Check the aircon, if it is an older "on-off" type instead of inverter then it will use more power and especially down South it will run a defrost element on the outside unit more often. This drops the efficiency benefits of an aircon significantly.
18 DegC is the minimum recommended for a healthy home. In Auckland Winter we do 20 at night, 18 during the day, set to heating only. Summer it is set to either 23 of 25 cooling, depending on how bad the humidity is.
Check for drafts, this significantly affects the heating required. We have a 3 year old home and shocked that it could be built with a 10mm gap under the internal door leading to the uninsulated garage. Also often the draft stoppers are removed from bathroom/kitchen vents as they reduce extraction efficiency, but then you end up with a bad draft... On eBay I saw draft stoppers which are like a sock collapsing when the fan stops, blows open when the fan runs. This has much less resistance than a mechanical draft stopper (flap), and I'm looking at making myself a few (it is overpriced on eBay).
Regarding the LED lights, are they LED bulbs in down light fittings or are they LED down light fittings? The former likely leaks a lot of heat while the latter would be sealed.