Ah, yes.. the water heater. After much research, we installed a natural-gas high-efficiency tank style heater. Not quite as efficient as a tankless design might be, but any losses from the tank merely contribute towards heating the home. In this climate, that's not really a loss for 9 months of the year.

On a related note, there's also a concrete "cold cellar" enclosure under the front steps, which we currently use as a walk-in beverage cooler.

Another design detail: the concrete slab for the (lower level) basement has rigid foam insulation underneath, plus a vapour barrier, plus rigid foam insulation around the inner perimeter of the floor. This helps prevent leaking heat to the concrete walls on that level, which are outside of the heating envelope. Think "warmer toes" in the workshop!

The concrete walls themselves, as well as all of the awkward joist header spaces, have an inch or so of closed cell spray foam applied to the inside, and then R30 Roxul over that. This seems to be the recommended best practice for preventing mould in basements.

Even better would be to have used insulated concrete extrusion forms for those walls, but our construction budget didn't allow for that.

Mistakes: well, not too many, though we do regret the brown colour on the lower-level siding.

We do love the sunny EPS stucco walls though. And that layer of polystyrene under the orange acts like an insulated wind breaker for the house. Good thing, too.. We get a LOT of wind in this location, something that surprised us and the workers building the place last year.