How do I find the balance point of a heat pump?

Plot the building's heat loss (which rises as it gets colder) against the heat pump's heating capacity at two rated temperatures (for example 47°F and 17°F); the outdoor temperature where the two lines cross is the balance point. Enter your design heat loss and the unit's capacity at two temperatures into the calculator and it finds that intersection for you and shows how much auxiliary heat is needed below it.