What units are used to express a normalized heating load?

Normalized heating load is typically expressed in relation to the heating degree days (HDD) per square foot of building area. This metric allows for a standardized comparison of heating requirements across different buildings by taking into account the outdoor temperature conditions and the size of the building.

The use of BTUs (British Thermal Units) indicates the amount of energy required to heat a given space, while HDD measures the demand for heating in terms of how much colder the average temperature falls below a baseline temperature. By dividing the heating load (in BTUs) by HDD and the area (in square feet), this expression enables the analyst to understand the heating efficiency and performance of a building in a consistent manner.

The other options provided represent different measurements that do not correlate with normalized heating loads. Gallons per day pertain to water usage, kilowatt hours relate to electricity consumption, and CFM (Cubic Feet per Minute) per square foot relates to airflow, none of which provide the same contextual information needed for evaluating heating loads in relation to temperature and building size.