The building industry is striving for environmental friendly and energy efficient facility developments, as we have used most of our natural resources for comfortable living. Therefore energy efficient houses are very significant to reduce energy consumption. Thermal mass can be used as one of the many techniques of energy efficiency in the housing industry. Thermal mass can store heat in it which can be released at a later time. This behaviour of thermal mass can play a significant role in heating and cooling energy consumption of houses. This study investigates the impact of thermal mass on heating and cooling energy performance of a detached house and a row attached house, which are two main types of housing in Canada. Energy Plus simulation software has been used in the study. Also the study includes two different climatic conditions in Canada, such as Toronto and Vancouver, to envision how thermal mass behaviour changes with climates. All these different studies show thermal mass has significant impact on reduced energy consumption (15% savings in Vancouver for CCHT house) and lowering indoor air temperature. Other strategies such as insulation high R value, increased south face glazing and reduced glazing U value have been integrated with thermal mass to see energy performance in both climates. It hows more energy reduction than only thermal mass strategy. For instance, in CCHT house insulation high R value with concrete high mass reduces maximum 27% of total energy for Vancouver location.