Insulation FOR heat and AGAINST heat. Is there a difference?

[Jack]

I've tried researching this to the Nth degree but have found nothing.  This leads me to believe that there's no difference between insulating against summer heat and insulating to keep warm in winter.  Is my assumption right?  I'm more concerned with staying cool than keeping warm.  

Also, are there some (durable) materials for interior siding on the walls, floors, and ceiling of your van that work better than others to keep a van cooler?  

I read the article Dealing with Heat and Cold on this site and have a question.  

First, within the legal requirements of your home state, tint all the windows as dark as you can.

How about when you plan to travel around the country?  What's legal in one state might not be legal in another.  If I have out of state plates, and my tint is too dark, can/will police stop me for simply "driving through" their state?

The article also talks about window coverings and that the added benefit is for privacy.  It mentions using a product like Reflectix.  Personally, I don't want the tin-foil look on my windows facing out.  That would seem to draw attention when you have it on every window by reflecting the light of passing cars, etc.,  Someone on YouTube uses Reflectix but covered the outside (facing the street) with black felt to make it more private and stealthy.  (Also helps it to stick to velcro to stay in place.)  Does the black felt (or another dark material) interefere with Reflectix's ability to repel the heat since dark colors hold heat?

Lastly, when it does come to keeping warm in cold climates, is there heat lost through vented items, like Fantastic Fans or holes drilled into the bottom of the van for various reasons?  (I've heard of people doing this to help with condensation to give it a place to drip out.  Also for venting composting toilets, air-conditioners, and other appliances that need venting.

 

[Riverman]

If you want the best R-value per inch of board insulation, get POLYISO from Home depot.

It is not cheap to insulate a van or cargo trailer properly.

Please use all you can afford... the thicker the better.

 

[Sylvan Secrets]

Black felt would definitely interfere. Reflectix works by reflecting heat and requires an air gap. I'm not saying the felt negates everything, but it is silver for a reason.

 

[lenny flank]

The laws of thermodynamics say that heat ALWAYS moves from the higher energy place to the lower energy place--i.e., from hot to cold.

Insulation works by delaying that motion.

So, whether YOU are warmer or cooler depends on which side of the barrier you are on. But the barrier works the same way.

Also, keep in mind that insulation works by delaying the transfer of heat. So it does almost no good at all unless you are actively heating or cooling the air on the side you want to be on. If you are not, the temps will eventually equalize.

 

[Trebor English]

Also, keep in mind that insulation works by delaying the transfer of heat. So it does almost no good at all unless you are actively heating or cooling the air on the side you want to be on. If you are not, the temps will eventually equalize.

It gets hot outside at 2 pm in August.  Without air conditioning the temperature inside equalizes.  Then it's hot inside.  Insulation will keep that heat inside after the sun goes down.  An exhaust fan can help defeat the insulation and cool off the inside.  Less insulation might need less defeating.  

In the winter running the same exhaust fan to manage moisture and condensation will defeat the insulation making it cold inside.  

If you are going to defeat the insulation maybe you could use less insulation.

 

[lenny flank]

I use no insulation at all. But then, I also use no heater and no AC. But then, I move with the weather and go north in summer and south in winter, so I don't often encounter temp extremes, and my sleeping bags (I have 3, each rated to a different temp) can handle anything I'm likely to run into.

 

[John61CT]

Yes the function of insulation is to **slow down** as much as possible the movement of heat where you don't want it.

So in winter, keeping it from escaping too quick. A small enough space, tightly sealed and high R-value, even just your own body heat can help. Add a dog or a few candles, even better (hi Lenny!)

Important to put more R-value on the ceiling.

Using aircon in summer, need more on the floor, you are then trying to keep the heat out. In homes Reflectix pointing out behind an outer air gap helps, but not enough room for that in a van.

If both, then the same all six sides. Windows are the enemy, one place where Reflectix can help.

Very important to have a very tight well-sealed envelope, so the only ventilation is 100% controlled.

But you do need high CFM ventilation sometimes, MaxxAir or Fantastic Fan.

Do not allow humidity to build up, vented heaters are **much** better than unvented, which can be fatally dangerous.

Easiest maybe cheapest strategy is to stay mobile, follow the 60's.

 

[jonyjoe303]

insulation will keep you cool in the summer and warm in the winter, the more you use the better the results. You also have to separate the front of van from the back with some sort of sliding insulated door. All the heat comes in from the front windshield. 

All the rear windows need to be insulated, too much heat comes in from those areas. You dont insulate your rear windows you will have a hot van all the time. Its also good for stealth. The windows the police dont want tinted are the windshield and driver window and window next to driver. The back windows don't matter. The driver window can in some places be mildly tinted but its best not to tint it.

On the roof remove the original headliner and install some rtech foam insulation, at east 2 inches. The windows you need at least 2 inches, the rest of the van you can get away with 1/2 to one inch of foam.  

I been using 1/2 inch rtech foam insulation, and I just stack it on top of each other to increase the thickness, 1/2 inch is easy to cut with boxcutter and will bend to curves. The best way to install is with a hot glue gun, ryobi makes a good 30 dollar cordless glue gun. No fumes, drys instantly and makes a very solid installation.

So far in the summer I can get a 50 degree difference between the front uninsulated van and the back heavily insulated section with a 2 amp swampcooler running, this is with van parked in the sun and all windows/vents closed. In the winter my van never got under 50 degrees, didn't use a heater and never had to sleep in a sleeping bag, the lowest temp in front of van was 42 degrees.  


This is the rtech foam I use it comes in 4x8 foot sections found at home depot, I bought another section this weekend , 1/2 costs 8 dollars, 1 inch cost cost 12 dollars and the 2 inch cost 22 dollars. 


This is how the back of my van looks like, I only care about one thing comfort, I'm not going to hang pictures on the wall or put wallpaper up, I'm always adding more layers of foam insulation, thats how important it is. Straight ahead is the driver compartment behind a sliding door.  No heat/cold comes into the back from that door. There is no windows in the back, its all LED lighting, if the back of your van is pitch black at daytime, you are doing a good job, sunlight equals heat.

 

[lenny flank]

How much water does your swamp cooler evaporate in an hour?

 

[Jack]

I see there really isn't going to be anything simple about my van build, is there?!  I'm definitely concerned about condensation and mold and will do anything I have to do to NOT make that a worry.  If I have to add ventilation panels to the side of the van, so be it.  

Like I said, I get much hotter than I ever get cold.  Would it be smart to figure out which kind of A/C unit I'm going to have first or does that not matter?  I'd get a window unit if I had to but I'd rather not.  I don't know how good the ceiling units are though.  Basically, I want the best, most reliable A/C there is that can run the longest (more than just an hour) and then figure out how much solar I'd need just to meet my A/C needs.

Life was easier when you could easily rank things as best to worst.  But now, with so many choices available to meet so many different needs... not so much.

 

[John61CT]

If you want aircon off-grid, reliably and regularly, you need a genny, full stop.

When parked in full sun, maybe possible to run a small 5000 btu unit directly off 1000-1200W of panels,

But then you're not re-charging your bank.

And no running off batteries, just not reasonable nor even practical without a very heavy duty 30' long rig, many tens of thousands just for your electrickery gear.

Of course none of this has anything to do with your insulation.

 

[Jack]

Of course none of this has anything to do with your insulation.

That helps, actually.  Someone told me that how I insulate depends more on if I want to keep my van cooler or warmer.

 

[John61CT]

Wrong. Only for heating, important to put more R-value on the ceiling.

Using aircon in summer, need more on the floor.

If both, all six sides the same thickness.