Balcony winter storage – insulation upgrade

After upgrading heating and air circulation of a previous year created winter storage on my balcony for the trees which don’t want to freeze it was time to upgrade the insulation.

The present insulation was: 1. not a proper one, 2. the front glass door are definitely made to insulate anything.

To the sides I “called” for Finnish technology solution: “Sauna Satu”, polyurethane 3 cm thick thermal insulation boards produced for insulating sauna spaces 🙂

Over the front face, over the doors I installed 6 mm polycarbonate twinwall sheets which allow some light still to enter the inside of the cupboard and still make a better thermal insulation. I used window seals to distance it ~3 mm from the glass door thus making the doors now 3 layers (2 from the sheet itself and 1 from the glass doors) transparent insulation.

So the cupboard looks like this now:




Thermometer view









On all photos are visible 2 small windows which can be opened/closed. They are to manually check the temperature/humidity on the upper/lower shelf whereas the middle shelf is measured by the sensor connected to the internet cloud. These windows allow me to check the temperatures/humidity manually while not removing any of the twinwall sheets.

I cut out the right door sheet wider than the door and the left one the same amount narrower so that the wider one covers the several mm distance between the doors. This way without extra seals I keep the warmth inside.

After couple of days I wanted to see what is the difference with the new insulation so I compared temperature graphs for similar 24h time periods:


Before new insulation


After installing the new insulation

The screenshot before the insulation shows 15-16 peaks when the heater temperature reaches maximum of +6C when the heater turns off. The screenshot after the insulation shows 10-11 similar peaks.

Therefore the number of peaks reduced ~33%. Quite OK for me.

I am now confident the installation can manage lower temperature drops though I already had tests for 20 degrees difference (inside vs. outside).

The next time I need to see how much the upper/lowest shelf temperature differs when outside is -25 degrees C 🙂


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  1. Andrew

    So. Do you still use this winter storage ?
    Here in Russia we also have kinda cold winters.
    And all i have is a cold balcony.

    • tato

      Yes I do and it works very well, after I fixed the air circulation as blogged.
      The drawback is that u need to take care sun doesn’t hit it for temperature not to rise too suddenly.
      I found it to be the working solution for to cold sensitive trees in need of dormancy to survive our winter.
      It would be very nice to get info how do you cope at your place with species/winter etc 🙂 Everyone usually figures out something new which can be useful to all.

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