Calculator: Cost comparison of Incandescent vs CFL vs LED globes

Thanks to Chris from MapaWatt.com and Mitra Ardron for extending the analysis by taking inflation into account – I have modified the calculator for South African (Cape Town) conditions: price of electricity, the price of the globes, and the inflation rate of power costs.


LED (Light Emitting Diode) globe, CFL (Compact Fluorescent Lamps), and the bad old fashioned incandescent globe

To quote Mitra:
”
The spreadsheet tracks the cost curves for Incandescent, CFL and LED globes so you can see at what point you would break even. 
“

HTT has changed the figures for South Africans: electricity cost per kWh, and prices for the different types of bulbs
Based on a set of assumptions (that I got from Mapawatt), it shows (at 4 hours/day usage):
* CFL's are better than all of them from year 1, it takes 17 years for LED's to beat CFL's but then need replacing after year 35. 
* LED's beat Incandescent globes after 3-and-a-bit years.


To quote Mitra again:
”
Obviously this depends on assumptions about inflation in electricity prices, so I've added a second tab, where I assume electricity inflates at 7% more than general inflation.
”
HTT has changed the inflation figures for South Africans: electricity is due to go up 25% for the next 3 years (and probably beyond that too).

Don’t give up on the LED globes - in the near future, I’m sure that their prices will drop drastically and will replace CFLs.

Here are the screen shots of the charts showing the results: no inflation, and with inflation (note: horizontal axis have different scales)
 
       

Is it just me, or do you also think that the power guzzling little incandescent globes should be banned!

To see the actual formulae and data download the calculator here:  HTT_Calculator_Lighting_cost_analysis_SouthAfricaAug2011.xls

The electricity rates for Cape Town for 2011 are here:  http://www.capetown.gov.za/en/electricity/tariffs/Pages/default.aspx

If you have a pre-payment meter, then you can save 31.3% on your electricity if you buy now, only 3 days to go!

Eskom electricity tariffs will go up by 31.3% on 01July - that leaves 3 days for you to stock up on cheaper electricity:
I'm going to save that 31.3% by pre-purchasing as much electricity as I can afford before 01July2009.
Once I've purchased all that electricity, I'll want to make it last as loooong as possible - I'll do that by checking where the biggest savings can be made by re-analysing my household's usage and cut down on the most expensive appliances: Saving electricity tips

See here for last year's posting (still relevant) for all the answers and the "Electricity Tariff Calculator tool": Beat Eskom price increases

This year's increase details:
When are the tariffs going up? @ 23h59 on Tues night 30 June 2009.
How much will the increases be? 2009's increase is 31.3%

The posting answers questions like:
How full can your pre-payment meter go?
How much can I purchase on my credit card?
Which tariff plan am I on?
If I fill my meter up too much will I lose my free 50 kWh per month?

And while you're saving money, why not ready the blog "Why pay cash for pre-paid electricity when you can use your credit card?" and earn cash back and "reward points".

How to save electricity:
*) turn down the temperature setting on your thermostat - here's where and how: Where is my geyser's thermostat? How do I turn it down?
*) use less hot water (ie. Install a low‑flow shower head). See here to purchase RST Profilence (RST contact details) and here for a report on savings (water and electricity
*) Shower, don't bath: see here for report on how much less power a shower uses than a bath
*) Install a geyser blanket to insulate your geyser and pipes. See here for a report on savings when using a geyser blanket (30% improvement)
*) use the ‘Electricity Usage Calculator’ to see where you ‘spend’ your electricity.
*) Reduce your pool pump's ON time per day
*) Install ceiling insulation. See here for more info and suppliers
*) Lastly, use solar power to heat your geyser: install solar panels. If you are building a new house or if you replace your geyser, then install solar panels and a time switch. See here for non-savings installing a time switch if you don't have a solar geyser: non-savings report

Update on 16June2010:

Watch out or, at least, be aware: #WTF Geyser's element has just blown <3 years after installation... 5 year geyser warranty, but only 3 months on the element! #FFS #RipOff

http://www.xstream.co.za/warranty.htm

Update on 09Aug2011:
I see the XStream warranty page has moved.... http://www.xstream.co.za/warrenty_document.html (and they can't even spell "warranty"!) 

Only 12 hours to go to pre-purchase that electricity before the 31.3% increase at midnight (later tonight)

There's only 12 hours to go before you'll be paying 31.3% more for your electricity. Here's some additional info if you benefit from getting free units per month for low usage clients:
As heard on Cape Talk this morning (Aden Thomas's show):
For low usage clients: If you load up your meter now, then you can still get your free units per month if you still purchase some units per month - so go to www.energy.co.za (or go to your local electricity vendor) and buy just R5.00 to get your free units - and do that once per month.
Note: HTT has not verified this practise.
Note: www.energy.co.za allows up to R2,000 per transaction, but multiple transactions are allowed (up to your credit card's limit of course)

{Low usage clients means: if you are on ‘Domestic 2‘ (i.e. low consumption: less than 600 kWh per month), then you qualify for 50 free units per month.}

Remember, if you've already got your free units this month, then your purchases will seem "more expensive" (ie: you won't get as many units as when you had purchased your electricity earlier this month).

See here for more detailed info:
Load your meter now, plus energy saving tips

1 more day to purchase 27.3% cheaper electricity... do it now

CapeTown electricity is going up by 27.3% on 01July - that leaves 1 day for you to stock up on cheaper electricity:  

Refer to my earlier blog "Does it pay to topup your pre-payment meter?", I have purchased a few months' worth of electricity.

Here are some of the questions that are answered:
3) How much pre‑paid electricity can I purchase before the increase?

To save money you can top up your pre-payment electricity to a maximum of 9,999 units. www.energy.co.za allows purchases of up to R2,500 per transaction but more than one transaction can be made…. as long as your credit card can take it! If you try and top up too much, then your meter will disallow entry of the ‘token’ – you will need to wait until you’ve used up some units.

Note: that if you pay a ‘daily service fee’ [on tariffs: ‘Domestic 1’ or ‘Domestic 3’], then you cannot pre-purchase ‘daily service fee’ “credits” (in other words, you can only stock up on units, not ‘daily service fee’). This means that if you purchase 4 months worth of units, you will pay the current per unit price of electricity, and in 4 months time when you purchase again, you will then be charged 4 months of ‘daily service fees’ (at the new increased rate)…. So, there’s no getting around the ‘daily service fee’ increase.

4) When must I key in my purchased units?
The purchase transaction is for units (not Rands) – the pre-payment meter has no knowledge of the actual price of the electricity, so it doesn’t matter when you enter the token into the meter – as long as the purchase is made before the price increase comes into effect (that’s probably 01July for City of Cape Town).

...and more

And while you're saving money, why not ready the blog "Why pay cash for pre-paid electricity when you can use your credit card?" and earn cash back and "reward points".

Eskom has just announced the electricity price increase for this year: 27.3%

The 27.3% is made up of 14% from December and 13.3% from today's additional award. I'm going to save that 27.3% by pre-purchasing as much electricity as I can.

Referring to my earlier blog "Does it pay to topup your pre-payment meter?", I will purchase a few months worth of electricity before 01July2008.

And while you're saving money, why not ready the blog "Why pay cash for pre-paid electricity when you can use your credit card?" and earn cash back and "reward points".

If you have a solar geyser, then make sure you install a timeswitch!

To further clarify my blog: Does a time switch on your geyser actually save electricity?, if you have a solar geyser then make sure you install a time switch!
Without a time switch installed, electricity (*not* energy from the sun) will heat up the cold water faster than the sun can.
With a time switch installed, *only* solar energy will be used to heat up the cold water - electricity will kick in if the time switch is set to use electricity for critical time periods (early in the morning and late at night).
See here for more details: Eskom info on using a time switch with solar panels?

*) Installing a time switch in a solar installation will:
1) ensure that electricity is not used on a sunny day (i.e. on a sunny day you would rather have a slower heating up of the water by the sun, rather than use electricity and solar to heat up the water faster) and
2) ensure that electricity is used so as to guarantee that there is hot water early in the early morning and, in late afternoon/night on cold/cloudy days.

Remember to also turn the temperature on the geyser's thermostat down! (mine is set to 35 degrees C, and it's fine i.e. this is the temperature of the water on cold/cloudy days, but on sunny days the temperature is much hotter due to the solar panel doing its job)

Update on 16June2010:

Watch out or, at least, be aware: #WTF Geyser's element has just blown <3 years after installation... 5 year geyser warranty, but only 3 months on the element! #FFS #RipOff

http://www.xstream.co.za/warranty.htm

Does a time switch on your geyser actually save electricity?

This is the question everyone has been asking and I too have been wondering.
I have created an “ElectricityUsageCalculator” (Excel spreadsheet) for you to calculate your usage and where you can make savings.

In fact, in the quest for the answer I have taken the long path of reducing my household’s electricity consumption and I thought that I’d share this information…

Before I get to the detail, I’d like to thank the following people/organisations/forums for sharing their valuable information:

• Talk Radio 702 Power Guide: http://www.702.co.za/power/usage_list2.asp
• “Parkhurst Post” Editor, Tim Truluck: http://www.parkhurst.org.za/post/feb08.htm
• http://energycrisis.co.za/?p=56
• Eskom’s Conserving Electricity page: http://www.eskom.co.za/live/content.php?Item_ID=274&Revision=en/0
• Eskom’s demand side management: Solar Heating: http://www.eskomdsm.co.za/swh_4_9_timer.htm
• Saving Electricity 101: http://michaelbluejay.com/electricity/howmuch.html

Why not pay these sites a visit?

Cutting to the chase:

OK, so some of you don’t really want to know how I got to the “findings”, you just want to know if turning your geyser off and on really saves you Rands, so here goes:

*) if you have a solar panels, then yes - installing a time switch on your geyser will definitely save you money (without time switch: electricity and solar will heat up the cold water, and so electricity will be used. With time switch: only solar will be used to heat up the cold water; electricity will kick in if the time switch is set to use electricity for critical time periods. See here for more details: http://www.eskomdsm.co.za/swh_4_9_timer.htm

*) if you don’t have solar panels, then you’ll probably not save a lot of money by installing a time switch: Niel says (see comment on 6^th February 2008 @ 10h08: http://energycrisis.co.za/?p=56) that you’ll “only save electricity if you leave your geyser off for 2.5 days”; and “you can’t save electricity by switching a heater on and off, as the amount of energy required to keep it at a certain temperature for a given time and to heat it up again after that given time is the same.”
Again, referring to Niel's comment February 12th, 2008 at 1:01 pm: <> "...my geyser was on for 46 minutes over a 24hr period or basically for 1 minute 55 sec every hour..." <>

….rather insulate your geyser (using a geyser blanket) and hot water pipes to reduce the heat loss.

….but if the time switch is set to turn the geyser off during peak times, then you will help Eskom to reduce the peak loads and perhaps reduce the need to load-shedding…. But isn’t Eskom installing those ripple switches for this? {Yeah, but until then…. best we do our bit to make our lives easier!}

If you do want to save money try these steps (in the order listed):

*) turn down the temperature setting on your thermostat (mine is set to 35^oC) – you know when it’s set right by the amount of cold water that you need to mix when you’re having a shower…. If you’re mixing a lot of cold water, then you know that your thermostat is set too high – you need to turn it down (colder), until you are mixing little or no cold water for your shower.

*) use less hot water (ie. Install a low‑flow shower head [I have an RST low flow one], and shower quickly) to save electricity – the less cold water that your geyser needs to heat up, the less electricity is used.

*) use the ‘Electricity Usage Calculator’ to see where you ‘spend’ your electricity.

Download from here: ElectricityUsageCalculator02.xls

I was amazed to see that my main “culprit” was not my geyser, but in fact my swimming pool pump! [thanks Tim Truluck for pointing this out to me!]

Don't edit the shaded cells....

Step 1) In the worksheet ‘PerHourCosts’: check the ratings (W) listed [column D] and adjust to your appliances' ratings;

(Note which appliance is the most costly to run per hour)

Step 2) In the worksheet ‘UsageCosts’: fill in the 'hours used per item per month' [column D];

(Note: 'Cost per item per month' - the high cost items is where you can save the most)

*) Lastly, use solar power to heat your geyser: install solar panels. If you are building a new house or if you replace your geyser, then install solar panels and a time switch.

Detailed explanations:

*) Electricity is used by a geyser each time the temperature of the water goes below the thermostat’s trigger temperature.

*) Refer to the worksheet ‘GeyserThermostat’ for the following explanations:

*) Assuming the water in the geyser is cold to start with, and the thermostat is set at 60^oC, then the thermostat will turn on and allow electricity to flow to the geyser’s element which heats up the water [this costs about R2.30 per hour]. After about 65 minutes, the water temperature will be above 60^oC and the thermostat will turn off and no electricity will be used.

*) When someone in the household decides to take a shower, the hot water exits the geyser and cold water replaces this hot water which forces the temperature to below the thermostat’s trigger temperature of 60^oC. At this point, electricity will again be used to heat up the water to 60^oC at which point the thermostat turns off again.

So, as more hot water is used, more electricity is used.

*) Heat loss will be small on modern (or geyser‑blanket clad) geysers and piping, but the lower the thermostat temperature, the lower the losses, and the lower the electricity that is used to get the water to the thermostat temperature. Comment from Dave on http://energycrisis.co.za/?p=56: “I turned my geyser down from 60^oC to 50^oC and saved 20% on my bill”

*) A solar‑only geyser will heat up the water more slowly (note: the thermostat plays no role in limiting the solar‑only upper temperature)

*) Installing a time switch in a solar installation will: 1) ensure that electricity is not used on a sunny day (i.e. on a sunny day you would rather have a slower heating up of the water by the sun, rather than use electricity and solar to heat up the water faster); 2) ensure that electricity is used so as to guarantee that there is hot water early in the morning and, in late afternoon on cold/cloudy days.

How do I find out how much electricity something uses?

Adapted from “Saving Electricity 101”: http://michaelbluejay.com/electricity/howmuch.html

Look at the label - nearly everything you can plug into the wall has a label that says how much electricity it uses.

If the label only gives the number of Amps and not the number of Watts, then just multiply the Amps by 220 to get the number of Watts. (Amps x Volts = Watts. So a hot plate that uses 3 amps uses 3 x 220 = 660 Watts.

Note that if a device is powered by a transformer (one of those great big plugs), then the transformer has converted the electricity from AC to DC, so you need to multiply by the DC voltage, not the AC voltage of 220. For example, if the device says "INPUT 9V, 0.5A", then that's 9 volts x 0.5 amps = 4.5 Watts.

Another tip:

*) Remember to turn off your ‘plug’ circuit breakers when you’re in “load-shedding” mode – this will ensure that your appliances are not connected to Eskom when power is turned on again – remember, when power is turned on again, there is usually a surge (over 220V) which could damage your appliances. Leave a light turned on, so that you know when power has returned, then turn your ‘plug’ circuit breaker back on again.

An alternative would be to purchase surge protectors for your most expensive/vital appliances.

Update on 16June2010:

Watch out or, at least, be aware: #WTF Geyser's element has just blown <3 years after installation... 5 year geyser warranty, but only 3 months on the element! #FFS #RipOff

http://www.xstream.co.za/warranty.htm