The present work shows the importance of using thermal insulation for new building walls. To decrease cooling and heating load, so the electric power consumption for air-conditioning equipment drop to more than 50% of that without insulation. The experimental work includes building of two models of (1X1X1) m width, length and height located at (32.5 latitude) kut city, Iraq. The model is set to be each wall faced south, east, north and west direction exactly. The models built from brick (24cm), thermo-stone (20cm) and sandwich panel (5cm). Another type of insulation material were tested and compared with normal brick wall is styropor. The heat gain was calculated for all the above insulations compared with brick model. The results showed that the best model in energy saving is the sandwich panel model with about 70% energy save, while the thermo-stone model gives 33% and outside styropor 54.28%.