As global warming persists under the influence of greenhouse gas, many nations are actively studying alternatives to reduce the emission of the most significant greenhouse gas - CO2. The U.S. plans to reduce CO2 emission by 20% between 2008 and 2018. The EU is developing technologies to ensure a 20% reduction in CO2 emission by 2020 as well. As a developing nation, Korea is exempt from the obligation to reduce CO2 emission during the first commitment period of the Kyoto Protocol, from 2008 to 2012. However, this obligation will also become applicable to Korea in 2013. This research has been prompted by the understanding that the construction industry accounts for over 30% of the total industrial CO2 emission in Korea and, thus, the construction industry's efforts to cut CO2 emission will contribute significantly to the nationwide drive to reduce CO2 emission. This study is intended to estimate the CO2 emission of bearing wall apartment housing, which accounts for more than 50% of all housing in Korea, and propose a new type of apartment that can deliver advantages not only in terms of construction cost and schedule but also in terms of CO2 emission.