Air conditioning in a rented Bangkok condo: the law names the machine

Almost every lease offered to a foreigner in this city says, in one form of words or another, that the tenant maintains the air conditioning. Tenants read that as covering everything, and pay for everything. It is worth knowing that Thai law draws a line through the middle of that sentence — and that for a large class of landlords, the line is not something a contract is allowed to move. The model lease published by the consumer regulator lists the air conditioner by name, and then forbids the clause most leases rely on.

Two duties, and the gap between them

Thai leasing law splits the upkeep of a rented thing in two, and the split is old, general and short. Section 553 of the Civil and Commercial Code requires the lessee to take as much care of the property as a person of ordinary prudence would take of their own, and to carry out ordinary maintenance and petty repairs. Section 550 points the other way: the lessor is liable for defects arising during the lease and must carry out every repair which becomes necessary, except those which by law or custom the lessee must do.

Read together they describe a boundary rather than a list. Everything small and routine sits with the tenant. Everything that has actually gone wrong sits with the landlord. The trouble is that the Code never uses the word air conditioner, never says how often a filter should be washed, and never tells you which side a gas top-up or a seized fan motor falls on. Between a tenant and a landlord who owns the one unit, that gap is filled by the contract, and the contract is usually written by the landlord.

This is where most English-language advice stops, with a shrug about it depending on your lease. It is also where the interesting part begins, because since September 2025 a large class of landlords have not been free to write that clause at all.

The three-unit test

On 6 June 2025 the Royal Gazette published a notification of the Contract Committee declaring the letting of buildings for residence to be a contract-controlled business. It replaced an earlier notification of 2019, and it took effect ninety days after publication, on 4 September 2025. Its scope clause is the one to read first: it applies to a business letting to a natural person for residence, short or long term, where the operator has three or more units to let, whether in the same building or in several buildings taken together, and it says in terms that building here includes a condominium. Dormitories and hotels are excluded, having statutes of their own.

Three units is a low bar, and it is not a bar about wealth. A Thai family that has bought three condos over twenty years is caught. A foreign owner letting the single unit they live in half the year is not. The distinction matters more than almost anything else in your lease, and you will not find it printed on the lease itself.

One more date matters. The notification provides that contracts made under the 2019 notification continue on the old rules until they expire. A lease signed in 2024 and running to 2027 is not silently upgraded. If your protection matters to you, the renewal is the moment it arrives.

The clause that decides the compressor

The notification works by listing clauses a contract must not contain. Three of them, taken together, dispose of the argument that tenants in this city have been losing for years. A contract must not make the tenant liable for damage arising from normal use of the building’s property and equipment. It must not make the tenant liable for anything that is not the tenant’s fault, or for force majeure. And it must not make the tenant liable for defects to the building, property and equipment arising from use, or from deterioration through normal use.

That last one is the operative sentence. A compressor that stops after four Bangkok summers has not been damaged by you; it has deteriorated through normal use. A clause transferring that cost to you is not merely unfair or unusual. It is prohibited, and the prohibition does not depend on you having noticed it before you signed.

The model contract annexed to the notification then does something we rarely see in Thai consumer instruments, and it is the reason this page exists. Its schedule of the property and equipment let with the unit lists the air conditioner by name. Clause 11 of the model repeats the tenant’s duty of ordinary maintenance and petty repairs, and adds expressly that the consumer is not liable for damage or defects arising from normal use, from deterioration through normal use, from anything that is not the consumer’s fault, or from force majeure. Clause 12 puts the corresponding duty on the operator: to carry out every necessary repair to the building, property and equipment, over and above the petty repairs the consumer owes under clause 11.

So for a covered landlord there is no room left for the usual dispute about whether the air conditioner is part of the premises or an appliance you were lent. The instrument names it, allocates it, and forbids the clause that would move it.

What to do when it stops working

The remedy in Thai law is quieter than the one tenants tend to reach for, and getting the order wrong can cost you the remedy itself.

Section 551 of the Code sets the sequence. Where the defect does not deprive you of the use of the property and the landlord can still put it right, you must first notify the landlord to remedy it. Only if the landlord fails to do so within a reasonable time may you terminate, and only if the defect is serious enough to warrant that. Clause 12 of the model contract states the same sequence for covered leases, with termination available where the defect is bad enough to deprive you of the use and benefit of the building.

Notice, in other words, is not a courtesy. It is the step that unlocks everything after it. Give it in writing, keep the message, and date it.

What the Code does not give you is a general right to call a technician and deduct the invoice from your rent. The nearest provision is section 547, under which the landlord must reimburse necessary and reasonable expenses you incur to preserve the property — expressly excluding ordinary maintenance and petty repairs. That is a claim for reimbursement, not a self-help set-off, and in a country where your deposit is already in the landlord’s hands it is a much weaker position than it sounds. If you are weighing that route, our page on getting a rental deposit back is the more realistic picture of how these arguments end.

There is one small piece of good news about the visits themselves. The Code lets a landlord inspect at reasonable times and intervals and says nothing about warning you. The 2025 notification is stricter: for covered leases, a clause permitting the operator or its agent to enter without notifying the tenant in advance is prohibited, except in an emergency. A technician arriving unannounced for a scheduled service is exactly the situation that clause was written for.

What the electricity actually costs

The second half of an air conditioner’s cost is the bill, and the bill is where the most confident numbers in circulation are the most wrong — including, until we checked, one of our own.

A Metropolitan Electricity Authority bill is not one rate. It is three lines plus tax: a banded energy charge, the Ft adjustment which the Energy Regulatory Commission resets every four months, and a fixed monthly service charge, with VAT applied to the total. Because the energy charge is banded, your effective all-in rate per unit is not a constant — it climbs as you use more, which is precisely the direction an air-conditioned bedroom pushes it.

The bands themselves were rebuilt this month. Following a National Energy Policy Council resolution of 29 April 2026 and a public consultation in May, the Energy Regulatory Commission approved a restructured residential progressive tariff effective from the September 2026 bill, with the first 200 units priced at 3.0000 baht each and the cost of public lighting stripped out of the upper bands.

Put the three lines and the tax together and the honest answer to what does a unit cost is a range that depends on you:

One date to keep in view: the reduced rate of VAT that produces the familiar 7 per cent was extended by royal decree only to 30 September 2026. What happens after that had not been published when we last checked, and we are not going to guess at it.

The rate your building invented

Against those numbers, the flat rate charged by many Bangkok buildings — six baht a unit, sometimes eight — is not a rounding convenience. It is a margin, and where the 2025 notification applies it is a prohibited clause. The notification bans any clause under which the operator sets an electricity or water rate above the rate the utility charges the operator.

The model contract does not leave the calculation to good intentions either. It prescribes it: derive the utility’s own rate for the month from the bill, then multiply by the units your meter recorded for your room. It adds that the rate may change only when the utility itself raises or lowers it, and then with advance notice. There is no version of that arithmetic in which a building rate survives. (A small drafting oddity: the printed formula states the division with its operands the wrong way round. The intent is plain from the sentence that follows it.)

The lever here belongs to the Office of the Consumer Protection Board, not to the energy regulator, because the prohibition lives in a Contract Committee notification made under the Consumer Protection Act rather than in an electricity instrument. Using a non-compliant contract is an offence: section 57 of that Act provides for imprisonment of up to a year, a fine of up to 200,000 baht, or both. We read the section in a legal-database reproduction rather than in the Gazette itself, so we quote the effect and not the punctuation.

Cleaning: what the machine thinks

Ask three people in Bangkok how often an air conditioner needs cleaning and you will get three confident and incompatible answers, usually attached to a price. The manufacturers publish something better, and they publish two different things because there are two different jobs.

For the filter, the Thai-market Mitsubishi Heavy Industries manual for its domestic split units recommends cleaning once every two weeks during the operating season. For the machine as a whole, the same maker’s packaged-unit manual gives a figure that is far more useful because it is not a calendar at all: the unit lights its filter lamp when cumulative running time reaches 120 hours, and the threshold can be changed by a dealer. A bedroom unit running eight hours a night crosses 120 hours in about a fortnight, which is how the two answers turn out to be the same answer.

That is worth holding on to, because it converts a vague obligation into something you can actually judge. Ordinary maintenance is the thing the machine asks for on its own schedule. It is also, under section 553 and clause 11, the part that is yours.

Whether a deeper clean pays for itself in electricity is a separate question, and here the measured evidence is more modest than the sales pitch. The most-cited study of coil fouling found that typical coils foul enough to double the evaporator’s pressure drop in about seven and a half years, well before the fifteen-to-thirty-year life of the coil — but that the reduced airflow this causes produces typical efficiency and capacity losses of less than 5 per cent, larger only for marginal systems or extreme conditions. The same paper cites an older figure of a 20 per cent performance loss over four to seven years for a condenser coil, and cautions that the older figure may be an overestimate.

So the case for regular cleaning is a real one, but it is mostly about airflow, comfort and hygiene rather than a dramatic line on your bill. If someone quotes you a percentage saving, ask where it comes from.

Two practical notes from the manuals themselves, which cost nothing to follow: do not use hot water at 40°C or above, petrol, thinner, benzine or scouring cleaner on the unit, and do not touch the aluminium fins.

The person who comes to do it holds a licence

This is the part almost nobody tells a tenant. Air-conditioning technician for domestic and small commercial premises is a designated occupation under the Skill Development Promotion Act, and since 29 October 2016 the person doing the work has been required to hold a certificate of knowledge and competency issued by the Department of Skill Development at the Ministry of Labour. The certificate runs for five years and has to be renewed; the Department has published figures on how many tradespeople have passed assessment across the designated trades and on the first waves of certificates coming up for renewal.

You are not the enforcement authority and there is no need to behave like one. But when a building sends someone you did not choose to open a machine on your wall and handle refrigerant, asking whether they hold the certificate is a reasonable question with a real answer behind it.

The machine you were given

You did not choose the unit in a rented condo, and its label tells you more than the landlord will. Thailand’s compulsory industrial standard for room air conditioners sets a floor rather than a target, and it does so using CSPF — a seasonal performance factor — rather than the EER or SEER figures quoted in imported advice. The nameplate is required to carry the CSPF, the cooling capacity in watts, and the refrigerant name and charge.

The floor itself is the most quietly informative number in this whole subject:

An inverter unit is not merely advertised as more efficient; it is required to be, by roughly a fifth at the smaller sizes, before it may be sold at all. That is a firmer basis for the comparison than any brochure.

Above that compulsory floor sits the familiar Label No. 5, which is a voluntary scheme run by the Electricity Generating Authority of Thailand, with star sub-levels added over the years and a current criteria set in force since 1 January 2024. EGAT publishes its own worked example of what the tiers are worth: for a fixed-speed 12,000 BTU/h unit at an assumed 3.96 baht a unit, it puts the running cost at 917 baht a month at plain Label 5, falling to 851, 794 and 744 baht at one, two and three stars. Those are EGAT’s figures on EGAT’s assumptions, and we reproduce them as such.

The gas inside it

Thailand ratified the Kigali Amendment on 3 April 2024, joining the schedule that phases down high-global-warming refrigerants, and it has been party to the Montreal Protocol since 1989. On the older ozone-depleting gases, a Ministry of Commerce notification of 16 January 2018 prohibits the import of HCFC-22-based air conditioning equipment below 50,000 BTU/h, a restriction Thailand has notified to the WTO and which remains current. Under the Protocol’s schedule for developing-country parties, HCFCs are to be phased out completely by 2030, with a small allowance retained through to 2040 specifically for servicing equipment already installed.

The practical reading for a tenant is narrow and worth keeping narrow. The import ban is on equipment, not a ban on servicing what is already on the wall, and we found nothing prohibiting the supply of R-22 for that purpose today. But a unit old enough to run on R-22 is a unit whose consumables are on a published path to disappearing, and that is a fair thing to raise with a landlord who is weighing a repair against a replacement. The Thai-market domestic models whose manuals we read run on R410A, with a stated global-warming potential of 2,088 and an explicit instruction never to vent it.

Running it

The official advice in Thailand is more specific than the version that circulates in English, and it comes as a pair rather than a single number. EGAT publishes a setpoint of 26 to 27°C, together with running a fan — the fan is part of the advice, not an afterthought. Separately, a Cabinet resolution of 10 March 2026 requires government offices to set their air conditioning to 26°C, alongside working from home and lighter dress codes, in response to energy prices.

What neither source does is attach a savings percentage to each degree. That figure is everywhere online and we could not find an official Thai publication of it, so it does not appear on this page. The same applies to the room-sizing coefficients you will be quoted in BTU per square metre: they are a trade convention, widely used and possibly sound, but we could not trace them to any Thai government publication, and the two energy-department documents that might have carried them would not open for us.

Two things genuinely worth knowing are less quotable. The first is that the tiered tariff means the marginal unit costs more than the average unit, so the last hours of cooling each month are the expensive ones. The second is seasonal: the load on the machine is not constant across the year, and the weeks when it works hardest are the ones our page on the hot season and the heat index covers, when the outdoor temperature the unit must reject heat into is at its highest.

The building has opinions too

One boundary sits outside the lease entirely. The Condominium Act requires a condominium’s registered regulations to cover the common property, and makes the juristic person’s object the management and maintenance of that common property in accordance with the co-owners’ resolutions. The facade, the risers and the external walls are not yours, and neither, in most buildings, is the balcony parapet a compressor might be bracketed to.

That is why replacing a unit is rarely a purely private matter between you and the landlord: relocating a condenser, drilling a new penetration or re-routing a drain touches parts of the building the juristic person manages. The Code adds a second reason to stop and ask, since a lessee may not alter or add to the leased property without the lessor’s prior permission, and must restore it and answer for damage if they do. The distinction that decides which rules bind you — the registered regulations against a notice from the management office — is the same one we set out in our page on moving in and out of a Bangkok condo, and it is worth reading before you agree to anything involving a drill.

Questions people actually ask

My lease says I must service the aircon every three months at my own cost. Is that enforceable?

If your landlord lets three units or more, a clause that loads normal-use deterioration onto you is prohibited, and a servicing obligation cannot be used as a back door to that result — though ordinary maintenance genuinely is yours under clause 11 and section 553, and a reasonable cleaning schedule sits comfortably inside it. If your landlord lets one or two units, the clause is a contractual term and the notification simply does not reach it. The practical distinction is between keeping the machine clean, which is your job either way, and paying for it when it fails, which is not.

The unit is old and cools badly, but it has not actually broken. Where does that sit?

Deterioration through normal use is named in the prohibited-clause list alongside outright defects, so for a covered landlord the answer does not change because the failure was gradual. What changes is the remedy. Section 551 gives you termination only where the defect is serious enough to warrant it, and clause 12 of the model contract frames the same test as being deprived of the use and benefit of the building. A unit that cools poorly is a strong reason to give written notice and press for the repair; it is a weaker basis for walking away from the lease.

Can I just have it cleaned or fixed and take the cost off the rent?

That is not what the Code provides, and it is the most common way tenants lose an argument they were winning. The sequence is notice first, then a reasonable time, then termination if the defect is serious. Section 547 lets you claim reimbursement for necessary and reasonable expenses incurred to preserve the property, expressly excluding ordinary maintenance and petty repairs — but that is a claim you have to make, not a deduction you are entitled to take, and your deposit is already on the other side of the table.

My building charges 7 baht a unit and says everyone pays it. Does that make it lawful?

No. Where the notification applies, a rate above what the utility charges the operator is a prohibited clause regardless of how many other tenants accept it, and the model contract prescribes the arithmetic to be used instead. Whether it is worth raising is a separate judgement, and depends on how long you intend to stay and how much the gap comes to over that time. The complaint route is the Office of the Consumer Protection Board rather than the electricity authority.

Is a mould smell from the unit something the landlord has to deal with?

Filters and the routine cleaning of the machine are the tenant’s ordinary maintenance. A drain that has failed, a tray that no longer falls to the outlet, or damp entering the wall behind the unit are defects rather than upkeep, and belong on the other side of the line. We are not going to offer health advice here; the relevant Thai indoor-air-quality instrument we found sets surveillance values for public buildings, not for private dwellings, so it is context rather than a rule that applies to your bedroom.

How we made this