Air conditioning vs heat pump in Ireland: which makes more sense?
The short answer
If you want cooling only, get air conditioning (€2,000–€3,500 per room). If you want to replace your home's heating system and get cooling as a bonus, get a heat pump (€12,000–€18,000 before grants, but up to €12,500 of that is grant-eligible). The technology is similar; the financial picture is very different.
This question comes up a lot now that air conditioning is becoming more common in Irish homes and heat pumps are being pushed hard by SEAI. People hear they're "the same thing" and don't know which one they actually want. They're related, but they're not the same purchase, and getting the wrong one can mean wasting thousands of euros or missing out on a grant that pays for half your install.
What's the actual difference?
Underneath, an air conditioner and a heat pump are the same machine. Both move heat using a refrigerant cycle. The compressor, the indoor unit, the outdoor unit. Same components, often the same manufacturers. The difference is what they're optimised and sold for.
Air conditioning
Designed and sold primarily as a cooling system. Most modern AC units can run in reverse and put heat into a room (handy on shoulder-season mornings), but that's a bonus, not the headline. Sold per room. Doesn't connect to your central heating system at all. No SEAI grant.
Air-to-air heat pump
Same physical kit as a reversible AC, but specified, installed, and registered as a primary heating system. Same indoor wall-mount units, same outdoor compressor. The difference is paperwork and intent: it's BER-assessed as your main heating source, and your installer is on the SEAI registered installer list. Qualifies for SEAI grants if it meets the criteria.
Air-to-water heat pump
A completely different setup. The outdoor unit heats water that runs through your radiators, underfloor heating, and hot water cylinder. Replaces your gas or oil boiler entirely. Cannot cool through radiators (they can't safely run cold), but some installs with underfloor heating can provide mild "passive cooling". This is what most people mean when they say "heat pump" in an Irish home context, and what most SEAI grants are designed around.
Cost comparison
| System | Typical install cost | SEAI grant | Net cost |
|---|---|---|---|
| Single split AC | €2,000 – €3,500 | None | €2,000 – €3,500 |
| Multi-split AC (2-3 rooms) | €4,500 – €7,500 | None | €4,500 – €7,500 |
| Air-to-air HP (as primary heating) | €6,000 – €12,000 | Up to €7,500 | €0 – €5,000 |
| Air-to-water HP (whole home) | €12,000 – €18,000 | Up to €12,500 | €2,000 – €6,000 |
The grant turns the conversation on its head. A multi-split AC system costing €6,000 can end up costing the same as or less than an air-to-water heat pump system once you factor in the €12,500 SEAI package. The heat pump replaces your oil or gas heating and cuts your bills on top of that.
The catch is the criteria. SEAI grants require the system to be specified by an SEAI-registered contractor, installed as the home's primary heating system, and typically require a Building Energy Rating assessment before and after. You can't just buy a heat pump off the shelf and claim the grant. It has to be a designed install.
Running costs
For cooling, an AC unit and an air-to-air heat pump cost essentially the same to run. They're the same machine doing the same job. At Irish residential rates of around 30c to 40c per kWh, a 9,000 BTU room being cooled for 4 hours a day costs €25 to €50 per month.
For heating, the comparison changes completely. Heat pumps are typically 3 to 4 times more efficient than burning gas or oil. Real-world Seasonal COP for a well-installed heat pump is around 3.0 to 3.5, versus roughly 0.9 for a modern gas or oil boiler. So for every unit of electricity you put in, you get about 3 units of heat out. In numbers:
- A typical Irish 3-bed semi might spend €1,700–€2,200 a year on oil heating including servicing
- The same house with a well-sized heat pump usually runs €700–€1,200 a year, less on a smart night-rate tariff
- That's €700+ a year saved on running cost, before factoring in the grant
Grants. The real deciding factor
This is where most people who think they want AC end up reconsidering. If your home is well-insulated and you'd been thinking about cooling, the grant economics make a heat pump look very different.
The current SEAI package for an air-to-water heat pump installed as primary heating:
- €6,500 for the heat pump itself
- Up to €2,000 for central heating upgrades (often needed when switching from oil/gas)
- €4,000 Renewable Heat Bonus
- Total: up to €12,500
For air-to-air heat pumps installed as primary heating: up to €7,500.
None of this applies if the unit is installed and registered as air conditioning. The paperwork and installer credentials are the difference between "expensive AC" and "subsidised heating with cooling included".
When AC makes more sense
- You only want cooling. Heating is fine as it is, you just want one or two rooms cooled for the summer.
- You're cooling a single room. A single-split AC is a one-day install, no BER assessment, no grant paperwork, no central-heating overhaul. Done.
- You're a renter or short-term homeowner. A heat pump pays back over 7-10 years. AC pays for itself in summer comfort immediately.
- Your home isn't well-insulated and you can't upgrade right now. SEAI will likely refuse the grant. AC doesn't care about your BER.
- You're cooling a business premises. Office cooling is rarely SEAI-eligible in the way residential heating is. AC is the standard answer.
When a heat pump makes more sense
- Your boiler is near the end of its life. If you're going to spend €3,000-€5,000 on a new boiler anyway, the heat pump grant maths suddenly look brilliant.
- You're renovating or extending. Easiest time to do the disruptive work and oversize the radiators or fit underfloor heating.
- Your home has a decent BER (B3 or better). The heat pump will be efficient and SEAI will approve the grant.
- You want both cooling and heating in the same package. Air-to-air heat pump installed as primary heating gets you both with a grant.
- You care about long-term running costs. Heat pumps win on energy efficiency once they're installed in a suitable home.
The "reversible AC" question
Almost every modern split AC sold in Ireland is reversible. Press a button on the remote and the same unit puts heat into the room instead of taking it out. So why doesn't reversible AC just count as a heat pump and get the grant?
Two reasons. First, the SEAI grant is for a designed primary heating system, not for a per-room cooler that happens to also heat. Your bedrooms need heat, your bathroom needs heat, your kitchen needs heat. An AC unit in your living room is not going to keep the upstairs warm.
Second, the registered-installer requirement. SEAI grants require the install be done by a contractor on their register. Most AC installers aren't on that register because their primary trade is cooling.
If you want the grant and the cooling, the path is: get a properly designed air-to-air heat pump system that covers every room you want heated, installed by an SEAI-registered contractor as your primary heating. You can use it for cooling in summer. That's the grant-eligible version of "AC that also heats".
What about hybrid setups?
Some Irish homes end up with a hybrid: keep the gas boiler for backup hot water and very cold spells, add an air-to-water heat pump for the bulk of the heating, and add separate AC units in 1-2 bedrooms for summer cooling. It's not the cheapest path, but it's the most flexible, and it can still attract the heat pump grant on the air-to-water portion.
Whether this makes sense depends on your specific home, your existing heating, and how much you actually need cooling. A good installer should be able to lay it out for you with numbers.
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Get matchedCommon questions
Is a heat pump the same as air conditioning?
They use the same underlying technology. Both move heat using a refrigerant cycle. The difference is what they're optimised and sold for. Air conditioning is sold primarily as a cooling system that can usually reverse-cycle for heating. A heat pump is sold primarily as a heating system and may or may not cool, depending on the type.
Can air conditioning replace my heating in Ireland?
A reversible AC unit can heat a single room well, but a typical residential AC install won't replace your whole heating system. It heats the rooms it's installed in, not the rest of the house. If you want to replace your boiler, you need a properly sized heat pump system designed as primary heating.
What grants are available for heat pumps in Ireland?
The SEAI Home Energy Grants package covers up to €12,500 for an air-to-water heat pump installed as the home's primary heating system: €6,500 for the heat pump itself, up to €2,000 for central heating upgrades, and a €4,000 Renewable Heat Bonus. Air-to-air heat pumps installed as primary heating qualify for up to €7,500. Air conditioning on its own gets no grant.
Which is cheaper to run?
For cooling, the running cost is similar because the technology is similar. For heating, a heat pump is dramatically cheaper than oil or gas. Typically 3 to 4 times more efficient than a gas boiler, so roughly a third the running cost for the same heat output.
Can a heat pump cool my house in summer?
Air-to-air heat pumps cool well. They work exactly like an AC unit in reverse. Air-to-water heat pumps that supply radiators cannot cool, because radiators can't safely run cold. Air-to-water systems with underfloor cooling enabled can provide mild cooling, but not the active cooling you'd get from AC.
Is air conditioning a worse environmental choice than a heat pump?
Both use electricity, both use refrigerant. The difference is what they replace. A heat pump replacing an oil boiler cuts heating emissions dramatically. AC added on top of an existing gas-heated home adds emissions. Whether AC is worse depends on what it displaces and how often you'd actually run it.