The project we are modeling belongs to System 5. There is however no cooling needed or designed. The system also are not like system 9, because it is mainly manufacturing area and an administration compartment with offices, etc.

As per G3.1.2.8 the example there for a temperature difference of 20OF applies presumably for cooling, because in heating mode with such a temp. difference there are lots of unmet hours. Is it OK if we apply the principle of System 9 whereby if needed to increase the supply air temperature so that to eliminate the unmet load hours.

Your assistance is highly appreciated.