Highland Council has produced a list of its least energy-efficient buildings.
The local authority is surveying more than 300 properties - mostly schools and leisure centres - over the next two years as part of its efforts to be greener.
It has produced an initial priority list of 40 sites that could be upgraded or replaced in the future to make the biggest impact in terms of meeting climate targets.
Nairn swimming pool is at the top of the list followed by Durness Primary School and Dingwall's St Clements School.
Parts of St Clements School are more than 100 years old.
Charleston and Fortrose academies and Inverness Botanic Garden also feature on Highland Council's top 40 list.
Fossil fuel heating systems and overall energy costs were factors behind how properties were rated.
The survey results could help guide future strategies, spending plans and funding bids.
The report is due be considered by councillors next week.