Question 1: "Ihr" is the form of address in this sentence (plural form of "Du"), it is not dative. The sentence's direct translation would be "How do you save energy at home?" Question 2: "Ausrüstung" can be anything (shoes, a bag, whatever) while Geräte is something more specific, something mechanical (like a machine). So - in the gym there are usually Geräte, Safety equipment would be (Sicherheits)ausrüstung as it could be a rope, a torch, etc. Hope that helps!