This shopfront is on Main Street, but in a group of detached dwellings (houses). To protect the character of this area, it could be coded T4-O, which would allow the looser form of T4 while preserving the commercial rights. (O stands for Open Function.)
The glazing is 30% of the first floor facade. Percentage of glazing is something that should be carefully calibrated to local character. You may want both minimums and maximums.
To measure glazing percentages on photographs:
1. Shoot the facade straight on, with no diminishing perspective. (The method will work with vertical or horizontal keystoning only if the glazing is symmetrical in the same direction as the keystoning. ) 2. Using Histogram>Show Statistics, record the number of pixels in the total first floor facade, or whatever area will be regulated. 3. Select only the glazing (OK to include muntins). Press Shift to select more than one area. 4. Clear the statistics cache using the refresh symbol in the palette, then record the total of the selected pixels. 5. Divide smaller number into larger in a percentage calculator.