Climate: Insulation and ventilation without serious mistakes

The climate in an enclosed space is a complex subject. There are many facets to climate, such as humidity, temperature, ventilation, condensation, rot and mould, damage to structures, emotions about comfort such as “stuffy” and “nice temperature” and “it’s chilly in here” and finally the CO₂ and O₂ content is important.

How not to do it

Visit Youtube and Pinterest to see how you should not insulate a camper van. There are a lot of mistakes being made – even by “professionals”. It is also sad to see how young couples try to make their dreams come true and at the same time push their investment to the edge of a cliff. I always hope they live in a dry and warm climate.

The point is that many people get going in their enthusiasm without really understanding the consequences of their actions. Moisture is trapped, PUR cans are emptied and untreated wood is used on floors. The conditions for mould and rot and disastrous rust processes have been created.

All this makes it a huge challenge to cover the whole subject in a short post in a practical and objective way. I write with a scientific approach and try to be brief and to the point. That will surely make it worthwhile to read.

The quick fixes

Let us first discuss and solve some things quickly:

• We are not talking about aeroplanes, submarines, residential containers and buildings, but we are talking about a van. That said, the knowledge discussed is very widely applicable.
• The CO2 and O2 content: Ensure that there is always sufficient ventilation, via a ventilation system, open windows and, as a last resort, occasionally air everything out.
• Ventilate with air that is dry enough to:
  • prevent most condensation and
  • allow any water present to evaporate.
• Air can be made relatively drier by:
  • Air conditioning
  • Heating
  • The combination of the two
  • Air from outside – if drier
• Do not use untreated organic materials in places where condensation can occur, such as spruce wood on a floor and cotton near a cold outer wall.
  • Mould infestation is almost irreversible, and you will never get rid of it without demolition.
  • Mistakes are made more often than you might think, even by “professionals”.
• Accept the limited occurrence of condensation, but ensure that condensation can always drain away:
  • Water that runs downhill: Never block the water course with insulating material or PU foam. During garage visits, check that the sills are open at the bottom and remove dirt.
  • Ensure sufficient ventilation between the exterior cladding and the interior cladding. Installing air vents in the interior and opening them when travelling and during storage is an option.
  • It takes a long time, but condensation on the inside will eventually evaporate, so choose a construction that can withstand it.
• Limit cold bridges by clever insulation. However, accept that you cannot prevent all cold bridges – think of window surfaces and gaps between rear doors and at a sliding door.
• Consider TCO – total costs of ownership. Consider that adding 1 kg of material will cost you tens of euros in fuel, maintenance, etc. over the lifetime of the vehicle. It is almost always profitable to use the lightest possible materials and to use smart constructions.
• How far do you want to go with climate regulation and the associated costs?
  • The requirements will be different if you are travelling to Norway in the winter, or to the Algarve for a long time in the summer. Or is a thicker coat in winter and a T-shirt and some sweat in summer acceptable?
  • Are you travelling only in a warm and dry climate? Then the harmful effects of condensation are less.

We have already discussed many points, but what follows is just as important.

What you need to know about the dew point.

What is the dew point temperature or dew point?

Air contains water vapour. Cold air is less able to contain moisture. When the temperature falls, the relative humidity increases. If the temperature continues to drop, there comes a point when the relative humidity is 100%: The air is saturated and cannot contain more water vapour. If the temperature falls further, water droplets are formed: Dew.

The dew point is therefore the temperature of a mixture of air and moisture at which the humidity is 100%. Dew forms below this temperature. The dew point temperature is therefore a quality characteristic of air.

Why don’t car windows fog up on a cold, rainy day?

You can easily draw a conclusion from this story, think of a car heater that heats outside air and blows it inside: The total amount of moisture in that air does not change. The temperature does rise and then the relative humidity decreases. However, the dew point remains constant.

That is why the car does not get wet on the inside through condensation on icy surfaces, such as windows and doors, when the heater is on and warm. For convenience, we are not including passengers who produce moisture (with wet clothing, breathing).

Why do you want to turn on the air conditioning in a cold car?

The result of air conditioning is more or less the same. Suppose the dew point outside is 10 degrees and the air-conditioner cools it down to 5 degrees. In that case, the dew point also drops to 5 degrees and condensation is removed by the air conditioning. You then get dry, drying air with a dew point of 5 degrees. Ideal for when the heater and engine are not up to temperature yet.

And if you do nothing?

If you put people in a room with limited ventilation, the dew point rises quickly. People release a lot of moisture through breathing and sweating. At 100% relative humidity, the process of condensation against the colder surfaces begins.

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