Yong Cheng

Response-surface-model-based system sizing for Nearly/Net zero energy buildings under uncertainty

Properly treating uncertainty is critical for robust system sizing of nearly/net zero energy buildings (ZEBs). To treat uncertainty, the conventional method conducts Monte Carlo simulations for thousands of possible design options, which inevitably leads to computation load that is heavy or even impossible to handle. In order to reduce the number of Monte Carlo simulations, this study proposes a response-surface-model-based system sizing method. The response surface models of design criteria (i.e., the annual energy match ratio, self-consumption ratio and initial investment) are established based on Monte Carlo simulations for 29 specific design points which are determined by Box-Behnken design. With the response surface models, the overall performances (i.e., the weighted performance of the design criteria) of all design options (i.e., sizing combinations of photovoltaic, wind turbine and electric storage) are evaluated, and the design option with the maximal overall performance is finally selected. Cases studies with 1331 design options have validated the proposed method for 10,000 randomly produced decision scenarios (i.e., users’ preferences to the design criteria). The results show that the established response surface models reasonably predict the design criteria with errors no greater than 3.5% at a cumulative probability of 95%. The proposed method reduces the number of Monte Carlos simulations by 97.8%, and robustly sorts out top 1.1% design options in expectation. With the largely reduced Monte Carlo simulations and high overall performance of the selected design option, the proposed method provides a practical and efficient means for system sizing of nearly/net ZEBs under uncertainty.

Behavioural, physiological and psychological responses of passengers to the thermal environment of boarding a flight in winter

Abstract In practice, passengers actively respond to the thermal environment when they board an aircraft in winter, which is not considered in the current standards. In this study, the behavioural, physiological and psychological responses to the thermal environment were examined at 22 °C (with 68 subjects), 20 °C and 26 °C (with 32 subjects). The results showed that the three air temperature levels had significant effect on nozzle usage and clothing adjustment behaviours, surface skin temperature, and thermal sensation vote (TSV). The walking/waiting states prior to boarding the aircraft cabin had a significant effect on the proportion of jacket removal, TSV and thermal comfort vote. After 10 min in the aircraft cabin, the subjects maintained their comfort in a wider range of the thermal environment when the behavioural adjustments existed compared to when they did not. Thus, a suggestion was made for behavioural adjustments to be provided in aircraft cabins. Practitioner Summary: Experimental investigation of human responses was conducted in an aircraft cabin. Analysis showed that the subjects maintained their comfort in a wider range of the thermal environment when the behavioural adjustments existed compared to when they did not. Thus, a suggestion was made for behavioural adjustments to be provided in aircraft cabins.

Effect of Gender, Age, Air-Conditioning and Thermal Experience on the Perceptions of Inhaled Air

The comfort range of inhaled air temperature is meaningful to the design of air conditioning parameters at breathing zone. In summer, eight college students and eight middle-aged people were recruited to conduct a thermal comfort study in the natural and air-conditioning environment respectively. The subjects were exposed to different inhaled air temperatures from 18 °C to 34 °C at an interval of 2 °C. The study found that the perceived air quality and thermal pleasure of warm inhaled air is better in the surrounding of natural environment than that of air-conditioning environment. The neutral temperature of inhaled air is 28 °C and 26 °C, respectively. The thermal sensation vote has no significant difference between middle-aged and young people, while the thermal pleasure, air freshness and perceived air quality of middle-aged people are better than that of the young people. When the temperature of the inhaled air is 2 °C higher than the ambient temperature, the SBS symptoms are significantly increased. Therefore, the comfort range of temperature of heated air in winter is worth to be further studied.