The efficiency of Lennox heat pumps depends on the model, with the seasonal energy efficiency ratio of the models listed on the official Lennox website ranging from 13 to 23.5. The heating seasonal performance factor of the same models ranges from 7.7 to 10.2.
As of 2015, every Lennox heat pump, except the Merit Series 13HPX model, is Energy Star qualified. The most efficient model, the Dave Lennox Signature Collection XP25, exceeds the guidelines for energy efficiency set by the Environmental Protection Agency, and customers may save several hundred dollars on a yearly basis in comparison to standard models. This model also features a dual-fuel functionality that allows it to alternate between gas and electric heat, helping the heat pump improve efficiency depending on the circumstances.