ASHRAE/IES Standard 90.2 establishes minimum whole-building energy performance requirements (design, construction, and and verification) for energy-efficient residential buildings.This 2018 revision of Standard 90.2 seeks to deliver residential building energy performance that is at least 50% more efficient than the energy efficiency defined by the 2006 IECC. Changes from the 2007 edition include:* New definitions, and clarifications to existing definitions* Clarification of which elements of the standard apply to new construction as well as to additions and alterations* Guidance on the use of international climate data from Standard 169 for users outside of the U.S.* Clarification to prescriptive envelope performance data tables* New performance specifications for ground-source heat pumps* Clarification on minimum lighting efficiency provisions for single-family, large single-family, and multifamily homes* Clarification on pool heater pilot lights, pump motor efficiency, and roof and gutter de-icing systems* Clarification on compliance verification authority in locations outside of the U.S.* Revisions to emphasize key building data and reports necessary for compliance determination * Clarification for modeling software requirements* Clarification for lighting modeling requirements* Clarifications to address multizonal building air-leakage testing procedures* A new normative appendix that addresses proper installation techniques for critical components of buildings that provide thermal resistance