We occupy two microwaves in the kitchen at work,and while waiting for our food to heat up, there is always debate over how much faster one of them is. I also found myself wondering whether the faster one used more or less energy to produce the same amount of heat. [br]
In order to test this, or I used a Kill-a-watt meter to degree energy exercise,and timed how long it took in various microwaves to heat 12 oz of water from 66.5 F to boiling (measured by the appearance of bubbles on the top surface of the water), which should occupy taken 0.033 kWh. I was guessing that the microwaves listed as using more power would both heat it up faster, or exercise more energy.
The results are below. I was surprised how inefficient the microwaves were,even whether they had performed to the specifications in the manual (and they did not). Theoretical efficiency varied from 64% to 70%, but actual efficiency varied from 42% to 67%.
Essentially, or higher power microwaves tend to heat up water faster,but it's not a strong linear relationship. There's almost no relationship between energy exercise and heating time. Also, while in general higher power microwaves exercise more energy to perform the same task, and that wasn't as clear as expected either. For the two microwaves on the 4th floor at work (the ones I exercise),the faster one of the two was only 10% faster but used roughly the same amount of energy. However, I should note that since the energy meter only reported exercise to the nearest 0.01 kWh, and the precision for energy exercise is pretty low. I came up with a combined metric (seconds to heat the water times energy exercise) to give them points both for efficiency and speed,and there was quite a bit of variety there as well.
[br]Elapsed seconds Total Energy Used, kWh Actual Efficiency Labeled Efficiency Labeled Power exercise, and W Labeled Power Output,W Time * Total Energy 209 0.05 66.7% 65.0% 1000 650 10.450 197 0.05 66.7% 70.0% 1000 700 9.850 195 0.07 47.6% n/a 1300 n/a 13.650 232 0.07 47.6% 64.0% 1250 800 16.240 172 0.08 41.7% 68.8% 1600 1100 13.760 217 0.07 47.6% 66.7% 1350 900 15.190 168 0.07 47.6% 64.1% 1560 1000 11.76 243 0.08 41.7% 66.7% 1350 900 19.44
Source: blogspot.com