The DOE is cooking up an energy conservation standard to limit the power that microwave ovens use when they’re not heating up our food. While that may seem obvious (shouldn’t they use zero watts when they’re not heating something up?), the reality is that they never get to turn off and consume a surprising amount while waiting to be used.
The DOE looked at standby power consumption on two product classes of ovens:
- Microwave-only ovens and countertop combination microwave ovens
- Built-in and over-the-range combination microwave ovens
Testing of currently available units showed that standby power consumption for microwave-only and countertop combination ovens ranged from 1.2 W to 4.7 W. Meanwhile, built-in and over-the-range combination ovens consumed from 4 W to almost 9 W of power while in standby. The DOE determined that the features driving the high levels of standby power included cooking sensors, display technologies (including clocks), and control strategies (control boards) to turn off power to components during standby. They also observed that, although technically available, microwave ovens in the U.S. did not include options that could cost-effectively reduce power consumption, including a mechanical on-off switch (to allow the oven to go into an off mode) or a user control that could turn the display (clock) off when not in use. Stakeholders have been asked to comment on whether the use of alternate technology options, such as switching power supplies, clock display controls, or automatic power-down could be employed in future models.
Table 1 below shows the proposed limits. If approved, the compliance date will be three years from the standard’s finalization date.
|Product Class||Proposed Energy
|Microwave-only ovens and countertop combination microwave ovens||Maximum standby power = 1.0 W|
|Built-in and over-the-range combination microwave ovens||Maximum standby power = 2.2 W|
Source: U.S. DOE
For more information, go to the Cooking Products section of the U.S DOE site.