Due to the harsh climate in summer of the Iraq, the outer shell of buildings is exposed to heat flow from the outside ambient to the inside building space, and causes increase of heat gain in the space, so it requires the using of air conditioning units, which is led to consume electrical energy to remove that heat gain. The objective of this paper to reduce levels of electrical consumption by choosing best building materials. The best building materials which are those have good resistance against heat flow, that’s why the cost of building material difference each of other in the local market. While Aso Company for Bricks is considered one of the largest modern companies producing building materials and the most present in the entire area of Iraq. The aim of this study to focus was on its products, and five types models were selected and compared with the traditional model that is still used now. Therefore, heat gain test was experimentally conducted in a test room located in Baghdad city (zip code 10016, latitude of 33.2°N and longitude of 44°E) for one day from 6 a.m. to 7 p.m. and for the 21st day of each of the summer months (May to September) in 2021. The electrical energy consumed by the air-conditioning unit in the test room was measured, and the researchers concluded that the percentage of energy savings achieved within the limits (13.88–1.2%) depending on the type and thickness of the building material. Results shown the best building material is (Type IV), these blocks can be used to create walls with a thickness of 200 mm or 100 mm. Building blocks (the fourth kind), on the other hand, have a delay time of 6:30 hours and a thermal shrinkage coefficient of 0.63. They also have a density of 919 kg/m3. Therefore, the electrical consumption by A.C. units if used the blocks (Type IV) less than others.