Grasshopper

algorithmic modeling for Rhino

# Dew Point Calculator for Assembly

This is a tool I scripted in grasshopper for my undergraduate architecture students in a building systems course. The tool abstracts a wall or roof 'typical' assembly to help inform where vapour controlling layers and potential condensing surfaces may occur in a design assembly by graphing the temperature gradient through the assembly and calculating the dew point (internal). By studying a proposed roof and wall in isolation, it can inform the process of detailing the juncture between those two assemblies.

Here's how the script looks with the algorithm doing all the calculation and drawing on the right and the control panel for material and design parameters on the left.

Here you can see the organization of the file with the notations and group labels. The script uses two different dew point calculations for comparison.
This is an example wall assembly with a total R value in US units of 22. Material thickness (mm) and thermal resistance (u value) parameters are inputted to calculate R value in SI units which is then converted to US units. Design parameters are set to study a particular interior/exterior temperature relationship and a desired interior relative humidity. The tool then graphs the temperature gradient through the assembly and located the dew point as a coloured point (the yellow and orange Xs).

Give it a go and feel free to comment or ask questions. A 2D typical assembly dew point calculator like this is of limited value, but can be a useful step towards developing well understood details at assembly junctures.

Views: 5562

Attachments:

### Replies to This Discussion

Dew point?

Excellent I must say > very few Architects understand what this means in real-life (result: use umbrella when INSIDE of a given building designed by the ignorant).

1M Q: what is your favored insulating material? (mine is FoamGlas).

Yeah it's also little understood what the dew point calc does tell you (and more importantly what it doesn't!). I am using this tool to teach my undergraduate students in architecture about this issue and how to use it in design.

I kind of love how cheap your R/inch is with blown in cellulose but if you mean high-tech insulating material... the national research council of canada did some research into VIPs (Vacuum Insulated Panels) that are pretty cool.

One of these days I'll mail you some stats (~ 250 buildings designed insofar all with the black smelly stuff): numbers tell another story (the classic one: if you are poor buy expensive shoes).

Have in mind that R and the likes have "some" role in our trade ... but the most important thing by a million miles is the assured longevity of a given solution (and obviously the failure rates, resulting claims, fire rates, potential repairs [never occurred to me, yet], polar bear matters etc etc).

So ... having the forest in mind nothing on this planet beats Pittsburgh Corning (all that before mentioning insulating HVAC pipes et all).

BTW: Gimme me ANY solution that comes close to this:

Or that (using serrated plates in order to avoid the obvious):

Context is everything - I work primarily in my practice in Canada in a fairly rural context. The availability of materials, trades (and skill/knowledge of those trades) is always a necessary design input.

Those details look very clean. In the case of a new construction, stick-frame house, adding some wall thickness and taking advantage of a cheap insulation source (which can be 100% post-consumer and environmentally sustainable) where the site is not overly constricting you can get a high performing building at relatively low cost. Of course the proof is always in the details - which is why I work with some great consultants!

I don't have any experience with foam glass, interesting material and obviously worth investigating further. Thanks!

Well this smelly black thing is brilliantly engineered in order to be used with the least possible experience/skills: in any developing country, in Planet Zorg, anywhere actually (provided that some iron hand controls the whole procedure on-site: simple/elementary requirements actually... but failing to comply > Armageddon). As an added bonus is ... er ...hmm .. eternal and utterly indifferent to any material in proximity. Can be used with the new bread of thin plaster coatings as well:

http://www.stocorp.com/building-solutions/new-build/coatings/

If you take the plunge some day ... pay attention to the requirement Numero Uno: for roofing applications COVER Foamglas (if the T4 variant is used) with bitumen [as that FM dictates] in order to avoid icing on the utmost surface and thus gradual deterioration.

Filed away for future use! It would be a good teaching tool to model that assembly you posted in the dew point tool and then show where vapour is controlled in the assembly, where the dew point falls and how there is no condensing surface within range of the moist interior air. The location of the foam in the assembly makes detailing at junctures simple.

Cheers, I might model this up for a lecture I have as an example of a newer high performance material assembly.

I was thinking:

due to the critical importance of this thread of yours (for those knowing their onions, that is) I wonder if you want a more "compact" version of all that stuff ... I mean ... entirely via code > just one "component" that does the job (plus some other things(*), plus some 3d stuff for the WOW [a bit cheapo, he he] part).

(*) Imagine having some data sets related with materials (that could been modified on-the-fly) et all ... and then having the ability to create/manage/exploit/recall/whatever different variants/combos/scenarios blah, blah.

I would love to see where a tool like this could go over a longer development period! For now I also use it as a soft-intro to modeling in Grasshopper and to have a conversation about parametric design where the focus isn't always on form generation and introduces the idea of scripting for analysis.

That said, I think a more elegant/sophisticated tool would be of interest to a number of my students and colleagues and probably others online here.

I am still building up my ability to script directly in python, C++, etc. and converting the tool entirely to a single component is probably outside my ability so far, so if you want to help me get started that would be amazing!

Well ... I'll do some stuff for you via the Dark Side (C#) this w/e. You'll be surprised with the "variant" management (I do hope).

The result would be very "slick" (just one thing) but the bad news are that you wouldn't be able to modify it until you get the gist of the Dark Side, he he (long is the path and hilly).

BTW:  on a pro level this should work with a proper RDBMS concerning materials AND especially their recorded application history (monitored Projects et all) with all the pros and cons: picking a material based on specs is nothing, taking into account the history is everything.

For instance: someone does some upside flat roof using some thermally bonded PVC membrane [hopefully pressure tested] ,  loosely applied on some drainage screed + DOW on short spacers + a separating layer + gravels. Is he a smart fella or just an ignorant?

BTW: Also have in mind that HVAC stuff MUST have some insulation (shown custom FoamGlas encapsulation) .. otherwise condensation may occur EVEN if the space is well insulated - this is especially true (for obvious reasons) if pipes/ducts are cold and spaces below the false ceiling are warm.

Here is a version of the same script that has a convenient "bake this" group to get the vectors out for Ai.

Attachments:

• View All