Welding blanket as thermal barrier?

[john61ct]

Insulating paint is snake oil.

Like using Reflectix without an airgap, just a waste of time and money.

Better than nothing is too low a bar.

Starlight ?

[Doktari]

A thin layer of heat shield is not worth the time and space compared to fluffier insulation is what I’m taking from this thread. However I’ve been wondering about a expedition roof to slow down how quickly the roof gets hot by shading the roof and providing a ventilated air gap between the roof and the expedition roof. Solar panels can essentially be a electricity generating expedition roof. I asked my friend who’s smart with energy and money if having water circulating in/under the solar PV panels would make economic and electrical sense and be worthwhile and he said no. But he was thinking of residential systems. Perhaps this combination would be worthwhile in a mobile setting if hot water is needed and space is limited? The cool thing about water is it can be pumped and the heat moved from the roof into a tank. So I’m hoping to test this concept someday. A few hundred feet of PEX under the PV panels with heat transfer plates transferring the heat to the tubing wouldn’t cost much. Freezing and leaking might be a issue

[john61ct]

Shading the outside will always be a fantastic idea.

That is why solar panels fixed on the roof can be counterproductive, if you have the option of parking tucked into a nice canopy of trees.

They also **produce** a heck of a lot of heat underneath, so yes you want good airflow there, not least to reduce the hit on conversion efficiency

There have been both DIY and commercial implementations of water cooling, some making use of the waste heat, but IMO too complex and heavy for a mobile use case.

[LargeMargeInBaja]

re -- efficient insulation
.
We are looking to move onto a boat permanently.
One boat we investigated is a retired fishing trawler.
.
The hold for their catch is insulated with 'vacuum panels'.
.
The key to stopping heat/cold transfer is reducing contact between differing temperature zones.
A vacuum eliminates heat/cold transfer because no medium exists for the transit.
.
.
PS:
Although we liked the ship enormously, the fragrance remained with us for days...

[john61ct]

Yes my statement that polyiso is greatest Rvalue per inch thickness

is ignoring the more modern and crazy expensive material advances in recent decades.

Besides vacuum panels, there is Cryogel Z / Aerogel

Amazing stuff but crazy pricey for building a consumer fridge/freezer box.

[Rucker]

Originally Posted by Doktari

A thin layer of heat shield is not worth the time and space compared to fluffier insulation is what I’m taking from this thread. However I’ve been wondering about a expedition roof to slow down how quickly the roof gets hot by shading the roof and providing a ventilated air gap between the roof and the expedition roof. Solar panels can essentially be a electricity generating expedition roof. I asked my friend who’s smart with energy and money if having water circulating in/under the solar PV panels would make economic and electrical sense and be worthwhile and he said no. But he was thinking of residential systems. Perhaps this combination would be worthwhile in a mobile setting if hot water is needed and space is limited? The cool thing about water is it can be pumped and the heat moved from the roof into a tank. So I’m hoping to test this concept someday. A few hundred feet of PEX under the PV panels with heat transfer plates transferring the heat to the tubing wouldn’t cost much. Freezing and leaking might be a issue

I'm considering using tent fabric to make a light covering over the back half of my bus. Something that would stand off of the roof and allow air circulation, and cut the direct solar gain.

Could look goofy, but might work well.

[Danjo]

Originally Posted by Rucker

I'm considering using tent fabric to make a light covering over the back half of my bus. Something that would stand off of the roof and allow air circulation, and cut the direct solar gain.

Could look goofy, but might work well.

You can shade the sides with awnings. I’ve thought that solar panels reduce conductive heat gain by a little bit.

[musigenesis]

Originally Posted by Rucker

I'm considering using tent fabric to make a light covering over the back half of my bus. Something that would stand off of the roof and allow air circulation, and cut the direct solar gain.

Could look goofy, but might work well.

I think it's a good idea, like one of those umbrella hats for a bus. I plan on doing the same if I ever end up traveling in the bus regularly and need shade for a stay of just a day or two. For static living I plan to rig up some sun sails suspended from trees or poles, if I can't park in natural shade somewhere.