Right. Here are the results for the first run using the BBC weather app.
Using a spreadsheet, I typed in the predicted values over 24 hours for temperature (oC), wind speed (mph) and sunshine (0-5) for two days – Wednesday 19th and Thursday 20th. I then calculated the average of each for both days and compared them.
Wed 19/10/2016 Thurs 20/10/2016
Measured Temp Wind Sun Temp Wind Sun
Average: 10.09 9.26 2.36 9.00 7.74 3.20 Difference -1.09 -1.52 0.84
Thus, Temp goes down by 1.09 oC (colder), Wind speed goes down by 1.52 mph (warmer) and the sunshine goes up by 0.84 units(warmer). I don’t know how sensitive my flat is to these three factors, so I have set starting values of 1.0 for each one. Temperature and Sunshine need to have negative factors (-1.0) since an increase in either will reduce the heat needed.
Factor -1.0 1.0 -1.0
Diff x factor 1.09 -1.52 -0.84
So, Thursday should be a bit warmer than Wednesday (I am writing this on Wednesday night) and I should reduce the input setting slightly on the storage heaters.
In fact, the range of values for the input dial is small, so I will leave it alone and see if tomorrow feels warmer than today has been.