Comparison of heating energy consumption and economy of pig house with different energy saving renovation measures

It is forbidden to use coal to heat pig house in "2+26" cities in Northern China at present, and the cost of alternative energy sources like electricity and gas used to heat pig house will increase. The aim of this paper is to evaluate and analyze the effect of different pig house envelope insulation renovation measures and ventilation modes in winter on energy consumption of space heating and cost. This paper covers theoretical and experimental methods. A natural ventilated and natural lighted farrowing house with 12 farrowing sows was selected to be an experimental pig house and the wall was made of bricks with the thickness of 240 mm and had no ceiling. In this experiment, the weight of sow was 238 kg, ventilation rate of the farrowing house was set to be 600 m3/h, and indoor temperature was set to be 18 ℃. The CO2 concentration indoors was less than 2 414 ppm when the ventilation rate was 600 m3/h, and it was thought the ventilation rate was enough in heating periods to save ventilation energy. The renovation measures were divided into 4 types or stages: uninsulated (the original farrowing house), wall insulated (Step 1, renovated in 2015), wall and ceiling insulated with ventilation inlet on the windows and doors (Step 2, renovated in 2017), wall and ceiling insulated with ventilation inlet on the ceiling (Step 3, renovated in 2017). Temperatures at the inlet on the ceiling, outdoors and indoors were measured and analyzed. Energy consumption of space heating and cost of different renovation types were calculated and compared. The results indicated that temperature at the inlet on the ceiling was 13.2 ℃ when the temperature outdoors was 0.1 ℃ and the temperature indoors was 18 ℃. Which part of the envelopes of the farrowing house used to be renovated would be more effective in energy saving depended on the values of heat transfer coefficients, air temperature at the inlet of ventilation, ventilation rate, and so on. Energy consumption in environmental control of farrowing house was divided into spacing heating and ventilation and localized heating in Beijing, China. Energy consumption of space heating in winter for uninsulated, wall insulated, wall and ceiling insulated with ventilation inlet on the windows and doors and wall and ceiling insulated with ventilation inlet on the ceiling was 118.2, 45.2, 35.3 and 0.2 kW·h/m2, respectively. Renovation cost of unit energy saving for Step 1, Step 2 and Step 3 was 1.2, 40.4 and 9.0 Yuan/(kW·h), respectively. Payback period of Step 1, Step 2 and Step 3 was 2.0, 67.3 and 15.0 a, respectively. For space heating of uninsulated, wall insulated, wall and ceiling insulated with ventilation inlet on the windows and doors, wall and ceiling insulated with ventilation inlet on the ceiling of the farrowing house, the time with no need for heating in winter was 284, 811, 952 and 2 785 h, respectively, the percentage of the time with no need for heating in 2 904 h was 10%, 28%, 33% and 96%, respectively. Ventilation and localized heating of farrowing house was calculated to be 43.7 kW·h/m2 in the whole year for the 4 types of energy efficiency renovation farrowing houses. Wall insulation was the best renovation measure on basis of least renovation cost of saving unit energy consumption, whereas wall and ceiling insulated with ventilation inlet on the ceiling was the best renovation measure on basis of least total energy consumption.