A knowledge of Russian building thermal-energy codes in effect in the post-World War II era is necessary for estimating the thermal performance of the existing building stock, quantifying the impact of energy conservation retrofits, and estimating the benefits of more stringent codes. This paper begins with a thorough review of the prescriptive based national codes that applied to heated buildings constructed in the Soviet era. The codes defined all envelope thermal performance requirements for space heating. The paper then describes two recent developments in Russian codes: (i) a novel municipal code for Moscow, in effect since 1994, that increases thermal performance levels in some buildings and unifies elements of formerly distinct codes; (ii) a revised national code, approved in 1995, that increases thermal performance levels of all buildings relative to the previous national code. Prescriptive thermal requirements established in the Moscow and new national codes are comparable to those in effect in the current version of ASHRAE Standard 90, used throughout the US. The paper concludes by describing a proposed new direction for the Russian national code that includes, for the first time, a performance requirement limiting buildings＇ normalized annual heating energy use.