My Jan 10th bill the usage was 470 Cubic meter but Feb 8th bill the usage was 309 Cubic metre.
The Jan bill was supposed to be higher. I adjusted little bit on the temperature, may be the less usage in Feb partially due to this change. The average temperature -8 degree in Jan 2018 and -5 degree in February 2018. So a drop in average temperature must resonate with a less usage in Feb 2018.
I still consider the Jan usage of 470 was way too high for a single home of 1880 sq feet.
I posted another thread trying to get explanation as to why two homes of similar size has much different gas consumption. It appears it must be to do with HRV unit, though the HRV unit has been shut off.
Here is that thread with some useful information by posters.
viewtopic.php?f=1&t=69947