Hi Arie,
I had a look at the monitoring data from your compost heating.
Questions:
To understand the data better:
1. What is exactly “binnen temperatuur” and where is it measured?
It is inside temperature, in the centre of the room about 1m above the floor
2. The same for “buiten temperatuur” and Gevoelstemperatuur.
It is outside temperature, it’s measured on top of the roof, at the highest point, in the open wind and sun,
though the sensor is shielded by a plastic cover (see pictures) so it’s always in the shade.
‘gevoelstemperatuur’ is ‘feeling temperature’, it’s calculated (I think) from a combination of wind speed,
outside temperature and humidity and/or rain
3. What is Dawpunt exactly, and what is the use of it here?
Dauwpunt is dewpoint, it is the temperature at which the air would become 100% saturated with moisture.
It is calculated from the inside temperature and the relative humidity inside. So if for example a glass
surface becomes colder then the dewpoint (because of cold outside temperature for example), the inside
surface will condensate and water will be visible. If the inside air temperature drows below the dewpoint,
there will be fluid water (aka mist/rain) inside ;)
Observations:
Just a few facts, that I see from the data, which may be obvious to you anyway :
1. Relative Humidity (RH) air inside is higher than outside. To see if this is real, I have this question:
a. Are the RH meters calibrated or in other words, do they measure the same values if they are placed
in the same spot? I did not check if they are calibrated, I will do so as soon as I get the chance. By
placing them side by side I can only relatively calibrate them off course, If you have any idea to
make an absolute calibration, this would be helpful.
Also, it is very plausible that the inside RH is higher than outside, see next point.
2. RH both inside and outside is very high >80% …. Inside should be something like 40% …. Why is it so high?
The RH inside has been very (extremely) high for the period until February/march. This is because I
put a lot of fresh wood inside in winter, which produced a lot of moisture while drying. Since there
is not very much natural ventilation (only two vents above the doors) the moisture wouldn’t
evaporate well. Especially in the very cold winter days the outside RH drops to low amounts, so the
difference becomes even bigger. Meanwhile the situation is much more natural with a lower RH
inside then outside and all around 40%. The wood has dried a lot and the inside temperatures are
higher.
3. Binnen Temperatuur is strongly correlated to:
a. Buiten temperatuur yes, these follow each other and react to one another. What would be
interesting is to see if the correlation becomes less if the heating is turned on, because then the
inside temperature should be more autonomous.
b. Gevoels temperatuur
 This makes sense I guess ….. interesting, I would expect it to be correlated to outside
temperature (since it’s calculated from that and the wind speed), but naturally, since that is again
correlated tot inside temperature it makes sense. I should ask Alecto how it’s calculated exactly.
4. Binnen Temperatuur is weakly correlated to:
a. Luchtvoichkeit binnen yes, this sounds plausible, because the humidity inside will change according
to the air temperature, but is also influenced by ventilation and evaporation of things inside
b. Dauwpunt
 Does this make sense to you? Yes, this is calculated directly from the inside temperature and the
inside humidity, so it should correspond
5. In the same way, you can look for other, perhaps less relevant to you, correlations ….
Yes, I would be very much interested in correlation of the inside and outside temperature while the
heating has been turned on, I’ll provide data of these (short) periods.
Also later it would be nice to see any correlation between the outside temperature and the
compost temperature, but this will be for a new compost pile where automatic sensors are put in,
perhaps in summer, or next winter.
Scatterplot Matrix