LEDs and electricity savings

[kien]

Originally Posted by sphelps

Oh no another LED thread to discuss electricity savings

Actually I just wanted to share some results I recently measured. Not long ago I wondered how much power I was actually saving with LEDs compared to a lighting source such as metal halides. One of primary reasons many of us make the switch is the potential for such savings, among others, but some of us have often wondered if the savings are that substantial when you consider your heater may have to work a little harder to combat those "cooler" LEDs. So I decided to measure the power consumption of each and see exactly what I'm saving. I'm sharing the results more for "food for thought" purposes, everyone will get different results and may make different assumptions than me.

Executive Summary:

• LED power used: 0.84 kWh per day
• Metal Halide Comparison: 6.12 kWh per day
• Heater power saved from Halides: 0.91 kWh per day
• LED power savings: 4.37 kWh per day
• In this case the power saved with LEDs is substantial including the extra power requirement from heaters.

Some system details

• Display tank volume: 270 gallons
• Connected frag tank and sump volume: 70 gallons
• Realistic water volume approximation: 300 gallons.
• Maintained water temperature: 78F
• Lights: 3 x Mitra
• Heaters: 2 x 300W

Insulation and equipment heat addition:

• 15mm glass with only view-able side but has an open top.
• Sumps are acrylic and contained in a humidity controlled room which stays fairly humid and warm meaning heat loss from the sumps will be minor.
• I'll installed all my pumps internal to take advantage of their heat loss.
• I also have fridges under the main tank which vent around the sides and back.

In other words I've taken some steps to add as much heat to the tank from equipment and keep it in as much as possible without doing something that would have negative effects. I mention this because I think it's important when looking at your own tank you consider how heat loss/addition will effect your savings.

Measured Results:

• Lights run for 12 hours, peak at 135W dimming up and down. Power used per day is 0.84 kWh
• I measured the power used by the heaters a few different ways, during the full 12 hours on different days, during the peak light time and 24-7 to get a feel for any changes in usage that occur. I concluded the heaters duty cycle doesn't fluctuate substantially and they use an average of 0.13 kW per hour.

Now for the debatable part, the comparison.

• The mitras run in high output mode, GHL claims it's comparable to 340W of halide, however I would no way compare the 12 hours of ramping up and down to that of a solid state 340W halide. Rather I believe it's comparable to 6 hours of equivalent halide which is 6.12 kWh per day excluding any inefficiencies.
• In my experience when halides are on, heaters are off. I also think another hour is fair for a cooling off period. In other words I'm assuming the halides save me 7 hours of heat which is 0.91 kWh per day.

Conclusion

• LEDs save me money in electricity even with heating cost included. A total savings of 4.37 kWh per day or approximately 70% decrease. However I believe the steps I've taken to with hold heat are a key player for this savings, I've noticed the heaters activate much less frequently from switching to acrylic sumps alone. I also maintain my temp at 78F while many SPS gurus will keep it closer to 80F which could play a role as well. This of course was also a winter reading, results will be different if house temperature climbs during hot summer days. Other peoples results will vary but the substantial difference I measured should conclude in virtually all cases the electricity savings are real.

TRANSLATION: LEDs can save you money (but it also might not).

[mrhasan]

Originally Posted by kien

TRANSLATION: LEDs can save you money (but it also might not).

Correction: LEDs can save you money (but it also will not)

[sphelps]

The point wasn't to compare fixture cost at all, only that LEDs can use substantially less power even with the added heater duty cycle considered. Something a few people have asked me.

PS, I didn't get the Mitras to save money and personally don't think you should buy LEDs for the purpose of saving money cause in all reality you probably won't save anything But that wasn't the point here.

[sphelps]

Originally Posted by kien

TRANSLATION: LEDs can save you money (but it also might not).

Yes

Originally Posted by mrhasan

Correction: LEDs can save you money (but it also will not)

No

[mrhasan]

Originally Posted by sphelps

No

Then why this line?

PS, I didn't get the Mitras to save money and personally don't think you should buy LEDs for the purpose of saving money cause in all reality you probably won't save anything But that wasn't the point here.

[fresh]

Originally Posted by mrhasan

Then why this line?

I presume he meant you will most likely upgrade to LEDs for the purposes of dropping temperature for example.

[mrhasan]

Originally Posted by fresh

I presume he meant you will most likely upgrade to LEDs for the purposes of dropping temperature for example.

Yap that's the whole point of LED. Save your reef during the summer and the versatility and aesthetics that LEDs give

[Aquattro]

Originally Posted by mrhasan

Yap that's the whole point of LED. Save your reef during the summer and the versatility and aesthetics that LEDs give

Maybe that's just your whole point to LED? Mine was solely to reduce evaporation. Nothing more. Sure, they're growing on me, but my point was not your point. And yes, I'll save money as I was changing 3 Radium bulbs every 9 months.

[sphelps]

Originally Posted by mrhasan

Then why this line?

I said probably which doesn't mean they won't save you money and that's just a personal opinion, far from fact. Quite simply put the potential is certainly there but whether most will be able to take advantage by sticking with the same fixture for long enough is debatable. Again the real point was additional heat isn't a huge factor and if it is it's something that can be minimized.

[mrhasan]

Originally Posted by sphelps

I said probably which doesn't mean they won't save you money and that's just a personal opinion, far from fact. Quite simply put the potential is certainly there but whether most will be able to take advantage by sticking with the same fixture for long enough is debatable.

People tend to upgrade before the break-even point (4 years on average) and hence the "not" unless you use DIY leds or generic chinese $200 LEDs which, I hear, is damn good for the price.