How do I factor in intermittent heating?

Heatpunk assumes continuous heating when determining the ODT and sizing the heat pump.

If the property will be heated intermittently, you can change the ODT (in line with MIS 3005-d) to the 99.6th percentile. Read here to see what the 99.6th percentile is for your area, note that you will also need to subtract 0.3 degrees for each 50m above sea level.