SkiFreak
Crazy Person
Not something that we normally have to consider, so most don't.
Here it's more about how well the insulation works when its' hot.
Mitsu Fuso Camper examples
- Thread starter haven
- Start date
Here it's more about how well the insulation works when its' hot.
Ferjablito
Active member
That's what I feared; it's not a good solution for traveling in cold climates.
Insulation is insulation. There is no such thing as insulation for cold weather and insulation for hot weather. The issues most Aussies won't run into is dealing with frozen pipes, installing tank heaters, condensate in air lines due to cold, etc. If you live in a cold climate, your engine is not subject to overheating as it would be in the hot, dry deserts of the Outback.
In the States, R-value is something like resistance to thermal transfer in BTU/hr, per square foot of wall, floor or ceiling area, per inch of thickness. In metric it's something like Watts/meter/Kelvin for each mm of thickness.
If it's 40*F and you want your camper 80*F, that is the same as you wanting your camper 70*F and it being 110*F outside. There is a 40*F temperature delta. The insulation does not "know" hot or cold. There is simply a resistance to thermal transfer in the product.
Add as much insulation as you can afford (dollars and wall thickness), minimise the size of the HVAC. Large units are heavy, expensive and suck lots of power or diesel fuel. Minimise window area, especially if they are plastic or single pane.
Reflectix and many other products marketed to van lifers and travellers simply do nothing but empty wallets. Even if a thermal break exists, it's so small that it may as well not be there at all. The resistance to thermal transfer offered by a 2-3mm thick sheet of foam with some aluminium foil on it, is laughable. Build it right or don't do it at all. This holds true whether you are building for 40*C in Oz or 0*F in Colorado and Utah.
In the States, R-value is something like resistance to thermal transfer in BTU/hr, per square foot of wall, floor or ceiling area, per inch of thickness. In metric it's something like Watts/meter/Kelvin for each mm of thickness.
If it's 40*F and you want your camper 80*F, that is the same as you wanting your camper 70*F and it being 110*F outside. There is a 40*F temperature delta. The insulation does not "know" hot or cold. There is simply a resistance to thermal transfer in the product.
Add as much insulation as you can afford (dollars and wall thickness), minimise the size of the HVAC. Large units are heavy, expensive and suck lots of power or diesel fuel. Minimise window area, especially if they are plastic or single pane.
Reflectix and many other products marketed to van lifers and travellers simply do nothing but empty wallets. Even if a thermal break exists, it's so small that it may as well not be there at all. The resistance to thermal transfer offered by a 2-3mm thick sheet of foam with some aluminium foil on it, is laughable. Build it right or don't do it at all. This holds true whether you are building for 40*C in Oz or 0*F in Colorado and Utah.
luthj
Engineer In Residence
Agree with most of your comments. The amount of hate I have gotten for calling Lizard Skin, and Reflectix snake oil is pretty crazy. If it doesn't have an ASTM or similar insulation test value, it isn't real insulation.
I will say that an important factor you are somewhat glossing over is solar radiation. In many situations outgoing or incoming thermal radiation from a camper is negligible. However direct sun has a pretty significant impact, especially on cooling.
For example IR reflective window shades/covers can dramatically improve the effective insulation value of window shades when direct sun is involved. Depending on the amount of thermal bridging and R value of the enclosure/chassis, the exterior color can have a significant impact on net heat transfer to the interior when in direct sun.
Another important factor that is often overlooked is that some insulation materials have different R values depending on the temperature. For example Polyiso foams use a blowing agent which condenses in cold weather, decreasing its R value.
Another consideration is for vehicles without full time HVAC, particularly air conditioning. If a vehicle is allowed to hot soak during the day, how quickly it can shed that heat for sleeping can be important. Its a fairly complex set of conditions that need evaluated. In a few corner cases, its better to have limited insulating and a powerful fan, to cool the rig off more quickly at night. However, it is typically better to have a well insulated shell, and use active ventilation to keep it as close to ambient as possible during the day. Ideally parking in the shade, but that is a luxury that isn't always feasible.
Heat is transferred three ways: convection (air movement), radiation or radiant heat (standing with your face to the sun on a cool day, your face feels warm) and conduction (grab an iron skillet or cookie sheet that is hot).
Radiant barrier coatings can certainly reduce solar gain and reflect sunlight in hot, sunny places like Oz and the US south/west. While this is helpful (folding car shade thingy in the car window/windscreen), it isn't insulation, in the way that PIR/PUR, XPS or EPS are.
Some combination of products is likely best and that is where engineering or lots of trial and error, come into play.
I met a guy a few years ago who was attempting to build a small camper with Vacuum Insulated Panels (VIPs) embedded into the wall, surrounded by foam to protect them. Each panel was one inch thick and had an R-value of 60, at its center. I've no clue if the camper was finished.
Radiant barrier coatings can certainly reduce solar gain and reflect sunlight in hot, sunny places like Oz and the US south/west. While this is helpful (folding car shade thingy in the car window/windscreen), it isn't insulation, in the way that PIR/PUR, XPS or EPS are.
Some combination of products is likely best and that is where engineering or lots of trial and error, come into play.
I met a guy a few years ago who was attempting to build a small camper with Vacuum Insulated Panels (VIPs) embedded into the wall, surrounded by foam to protect them. Each panel was one inch thick and had an R-value of 60, at its center. I've no clue if the camper was finished.
Peter_n_Margaret
Adventurer
It does not matter how good the insulation is, if the heater / cooler is not working, eventually the inside temperature will be the same as the outside temperature.
A human body can be considered as part of the heating system.
The plan needs to be to have the heater/cooler exceed the energy transfer rate into or out of the box.
Better insulation reduces the heat transfer rate, it does not stop it.
A chosen temperature inside can be just as easily accomplished with poor insulation and a larger capacity heater/cooer.
Cheers,
Peter
OKA196 motorhome
A human body can be considered as part of the heating system.
The plan needs to be to have the heater/cooler exceed the energy transfer rate into or out of the box.
Better insulation reduces the heat transfer rate, it does not stop it.
A chosen temperature inside can be just as easily accomplished with poor insulation and a larger capacity heater/cooer.
Cheers,
Peter
OKA196 motorhome
Similar threads
