Heating Conservation Methods and Economy Analysis of Winter Heating in Rural Residential Buildings in Southeast China: A Case Study

In this paper, energy conservation approaches for residential buildings in rural area of southeast China are studied. There used to be no heating habits in rural buildings of southeast China, which is due to the relatively warm weather in winter. However, as the stand of living is increasing, heating in winter has become more popular in recent years. It is quite important to choose proper heating conservation materials taking both initial cost and operating cost into consideration. In this paper, a typical house in southern part of Henan Province is selected for study. It is a two-level house made of bricks, which was built in 2014. A set of radiators were installed for heating in winter. Water, which is heated by electrical heater, is used as heating medium for these radiators. As compared with heat pumps, draft sensation problem is avoided and temperature in the heating space is more uniform. However, operating fee is very high, which makes this heating method less attractive. To reduce power consumption of winter heating, heating load needs to be reduced and the efficiency of heating equipment needs to be increased. In this study, researches are carried out as following. First, a model is built in DeST, which is a software that can calculate hourly heating load and room temperature. Then, the effect of thermal preservation quality of envelops on room temperature and heating load are investigated. Six models with different envelopes are simulated. Then, heating load as well as power consumptions of electrical heaters and heat pumps among the six envelopes are compared. Lastly, economic analysis is carried out for the energy efficient retrofit case so that the payback period is calculated. The results show that heating load capacity of case F, envelope of which made of 240 bricks plus foamed plastic and hollow glass windows, can be reduced to 1/3 that of case A, envelope of which made of 240 bricks and single glass windows. Considering power consumptions of both compressors and fans, energy consumption density (divided by area) can be reduced from 21.6∼25 kWh·m−2·year−1 of case A, which has the worst heat conservation property, to 6.7∼7.7 kWh·m−2·year−1 of case F. If the building is improved from case A to case F and heat pumps are adopted, the payback period is 3.3∼3.8 years. Because of high cost of window retrofit and small influence of its heat conservation property on the reduction of heating capacity, it is recommended to just improve walls. Air tightness of window is more effective than thermal quality.