Buildings composited with thermoelectric cooling and heating systems use solar energy to cool rooms in summer and heat rooms in winter via thermoelectric devices and photovoltaic/thermal (PV/T) dual function modules. In summer, the thermoelectric device works as a Peltier cooler when electrical power supplied by PV/T modules is applied on it. The cold side absorbs heat from indoor to decrease the temperature of the room. In the meanwhile, the thermal energy gained both from the hot side and PV/T system is collected to heat domestic water by heat pipes. In winter, the voltage applied on thermoelectric device is reversed with PV/T modules being power and heat source simultaneously to thermoelectric device and then thermoelectric device could release heat to increase the temperature of the room. The experiments has been done in a model room whose volume is 0.125 m3, in summer condition, using solar panel whose area is 0.5 m2. The minimum temperature 17 °C is achieved, with COP of the thermoelectric device higher than 0.45. The temperature of water in the storage tank with a volume of 18.5 L has risen about 9 °C. The thermal efficiency of the system is 12.06%. This simple and environmentally friendly can reduce cooling and heating load in room.