Step Code performance requirements can be separated into three main categories:

• Airtightness - Measured in Air Changes per Hour at 50 Pascals (ACH), it is the amount of air leakage across the enclosure of a building, commonly referred to as "air leakage rate". Higher airtightness can result in improved durability and greater condensation and rain penetration control. Airtightness has also been determined to be one of most costeffective ways to reduce building heating and cooling energy use, and testing is required for all steps of the Step Code.
• Thermal Energy Demand Intensity - The Thermal Energy Demand Intensity (TEDI) metric addresses energy gains and losses through the building enclosure. TEDI limits the annual heating required by the building for space conditioning and for conditioning of ventilation air, estimated by using an energy model, normalized per square metre of area of conditioned space and expressed in kWh/(m²/·year). TEDI considers thermal transmittance of the building enclosure components (including assemblies, windows, doors, and skylights), solar heat gains through building enclosure components, air leakage through the air barrier system, internal heat gains from occupants and equipment, and heat recovery from exhaust ventilation.
• Equipment and Systems - Measures the energy consumption from mechanical systems including domestic hot water, pumps, and fans, omitting base loads such as plug-loads and lighting for Part 9 buildings. The metrics for equipment and system energy use are:
  • % Lower than Reference House (% < REF) - uses comparative analysis of the proposed buildings mechanical energy use intensity versus that of a reference building (reference house). The mechanical energy use of the reference building and the proposed building is determined by energy modelling.
  • Mechanical Energy Use Intensity (MEUI) - is the metric for mechanical and systems energy use over a year. It is estimated by using an energy model normalized per square metre of area of conditioned space, and expressed in kWh/(m²·year).