This standard provides minimum energy efficiency requirements for the design and construction of(a) new residential dwelling units and their systems@ and(b) where explicitly specified@1. new portions of residential dwelling units and their systems@ and2. new systems and equipment in existing dwelling units.Note: There are no requirements in this standard that apply to new portions of residential dwelling units and their systems@ nor to new systems and equipment in existing dwelling units.For the purposes of this standard@ ??residential dwelling units?? include single-family houses@ multi-family structures (of three stories or fewer above grade)@ and modular houses. This standard does not include ??transient?? housing such as hotels@ motels@ nursing homes@ jails@ and barracks@ or manufactured housing.This standard applies to the building envelope@ heating equipment and systems@ air-conditioning equipment and systems@ domestic water-heating equipment and systems@ and provisions for overall building design alternatives and tradeoffs.This standard does not apply to(a) specific procedures for the operation@ maintenance@ and use of residential buildings;(b) portable products such as appliances and heaters; and(c) residential electric service or lighting requirements.This standard shall not be used to abridge any safety@ health@ or environmental requirements.