Quantified Study On CO₂ Reduction Effect Of Low-Carbon Housing Technology In Hot Summer And Cold Winter Zone

Facing energy crisis and climate crisis around the world, before the Copenhagen conference, China announced CO2 intensity target for 2020 that reducing the CO2 emissions per unit of GDP in 2020 by 40 to 45 percent compared with the level of 2005. Under this background, the "low-carbon housing" concept emerges with the ascendant "low-carbon economy". The Hot Summer and Cold Winter Zone (HSCW) covers the most densely populated areas in China compared to other climate zones, which leads to considerable energy consumption and CO2 emission in the residential building sector. Energy saving in these areas would affect 50.8% of national goal in this sector according to China's the Eleventh Five-year Plan. The purpose of this paper is to make quantified assessment to the effect of low-carbon housing technology in this area.Firstly, made summary of primary low-carbon housing technologies on the basis of field research and international practice exploring, then classified the technology into two categories:improved ones and innovative ones using the theory of Tecnlogy Innovation. Furthermore, pointed out that the former take CO2 reduction effect mainly on occupancy phase of life cycle stage with the push of code and the latter work well during construction phase, triggered by industrial production methods.Secondly, made quantified analysis on the technologies efforts of the two phases with computer simulation and mathematical model.1) For the occupancy phase, presented an energy modeling study with Design Builder/Energy plus software to quantify the annual amount of operational energy consumption and CO2 emission of major types of residential building by comparing four illustrative scenarios. Each scenario has a close relationship with relevant national energy conservation/efficiency standards.2) For the construction phase, the phase was subdivided into manufacture, transportation and erection, mathematics models of CO2 emission are set up for each one. Case study was made to compare the differences between factory-build and traditional methods on CO2 emission. The respective results indicate that when low-carbon housing measures are taken, the range of total energy consumption is 62.2-37.0 kWh/(m2·yr) the CO2 emission range is 36.0-21.7 kg/(m2·yr) Compared to conditions without the measures, the potential range of energy saving is 24.9-55.3% while CO2 emission reduction is 30.3-58.1%. The total CO2 emission in construction phase is 296.2kg-CO2/m2, the CO2 reduction can achieve 14.6% by factory build method in construction phase. The range of CO2 emission in the whole phase which covers occupancy and construction is 2096.2-1381.2kg-CO2/m2 when the life time of housing is calculated as 50 years.The conclusions include that, the low-carbon housing technologies make stronger effect in occupancy phase rather than construction phase during the whole life time, but the latter works more efficient. If the technologies are taken in both of the two phases, the CO2 reduction can be maximized. For the specific technologies, making use of renewable energy and high energy efficiency household appliances are the most effective choices in occupancy phase. In the construction phase, the pre-frication and on-site assembly plays significant role in CO2 reduction. The effect would be better if the ratios of prefabrication and recyclable materials rise in the main body of housing structure.