Warning Energy Performance Certificates costing homeowners thousands
Most participants in the survey said their EPC did not appear to be accurate.
There is a warning home owners across Scotland are struggling to get energy performance certificates when it becomes time to sell.
Most participants (eight out of 11) told Which? their EPC did not appear to be accurate - they said the descriptions of key aspects of their home like the windows, roofs and heating systems were incorrect.
Frazer Scott from Energy Action Scotland told Tay FM: "The energy performance system really needs to be reformed.
"It can often be difficult to actually find an assessor with the appropriate experience levels and qualifications.
"If you do manage to find someone it is also tricky know if the work is being carried out to a high standard."
Many people who took part in the survey also felt the recommendations, like fitting a new wall or putting in insulation, were unaffordable.
Frazer added: "People need better information to make more informed choices about making their properties more efficient.
"We need to see a system which is genuinely objective, something where the person assessing your home is not influenced by the grants available to you or whether you are selling the house."