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Discussion Starter · #141 ·
The 8.52W number is based on natural convection within the closed space. So no forced air. Forced air makes a massive difference in heat transfer (which is why we use fans etc. for cooling stuff).

I think your confusion is coming from the idea that the heat HAS to get in. Heat does not work like a pressurized hose. Heat transfer rate does not increase through a thermal bridge because you have added other insulation. The heat transfer through the thermal bridge is always constant (in a given scenario). The insulation does not affect sidewalls of the pillar at all. The heat transfer runs in parallel. The only way to reduce the heat transfer through a thermal bridge is to use a thermal break, as you have discussed. But the heat transfer through the open interior space can be significantly improved with insulation.
I appreciate you breaking it down like that. It helped significantly. I figured if this thread were up long enough, someone with the background could provide an angle that explained how it works in enough detail to cover the many aspects in play.

What Antoine and others recorded in photos and imaging supports how critically important it is to cover the bridge completely inside the van to retain heat in the Winter by creating a break point there, without Summertime imaging I'll presume the reverse direction will be helped as well. Most importantly, based upon what you have shared there appears to be more benefit to breaking the heat path inside than it was reflected in the tables of material heat transfer rates I referenced.

Thanks to Kabouter's skills in both the thermal and communication realms!
 

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All of this points out the opportunity for the van mfgs to really help out the conversion community by using either carbon fiber or fiberglass to build the bulk of the van body vs the existing steel approach.

If the van skin and framework were relatively non thermal conductors vs the existing thermal conductor, imagine how much easier a conversion build would be.
 

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All of this points out the opportunity for the van mfgs to really help out the conversion community by using either carbon fiber or fiberglass to build the bulk of the van body vs the existing steel approach.

If the van skin and framework were relatively non thermal conductors vs the existing thermal conductor, imagine how much easier a conversion build would be.
Easier to get to an acceptable state, yes.

At the end of the day, the van is a very small space - and one would be wise to do as much as possible to insulate the van regardless of van body material. If you can throw a 1/4in of XPS or ez-cool in as a thermal break you should, its neither difficult or expensive.

Same for stuffing the body channels, its not very hard (yes I've done it) and not expensive at all so why not just go for it.
 

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2017, cargo, 130inch, mr, dbl sliders, 3.2 dsl, 3.31 rear end, used 13.5k mi.
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Reviving an aging thread... A builder was glad to accept my cash to eliminate >95% of any interiorly exposed surface metal with a disruption to thermal bridging heat transfer/loss. This involved applying 1/8 inch closed cell polyethylene to all metal surfaces and then 1/16 inch pretty woven material on the closed cell surfaces. Subjective assessment makes me believe that there is a significant benefit in reducing heat loss in cold weather and with both insulating cavities previously discussed AND attending to the disruption of thermal bridging, a year-round benefit will be realized. As one who space heats with only electricity, not liquid fuel, I have noticed far less electrical loads in cold weather. Now, off to the Missouri breaks for a few days to again evaluate the thermal breaks...
 

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This hardly qualifies as hard science ... but, I filled one ceiling channel with Havelock Wool and on the next sunny day the rib was much cooler than the unstuffed ribs. Since the ribs are separated by foam, the heat transmission from the bare roof panel through the open space of the rib is pretty different than if the transmission is just through the foam to the rib. It wouldn't actually be too hard to do the calculations on this. Have at it!
 
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