This construction industry is responsible for over 30% of the total industrial CO2 emission in Korea, and bearing wall apartment housing represents more than 50% of all housing in Korea. A new multi-residential Modularized Hybrid System (MHS) for construction of apartment housing may reduce the amounts of construction material used as well as the amounts of CO2 emission. This paper collected and compared data on the CO2 emission properties of construction materials for bearing wail and new MHS apartments including concrete, reinforcing steels, formwork, and gypsum board. MHS construction techniques reduce CO2 emission by 25.1% by requiring less concrete and reinforcing steels for slabs and walls that would otherwise be needed in conventional bearing wall structures. This paper also shows that migration to a Rahmen structure utilizing an MHS frame can provide an alternative solution to reducing CO2 emission. (C) 2009 Elsevier Ltd. All rights reserved.