Only ever had one house where we had an issue. It was a holiday home and the central heating boiler had broken.
You will come across the odd conservatory where you might have this happen. On those odd occasions you will have to use more water so you can warm the glass up a bit. All you need to do is wash and rinse it as best you can. The water will freeze but when it melts the glass will be left clean.
We know which conservatories aren't heated and we find that the troublesome ones are North situated. We leave them until the afternoon so they are warmer than they are first thing in the morning.
I had a similar issue with the council offices I clean. I did them between Christmas and New Year but found they had switched the heating off. The water froze on 33 windows and 7 sets of doors.
It took me twice as long to clean, used more water, but when I checked back on the windows the following week, they were spotless.
When this happens you have to be prepared to check you work a few days later.
So for us this is a none issue TBH. By we are on the North East coast so we have more moderate winters that inland. Where we have more of an issue is causing a slip hazard on paths etc. We have a bag of de-icing salt we sprinkle down in those areas. We also do a block of flats on a main street pavement. We only do those when the water won't freeze, and then we sweep any puddles off the pavement to be sure.
It all about common sense and rethinking your risk assessment in periods like these.
Sometimes when its too cold to go out, stay at home. Your risk assessment should also include driving to the job. If the roads are icy then you have a greater chance of having an accident. The aftermath of an accident isn't worth the risk sometimes.
