Got a couple of things now in my OpenHAB, still finetuning but I can see the potential! 
One of the important factors when determining states or make decisions would be the power consumption of different devices. My house is equipped with a full KNX system and most of my single use outlets do have current measurement.
My switching actor provides two values: mA and kWh. I was able to get a value of mA in my sitemap but this is not derived correctly, the value is sent over the bus as a value in mA but OpenHAB displays it divided by 100. So 289mA current usage shows up as 2.890. I would like to get this fixed but cant figure out how.
The mA value OpenHAB receives is put back on the bus by OpenHAB as an mA-value, so there no issue for other KNX actors except for the fact that OpenHAB is causing an amplification of traffic but some people are working on that bug if I understood correctly?
So my next idea was to work with the kWh value, but this gets even more complicated since some bizarre things happen then:
15.1.3 is my PC running ETS
10.1.2 is one of my MDT units reporting the kWh (if needed I can also set this in Wh)
15.3.2 is my OpenHAB instance
If I request the power consumption, the MDT actor responds as it should, But for one reason or another OpenHAB decides to send some telegrams back. I have found some bug but no solution to this issue. This issue is not THAT blocking if it weren’t for the fact that OpenHAB sends back “wrong” values as 9.* 2 bytes instead of the 13.* DPT which leads me to think that OpenHAB is processing the 46kWh value wrong, this is confirmed when looking at the BasicUI, all consumption numbers are 0.
My sitemap fragment relating to this:
Frame label=Stroom {
Text item=number_Amps_Wasmachine
Text item=number_Amps_Droogkast
Text item=number_Amps_Dampkap
Text item=number_Amps_Ventilatie
Text item=number_Energy_Wasmachine
Text item=number_Energy_Droogkast
Text item=number_Energy_Dampkap
Text item=number_Energy_Ventilatie
}
My items file relating to this:
Number number_Amps_Wasmachine "Wasmachine Amperage[%.3f]" <washingmachine_2-1> (grp_Amps) { knx="<2/6/13" }
Number number_Amps_Droogkast "Droogkast Amperage [%.3f]" <dryer-2> (grp_Amps) { knx="<2/6/14" }
Number number_Amps_Dampkap "Dampkap Amperage [%.3f]" <kitchen> (grp_Amps) { knx="<2/6/14" }
Number number_Amps_Ventilatie "Ventilatie Amperage [%.3f]" <fan> (grp_Amps) { knx="<5/6/1" }
Number number_Energy_Wasmachine "Wasmachine Verbruik[%.3f]" <poweroutlet> (grp_Energy) { knx="<2/5/13" }
Number number_Energy_Droogkast "Droogkast Verbruik [%.3f]" <poweroutlet> (grp_Energy) { knx="<2/5/14" }
Number number_Energy_Dampkap "Dampkap Verbruik [%.3f]" <poweroutlet> (grp_Energy) { knx="<2/5/14" }
Number number_Energy_Ventilatie "Ventilatie Verbruik [%.3f]" <poweroutlet> (grp_Energy) { knx="<5/5/1" }
This results in:
