The ASHRAE folks develop most of the standards used in determining the energy requirements of snow- and ice-melt systems. These requirements are based on numerous variables affected by geographic location and system performance expectations. The actual loads are separated into sensible and latent requirements. Once these have been determined, based on location, the expectations portion comes into view.
This is a very important conversation that needs to happen between the system designers and the system operators in order to establish the consumer’s expectations, as well as to manage installed costs. In some cases, if a qualified engineer has been retained for the job, many of these questions will have been asked and energy demand calculations will already have been performed.