An Environmental Investigation Agency report slammed the retailer, and said great progress had been made by other UK supermarkets.
The Chilling Facts III research quizzed retailers on the impacts of their refrigeration, and found 239 stores now use climate-friendly refrigeration up from just 14 two years ago.
Waitrose, Sainsbury's M&S and Tesco were credited with moving away from HFC refrigeration, but Asda came under fire for declining to take part.
The report said Asda should be "lambasted for what appears to be a u-turn on previous climate commitments". But Julian Walker Palin, Asda's head of sustainability, argued Asda is committed to reducing the environmental footprint of its refrigeration, but does not believe natural refrigerants alone offer the answer.
He said Asda "reluctantly" decided not to take part after spending "huge time and effort" with the EIA to talk through their strategy. "Unfortunately they chose to ignore the information we gave them."