restaurants. For Part 9 buildings, there are five steps of the BC Energy Step Code; Part 3 buildings have four steps, while commercial buildings have three. Each step represents a more stringent set of energy-efficiency requirements. As communities climb the steps, they gradually increase the level of energy efficiency in their new buildings. The BC Energy Step Code applies to new construction only. For small buildings, Steps 1 to 3 (collectively, the "Lower Steps") can be achieved using construction techniques and products readily understood and available in today's market; homes built to Steps 4 and 5 (the "Upper Steps") are more ambitious and may require more training and incentives to achieve. The regulation is performance-based, not prescriptive, in that it does not specify the specific materials and strategies a builder must use. Instead, it sets measurable performance targets that the proposed building must meet. To ensure that builders have the skills and capacity they need to cost-effectively produce higher performance buildings, until 2020, governments that wish to use the BC Energy Step Code may incentivize all steps, but may only require Lower Steps. What it measures The BC Energy Step Code measures a building's energy performance via a variety of metrics. The Building Envelope Metrics and the Equipment and Systems Metrics are demonstrated through a whole-building performance simulation, while the Airtightness Metric is demonstrated through an on-site blower door test of the building before occupancy. Building envelope metrics Thermal Energy Demand Intensity (TEDI): The amount of annual heating energy needed to maintain a stable interior temperature, taking into account heat loss through the envelope and passive gains (i.e., the amount of heat gained from solar energy passing through the envelope, or from activities in the home such as cooking and lighting, and that provided by body heat). It is calculated per unit of area of the conditioned space over the course of a year, and expressed in kWh/(m2·year). Equipment and systems metrics Percent Lower than EnerGuide Reference House: An EnerGuide reference house establishes how much energy a home would use if it was built to base building code standards. This metric identifies how much less energy, stated as a percentage, the new home will require compared to the reference house. Mechanical Energy Use Intensity: The modelled amount of energy used by space heating and cooling, ventilation, and domestic hot water systems, per unit of area, over the course of a