Industry body Scottish Renewables (SR) labelled the figure as "underwhelming".
21 Councils have invested almost £8m making sure 225 schools, 17 leisure centres, 17 care homes and 63 other public buildings across Scotland are heated this way, however, Scottish Renewables has discovered 24,806 are not.
The news comes as it is revealed Scotland looks set to miss its 2020 target for the sector.
Yet, while local authorities have invested £8m, they have already earned almost £770,000 from the UK Government's Renewable Heat Incentive support scheme.
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Stephanie Clark, Policy Manager for Scottish Renewables, authored the document titled 'A Vision for Low-carbon Heat in Scotland.'
The publication calls for action from both Scottish and UK Governments in the sector.
She said: "More than half of the energy we use in Scotland is in the form of heat, but we are failing to make the most of our renewable technologies, as these underwhelming figures show.
"While Scotland has made great progress in the development of renewable electricity, the heat sector continues to lag behind. As of 2014, the proportion of heat demand met by renewable sources stood at an estimated 3.8%, against a 2020 target of 11%. This leaves us well below the European average.
"Our key ask from the heat vision document has to be for the continuation of the Renewable Heat Incentive – the mechanism which supports the uptake of heat pumps, biomass boilers and solar thermal, for example. The document also identifies other challenges which must be addressed if we are to have any chance of hitting that 2020 target."
(LM)
