Building Energy Rating (BER) costs can be three times as expensive depending on who does them for you.
A new survey by the National Consumer Agency found that the price of getting a BER for an identical house can vary from €99 to €300.
And for an apartment the price varied even more, from €100 to €308.
Owners are now legally obliged to supply the BER of any house or apartment being sold or rented out, meaning this is a cost many householders cannot avoid.
BERs measure how energy-efficient a home is – in order to give buyers or renters an idea of how warm they'll be and if their heating bills are likely to be high or low, with A the best rating and G the worst.
The NCA did a mystery shop survey across the country and found that the average BER quote for a three-bedroom semi was €165.
Nationally, the quotes ranged from €99 in Cork to €300 in Donegal.
Meanwhile, for a two-bedroom apartment the average quote was €156 – but prices ranged from €100 in Cork, Limerick, Galway, Waterford and Kerry to a whopping €308 elsewhere in Galway. Even within counties, the prices quoted varied considerably.
For example, within Dublin the price quoted for a three-bedroom home ranged from €125 to €230, while in Donegal it ranged from €120 to €300.
And in Galway, the cost of getting an apartment BER ranged from €100 to €308.
The NCA obtained 210 quotes from registered BER assessors, accounting for a quarter of all those registered, but it did not publish details of who supplied which quotes as the survey was carried out anonymously.
The prices quoted are inclusive of VAT and the Sustainable Energy Authority of Ireland's €25 levy.
Tipperary had the highest average prices, coming in at €286 for the house and €284 for the apartment.
Kildare had the cheapest average house BER prices at €142; and Dublin was cheapest for apartments, at €138 on average.