Abstract

Effective analysis methods/tools and assessment indicators appear to be essential in the design process, in order to improve the energy performance of buildings. With respect to HVAC system, which contributes to a major fraction of the building energy use and CO 2 emissions, the second law analysis is an appropriate tool to evaluate its performance. This thesis presents the second law analysis of 20 design alternatives of the HVAC-DHW system of a house located in Montreal. The following design alternatives were considered: (1) heating system: (a) electric or hot water baseboard heaters, (b) forced air system, and (c) radiant heating floor; (2) heating equipment: (a) electric or gas-fired boiler, (b) ground-source-heat-pump, and (c) air-to-air heat pump; (3) heat recovery: (a) air-to-air heat exchanger, (b) earth-tube heat exchanger, and (c) boiler economizer. Engineering Equation Solver (EES) program was used to perform the second law analysis for both peak design conditions and annual operating conditions. The results show that the HVAC-DHW system using electric baseboard heater and separate electric air ventilation heater has the lowest exergy efficiencies of 7.4% and 4.1%, respectively, under the above two conditions, while its energy efficiencies are 64.2% and 61.6% respectively under the same conditions. The HVAC-DHW system with the highest exergy efficiency of 23.2% (at peak design conditions) and 10.9% (at annual operating conditions) is composed of: radiant floor heating system; ground source heat pump; air-to-air heat exchanger; earth tube heat exchanger; gas-fired DHW heater.