VW Vanagon Westfalia Pop-Top – Reducing Heat Loss – Part 3 – Window Glass

This is part 3 in my series about reducing heat loss in my Vanagon Westfalia.  In this installment, I show the affects of exterior insulation on the van windows.  If you haven’t read PART 1 or PART 2 of this series then check them out here:

VW Vanagon Westfalia Pop-Top – Reducing Heat Loss – Part 1- Roof

VW Vanagon Westfalia Pop-Top – Reducing Heat Loss – Part 2 – Tent Sidewalls

Here’s what the van looks like with the Reflectix style insulation mounted on the van:


The insulation is made by, yet again, Fanchers.com.  Here is a direct link to the product on their website: Vanagon Outside Window Thermals R-4

This test was done on the evening of December 31st, 2016.  The same evening I did the test for Part 2 of this series.

As a reminder, here are my baseline temperature readings for inside the barn and van. The temperature inside the unheated barn, as measured from the inside of the insulated barn door, was 29.4 degrees Fahrenheit:


The temperature of the floor was 32.2 degrees Fahrenheit:


The temperature inside the van was 70 degrees Fahrenheit:


The following pictures show the windows with no insulation on the windows. The temperature of the windows is approximately 47 degrees Fahrenheit. Considering that the inside of the van is 70 degrees, the windows aren’t doing too bad of a job of insulating by themselves. I thought it would be worse.



These next pictures show the windows with the insulation in place.  You’ll see that the temperature readings are right in line with the ambient temperature of the barn.  That’s a 12-15 degree drop, which is great news!



Here’s one last picture showing the temperature of the sliding door below the window, where there is no insulation (that I know of).



In practice, I was really surprised by how well the exterior window thermals were working.  Even before I took the thermal pictures, I could feel a difference when inside the van.  The windows just felt much warmer and less drafty when the thermals were in place.  These thermal images cement this feeling for me even more.  Here are some pros/cons of using this style of insulation:


Works great!!  Really helps keep the heat in for me.

Gets really dark inside the van, if you want to sleep during the day. Better than blackout curtains.

Easy to install.  Held on by magnets. Way easier than the interior thermals that are held in by suction cups (I have a set of these too).


Really gets dark inside (I realize this was a pro too). It can be a little discombobulating when waking up in the morning.  it seems like night time still, even if it’s bright outside.

If you want to peak outside through a window from inside the van, you can’t.

Potentially a problem when camping in high wind? I have not tested this.


6 thoughts on “VW Vanagon Westfalia Pop-Top – Reducing Heat Loss – Part 3 – Window Glass

  1. Pingback: VW Vanagon Westfalia Pop-Top – Reducing Heat Loss – Part 4 – Rear Hatch | VW BLVD – And Other Stuff…

  2. Thomas

    The sliding door is actually insulated, but with the same crappy mineral wool insulation used elsewhere. I am in the process of swapping all insulation out with Thinsulate instead, which makes a huge difference

  3. Cliff

    I cut out a set of these to reduce summer heat build up. Although I do not have your kind of thermal image data, they keep our internal temps quite a bit cooler.

    1. Wolfy Post author

      Hi Cliff. Excellent! The practical hands-on experience can be more important than the thermal imaging that’s for sure. The thermal images really help support my thoughts on how well it works. Thanks!

  4. Rob

    Why not place window insulation inside? No wind worries, doesn’t get wet in the rain, you can pull a bit aside to see the light and check conditions outside.


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