Heating Your Water to Cool the Planet
by Union of Concerned Scientists on 10.23.06
Heating up water for showers, dishwashing, and other activities accounts for approximately 15 percent of average household’s energy consumption. If the water heater in your house is more than 10 years old, it’s probably running at less than 50 percent efficiency. Upgrading to a new, more efficient model is one of the many ways you can save money while also reducing the amount of heat-trapping emissions that cause global warming.
Most households have tank water heaters, which keep a large volume of water at a constant, set temperature. While they’ve become more efficient over the years, they waste energy when no hot water is being used (known as standby energy loss). Upgrading to a more efficient water heater can still save you money, though. The U.S. Department of Energy (DOE) has a worksheet for figuring out how big a tank you need and advice for finding the most energy-efficient models to fit your needs.
Tankless water heaters operate only when you need them, resulting in less standby energy loss. The DOE can help you figure outwhether a tankless heater is right for your home.
You can also tap into the power of the sun to supply part or all of your hot water needs. Solar hot water heaters have higher up-front costs than conventional water heaters, but much lower operating costs. Under favorable conditions, they can pay for themselves in energy savings within 4 to 10 years.
Federal, state, local, and utility incentives are available for residential and commercial energy efficiency upgrades, allowing you to reduce costs even more. To find out what’s available in your area, visit the the Database for State Incentives for Renewable Energy.
The American Council for an Energy Efficiency Economy also has a list of energy efficiency ratings for various types of water heaters.
Before you shop for a new water heater, make sure you’ve done everything you can to minimize your hot water use. Installing water-saving fixtures and appliances and insulating your pipes can reduce your water and energy use, allowing you to buy a smaller water heater and further reducing your contribution to global warming. See also ::New Tankless Water Heater Uses Microwaves, ::Cut Your Gas Consumption in Half in One Day, ::Using Evacuated Tubes for Solar Hot Water, ::Home Power's Solar Water Heating Overview, ::Lightweight Solar Water Heater Announced
I just replaced my hot water heater a few months ago. I went from a gas tank to an other gas tank. I thought about on demand but the initial cost was too much at the time. I should look at my gas bills and see if going from a 20+ year old water heater to a new one made a difference.
I've got an old boiler. Surely it is better to wait for it to konk out than get a new one. How much embodied energy does a boiler repersent? i.e. How long would it take before I saved back the equivalent amount of energy as that used to make the new boiler?
"Surely it is better to wait for it to konk out than get a new one. How much embodied energy does a boiler repersent?"
I seriously doubt that it's better to wait. The old boiler materials can be recycled, and these old things can last for deccades.
We need to save energy NOW, not in 20 years.
Tankless water heaters, as well as solar water heaters, should be the default everywhere. They just make more sense.
Surely it is better to wait for it to konk out than get a new one.
This is a commonly-held assumption, and one which frequently turns out to be wrong. The assessment really has to be done on a case-by-case basis. Certain appliances have gotten so efficient lately, that a new model will save (compared to an older model) their embodied energy within only a few years of operation. This is definitely true of refrigerators, and I believe it's also generally true of air conditioners and boilers. According to the -
For low-water-use homes (e.g., about 41 gallons per day and less), demand heaters were 24–34 percent more efficient than storage tanks. Further research by NREL showed that even greater savings (of 27–50 percent) could be achieved using on-demand heaters at each water outlet
So if this is true, you can kind of get an idea (from your bill) of how much gas you'd save. I don't know how much energy it takes to make a boiler, but it's probably correlated to cost: the financial payback period will be close to the energy payback period.
Anyway, this and many more fun facts about hot water are to be found at: http://www.rmi.org/images/other/Energy/E04-15_HEB5WaterHeat.pdf
From my research tankless water heaters are not worth the premium.
Do you use a tankless water heater? Is it hard to set up and use? Do you have suggestions on where to buy one? Our hot water tank is about to die and I wnted to do a green replacement!
"From my research tankless water heaters are not worth the premium."
From an energy point of view, they are worth it.
From a money one, it depends on energy prices where you live.. But since these things probably last a long time (decades?), I bet they are often worth it in that way too. It just depends how long ahead you look forward.
They are more than twice as much at Home Depot, than the bottom of the line tank heater. They would have to be fairly efficient to make that up. And I don't think they are. It also depends on how hot you like your water and how much hot water you use. I wanted one, but could not afford it at the time. They are no harder to set up than a normal water heater. Though since they hang on the wall you may need to reroute some pipes, both water and black. Not too hard.
I'm in the midst of replacing a 20 year old tank right now -- tankless is cool, and the heaters themselves are a bit expensive, but what really kills is the installation. I just got quoted $2000-$2500 to INSTALL the durn thing. Apparenlty you have to revent, increase the water flow to the unit, and increase the gas flow to the unit.
I'd love to go tankless, but not at that pricepoint. It'd take you 100 years to recoup the energy costs.