The residential sector in Mexico requires around 25% of the national electric energy consumption. In hot-dry climate cities like Mexicali, the per capita consumption is 5924 MWh/year, 3.5 times more than the national average. The high temperatures during summer in the city generate conditions of thermal discomfort in dwellings. Therefore, the use of air conditioning equipment and non thermal adequate constructions promote high electrical consumptions. The objective of this study is to determine how electrical consumption in the low-income dwellings depends on the characteristics of design and construction or the occupant's perception has of the conditions of thermal comfort. A field study was done, consisting on the application of surveys. Electrical energy consumption of low-income dwelling was obtained and related with the perception of thermal comfort. The results showed that in this kind of houses, the electricity energy consumption was higher than the average of Mexicali's dwellings, due to the conditions of design and construction of the houses and particularly, by occupant's behavior. (C) 2012 Elsevier Ltd. All rights reserved.