An exemption means part of the Healthy Homes Standards doesn't apply to your property, but you can't just assume you qualify. For ventilation, an exemption applies if it genuinely wasn't possible to fit an extractor fan when the kitchen or bathroom was built, and that exemption disappears the moment fitting one becomes possible. For insulation, an exemption applies where compliant insulation genuinely can't be installed, with a newer, narrower exemption for some properties with very limited roof space. Whatever the reason, it has to be written down and explained on your compliance statement, not just assumed. And an exemption only covers the standard it applies to; being exempt from ventilation doesn't excuse you from heating, insulation, or anything else.