Number 5 is not a prize. It is a pass mark
Everything that clears the threshold carries the same Number 5 label.
So the words themselves tell you only that the machine passed, not whether it scraped through or cleared the bar by a distance.
The number that tells you that is on the same label, in the line nobody reads.
That line is the electricity used per year.
Compare two machines of the same size and see which uses fewer units.
That is the whole answer, and it takes ten seconds.
The rest of this article is about why the other numbers on the label deserve less trust than that one.
What is printed on the label
The Number 5 energy label is issued by the Electricity Generating Authority of Thailand, and the new star format has been in use since 1 January 2019.
What appears on it is this.
- The star level, of which there are four: Number 5, Number 5 with one star, with two stars, and with three stars.
- Electricity used per year, in kilowatt hours.
- Approximate annual running cost, in baht.
- An efficiency figure, which for air conditioners is measured across a seasonal range of temperatures.
- The year of the efficiency criteria used to judge it.
- A QR code for checking that the label is genuine.
Notice there are three sets of numbers, and they do not all deserve equal trust.
Why the baht per year figure is the least reliable
The annual cost is calculated from the annual units multiplied by an assumed tariff.
The problem is the word assumed.
Your household's actual rate depends on your tariff category and how much you used that month, and there is also the Ft charge revised by period, as explained in the Ft charge on your electricity bill.
A house that uses a lot pays more per unit than a house that uses little, because the rate structure is stepped.
So the baht figure is not wrong. It is the figure for a hypothetical household rather than yours.
Hours of use are an assumption too.
An air conditioner's label figure is based on a standard number of hours per year. A house that runs it every night uses more than that, and a house that runs it only on hot days uses less.
The baht figure is therefore for comparing machines, not for predicting your bill.
The number to actually use is units per year
Annual units come from a measurement rather than from an assumption about price.
Comparing two machines of the same size, that figure compares directly.
The operative words are the same size.
A 12,000 BTU air conditioner cannot be compared on annual units with an 18,000 BTU one, because the larger machine naturally consumes more.
The same applies to a seven cubic foot refrigerator against a twelve.
Somebody who buys the wrong size and then picks the lowest consumption model within it still pays more than somebody who bought the right size.
So the correct order is to get the size right first, then compare annual units within that size.
What the stars say, and what they do not
The star system was added to separate machines that all clear the Number 5 threshold.
Each star level saves on average around five to ten per cent more.
The words to read are on average.
Because that percentage is of that machine's own consumption, not of the whole household bill.
If the machine is a small share of the bill, ten per cent of a small share is still small.
Which is why upgrading an air conditioner from Number 5 to three stars makes a real difference while upgrading a rice cooker is barely noticeable.
How to find out what share each machine is of your bill is in which appliance uses the most electricity, and how to measure it.
The criteria year, the line most people skip
Efficiency criteria are tightened periodically as the technology improves.
Which means a Number 5 judged under old criteria and one judged under new criteria are not at the same level.
Stock that has sat in a shop for years may carry a label issued under an earlier set.
The check is to look at the criteria year on the label and compare it with the other models on the shelf beside it.
Where the years differ, compare on annual units instead, because that figure is a measurement and always comparable.
Checking that a label is genuine takes under a minute
Fake labels, and genuine labels moved onto a different model, both exist in the market.
Four things to check.
Scan the QR code on the label, which displays the information for that model.
Confirm the model and code on the label match the actual machine, which is where a transplanted label is most often caught.
Check that the authority's marks are complete and that the label layout is the correct format.
Look the model up again in the scheme's own database on its website.
All four take under a minute standing in front of the product, and they answer immediately whether the figures you are about to decide on can be trusted.
Work out the payback yourself, in four steps
The question to answer is how many years it takes to recover the extra price paid today.
Step one, find the difference in annual units between the two models, comparing within the same size.
Step two, multiply by your household's real rate per unit, which comes from your latest bill: the amount charged divided by the units used.
That number is what a unit actually costs at your house, which is usually different from the label's assumption.
Step three, divide the price difference by the annual saving. The result is the payback in years.
Step four, compare it with the expected service life. Paying back in three to five years on something that lasts ten is worth it.
Paying back in twelve years on something that lasts eight means the extra money bought a good feeling rather than a saving.
And if you use it far less than the assumption, an air conditioner run ten days a month for instance, the payback stretches out further still.
Where the label matters most, and where it barely matters
It matters most on machines that run long hours and draw heavily.
- Air conditioning, which varies most of anything in an ordinary house.
- The refrigerator, because it runs around the clock all year.
- Water heaters and water pumps, in houses that use them often.
It matters little on machines that run briefly or draw little.
- Rice cookers, microwaves and irons, used for minutes a day.
- Fans, which draw little to begin with.
- Electronics drawing tens of watts.
So on a limited budget, spend the stars on the air conditioning and the refrigerator, and buy the second group on preference.
That genuinely changes how the money is spent, because plenty of households pay the same premium on everything without separating what pays for itself.
What the label does not tell you
The label answers a question about electricity, and answers nothing else.
It says nothing about durability. The most efficient machine that fails in three years costs more than a slightly thirstier one that lasts ten.
It says nothing about after sales service, which for air conditioning is a real annual cost.
It says nothing about installation quality. The most efficient unit installed badly or undercharged draws more than an ordinary one installed well.
It says nothing about whether it suits your room, which is a matter of size and sun exposure rather than of labels.
That last matters most, because an undersized air conditioner runs at full output continuously and uses noticeably more than a correctly sized one.
Frequently asked questions
How much difference is there between Number 5 and three stars?
Each star level saves on average around five to ten per cent of that machine's own consumption, not of the whole bill. So it pays handsomely on air conditioning and refrigeration and is barely noticeable on things used for minutes a day.
Can I trust the annual cost printed on the label?
As a comparison between machines, yes. As a prediction of your bill, no, because it rests on assumptions about hours of use and tariff that do not match every household.
Which number should I go by?
Electricity used per year, because it is measured rather than assumed and compares directly. But compare only within the same size.
How do I check a label is genuine?
Scan the QR code, confirm the model on the label matches the machine, check the authority's marks are complete, and look the model up in the scheme's database.
Why does the criteria year matter?
Criteria are tightened periodically, so a Number 5 under old criteria is not the same as one under new criteria. Where two models show different years, decide on annual units instead.
Is the most stars always worth it?
Not always. Work out the payback by dividing the price difference by the annual saving, then compare that with the expected service life.
Does the label say anything about reliability?
No. It answers only the electricity question, not durability, after sales service, or whether the machine suits your room.
In short
- Number 5 is a pass mark, not a level of efficiency.
- The figure to decide on is electricity used per year, compared within the same size.
- The baht per year figure rests on assumptions, so it compares rather than predicts.
- Each star level saves around five to ten per cent of that machine's own consumption.
- The criteria year means two Number 5 labels are not always equivalent.
- Verify a label by QR code, matching model, the authority's marks, and the scheme's database.
- Calculate payback using your own rate per unit rather than the label's assumption.
- Spend the budget on the air conditioning and the refrigerator, where the label matters most.
- Get the size right first, because the wrong size costs more than the label can save.