I compared one year of temperature stability of the two LIGO facilities using the quadruple suspension blades sag as a proxy for changes in building temperature.
The first figure shows the corner station data, the second figure the end stations.
The LHO corner station looks more stable than LLO, whereas the LLO ends (after the temperature sensors were moved away from the walls) look more stable than LHO.
I am reviewing how LHO controls their corner temperature so LLO could benefit from their stability. My understanding so far is that several of the in-loop temperature sensors are located on top of the beamtube (see picture attached for the HAM5 temperature sensors for instance). It is not yet clear to me how many sensors are used in-loop for the LHO corner station, and if any still from the wall sensors. At LLO we use all 34 wall sensors and do not have sensors near the chambers.
LHO could certainly improve the end stations temperature by moving the sensors away from the walls. Robert mentioned at last commissioning meeting this was a planned upgrade. A picture of the newly placed LLO end stations sensors is shown in this alog.