FEMP plays a key role in helping agencies understand and meet the federal building energy efficiency standards for agencies' new construction and major renovation projects. These standards include base building efficiency as defined in the CFR by subpart A of 10 CFR 433 and 10 CFR 435, commonly referred to as the "residential" and "commercial" rules, respectively. This also includes the Clean Energy Rule for qualifying projects as defined by subpart B of 10 CFR 433 and 10 CFR 435. The Clean Energy Rule supplements both the base commercial and residential rules, transitioning new buildings and major renovations away from on-site fossil fuel derived energy consumption. Projects meeting the cost thresholds that trigger compliance with the Clean Energy Rule must also comply with both subparts A and B of the energy efficiency standards by first designing an efficient building (per subpart A) and then optimizing the design to reduce or eliminate on-site fossil fuel usage (per subpart B).