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Insulating is only one approach to avoid heat gain/loss. Passive cooling techniques were developed for the home, yet also apply to recreational vehicles.
Cooling is enhanced through natural breezes or by fans that move the air; improved evaporation exposes the skin to dryer air as long as the humidity is not too high. Rising warm air flows out out the vehicle through the roof-mounted vent and that pulls in cooler air from lower ventilation openings.
There are some limitations to introducing a new opening in the floor of your cargo van. Not only do I feel uncomfortable to cut a sizable hole in the vehicle’s body, but it also may expose the interior to exhaust gases, vermin, dust and road debris. Yet increased circulation and relatively cooler air may offset any negative issues.
More Conventional Passive Cooling Techniques:
A shady spot will avoid the harsh summer sun rays to hit your van and keep you consistently cooler during the day. As more and more RV owners install solar panels in their rig, this option becomes less relevant on their boondocking trips.
Oceanside locations, lake or river settings have continual breezes and natural cooling in place.
Residential outdoor shade fabric can be used in addition or in place of an awning and provide a cool and protected place to sit, while preventing the sun rays from reaching your van.
Heavy-duty, blackout window shades keep the heat and noise out and offer, sometimes much needed privacy. A similar floor-to-ceiling curtain between the front cabin and the living area of the van, will repel the heat generated by the large front windows. In winter, they reduce the area to be heated at night, while opening up during the day allows for a quick warm-up.
Crucial for proper ventilation, these vents also allow heat to enter the van. A double-insulated dome will mediate heat gain/loss and a vent cover enhance it’s use measurably.
Preventing the sun from hitting the back of your refrigerator, will reduce operating cycles and keep your drinks cooler with lower energy use.
Somewhat Less Passive Cooling
Continuously circulating air or directing it at your body with fans, will help you feel cooler.
An evaporator fan in the form of a small computer fan uses little energy, but improves the circulation behind the fridge immensely.
I’m not an expert in passive cooling techniques and these are just my personal views on a complicated issue.
NEXT: Thermal Insulation