The IECC requires that homes have a programmable thermostat for forced-air (HVAC) systems. It also requires that heat pumps not provide supplemental heat when the heat pump is capable of meeting demand. Automatic snowmelt control requirements ensure snowmelt systems do not run when the outside surface temperature is 50°F or higher and there is no precipitation. Homeowners should know the advantages of programmable controls and be knowledgeable about their use.

building codes


The 2009 IECC covers temperature controls in Section 403.1. and snowmelt in Section 403.8. Building code officials must be aware of the requirements covered in the 2009 IECC and need to ensure that:

  • Programmable thermostats are installed for each HVAC system
  • Homeowners know the advantages of programmable controls and are knowledgeable about their use
  • Each HVAC system has a thermostatic control (visually and within the building plans)
  • Heat pumps have controls that do not allow heating when outside conditions are above 50 degrees

Temperature controls are mandatory for all climate zones. Snowmelt controls apply only to buildings with snowmelt systems.

Code History

Previous editions of the IECC required a thermostat for each HVAC system. The 2009 IECC took this requirement one step further by mandating that it be programmable. The heat pump supplementary heat requirements did not change. Snowmelt controls were first introduced in the 2009 IECC.

Typical Issues

Standard issues/concerns that arise include installing standard (non-programmable) thermostats and builders not informing clients of the energy saving features of controls.