Safety factors are used to account for uncertainties and variations in heating load calculations. They ensure that the heating system is sized to meet the maximum heating demand, even under extreme conditions. Safety factors are applied to different types of loads, such as room space peak loads, floor zone loads, and building loads, to provide a buffer against unexpected heat losses or gains. By incorporating safety factors, HVAC designers can ensure that the heating system is capable of maintaining a comfortable indoor temperature, even during periods of high heating demand.