Which appliance should I replace first?

Question

I recently bought a home with many appliances approaching 20 years old. As I expect that many of them will fail over the next several years, I want to get a head start on replacing them (since last-minute replacements are typically quite costly and inconvenient). Here are the appliances I am considering replacing:

• Dishwasher (cold water line only -- uses electric coil to heat water)
• Furnace (natural gas-fired)
• Water heater (natural gas-fired, 40 gallons / 150 liters)
• Refrigerator
• Clothes dryer (vented, electric resistance)

In order to have the greatest sustainability benefit, which of these should I replace first?

Other important factors:

• The clothes dryer is paired with a recently purchased ENERGY STAR rated front-loading clothes washer which is very effective at extracting water from the clothing
• Our climate is humid continental (southern Wisconsin, USA)
• Where possible/practical, we are using these appliances in the most water- and energy-efficient way -- air-drying dishes, turning down the thermostat at night/while at work, line-drying clothing, etc

Answer 1

I'd say that you need to analyse the use you get from each appliance, and how inefficient the current ones are - for example, if you only use the dryer occasionally when it's too damp to dry clothing on a line, that's probably a lower priority.

I'd probably go for the following order:

Refrigerator - This tends to be on all of the time, so it's always using energy, and the difference in consumption between a modern energy-efficient one and a 20-year-old one will be huge.

Furnace/Water heater - here in the UK they tend to be combined into one appliance. Like the fridge, efficiency of these has come on leaps and bounds over the last 20 years, so will make a big difference - but buying them at the start of the winter is going to be expensive - you'll get a much better deal in the spring or summer... As Erik says in his comment, investigate other sources of heat too - I'd also suggest looking at ground-source heat if it's feasible in your area, but solar-thermal could make a big difference to your energy use, especially in the summer, where you could probably eliminate gas usage completely.

An immediate improvement you can do straight away is to get a controllable thermostat - this will allow you to program the on-off times and so avoid having to remember to switch off the heating when you go to work etc.

Dishwasher - a lower priority as you can always wash dishes by hand if it breaks. Many modern dishwashers actually use less water than hand washing.

Clothes Dryer - As mentioned above, not essential as you can always line-dry, though we use ours in the worst of the winter as we don't have a suitable indoor drying space, and the risk of getting damp/mildew in the house is worse than the increased energy consumption.

Answer 2

It will depend on the age of the appliances. The refrigerator had a significant effect on my power bill. Next up is my water heater. They calcify at the bottom, limiting their efficiency over time (like your kettle). A measure of this is if you can actually get 40 gallons of hot water out of your tank - i.e. how many hot showers. Plus tanked water heaters rust and can leak (it's just a matter of time...). Plus, they are much better insulated now than they were (although you could buy a water heater blanket to help in the meantime). Tankless water heaters are even better, since the hot water does not stick around to lose heat. I've looked at them but I don't think they're worth the extra cost yet.

Nick's answer regarding use is probably very applicable in relation to costs saved. The fridge is on all the time, the furnace half the year, and the water heater every day. For furnaces, get one with a DC (direct current) fan as they are significantly more efficient in terms of power (vs. AC). But it's actually the thermostat (controller) that specifies how often to run the fan: while heating, half the time, all of the time. Not all models have all of these options, much like the schedule features.