With the apparent growth of environmental awareness across the world, one would assume that there will also be an increased interest of the population in products with environmental features. From the marketing standpoint, it is important that such a phenomenon be accompanied by an investigation into how consumers make their choices and what value they attribute to the characteristics of the products that have less detrimental impacts on the environment, such as recyclable or reusable materials, organic or natural inputs, or lower power consumption, among others. Studies have shown, however, that consumers do not always value these features as much as others, such as brand and price. Part of the explanation may be in the consumers disbelief in the actual presence of these features in the products they buy. This study presents the results of a study into the role played by two seals found in the electrical products market which certify the energy efficiency and environmental contributions: Procel e Ence. The aim of the Procel seal is to promote a rationalization of the electric power production and consumption. The Ence label seeks to inform consumers of the power consumption and the energy efficiency of some products sold in the country. The research is based on incandescent and fluorescent lamp purchase simulations and the data were processed using conjoint analysis. 172 simulations were carried out with 86 people. The results showed that although the seals were noticed on the packaging, they were not the most valued feature in the decision-making process. Price and lamp life were the most relevant variables when choosing the lamps. Most respondents did not fully recognize the role of the seals and exhibited contradictions in their choices. However, women valued the seals more than men, as did higher income earners. Other variables help to explain the results found in the study.