The Scottish Government has missed a target for 11% of non-electrical heat to be generated by renewables in 2020, with the figure falling slightly from 2019.
A report found the total non-electrical heat coming from renewable sources such as biomass or heat pumps was at 6.4% in 2020, down from 6.6% in 2019.
The decline was put down to a reduction in output by several large biomass facilities, however the economic impact of the pandemic may also have reduced demand.
The Scottish Government said there had been a steady increase in the number of heat pumps being installed every year, with 3020 new installations reported in 2020.
Under the latest strategy to decarbonise Scotland’s buildings, which is being overseen by Green minister Patrick Harvie, one million homes and 50,000 other premises will need to transition to low-carbon heat by 2030.
The 11% target for renewable heat was set as part of the Climate Change (Scotland) Act in 2009.
The Energy Saving Trust produced a report on progress towards the target for the Scottish Government.
It said: “The decrease in renewable heat output and progress towards the renewable heat target between 2019 and 2020 is largely due to changes in operation at a small number of very large biomass sites.
“Their reduction in output masked the growth in output from new biomass installations and those of other renewable technologies.”
The Government’s own progress report said: “Whilst biomass and biomethane dominate renewable heat generation, there has been a steady growth in heat produced by heat pumps.
“Heat pumps saw the largest increase in number of installations and output with an additional 3020 installations contributing to an additional 83GWh of output, compared with 2019.
“This brings the total heat output from heat pumps in Scotland to 390GWh and the total number of installations to around 21,000.”
Increased energy efficiency has also reduced demand for heating, the Government said.
Scottish Labour MSP Monica Lennon said the SNP has failed to match rhetoric on the environment with action.
She said: “Despite all their warm words, the SNP’s track record on the environment is one of failure.
“Not only have they missed yet another key target, but things are actually getting worse.
“With COP26 a matter of days away, this exposes the gulf between SNP rhetoric and reality.
“Being a world-leader on the environment requires deeds not words – the First Minister should take her own advice and deliver credible action.”