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The paper presents the effect of exhaust gas and inlet air temperature on thermal efficiency for boiler system. Based on the numerical model, the performance indexes of boiler system are calculated at different conditions using EES (Engineering Equation Software). The results show that when the exhausted gas or inlet air temperature increases 10-15°C, the heat loss of exhaust gas decreases 0.8%-1% and thermal efficiency of boiler system increases 0.8%-1%; The crucial factors that can affect thermal efficiency are exhaust gas temperature and fuel volatile ratio; seven optimized schemes are designed for a case of boiler system. A new methodology is provided for evaluating the efficiency of boiler system.

The paper presents different kinds of optimization scheme of air-condition system based on equipment technologies and variable parameters in Guangzhou. Coefficients of performance (COP) and energy efficiency of rate (EER) are the main index of air-condition system. The results show that the percentage of optimized air-condition systems are of different weight ratio based on analytic hierarchy process method. Pump and compressor frequency conversion technologies and higher indoor temperature are the main energy efficiency measurements for air-condition system. The results provide a new methodology for evaluating the air conditioning system construction.