hi Yellowbox, no problem, I've used SUMIF elsewhere and it works well, but obviously this requirement is a little different and I could only get IF to work. Now that it does, I realised that I needed a similar formula to show 0 (zero) if the original cell had a value in it. It's all to do with options!
plus it's all getting very complicated!
here are some screen grabs that will hopefully make sense (cell and formula)....



this is my standard formula for all items on my sheet.
the cost will vary depending on which building is selected in C1.
(missing row names are 1 for the building type, 54 for electric heating and 55 for water heating)


if a checkbox is selected on a different sheet, then the option will be water heating, otherwise it's electric.

however, the cost for the electric still shows in the table, and i want this to change to 0 (zero). I thought the easiest way was to test the cell directly below, so that if it showed any figure more than 0, then the value for electric heating would be 0.
hope this helps!
