Evaluation of the Indoor Thermal Environment and Energy Consumption of High-Rise Zero Carbon Green Home

In total 80% of new residential buildings in Korea are high-rise buildings. Compared with Europe, where most residential buildings are low-rise, there are a lot more households that live in these high-rise buildings. In high-rise buildings each household has less surface area exposed to the outside air, which is advantageous in saving energy. In this research, energy consumption rates were measured for fifteen households in an eight-story apartment tower, Zero Carbon Green Home (ZCGH). Three types were established within the ZCGH: 1) households with controlled heat but with no residents, 2) household with residents, and 3) vacant household. We set the indoor temperature at 20℃ in the winter, but the actual temperature during the daytime reached up to 26.9℃ due to the solar radiation. Depending on the residents and internal heat gain, there was a 0.6K temperature differential. The mean differential between indoor and floor temperature was found to be 1.0K, with the bedroom temperature higher than the living room temperature. In addition, heating was terminated in the ZCGH for approximately 14 days in the winter to observe the temperature variation in the different types of households. During the 14-day period, the lowest outdoor temperature was –9.4℃, the highest 7.7℃, and the average was -0.5℃. The mean indoor temperature of the household with residents was 18.4℃; whereas the mean indoor temperature of the vacant household was 17.8℃. This small drop of 1.6K – 2.2K in the temperature appears to be due to the high thermal insulation and the solar radiation. The lowest indoor temperature was 17.0℃ and 16.2℃ respectively. The temperature of the household with residents living in them was approximately 0.8K higher than that of the vacant household due to the internal heat gain from the residency. Moreover, the heating energy consumption rate of ZCGH was found to be 1,884 kWh, whereas the mean energy consumption rate of an ordinary apartment of an equivalent size was 9,088 kWh. There was an 80% decrease of energy consumption in ZCGH. The rooftop solar photovoltaic system produces 46,000 kWh of electricity per year, providing 255 kWh per month to each household. This constitutes 85% of the monthly electricity consumption (300 kWh) in a conventional apartment tower. Compared with conventional low-rise apartment buildings, ZCGH uses 80% less heating energy through passive and active technologies and 85% less energy power through solar photovoltaic systems. The evaluation shows that eight-story apartment buildings are also capable of becoming nearly zero energy buildings.