set in earlier posts. I’m sure the documentation for the next version of ArchiCAD and specifically for EcoDesigner STAR will cover even more.

While doing research on BEM, I came across Here’s their article on Buildings and Heat Transfer. I’ll be returning to that again and again.

And here’s another good page: this one is from It covers some basics on heat loss through buildings and gives some common numbers. Many of these common numbers are in ArchiCAD as well. Reading through a page like this gives some additional context and explains things in a different way which might make them stick better.

One More Post then on to some other ArchiCAD topics

Okay so I’ve got one more post (mostly written too!) in this series. So in a day or two I’ll go over some lessons learned and thoughts on this whole process. I might also include a few thoughts that didn’t fit elsewhere.


  1. Ray McNally

    Excellent post and great writing style. Enjoying the journey through Thermal bridging through your writing style.


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