The clean energy transition in Poland means replacing coal with natural gas in the household sector, resulting in an increase of heating costs. The aim of this article is to examine the impact of changing the energy source on the extent and depth of energy poverty in Poland. In the study, we use a definition of hidden energy poverty and simulate theoretical energy expenditures in two scenarios. The first scenario assumes the status quo, and the second one – the transition to natural gas. The result shows that the rate of energy poverty increases from 16.5% in the first to 19.3% in the second scenario. Furthermore, the transition to gas translates into an increase on average by 22.9% per household. The results obtained indicate that shielding policies for energy poor households are necessary.