KWH to $$ Conversion

[A/A Fuel GTX]

I have a project I'm trying to justify regarding replacing 400W HPS lamps with 150W LED lamps. I'd like to show my customer the cost savings in real dollars but have no clue on how to do the calcs. The cost per KWH is .217970. The fixtures are on 16 hours per day, 6 days per week. One lamp per fixture. I would like to show the comparison on a per fixture basis. HELP :?..............TIA

 

[don_resqcapt19]

I have a project I'm trying to justify regarding replacing 400W HPS lamps with 150W LED lamps. I'd like to show my customer the cost savings in real dollars but have no clue on how to do the calcs. The cost per KWH is .217970. The fixtures are on 16 hours per day, 6 days per week. One lamp per fixture. I would like to show the comparison on a per fixture basis. HELP :?..............TIA

The 400 watt fixture will cost (400/1000) x 0.217970 per hour to operate and the LED will cost (150/1000) x 0.217970 per hour. Note there are ballast losses for the HPS and the actual wattage will exceed 400. I am not sure how they rate the LEDs, but expect the 150 watts is the total load.

 

[Smart $]

I have a project I'm trying to justify regarding replacing 400W HPS lamps with 150W LED lamps. I'd like to show my customer the cost savings in real dollars but have no clue on how to do the calcs. The cost per KWH is .217970. The fixtures are on 16 hours per day, 6 days per week. One lamp per fixture. I would like to show the comparison on a per fixture basis. HELP :?..............TIA

You will have to get actual usage data... i.e. power consumed, not just lamp usage.

As to the calculation, I'll demonstrate using lamp wattage:

0.400kW*16hrs/day*6days/wk*52wks/yr*$0.217970/kWh=$435.24/yr

0.150kW*16hrs/day*6days/wk*52wks/yr*$0.217970/kWh=$163.22/yr

 

[mgookin]

I have a project I'm trying to justify regarding replacing 400W HPS lamps with 150W LED lamps. I'd like to show my customer the cost savings in real dollars but have no clue on how to do the calcs. The cost per KWH is .217970. The fixtures are on 16 hours per day, 6 days per week. One lamp per fixture. I would like to show the comparison on a per fixture basis. HELP :?..............TIA

Your $ per kwh seems high. Also, does that include all taxes and fees which are a function of kwh used?
Around here units of government pay $0.09 - $0.11 per kwh and they pay no taxes.
But consumers, business & industry pay around 25% more in taxes which are based on kwh used.

I'm guessing these are indoor lamps used in a facility running 2 shifts per day 6 days per week?

Simple formula is always 1kw for 1hr = 1kwh and then kwh x rate = cost.

 

[fmtjfw]

You need to base your load calculations on the input power to the ballast or power supply, not the "lamp" wattage. Also is your power factor metered and charged for? if so you need to look at the PF for ballasts ....

 

[A/A Fuel GTX]

You need to base your load calculations on the input power to the ballast or power supply, not the "lamp" wattage. Also is your power factor metered and charged for? if so you need to look at the PF for ballasts ....

No, the power factor is not metered. As far as the ballast goes, it's a 120V, 400W HPS unit. How do I arrive at the total power consumed if not just using the 400W as a standard?

 

[GoldDigger]

No, the power factor is not metered. As far as the ballast goes, it's a 120V, 400W HPS unit. How do I arrive at the total power consumed if not just using the 400W as a standard?

You measure it on a sample with a watt meter or you look for information from the manufacturer.

 

[A/A Fuel GTX]

Your $ per kwh seems high. Also, does that include all taxes and fees which are a function of kwh used?
Around here units of government pay $0.09 - $0.11 per kwh and they pay no taxes.
But consumers, business & industry pay around 25% more in taxes which are based on kwh used.

I'm guessing these are indoor lamps used in a facility running 2 shifts per day 6 days per week?

Simple formula is always 1kw for 1hr = 1kwh and then kwh x rate = cost.

Actually, the metering is On Peak and Off Peak with On Peak being 9AM to 9PM and that is the KWH cost I cited. Off Peak is a lower rate but I didn't want to over complicate the math. I know the user will see a great return on retro fitting with LED's so I wanted a worse case scenario to build my sales pitch. I've got 25 of these fixtures I would modify and I'm sure the post modification electric bill will make the tenant very happy. The proposed lamps have a 50,000 hour rated life so I figure at 16 hours per day, six days per week, there should not be any issues for 10 years. BTW, the lamps are $473.00 ea.

 

[Jraef]

Actually, the metering is On Peak and Off Peak with On Peak being 9AM to 9PM and that is the KWH cost I cited. Off Peak is a lower rate but I didn't want to over complicate the math. I know the user will see a great return on retro fitting with LED's so I wanted a worse case scenario to build my sales pitch. I've got 25 of these fixtures I would modify and I'm sure the post modification electric bill will make the tenant very happy. The proposed lamps have a 50,000 hour rated life so I figure at 16 hours per day, six days per week, there should not be any issues for 10 years. BTW, the lamps are $473.00 ea.

You keep saying "lamps", not "fixtures". Are these LED lamps designed to retrofit into the same fixtures as the HPS, i.e. strictly a lamp swap? If that's the case, since the ballast does not change then you can truly look at the lamp power differences alone and this should be a no-brainer, unless the lamp life is severely different and you have to change the LED lamps more often.

How do the lumen outputs and color temperature compare?

 

[A/A Fuel GTX]

You keep saying "lamps", not "fixtures". Are these LED lamps designed to retrofit into the same fixtures as the HPS, i.e. strictly a lamp swap? If that's the case, since the ballast does not change then you can truly look at the lamp power differences alone and this should be a no-brainer, unless the lamp life is severely different and you have to change the LED lamps more often.

How do the lumen outputs and color temperature compare?

Yes, these LED lamps are installed in the existing HID fixtures but the ballast is bypassed and line voltage is applied to the lampholder. The LED lamps would be 5700K @ 13725 Lumens. The whiter light will be a welcome change given the type of work being performed in this setting.

 

[raberding]

I've seen 400w HID fixtures that are around 465 input watts

 

[dereckbc]

The 400 watt fixture will cost (400/1000) x 0.217970 per hour to operate and the LED will cost (150/1000) x 0.217970 per hour.

Put another way:

400 watt lamps cost = 8.72 cents per hour
150 watt lamps cost = 3.27 cents per hour

Glad I live in TX where a Kwh cost me 7.9 cents for the first 1500 Kwh, and 7.2 cents over 1500 Kwh.

 

[BostonEE]

Utility Rebates

Utility Rebates

I have a project I'm trying to justify regarding replacing 400W HPS lamps with 150W LED lamps. I'd like to show my customer the cost savings in real dollars but have no clue on how to do the calcs. The cost per KWH is .217970. The fixtures are on 16 hours per day, 6 days per week. One lamp per fixture. I would like to show the comparison on a per fixture basis. HELP :?..............TIA

Others have already given you useful advice for performing the calculation so I'd like to add that the local utility company might offer a rebate for replacing the lamp with a lower wattage type. This could help your justification.

 

[kwired]

Yes, these LED lamps are installed in the existing HID fixtures but the ballast is bypassed and line voltage is applied to the lampholder. The LED lamps would be 5700K @ 13725 Lumens. The whiter light will be a welcome change given the type of work being performed in this setting.

What is the HPS lighting performance in comparison. I'm sure the LED is better color, how will working footcandles at specific areas differ before and after. Otherwise just 400 watt to 150 watt without considering ballast loss should alone come to somewhat significant number. One drawback could be daily hours of operation though. You will use less energy, but if you don't have enough hours of operation that will mean longer time before payback of the installation is achieved.

 

[Timbert]

You will use less energy, but if you don't have enough hours of operation that will mean longer time before payback of the installation is achieved.

Typically, this is what I would expect the bean counters to want. How long do I have to wait before this change pays for itself? This includes the cost of the lamps and the labor to convert the fixtures. It will take roughly two years to pay off.

Also, I know you didn't want to complicate the math, but don't ignore the 4 hours a day they operate at a lower rate (is the sixth day also lower?), that is at least 25% of the time. If you are dealing with bean counters they will want all the math.

 

[kwired]

Typically, this is what I would expect the bean counters to want. How long do I have to wait before this change pays for itself? This includes the cost of the lamps and the labor to convert the fixtures. It will take roughly two years to pay off.

Also, I know you didn't want to complicate the math, but don't ignore the 4 hours a day they operate at a lower rate (is the sixth day also lower?), that is at least 25% of the time. If you are dealing with bean counters they will want all the math.

Yes demand rates can become complicated sometimes if they apply.

There are some plants that run at odd hours mostly because they get better energy rates during those hours, and if they have significant enough load they may get much better rates to run at off peak hours for the utility. Lighting is one of those things that may be operating any way even though other loads may not be running because of peak demand rates. All depends on the needs of the operation. They may still have lighting on while doing maintenance or cleaning during high rate periods and process load is all that is reduced.

 

[Smart $]

Typically, this is what I would expect the bean counters to want. How long do I have to wait before this change pays for itself? This includes the cost of the lamps and the labor to convert the fixtures. It will take roughly two years to pay off.

Also, I know you didn't want to complicate the math, but don't ignore the 4 hours a day they operate at a lower rate (is the sixth day also lower?), that is at least 25% of the time. If you are dealing with bean counters they will want all the math.

If he's going to add in the material and labor cost for the new, then he'll also have to throw in the projected costs of maintenance over time to get a true ROI comparison.

 

[kwired]

If he's going to add in the material and labor cost for the new, then he'll also have to throw in the projected costs of maintenance over time to get a true ROI comparison.

Of both the old and the new, though the expected life of the LED should be longer than the ROI period.