In response to the growing energy consumption levels in buildings, many countries have introduced standards and codes aimed at reducing their national building energy consumption and managing the amount of emissions. Title 19 of Iran’s National Building Regulation (NBR) was first introduced in 1991. It was projected that Title 19 can lead to a 30 to 50% reduction in building energy consumption in the country. Nevertheless, evidence suggests that the introduction of Title 19 NBR has not led to substantial saving in building energy consumption. Unlike Title 19 NBR, similar standards in other countries have proven to be very effective in reducing the building energy consumption levels. For instance, it is believed that the implementation of Title 24 of California’s Building Energy Efficiency Standards has led to $66 billion dollars of energy savings over the past 35 years. The objective of this study is to utilize content analysis and experts’ opinion in order to identify and categorize the barriers that hinder the effective implementation of Title 19 NBR in Iran. The contribution of this study to the state of knowledge is the identification of barriers that could hinder the effective implementation of building energy codes.