Question: What is the thing in your household that almost certainly uses the most power when in use?
Answer: Your shower! It's using energy at a rate of ~15 kW and uses a total of about 2 kWh of energy.
Answer: Your shower! It's using energy at a rate of ~15 kW and uses a total of about 2 kWh of energy.
I've assumed 2.3 gallons minute flow rate, 8 minute shower, and a 25 C (45 F) temperature increase from the cold-water tap. In some colder climates with deep well water, I suspect the tap is colder than the 60 F tap water that I've assumed here. So power is even higher there.
One thing I try to make clear to my students in my Energy and the Environment course: the specific heat capacity of water is very large! Translation: It takes a lot of energy to increase the temperature of water.
8 years ago I replaced my shower head with a $30 @EPAwatersense rated shower that decreased the flow rate by 33%. That has saved approximately 3 MWh or 100 therms of natural gas (125 therms with some heat loss).
So this has saved me ~$125 in natural gas costs (at $1/therm).
So this has saved me ~$125 in natural gas costs (at $1/therm).
The switch has saved about 2/3 of a ton (~663 kg) of CO2 emissions so far, or ~$20/ton (and decreasing as it continues to save).
In terms of cost for energy, $30 for 3 MWh is about ~1 ¢/kWh, so that's very cheap!
In terms of cost for energy, $30 for 3 MWh is about ~1 ¢/kWh, so that's very cheap!
I'll note that the showerhead is well designed so that it doesn't feel much different, but it saves a whole lot of energy. It is not "dripping out" as the President recently claimed. I'll also note that this additional water savings is not mandated, but optional.
Finally, if we clean our electricity with renewable energy and use heat pumps to efficiently heat our water, we can dramatically reduce our carbon emissions associated with water heating. #electrifyeverything @RachelEGolden @brucenilles @energysmartohio
@RachelEGolden @brucenilles @energysmartohio Lower flow shower heads have come a long way since those old school shower heads that resulted in a lot of mist and not a lot of comfort. Fear not!
@RachelEGolden @brucenilles @energysmartohio It was pointed out by @JohnSemmelhack that many homes have large gas furnaces (60,000 BTU/hr or 18 kW). So this is not true in a lot of homes.
@RachelEGolden @brucenilles @energysmartohio @JohnSemmelhack And it should be pointed out that what matters for energy, cost, emissions, is the power times the amount of time you use it. Nonetheless, it's pretty important. Because the rest of our home is pretty efficient, the shower amounts to ~20
% of energy usage!
% of energy usage!
@RachelEGolden @brucenilles @energysmartohio @JohnSemmelhack As I say in the previous tweet, energy is more important than power, so you also need to consider the duration of use. I suspect the typical household uses the shower for ~20 min. Not bad. Nonetheless, it's probably the easiest way to take a decent chunk out of your energy use.
