Application of Modelling and Statistical Inferences To Compare Performance of Hot Water Heating Devices in the Residence of University Campus

Abstract

Implementation of an energy efficiency intervention in a university campus can resulted in both energy and electricity cost saving. The study focused on retrofitting a 12 kW electric boiler of 1000 L tank with a 4.0 kW air source heat pump (ASHP) unit. A data acquisition system was built to monitor the performance of the electric boiler before intervention and the ASHP water heater after implementation. The results depicted that the average daily electrical energy and hot water consumed during the summer season with the utilization of the electric boiler and the ASHP water heater were 132.53 kWh and 1836 L, and 37.52 kWh and 1818.2 L, respectively. Wilcoxon rank sum test was employed to compare both the daily volume of hot water and electrical energy consumed for both winter and summer seasons by the electric boiler and the ASHP water heater. Linear regression models of the electrical energy consumed as function of volume of hot water consumed, per day for both hot water heating devices was established. The models’ determination coefficients and the root mean square errors of the electric boiler and ASHP water heaters was 0.960 and 1.33, and 0.970 and 0.23 for summer and 0.970 and 0.21, and 0.980 and 0.08, for winter seasons. All four models gave very good predictions with the measured experimental values.