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What Do You Want to Know About Air Conditioning?
Pick the topic you came for. Each card jumps to the section that answers it.
Air conditioning or gas, which is cheaper?
The break-even point, plus cost per kWh of heat.
See the comparison →Running costs and sizing
Cost per day, per season, and which kW for your room.
See the figures →Price and SEAI grant
What an installation costs, and what support exists.
Prices and support →Installation, noise and neighbours
Who may fit it, where the outdoor unit goes, servicing.
The rules →An Air Conditioner Is an Air-to-Air Heat Pump
A modern split air conditioner does not create cold or heat. It moves it. In summer it carries heat out of your home; run in reverse it pulls heat out of the outdoor air and blows it inside. There is usable energy in outdoor air well below freezing, which is why the same box that cools your bedroom in July can heat it in January.
That is not a marketing analogy, it is the same machine. An air-to-air heat pump and a reversible air conditioner share the refrigerant circuit, the compressor and the outdoor condenser. The difference is which direction the installer commissions it to run, and whether the paperwork calls it a heat pump.
Split unit
One outdoor condenser, one indoor unit on the wall. Cools and heats, quietest indoors because the compressor sits outside, and the most efficient. The standard choice for an Irish home.
Requires a certified refrigerant technician to install.
Portable unit
A wheeled appliance with a hose venting hot air out of a window. No installation, no certification, plugs into a normal socket.
Loudest option, and most models only cool.
Multi-split or ducted
One outdoor condenser feeding three to five indoor units, or hidden ductwork in the attic serving ceiling grilles. Room-by-room thermostats.
The only route to whole-house cooling, and the most disruptive to fit.
Performance is quoted as two numbers. The COP (Coefficient of Performance) describes heating and the EER (Energy Efficiency Ratio) describes cooling. A COP of 4 means one kWh of electricity delivers four kWh of heat. Measured across a whole season they become SCOP and SEER, which are the figures worth comparing because they include the cold mornings as well as the mild afternoons. Heat pumps on the Irish market typically run a COP of 3 to 4.
One limit to keep in mind: an air-to-air unit heats the air in the rooms it serves. It cannot heat your hot water. Replacing a boiler outright means an air-to-water system instead.
Is Heating With Air Conditioning Cheaper Than Gas in Ireland?
Against gas, yes, and by a wider margin than most people expect. Against heating oil it is much closer, and that matters because oil still heats a large share of Irish homes outside the cities. The comparison rests on three numbers: the electricity price you pay, the price of the fuel you are replacing (gas or oil), and your unit's COP.
A reversible air conditioner beats a gas boiler above a COP of 2.6, and a heating oil boiler above a COP of 3.0. Most modern inverter units clear both, but the oil margin is the tighter one and the one that matters outside the cities.
The sums: gas at 11.00 c/kWh through a 90% efficient boiler delivers heat at 12.22 c/kWh, so break-even is 31.95 ÷ 12.22 = 2.61. Oil at 98 c/litre is 9.47 c/kWh of fuel, and through an 88% efficient boiler that is 10.76 c/kWh of heat, so break-even is 31.95 ÷ 10.76 = 2.97.
What a kWh of heat actually costs
The only fair way to compare heating systems is the cost of a delivered kWh of heat, after efficiency losses.
| Heating method | Efficiency or COP | Cost per kWh of heat |
|---|---|---|
| Air conditioner, high efficiency | COP 5.0 | 6.39 c |
| Air conditioner, typical | COP 4.0 | 7.99 c |
| Air conditioner, cold weather | COP 3.0 | 10.65 c |
| Heating oil boiler | 88% | 10.76 c |
| Gas boiler | 90% | 12.22 c |
| Electric heaters or immersion | COP 1 | 31.95 c |
Air conditioner, high efficiency
- Efficiency or COP
- COP 5.0
- Cost per kWh of heat
- 6.39 c
Air conditioner, typical
- Efficiency or COP
- COP 4.0
- Cost per kWh of heat
- 7.99 c
Air conditioner, cold weather
- Efficiency or COP
- COP 3.0
- Cost per kWh of heat
- 10.65 c
Heating oil boiler
- Efficiency or COP
- 88%
- Cost per kWh of heat
- 10.76 c
Gas boiler
- Efficiency or COP
- 90%
- Cost per kWh of heat
- 12.22 c
Electric heaters or immersion
- Efficiency or COP
- COP 1
- Cost per kWh of heat
- 31.95 c
Electricity at 31.95 c/kWh, the Electric Ireland Standard 24-hour urban unit rate including VAT, verified 6 August 2026. Gas at 11.00 c/kWh, the Electric Ireland domestic gas unit rate on the same date, and home heating oil at 98 c/litre, which is 9.47 c/kWh of fuel at 10.35 kWh per litre. Standing charges excluded, since you pay those either way.
Note the order. Oil is currently cheaper than gas per kWh of heat in Ireland, which is the opposite of the assumption most cooling-versus-heating comparisons start from. And the margin over oil is thin: an air conditioner holding a COP of 3.0 delivers heat at 10.65 c against oil's 10.76 c, so in a cold snap the advantage disappears entirely.
What that means over a year
An average Irish home on gas burns about 11,000 kWh a year for heating, which is roughly 9,900 kWh of delivered heat once boiler losses are taken out.
| Setup | Annual energy cost | Versus gas | Versus oil |
|---|---|---|---|
| Gas boiler only | €1,210 | baseline | €145 dearer |
| Heating oil boiler only | €1,065 | saves €145 | baseline |
| Air conditioning only, COP 4.0 | €791 | saves €419 | saves €274 |
| Air conditioning only, COP 3.0 | €1,054 | saves €156 | saves €11 |
| Hybrid: gas base, air conditioning on the living area (30%) | €1,084 | saves €126 | €19 dearer |
Gas boiler only
- Annual energy cost
- €1,210
- Versus gas
- baseline
- Versus oil
- €145 dearer
Heating oil boiler only
- Annual energy cost
- €1,065
- Versus gas
- saves €145
- Versus oil
- baseline
Air conditioning only, COP 4.0
- Annual energy cost
- €791
- Versus gas
- saves €419
- Versus oil
- saves €274
Air conditioning only, COP 3.0
- Annual energy cost
- €1,054
- Versus gas
- saves €156
- Versus oil
- saves €11
Hybrid: gas base, air conditioning on the living area (30%)
- Annual energy cost
- €1,084
- Versus gas
- saves €126
- Versus oil
- €19 dearer
Energy cost only, standing charges excluded. Based on 11,000 kWh of gas, or the equivalent 9,900 kWh of delivered heat, at the average Irish rates above.
What tips the balance
- Solar panels. You run the unit on your own generation instead of grid electricity, which pushes the effective cost per kWh of heat well below gas;
- A dynamic tariff. You heat when wholesale prices are low, typically windy nights and sunny middays;
- Room-by-room heating. A boiler heats the whole house through one circuit, while an air conditioner heats the room you are actually in - a saving the tables above do not even capture;
- Cold snaps. Below about −5 °C the COP drops noticeably, and gas becomes competitive again for those few days;
- Your actual tariff. The spread between the cheapest and dearest standard electricity rates on the Irish market is wide enough to move the break-even COP by a full point.
For whole-house heating rather than room-by-room, the systems worth pricing against this are in our guides to home heating and geothermal heating.
Save on Your Home Heating Bills Today!
Our heating experts at Selectra can help you save on boiler services, heat pumps, and home heating oil - for free.
How Much Does an Air Conditioner Use, and What Size Do You Need?
An air conditioner is one of the heaviest loads in a home, drawing between 0.75 kW and 3 kW while the compressor runs. That puts it alongside an electric shower or a tumble dryer, except that you leave it on for hours.
Cooling cost per day
| Unit | Power draw | Typical daily use | Cost per day | Over a 2-week warm spell |
|---|---|---|---|---|
| Pedestal fan (for comparison) | 50 W | 8 hours | €0.13 | €2 |
| Portable air conditioner | 1.0 kW | 4 hours | €1.28 | €18 |
| Wall-mounted split unit | 1.5 kW | 6 hours | €2.88 | €40 |
| Multi-split or ducted system | 3.0 kW | 8 hours | €7.67 | €107 |
Pedestal fan (for comparison)
- Power draw
- 50 W
- Typical daily use
- 8 hours
- Cost per day
- €0.13
- Over a 2-week warm spell
- €2
Portable air conditioner
- Power draw
- 1.0 kW
- Typical daily use
- 4 hours
- Cost per day
- €1.28
- Over a 2-week warm spell
- €18
Wall-mounted split unit
- Power draw
- 1.5 kW
- Typical daily use
- 6 hours
- Cost per day
- €2.88
- Over a 2-week warm spell
- €40
Multi-split or ducted system
- Power draw
- 3.0 kW
- Typical daily use
- 8 hours
- Cost per day
- €7.67
- Over a 2-week warm spell
- €107
Power draw multiplied by hours at 31.95 c/kWh, the Electric Ireland Standard 24-hour urban rate including VAT, verified 6 August 2026.
Two caveats. These assume the compressor runs at full draw throughout, which is the worst case: an inverter unit throttles back once the room is at temperature, so a modern split system usually lands 20% to 40% lower. A fixed-speed portable unit gets no such benefit, which is why the cheapest unit to buy is rarely the cheapest to own.
The fan row is the one worth sitting with. A split unit costs roughly 22 times a fan's daily running cost. If your real problem is a stuffy rather than a genuinely hot room, our guide to how much electricity a dehumidifier uses covers a cheaper tool for that job.
Consumption across a full year
Because a reversible unit works in both seasons, the annual figure matters more than the daily one. These are derived from the 9,900 kWh heat demand above at a COP of 4, and from roughly 15 genuine cooling days in an Irish summer.
| Setup | Heating (winter) | Cooling (summer) |
|---|---|---|
| One room (living room, well insulated) | 500-750 kWh | 100-150 kWh |
| Living room and bedroom (multi-split) | 900-1,400 kWh | 200-300 kWh |
| Whole home (multi-split) | 2,000-3,000 kWh | 300-600 kWh |
One room (living room, well insulated)
- Heating (winter)
- 500-750 kWh
- Cooling (summer)
- 100-150 kWh
Living room and bedroom (multi-split)
- Heating (winter)
- 900-1,400 kWh
- Cooling (summer)
- 200-300 kWh
Whole home (multi-split)
- Heating (winter)
- 2,000-3,000 kWh
- Cooling (summer)
- 300-600 kWh
Derived from an average Irish heat demand of 9,900 kWh a year at COP 4, apportioned by the rooms served. Real consumption depends on insulation, sizing and use. Put it in context with our guide to average electricity usage.
What size unit do you need?
An underpowered unit runs flat out and never satisfies. An oversized one short-cycles, wastes energy and switches off before it has removed the humidity, leaving the room cold and clammy. Bigger is not a safety margin. Two rules of thumb are in common use.
About 100 W of cooling capacity per m² in a standard insulated room with a 2.5 m ceiling.
Example: a 30 m² living room needs about 3 kW.
30 W/m³ for a new airtight build, 40 to 50 W/m³ for an older Irish house or a room with a lot of glass.
Example: 30 m² × 2.5 m = 75 m³ × 40 = 3,000 W.
| Room size | Cooling capacity | Approx. BTU/h | Typical room |
|---|---|---|---|
| Up to 15 m² | 1.5 kW | 5,000 | Small bedroom, home office |
| 15 to 25 m² | 2.0 to 2.6 kW | 7,000 to 9,000 | Double bedroom, small living room |
| 25 to 40 m² | 3.5 kW | 12,000 | Living room, open-plan kitchen |
| 40 m² and above | 5.0 kW and above | 18,000+ | Whole floor, large open-plan space |
Up to 15 m²
- Cooling capacity
- 1.5 kW
- Approx. BTU/h
- 5,000
- Typical room
- Small bedroom, home office
15 to 25 m²
- Cooling capacity
- 2.0 to 2.6 kW
- Approx. BTU/h
- 7,000 to 9,000
- Typical room
- Double bedroom, small living room
25 to 40 m²
- Cooling capacity
- 3.5 kW
- Approx. BTU/h
- 12,000
- Typical room
- Living room, open-plan kitchen
40 m² and above
- Cooling capacity
- 5.0 kW and above
- Approx. BTU/h
- 18,000+
- Typical room
- Whole floor, large open-plan space
Add 10% to 20% for large south-facing glazing, an attic room or poor insulation. A certified installer should do a proper heat-loss calculation before quoting.
What Does Air Conditioning Cost in Ireland in 2026?
The total depends on the type, the number of indoor units and how awkward the pipe runs are. On a single split system the hardware is only €700 to €1,300 of the price. The rest is labour, brackets, pipework, an electrical connection and drilling an external wall, which is why quotes for the same equipment vary by several hundred euro.
| Type | Price (incl. installation) | Suits |
|---|---|---|
| Portable unit | €275 to €650 | Temporary cooling of one room, retail only |
| Split system, 1 indoor unit | €2,100 to €3,500 | One room, cooling and heating |
| Multi-split, 2 to 3 indoor units | €3,500 to €6,500 | Several rooms |
| Multi-split, 4 to 5 indoor units | €6,500 to €10,000 | Whole house |
| Ducted system | €8,000 to €15,000+ | Whole house, plant hidden in the attic |
Portable unit
- Price (incl. installation)
- €275 to €650
- Suits
- Temporary cooling of one room, retail only
Split system, 1 indoor unit
- Price (incl. installation)
- €2,100 to €3,500
- Suits
- One room, cooling and heating
Multi-split, 2 to 3 indoor units
- Price (incl. installation)
- €3,500 to €6,500
- Suits
- Several rooms
Multi-split, 4 to 5 indoor units
- Price (incl. installation)
- €6,500 to €10,000
- Suits
- Whole house
Ducted system
- Price (incl. installation)
- €8,000 to €15,000+
- Suits
- Whole house, plant hidden in the attic
Indicative prices researched by Selectra from Irish retailers and installers, August 2026. Always get two itemised quotes.
Is there an SEAI grant for air conditioning?
SEAI grants support heat pump systems installed by an SEAI-registered contractor. A cooling-only air conditioner is not a heat pump system and attracts nothing.
Specify a reversible unit that heats as well as cools and you are buying a heat pump, which brings grant support into play. The hardware premium over a cooling-only model is small, so on a fixed installation there is rarely a good reason not to.
The heat pump grant was increased substantially on 3 February 2026. What matters here is that air-to-air systems are funded at a lower rate than wet systems, because they heat air rather than water and so cannot use the radiator and pipework component.
| Grant component | Air-to-air (a reversible air conditioner) | Air-to-water, ground source, water-to-water |
|---|---|---|
| Heat pump unit | €3,500 | €6,500 |
| Radiator and pipework upgrade | Not applicable | €2,000 |
| Renewable heating bonus | €4,000 | €4,000 |
| Maximum total | €7,500 | €12,500 |
Heat pump unit
- Air-to-air (a reversible air conditioner)
- €3,500
- Air-to-water, ground source, water-to-water
- €6,500
Radiator and pipework upgrade
- Air-to-air (a reversible air conditioner)
- Not applicable
- Air-to-water, ground source, water-to-water
- €2,000
Renewable heating bonus
- Air-to-air (a reversible air conditioner)
- €4,000
- Air-to-water, ground source, water-to-water
- €4,000
Maximum total
- Air-to-air (a reversible air conditioner)
- €7,500
- Air-to-water, ground source, water-to-water
- €12,500
Amounts for houses, effective 3 February 2026. Apartments are funded at lower rates. The grant is not means-tested. Conditions and the application process are on our SEAI heat pump grant page.
So a reversible air conditioner fitted by an SEAI-registered contractor, replacing an oil or gas boiler, can attract up to €7,500. Against an installed cost of €2,100 to €3,500 for a single split unit, the grant can exceed the price of the equipment itself - which is the strongest argument on this page for specifying a reversible model rather than a cooling-only one.
What the grant requires
- The property must have been built and occupied before 2021;
- The work must be done by an SEAI-registered contractor, so confirm registration before signing anything;
- The home must have low enough heat loss, which in practice means a BER of C or better, or insulation upgrades done first;
- A post-works BER assessment is required before the grant is paid out;
- The €4,000 renewable heating bonus applies where the heat pump replaces an oil, gas, solid fuel or electric storage heating system, and is paid after the system has been running;
- An air-to-air system has no radiators or pipework, so the €2,000 component never applies to it.
Who Can Install an Air Conditioner, and What Rules Apply?
A portable unit is an appliance: unbox it, run the hose out a window, plug it in. A fixed unit is building work with a pressurised refrigerant circuit, and the rules are different.
Who may install a fixed unit
Split and multi-split systems are charged with fluorinated refrigerant. Under EU F-Gas rules the refrigerant circuit must be handled by a certified technician, so a DIY installation of a fixed unit is not lawful. Ask any installer for their F-Gas certification before they quote, and ask separately about SEAI registration if you intend to claim the grant, because the two are not the same thing.
Beyond the certificate, the work involves drilling an external wall, mounting and levelling the outdoor condenser, running insulated pipework, making a permanent electrical connection and vacuum-testing the circuit before charging it. None of that is a weekend job.
Where the outdoor unit goes
The condenser needs a solid wall or a level ground base with free airflow all around it. Several things are worth settling before the installer arrives rather than after.
- Noise and neighbours. A typical outdoor unit produces 45 to 60 dB(A) at one metre. Keep it away from your own bedroom windows and from a boundary where it will carry, and ask the installer for the quoted sound level of the specific model;
- Planning and permissions. Exemptions for external plant are conditional, so check with your local authority before ordering if the condenser would sit on a front elevation, on an apartment balcony or on a protected structure;
- Shared walls. In an apartment or a managed estate, the owners' management company normally has to agree to anything fixed to a common wall or balcony;
- Condensate drainage. Every cooling unit produces water, and the drain run is one of the most common sources of trouble in a retrofit;
- Acoustic enclosures can shave a few dB(A) off, but only if they do not choke the airflow the unit needs.
Servicing and running it well
Filters need cleaning at least annually or the unit loses efficiency and starts recirculating dust. Refrigerant pressures need a periodic check by a certified technician, both for performance and because a leaking circuit is an environmental issue rather than just a broken appliance.
On the settings, every degree matters more than people expect: aim for 24 °C in cooling rather than 18 °C, and 19 to 21 °C in heating. Keep windows and internal doors shut while it runs and use the timer instead of leaving it on all day. If you are on a smart meter plan, cool the room before 5pm and let it coast through the 5pm to 7pm peak band, which costs 34.60 c/kWh against 32.43 c/kWh during the day and 17.04 c/kWh at night.
Is Air Conditioning Worth It in Ireland?
For cooling alone, in most Irish homes, no. The climate produces a handful of days above 25 °C, and a €3,000 installation used for two or three weeks is hard to justify when shading and night ventilation solve the problem for nothing. For heating and cooling together on a reversible unit, the answer flips: the figures earlier on this page show it beating gas on cost per kWh of heat, and it then earns its place for most of the year.
Fan, portable unit or split system?
| Criterion | Pedestal fan | Portable unit | Fixed split unit |
|---|---|---|---|
| Upfront cost | €20 to €100 | €275 to €650 | €2,100 to €3,500 installed |
| Cost per day at typical use | €0.13 | €1.28 | €2.88 |
| Actually cools the air | No, it only moves it | Yes, one room | Yes, one room, efficiently |
| Installation | None | None, but a window stays part-open | Certified installer, outdoor unit |
| Bedroom noise | Low to medium | High, compressor in the room | Low indoors |
| Heats in winter | No | Some models | Yes on reversible models |
| Grant eligible | No | No | Yes if specified as a heat pump |
Upfront cost
- Pedestal fan
- €20 to €100
- Portable unit
- €275 to €650
- Fixed split unit
- €2,100 to €3,500 installed
Cost per day at typical use
- Pedestal fan
- €0.13
- Portable unit
- €1.28
- Fixed split unit
- €2.88
Actually cools the air
- Pedestal fan
- No, it only moves it
- Portable unit
- Yes, one room
- Fixed split unit
- Yes, one room, efficiently
Installation
- Pedestal fan
- None
- Portable unit
- None, but a window stays part-open
- Fixed split unit
- Certified installer, outdoor unit
Bedroom noise
- Pedestal fan
- Low to medium
- Portable unit
- High, compressor in the room
- Fixed split unit
- Low indoors
Heats in winter
- Pedestal fan
- No
- Portable unit
- Some models
- Fixed split unit
- Yes on reversible models
Grant eligible
- Pedestal fan
- No
- Portable unit
- No
- Fixed split unit
- Yes if specified as a heat pump
Advantages
- It genuinely works: unlike a fan it lowers air temperature and removes humidity, so it still helps at 30 °C indoors.
- Cheaper heat than gas on a reversible unit, at 7.99 c per kWh of heat against 12.22 c for gas and 10.76 c for oil.
- Room-by-room control: heat or cool only the room you are in, with a thermostat and timer.
- Up to €7,500 in SEAI grant when it is specified as a reversible heat pump and fitted by an SEAI-registered contractor.
- Filters the air, which is useful during pollen season.
Disadvantages
- High cooling cost: a split unit costs roughly 22 times a fan's daily running cost.
- No hot water: an air-to-air unit cannot replace a boiler outright.
- Only heats the rooms it serves, so a hallway or bathroom stays cold without its own indoor unit.
- Needs a certified installer and an outdoor condenser, with the planning and neighbour questions that follow.
- Efficiency drops in a cold snap, below roughly −5 °C.
Cheaper ways to cool an Irish home
Most Irish overheating is solar gain through glass rather than hot outdoor air, and that is cheap to fix.
- Close curtains or blinds on south and west windows during the day, before the room heats rather than after;
- Fit external shades, awnings or solar-control film, which stop the heat before it reaches the glass;
- Open windows on opposite sides of the house at night for a through-draught, then close them by mid-morning;
- Run a fan, which for 13 cent a day makes a room feel 3 °C to 4 °C cooler through air movement alone;
- Cook cold meals or use an air fryer instead of the oven during a warm spell;
- Switch off unused electronics, since standby loads dump their heat straight into the room.
If overheating is structural rather than seasonal, the fabric of the house is the real lever: the same insulation that keeps heat in during winter keeps it out in a heatwave. Our guide to the best home heating options sets out where a reversible unit sits against the alternatives.
Frequently Asked Questions About Air Conditioning in Ireland
Save on Your Home Heating Bills Today!
Our heating experts at Selectra can help you save on boiler services, heat pumps, and home heating oil - for free.