savings from turning the lights off

[dean008]

In my condo building in Bangkok they have decided to turn the lights in the corridors off for 5 hours a day, they reckon it will save about 20,000 baht a month, and are already planning on how to spend the savings. I suspect it is bullxxxx and wish to work out how much they will save:

there are 1740 low energy bulbs (10 w each) that will be switched off for 5 hours a day, i do not have an old electricity bill so can't confirm the price per kw hour, but assume it is the same throughout the country?

I suspect they just want an excuse to initiate a new capital project with the savings so they can dip their fingers in the till, if anyone can confirm the actual savings (with workings out) that would be appreciated

Thanks

[trogers]

Change all those lights to 3-4 watts LED bulbs and leave them on as usual.

[dean008]

i think i have it

10 watts* 5 hours =50

50/1000 *3.9 (cost of electric per kwh) is .195 baht per 5 hour day

.195 * 30 days is 5.85 baht pm

* 1700 bulbs is 99450 baht pm

does that sound tight?

assuming the electricity for a condo building is 3.9 baht per kw/h

[cooked]

Turning low energy bulbs on and off can often shorten their lives and finish up costing more.

[Sophon]

i think i have it

10 watts* 5 hours =50

50/1000 *3.9 (cost of electric per kwh) is .195 baht per 5 hour day

.195 * 30 days is 5.85 baht pm

* 1700 bulbs is 99450 baht pm

does that sound tight?

assuming the electricity for a condo building is 3.9 baht per kw/h

Two errors in your calculations.

1. The rate the condominium building is paying will be considerably more than 3.9 Baht/unit. I don't know the rate, but you would probably have to add at least 50%.

2. 1,700 bulbs at 5.85 Baht/month (your estimate) is 9,945 Baht - not 99,450 Baht.

I sounds like the cost savings estimated by the condo management is reasonably realistic (maybe a tad on the high side).

Sophon

[KittenKong]

Change all those lights to 3-4 watts LED bulbs and leave them on as usual.

Hmmm. 1700 new bulbs at (say) 100B each = 170,000B initial outlay. Not to mention the time taken for staff to change them.

And what on earth do they do with the 1700 used bulbs they take out?

(In some buildings it might also be important to consider if residents will steal the nice new 100B LED bulbs.)

No, having examined this exact same problem in my own building I would say that the answer is to turn off the lights for now and progressively replace the old bulbs with new LED ones as they fail. Then when most are changed they can reconsider whether to keep the lights on all day.

Edited September 27, 2015 by KittenKong

[trogers]

Change all those lights to 3-4 watts LED bulbs and leave them on as usual.

Hmmm. 1700 new bulbs at (say) 100B each = 170,000B initial outlay. Not to mention the time taken for staff to change them.

And what on earth do they do with the 1700 used bulbs they take out?

(In some buildings it might also be important to consider if residents will steal the nice new 100B LED bulbs.)

No, having examined this exact same problem in my own building I would say that the answer is to turn off the lights for now and progressively replace the old bulbs with new LED ones as they fail. Then when most are changed they can reconsider whether to keep the lights on all day.

Turning lights off even during daytime in corridors and stairs that have no source of natural illumination would be a violation of fire safety.

[glassdude007]

not sure about condos but as my house goes.....

if the electric meter ain't spinning I am saving money...

off the lights good idea fans and air con 2

[trogers]

Change all those lights to 3-4 watts LED bulbs and leave them on as usual.

Hmmm. 1700 new bulbs at (say) 100B each = 170,000B initial outlay. Not to mention the time taken for staff to change them.

And what on earth do they do with the 1700 used bulbs they take out?

(In some buildings it might also be important to consider if residents will steal the nice new 100B LED bulbs.)

No, having examined this exact same problem in my own building I would say that the answer is to turn off the lights for now and progressively replace the old bulbs with new LED ones as they fail. Then when most are changed they can reconsider whether to keep the lights on all day.

Buying a large order of LED bulbs directly from the factory would probably cost only around Bt80 per bulb.

The energy saved over 6-8 months would pay for these new bulbs and then the real savings kick in.

The old bulbs can be distributed evenly to the condo owners for their use.

[IMHO]

10w x 1740 = 17.4 units(kW)/hr

17.4 x 5 hours x 30 days = 2,610 units/mth

Now go find out how much they pay per unit on average, and you'll have your final price.

[KittenKong]

Turning lights off even during daytime in corridors and stairs that have no source of natural illumination would be a violation of fire safety.

True, but I see no suggestion from the OP that this is the case in his building.

It isnt the case in mine either.

[KittenKong]

Buying a large order of LED bulbs directly from the factory would probably cost only around Bt80 per bulb.

The energy saved over 6-8 months would pay for these new bulbs and then the real savings kick in.

The old bulbs can be distributed evenly to the condo owners for their use.

That could work but it would be a pain to implement in my building (implementing anything in my building is a pain). Personally my share of the old bulbs would not get used as none of our corridor bulbs fit any of my fittings. But most people would probably benefit.

[trogers]

Buying a large order of LED bulbs directly from the factory would probably cost only around Bt80 per bulb.

The energy saved over 6-8 months would pay for these new bulbs and then the real savings kick in.

The old bulbs can be distributed evenly to the condo owners for their use.

That could work but it would be a pain to implement in my building (implementing anything in my building is a pain). Personally my share of the old bulbs would not get used as none of our corridor bulbs fit any of my fittings. But most people would probably benefit.

With 1,740 bulbs in the common area, I could safely guess that this project has multiple buildings with quite a few hundreds of condo units.

[zappalot]

We have 32 floors with in average 8 bulbs, thats 256 lightbulbs...

to replace them they would need to invest between 20000 and 25000 baht, saving per year would be 60000 Baht. Old bulbs 9 w/hr, same brightness achieved with 3 w/hr for the LED bulbs, I assume 4.5 Baht/kw...

We replaced them on our floors by ourselves. Yet the management say it is not so easy to do so... I could do the change in 5 minutes... To my calculation they say: "No nono, you dont understand". Plain stupid....

[KittenKong]

To my calculation they say: "No nono, you dont understand". Plain stupid....

Par for the course. Imbeciles.

[sandyf]

10w x 1740 = 17.4 units(kW)/hr

17.4 x 5 hours x 30 days = 2,610 units/mth

Now go find out how much they pay per unit on average, and you'll have your final price.

Agreed.

This month I was 3.975 per unit plus VAT of 7 percent. That would come to just over 11K.

[trogers]

10w x 1740 = 17.4 units(kW)/hr

17.4 x 5 hours x 30 days = 2,610 units/mth

Now go find out how much they pay per unit on average, and you'll have your final price.

Agreed.

This month I was 3.975 per unit plus VAT of 7 percent. That would come to just over 11K.

When all bulbs are changed to 4 watts, the saving would be almost 3x of 2,610 units.

1.74 x 6w(savings) x 24 hrs x 30 days