Can I use Houndoom's "Single Strike Roar" Ability to search my deck for the special energy card Impact Energy?
No, you cannot. Single Strike Roar is only able to target a specific card named "Single Strike Energy". Although Impact Energy is a "Single Strike" Energy card, it is not "Single Strike Energy".
Source: Chilling Reign FAQ; TPCi Rules Team (2021-06-17)

Relevant cards

Note: All applicable cards may not be listed below.
SWSH5_96
SWSH5_96
SWSH6_157
SWSH6_157