Heat Pumps Work Miracles
Heat pump water heaters have efficiency of 3x+ vs .9 or so for gas or electric resistance.  If you have have an electric resistance water heater get a heat pump model.  It costs more upfront but will pay for itself in not too many years, especially considering many places have incentives.  In the US natural gas is so cheap the economics are not nearly as good, it takes a long time to pay back the difference but does eventually.  With even a modest carbon price obviously this would be different.<p>If you are going to replace your furnace or AC get a quote for replacing with a heat pump instead, either central or multiple mini-split heads.  Heat pumps have gotten a lot better in recent years, particularly being able to work in cold weather down to 0F or below, expanding northward the places they are practical.