Homeowners in Northern Ireland not putting together an Energy Performance Certificate (EPC) could be slapped with a £200 fine.People in the country selling houses must ensure an EPC is in place from the end of June, with other types of property coming under the rule later in the year.The Belfast Telegraph reports it is understood the government will be allowing the market to set a level of cost for the certificates rather than setting down fees.Quoted by the paper, Noel Williams, Head of the Northern Ireland sector of the Energy Saving Trust, said: "What does surprise me is how many householders admit to being unaware about the Energy Performance Certificate."He added the trust had to inform people about energy efficiency as families were likely to show greater interest once they were aware of the issue.EPCs were introduced in the UK to inform buyers of how energy efficient a house is on a scale of A to G.