Split systems or multi-split options? A plain-English guide to finding the perfect air conditioning solution for your Irish home — with costs, energy ratings, and expert recommendations.
Rising summer temperatures, improved home insulation trapping heat indoors, and the growing popularity of home offices have made residential air conditioning one of the fastest-growing HVAC segments in Ireland. Met Éireann has recorded several of the warmest summers on record in recent years, leaving homeowners searching for effective cooling solutions.
Modern AC systems are whisper-quiet, energy-efficient, and can heat your home in winter just as effectively as they cool it in summer. Gone are the days of noisy, inefficient window units — today's sophisticated air conditioning systems seamlessly blend into modern Irish homes while providing year-round comfort.
One outdoor unit connected to one indoor unit
Best for: Individual RoomsOne outdoor unit connected to 2-5 indoor units
Best for: Multiple RoomsFreestanding plug-in unit venting through window
Best for: Temporary UseA single split system consists of one outdoor unit connected to one indoor unit via refrigerant pipework. This is the most popular choice for cooling individual rooms such as bedrooms, living rooms, or home offices. Top brands like Daikin, Mitsubishi Electric, and Samsung offer units with advanced inverter technology that automatically adjusts compressor speed to maintain desired temperatures while minimising energy consumption. Modern split systems operate at just 19-22 dB — quieter than a whisper — making them ideal for bedrooms and study rooms.
A multi-split system uses a single outdoor unit connected to between two and five indoor units, each with independent temperature control. This allows different family members to set different temperatures in different rooms simultaneously. While more flexible than single splits, system design requires a qualified HVAC installer to ensure the outdoor unit's capacity is correctly matched to the combined load of all indoor units. Multi-splits are ideal for apartments or terraced houses where outdoor wall space is limited.
Portable air conditioning units require no installation — simply plug into a standard socket and vent the exhaust through a window adapter. However, they are significantly less energy-efficient, noisier, and less effective than fixed split or multi-split systems. They best serve temporary or rental situations where permanent installation isn't possible.
| Feature | Single Split | Multi-Split |
|---|---|---|
| Rooms Covered | 1 room | 2-5 rooms |
| Installation Cost | €€ | €€€ |
| Energy Efficiency | Excellent | Excellent |
| Noise Level (Indoor) | 19-22 dB | 19-22 dB per unit |
| Aesthetics | Wall unit visible | Wall units visible |
| Heating Capability | Yes (Heat Pump) | Yes (Heat Pump) |
| Retrofit Suitability | Excellent | Good |
| Independent Room Control | Single room only | Yes per unit |
| Installation Time | 1 day | 1-2 days |
A modern air conditioning system is essentially a heat pump — it uses identical technology to heat your home in winter and cool it in summer. In summer, the system extracts heat from inside your room and expels it outside. In winter, this process reverses: the system extracts heat from the outdoor air and delivers it inside for warming.
Inverter-driven systems achieve a COP (Coefficient of Performance) of 4.0 or higher, meaning they produce up to four units of heat for every one unit of electricity consumed. Compare this to a direct electric radiator which produces just 1:1 heat — for every 1kW of electricity, you get 1kW of heat.
Each unit is rated for a specific room size in square metres. Undersized systems run constantly trying to reach the set temperature, while oversized systems cycle on and off inefficiently, leading to poor humidity control and increased wear.
Well-insulated homes retain cool air more effectively. Large south-facing windows increase solar heat gain, requiring more cooling capacity. Consider your home's insulation quality and window orientation when selecting system capacity.
One room = single split system. Two to three rooms = multi-split system. The number of rooms you need to condition directly influences the system type and cost.
If you plan to use your AC system for heating as well as cooling, choose a system with a strong heating COP. Most modern units can heat effectively down to -15°C, well below typical Irish winter temperatures.
Look for A++ or A+++ rated systems. SEER measures cooling efficiency; SCOP measures heating efficiency. Higher ratings mean lower running costs — a system with SEER 8.5 and SCOP 5.1 would carry an A+++ rating.
Critical for bedrooms — the best units operate at just 19dB. Check both indoor and outdoor unit noise specifications. Outdoor unit noise matters for neighbours and your own outdoor living spaces.
Factor in both installation cost and long-term energy bills. A higher-rated system costs more upfront but saves money every year through lower electricity consumption. Calculate the payback period based on your expected usage.
A reputable HVAC installer will perform a heat load calculation considering room dimensions, insulation levels, window area, orientation, occupancy, and heat-generating appliances. This ensures the system is correctly sized for your specific needs — not just a guess based on room size alone.
Understanding energy ratings helps you choose a system that minimises running costs while maximising comfort. Two key metrics define air conditioning efficiency:
Seasonal Energy Efficiency Ratio measures cooling efficiency. The higher the SEER, the more efficient the system is at cooling. Modern high-quality split systems achieve SEER ratings of 6.0 to 8.5 or higher.
Seasonal Coefficient of Performance measures heating efficiency. A system with SCOP of 5.1 produces over 5 units of heat for every 1 unit of electricity — that's over 500% efficiency. Look for A+++ ratings with SCOP above 5.0.
A system with SEER of 8.5 and SCOP of 5.1 would carry an A+++ rating — the highest available. While these premium systems cost more initially, the energy savings over their 15-20 year lifespan can amount to thousands of euros.
A typical 3.5kW single split system running 6 hours a day in summer costs approximately €0.30-€0.50 per day at current Irish electricity rates — roughly €50-€90 over an entire summer. For heating, running costs can be 50-70% lower than oil-fired central heating, making air conditioning a cost-effective heating solution.
The Sustainable Energy Authority of Ireland (SEAI) offers grants for heat pump installations under the National Home Energy Upgrade Scheme. While air-to-air systems (traditional AC) have limited grant availability, air-to-water heat pumps may qualify for significant grants. Contact SEAI or your HVAC installer to understand current eligibility.
All air conditioning systems containing fluorinated greenhouse gases (F-Gases) must be installed and serviced by a certified F-Gas engineer. This is a legal requirement in Ireland under EU F-Gas Regulation. Always verify your installer's F-Gas certification before proceeding with installation.
Understanding real Irish pricing helps you budget accurately and avoid unexpected costs. All prices below are fully installed costs including indoor and outdoor units, mounting brackets, copper pipework, drainage, electrical connection, and system test.
Ideal for cooling/heating a single room such as a bedroom, living room, or home office. Includes one indoor unit and one outdoor unit.
One outdoor unit serving two to five indoor units with independent temperature control. Each additional indoor unit adds approximately €1,200-€1,800.
A good installer provides a fixed-price quotation with no hidden extras. Always ask for a detailed breakdown.
Proper installation is the difference between a system that performs efficiently for 15-20 years and one that fails within a few years. Here's what professional installation ensures:
An experienced installer performs a thorough heat load calculation considering ceiling height, insulation quality, window area and orientation, heat-generating appliances, and occupancy. Undersized systems work too hard; oversized systems short-cycle — both waste energy and reduce comfort.
Refrigerant pipework must be correctly sized, properly insulated, professionally flared, and pressure-tested. Professional installers use nitrogen pressure testing on every joint and vacuum the system before charging with refrigerant — this removes moisture and non-condensables that can damage the compressor.
Every indoor unit produces condensate (water) that must be properly routed to a drain. Poor drainage causes water leaks, damp problems, and mould growth. Professional installers route condensate lines correctly and test them before completing the installation.
The installer verifies refrigerant charge, airflow settings, temperature differential, drainage, electrical connections, and controls. They then provide a commissioning certificate, warranty documentation, and a full system walkthrough explaining operation and maintenance.
We supply, install, and maintain residential air conditioning systems across Ireland — from single-room split systems to multi-room solutions. Get a free home survey and fixed-price quotation with no obligation.
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