Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It only takes a minute to sign up.
Sign up to join this community
In my home, I have some halogen spot lights, which have an energy efficiency rating of 'C':
I would like to replace them with more efficient LED bulbs, but looking on the Philips website, they claim their bulbs are rated 'F'!
LEDspot VLE GU5.3 MR16 7W 830 36D
LEDspot VLE GU5.3 MR16 7W 830 24D
Why would a 50W bulb be rated better than a 7W equivalent?
EU energy ratings get re-done regularly; a rating indicates placement in the field of competitors at the time of rating.
Things that were A a couple years ago might now be G; hence, you need to evaluate things with comparable tests. Since new halogen reflector lamps haven't been into the market in the last decade, these ratings are simply outdated.
Standardized Energy label. Note (VII) needs to be the same for different labels to be comparable. The currently valid regulation, as per the consolidated regulation linked to below, is 2019/2015 (state of 2021-09-01)
As far as I could figure out quickly, the valid energy efficiency classes since 2019 are:
| Energy efficiency class | Total mains efficacy ηTM (lm/W) |
|---|---|
| A | 210 ≤ ηTM |
| B | 185 ≤ ηTM < 210 |
| C | 160 ≤ ηTM < 185 |
| D | 135 ≤ ηTM < 160 |
| E | 110 ≤ ηTM < 135 |
| F | 85 ≤ ηTM < 110 |
| G | ηTM < 85 |
And halogen incandescent lamps achieve of only up to 24 lm/W, so they can't be any better than G.
The old ratings were designed for incandescents, so all the modern LED bulbs were getting absurd ratings like A+++, so they just changed the scale to make it harder to get the A rating. Basically C is the new A++. So you can't compare the old scale and the new scale.
Of course, this means the previous labels on your fixtures that said "do not use bulb below class C" no longer mean anything. But these labels were meant to prevent you from using incandescent bulbs in fixtures made of plastic that wouldn't tolerate the heat, and there are no more incandescent bulbs, so who cares.
The useful thing about this regulation is they made it mandatory to specify the light output in lumens. So you can look at how many lumens it outputs, look at the power, divide, and you get the efficacy in lumen/W.
Now you may ask, why is the efficacy in lumen/Watt not what is printed on the box instead of useless "ABC" ratings? Well, it's brought to you by the same bureaucrats that give my gas-guzzling V6 a better pollution rating than my high mpg diesel, lol.
Note luminous efficacy of LED lightbulbs is not relevant unless you have a very large number of them. If you upgrade a bulb from a 13lm/W 60W incandescent to a 100lm/W 8W LED, both output about 800 lumen, and you save 52 Watts, and it does add up. But if you upgrade that 100lm/W 8W LED to a 200lm/W 4W one, you only save 4 watts.
IMO it's better to focus on quality: no flicker first, then higher color rendering bulbs which have a bit lower efficacy, but they are absolutely worth the extra watt. If you like the color rendition of halogens, the 3000K CRI90 spots from Osram are a nice match.
To add to Marcus's answer, the luminous efficiency of that bulb is 78 lm/watt at a CRI of 80-90. In an absolute sense that is fairly good, reaching something like 20% of the theoretical perfect efficiency for a white phosphor LED at that CRI value, which is far better than an incandescent. However, LEDs can be extremely efficient, and diodes in that CRI class of about 200 lm/watt are available. Thus in a relative sense, those lights are quite poor, using about 2.5x more energy then is required for that amount of light.
Think carefully about how often you will use the lights and the absolute amount of energy savings. A 6w light used an hour a day will not save a large amount of electricity if you double the efficiency. A 50w flood light used 12 hours a night will benefit a lot more from higher efficiency.
