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Results tagged with energy-efficiency
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user 3379
The percentage ratio of energy produced to energy supplied to a system; or a measure of minimum energy required relative to energy actually consumed; or a measure of relative energy consumed to provide the same energy service.
5
votes
How much energy am I harvesting?
Energy in the pumped water
54 gallons is about 200 L, equivalent to 200 kg
30 feet is about 9 m
Using the formula @JanDoggen mentioned:
m ⨉ g ⨉ h = (200kg)(9.81m/s²)(9m) ≅ 18,000 kg*m²/s²
Th …
- 12k
3
votes
Accepted
Why is there no energy star certification for portable or box fans?
tl;dr: fans are cheap and already pretty efficient, so an ENERGY STAR certification wouldn't do much to reduce energy usage.
ENERGY STAR provides a list of scoping reports with details of products …
- 12k
2
votes
Accepted
How to test accuracy of my Kill-A-Watt or similar device?
According to the manual, the Kill-A-Watt is calibrated to accuracy within 2%, with 0.5% being typical. In contrast, any conventional electrical load which you might have in your house won't be calibra …
- 12k
4
votes
How much gas does it take to heat water from 15 to 60 degrees C?
The amount of energy needed
From EnergyNumber's answer to the electricity version of this question:
...the energy needed is 180,000 x 45 x 4.2 = 34 MJ
1kWh = 1000W x 3600s = 3.6 MJ
Henc …
- 12k
4
votes
Accepted
What is the most efficient setting on my oil-filled radiator?
Efficiency of the heater
Like most space heaters, an oil-filled radiator uses resistive heating, which is greater than 99% efficient at converting electric energy to heat. But there are a few other c …
- 12k
1
vote
Is an air to water heat pump appropriate to keep a hot tub at temperature throughout the year?
tl;dr: heat pumps are widely used for swimming pools, can probably be used for hot tubs, and should work reasonably well in your climate.
Swimming pool with cover
I couldn't find good information on …
- 12k
0
votes
Accepted
Why is the Energy Guide efficiency rating of my air conditioner so much lower than the speci...
Thanks to MonkeyZeus' answer to a related question on DIY.SE, I sorted this out.
The AHRI product search lets you see the SEER rating for different combinations of A/C indoor and outdoor units. (AHRI …
- 12k
1
vote
Accepted
How to keep my tankless water heater safe in a cold room?
Since the water heater is not on an exterior wall, it is likely that the pipes you mention which do pass through the exterior wall would freeze before pipes inside the heater do. This would cause dama …
- 12k
3
votes
More sustainable pick-me-up: can of coke or cup of tea/coffee?
TL;DR -- The best option, per liter, is tea. Soda is about twice as "bad," and coffee is two times worse than that.
To compare the environmental impact of various beverages we need to perform a lif …
- 12k
3
votes
Accepted
Are building certificates under EU Directive 2002/91/EC, such as EPC, Energieausweis, DPE, d...
No. The letter rankings cannot be compared between nations in the EU, as each nation has a different number of grades (or no grades at all).
From "A comparative analysis of the energy performance cer …
- 12k
1
vote
Options to suggest to landlord for cost savings via renewable energy?
You asked this question a while ago so not sure if you still need an answer, but I used to live in Silver Spring, MD, so the question caught my eye. If you're in Montgomery County or Prince George's, …
- 12k
2
votes
Accepted
Water heater vs stovetop: most efficient way to heat water using natural gas?
Stovetop vs water heater efficiency
A gas stove-top is about 44% efficient (source), and a modern natural gas water heater with a tank is up to 67% efficient (source (pdf)).
Basic formula
From this …
- 12k
3
votes
Accepted
How can I conserve energy and water in my bathroom?
Others have already suggested low flow fixtures and reducing water usage, but here are a few other ideas, from least to most expensive:
Turn down your water heater. The U.S. Department of Energy rec …
- 12k
2
votes
Accepted
Most energy-efficient way to keep my pipes from freezing without tearing up walls/floor?
Leave the faucet open at a trickle. From Consumer Reports:
Let the cold water drip from a faucet served by exposed pipes. Running water through the pipe—even at a trickle—helps prevent pipes from fre …
- 12k
2
votes
Accepted
Why do the best energy star freezers have higher capacity and lower rated power consumption ...
Although it seems logical that a refrigerator would be more efficient since it doesn't have to keep things as cold, there are a few different factors affecting real-world performance.
Freezers are sim …
- 12k