Bret, just over the border in NB, I don't quite follow your sheathing discussion above. Most houses here of the 70's/80's had much lighter roof sheathing than now. The roofs used to use H clips at the joints vs T&G. Nowadays due to cost we're seeing a return to 1" board sheathing of roofs and I even saw a recently framed house with diagonal board sheathing! I'm not a LEEDS person but have seen local projects source LEEDS certified lumber from 3000 miles away when the site was located next to a mill producing lumber from local sustainably grown trees. Nonsense to me. We don't have exactly the same energy codes but in general the codes here have dramatically cut energy consumption in residential homes. Contractors building spec homes always built to the minimum, 2x4 walls, min insulation in ceiling, no insulation on rim joists, uninsulated basements, vapor barrier all punched to pieces etc while they put money into fancy cabinets. Now have min requirements in walls and ceilings. Related to the increase in heat requirement, I worked 10 years in an early 1980's 4 story building that was extremely tightly built, foot print about 100x100, tilt-up precast, caulked joints, fixed windows caulked in place etc. It had won all kinds of design awards and efficiency awards but I constantly had headaches. When we remodelled our office a friend who was an engineer with the designer was in doing some testing. Got talking, the only fresh air in the building was from leakage induced by the 2 bathroom fans on each floor that were automatically shut down at night. They were little tiny home style fans. Each suite had a dehumidification function built into the heat pump to remove the excess moisture. If someone laid carpet in the building, the solvent would stink for better than a week in the whole building. I'm sure this building would use more power if brought up to a minimum air change standard.