An increasing trend in energy consumption can be seen worldwide. Projections for the world energy consumption indicate an increase of nearly 50% by 2050. In Canada, the electric power selling price has risen by 250% in the last four decades. The rising trend in energy consumption and cost is a pressing concern. Within that trend, residential, commercial, and institutional buildings are big contributors, accounting for 28% of the total secondary energy use in Canada. As a direct response to the increase of energy use in buildings, minimum energy efficiency requirements were proposed and compiled into energy standards, seeking to provide guidelines and instructions in the design, construction, and operation stages. These standards proved to be a powerful tool to improve energy efficiency, especially if adopted by state and federal legislators as mandatory requirements. Given the major role that such standards play, attention is drawn to the process used in updating these energy efficiency requirements. This research proposes a method for identifying the most impactful factors in the energy efficiency of buildings and for quantifying the impact that changes in these factors have on a range of energy related KPIs. This method can help policy makers and parties involved in the update of building energy code requirements by providing a metric to prioritize changes based on their impact. Additionally, the proposed method can aid in the allocation of R&D resources in the proposal of improvements to the building envelope and HVAC equipment, based on the impact of each of the studied improvements.