Update:
I managed to measure the boundary layer temperature of my heavy load-bearing wall somewhat directly. I basically just used an additional air temp sensor, put it on the wall, and covered it with a blanket, leaving a small hole that was faced away from airstreams to account for moisture.
The data is not yet fully clear but as you can see via the graph, the green air temp stops raising when it approaches the yellow wall temp.
I am somewhat sure now that the temp of this wall is the most significant indicator of room temperature after I closed my windows and rolled down the blinds.
Until around 2:30 AM I pointed both of my fans to the windows, after that I let one of them cycle between the window and the wall.
I am still not sure if the fan pointed to the wall to get rid of the boundary layer is significant or if it would be better to just point the fan to the window.
There is almost no air movement I can measure or perceive at the wall if I point both fans to the window.
I think thermal inertia of the wall is quite impressive! It got blown on the entire night with 2C lower air and only lost temp very slowly.
So it is either very bad at conducting heat or it is a good thermal battery.
After calculating the wall is about 3m³ of concrete which is round about 1.75 kWh/K. Which is lower than expected.
The convection exchange of this wall should be pretty low as it is obviously vertical... after looking into convection vs forced exchange (blowing onto the wall) calculation examples I guess that the temp exchange is about 3 to 5 times as high as with normal unsupported convection.
Thinks I want to test and see if they are relevant:
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Messure different setups and distances from the window to the fans
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Messure outside temps to optimize the "closing window" time. I think this should be the time when outside temps are maybe 0.5C under the wall temp as air kWh/K is super low and will be heated almost immediately to wall temp if closed. So even if indoor temp is cooler then outside temp it does not make sense to close the windows as long as outside temp is lower then wall temp.
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Calculate how long and how often a given location on the wall must be blown upon to hit diminishing returns regarding the removal of the boundary layer to determine if it would be better if one fan just randomly blows at all walls, floor and sealing.
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Set up better temp sensors for measuring wall temps.
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Search for heat bridges
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Blowing air at the upper portion of walls since I expected that the delta is bigger there.
Until now it is quite amazing that I can basically safe each day about 3 to 5 EURO on energy because I do not use a AC... which is also not very practical in my apartment.
There are times when this will not work like Sunday when we will have 25C at night and 40C at day.... but yah it is also questionable if a mobile renter friendly AC can even pull down the room temp at these outside temps especially if it is only a unit with 1 or 3 hoses instead of a split AC unit... which are a lot more expensive like 1k EUR and gigantic space wise... for about 3 days a year I cannot cool with Lüften.
Let's see how I think about this at Sunday 
#climatechange #ac #cooling #lüften #heat #extremeheat
grocery stores are removing the fraudulent maple syrup from shelves and are asking customers to return it
