The frosting and soil imbalance performance issues of building heat pumps: An overview

•Overviewing the performance behavior of air source heat pumps under frosting conditions.•Overviewing the performance behavior of air source heat pumps with different defrosting/frost suppression methods.•Analyzing the performance of ground source heat pumps under soil thermal imbalance.•Overviewing the performance behavior of ground source heat pumps with different remedies to the soil thermal imbalance issue.•Analyzing the economic impact of frosting and soil thermal imbalance in heat pumps.