Note: some of these items may or do require a specialist contractor.

Insulate your attic and walls. A surprising number of homes either have no insulation in the walls, not enough insulation in the attic, or both. Before you take this step, you will want to hire an electrician and, at least in the areas which need insulation, bring your wiring up to current standards. Within uninsulated walls, insulation can be added using blown-in cellulose—holes are drilled into every stud cavity (every 18” or so at the top of the wall), insulation is blown in, the hole plugged, and the wall repainted. Adding insulation to the attic is more straightforward. Be sure to air seal any protruding can lights first, make sure all venting (especially if it is in the soffits) is kept clear, and then insulate to R-60, about 17 inches thick. I prefer recycled cellulose, which has low embodied carbon.

We took these steps on our previous old Craftsman. We were shocked by how much quieter and cozier the house became; in addition, we noticed about a 1/3 drop in our energy bills. It was well worth it.

If you have single-paned or metal-framed double-paned windows, install storm windows. These two window types have only 7-10% of the insulative value of an insulated 2x4 wall—not much. Window replacement is costly, and storm windows can be a good alternative short of fully replacing the windows. And, like adding insulation, you will notice less outside noise and feel cozier too.

Install solar on your roof, especially when you reroof. One of the great pleasures in life is making your own fuel—truly. Talk about energy independence. When the sun is out, we usually make all the electricity we need, including for our Nissan Leaf. When we need additional electricity, we draw off the grid; when our panels produce  more than we need, that electricity feeds back into the grid, the meter spins backwards (literally), and we gain a credit. Solar has come down a lot in price; in most parts of the country the savings over time easily cover the solar installation costs. We recently hit the point where the value of the electricity generated fully offset the cost of our array—meaning, from here on out, we are getting free electricity from it.

One thing I do want to highlight is that you don’t want to install solar when you only have 10-15 years of life left on the roof. The cost of deinstalling/reinstalling the array is pretty substantial, and you don’t want to do it early in the life of the array. Ideally, you install solar when you reroof. We learned this the hard way when we had to reroof early due to premature roof failure and had to cover the de/reinstall along with the new roof. I also suggest getting the most durable roof material you can for the same reason.

A key element of the Inflation Reduction Act is that it provides a 30% tax credit for solar installed on homes—an absolute gamechanger. This changes the math completely and means that in many areas solar pays for itself with electricity savings in 10-15 years. energy.gov/eere/solar/homeowners-guide-federal-tax-credit-solar-photovoltaics

Replace your toilets with Watersense certified toilets. Many old toilets use 3-5 gallons per flush—Watersense toilets use only around a gallon.

Plant a climate appropriate yard that doesn’t need irrigation. You'll need to water to get your yard/plants established, but after that watering shouldn't be needed (except during drought). Double-dig your yard with lots of compost, so that it holds water. Plant native plants, or, at a minimum, plants that match your climate zone. Take a laissez-faire attitude—if a plant can’t make it, it doesn’t belong.

Air seal your house, using a blower door to find leaks. Fair warning—this process can be pretty tweeky—but it also will make your house cozier, healthier, and more durable, because it will reduce mold and air coming from gross areas like crawlspaces and attics. A blower door assembly is a fan mounted in a fabric surround that is temporarily sealed in place in an outside doorway. The fan pulls air out of the house, depressurizing it somewhat, allowing any leak points to be found with a thermal camera or a smoke pencil. The blower door includes a computerized system with pressure gauges that sets the fan speed appropriately and measures the leakiness of the house. In some areas you can rent these, but typically you will need to hire someone to do it. Typically the blower door tester is savvy on leaks and can help you find them. In most areas you can hire a testing/sealing contractor who will test and use the test to direct sealing in real time.

You may be shocked to see how leaky your house is. Sometimes there are a couple items or two that might be substantial culprits, but often it is a lot of little things. Hopefully you have already sealed any ducts in the crawlspace and/or attic. On top of that, you should seal (using caulk and backer rod, if necessary) any leaks between the house and any crawlspace, as well as the upper floor ceiling—because hot air rises within enclosed spaces, and air is drawn from moldy, drafty crawlspaces up through the house. Home sealing professionals recommend not oversealing a house that doesn’t have a heat recovery ventilator (Tier 4), so I suggest focusing on the bottom floor and top ceiling, then sealing until you’ve reached the air leakage threshold recommended here. If you are working with a house sealing professional, follow their advice.

Electrification, and a note on electrical capacity. The next set of recommendations start placing demands on your electrical system. In older homes, you may not have adequate capacity on your electrical panel to electrify/add all these items and may need to upgrade your panel to a modern, standard 200-amp service, or use a smart switch to enable sharing of a circuit with large loads (such as an EV and induction range). (Note: your house service size is listed on your main panel shutoff). Bear in mind, if you have an old panel it might be due for replacement anyway. Also, ground fault interrupting circuit breakers, which make all your outlets GFCI protected and thus significantly increases safety, are now available. Adding those when you’re replacing your panel is smart—check out this helpful video for an overview of options. Note that the very high upper costs for panel replacement involve new electrical side line service upgrades—which are usually not required. A typical panel replacement should be less than $5,000. All these details should be worked through with a professional electrician.

Replace your gas or electric resistance water heater with an electric heat pump water heater. This technology is totally developed and ready for prime time. We’ve had ours for ten years and it’s been great. Typically, these units have both a heat pump and electric resistance element, so if you need them to reheat quickly they really can—even faster than an electric only unit. However, I recommend using them in heat pump only mode, unless you are using a lot of hot water (when your teens move out, you can put it on heat pump only mode!).

Replace dryer with heat pump dryer. These are like an electric resistance dryer, but add a heat pump into the system to enable efficient drying. Also, most (though not all) of them do not vent outside—but rather exhaust hot air inside. I personally really like this, because it means a 3” diameter hole to the outside is avoided, and all that hot efficiently created air can be kept inside. I can definitely tell in the winter that our heat pump dryer, when in use, supplements our house heat pump—why blow all that warm air outside? If you are in a hot climate, I recommend keeping heat pump dryers in the garage for this reason, or getting one that does vent outside. Note: based on personal experience, I do not recommend the Whirlpool heat pump dryer. I am happy to see new heat pump dryer options have come to the market in 2023.

Replace your electric resistance or gas range with an induction range. Electric induction ranges cook efficiently without substantial waste heat. Plus, if you get rid of a gas appliance in the process, that’s great. Major co-benefits of eliminating a gas range include:

• Gas cooking is a substantial source of nitrous oxide, a poisonous gas, and contributes to childhood asthma.

• Burners and cookware are cooler, significantly reducing burns and overheating.

If doing construction, minimize the use of concrete, brick, extruded polystyrene (blueboard), and spray foam that doesn’t use water as the blowing agent. Manufacturing these four items generates a lot of carbon  (known as embodied carbon). Concrete can be difficult to get away from in some situations (foundations), but there are concrete alternatives in many cases. There is also a new way to inject carbon into concrete (Carbon Cure). Available in some markets, its use is expanding rapidly—if available, use it. Also, extruded polystyrene made with Solstice is totally fine.

Green Building Advisor is a great resource for going deeper on house efficiency. I am a long-time fan of this domaine of home energy nerd-dom—and I know they take this as a compliment. I learn something every time I read it.