How many BTU is 3.5kW?

Approximately 12,000 BTU/h. Multiply kilowatts by 3,412 to convert to BTU per hour.

Can one unit cool two rooms?

Only if they are genuinely open to each other. A wall-mounted unit cannot push conditioned air through a doorway effectively, so separate rooms need separate indoor units or a ducted system.

Should I size up to be safe?

No. Sizing up causes short cycling, poor dehumidification and higher running costs. Size to the calculated load and rely on the inverter's headroom for extreme days.

Air Conditioning Guides

Practical, editorially reviewed articles on air conditioning costs, installation, system sizing, running costs, air-to-air heat pumps and country-specific rules across Ireland, the UK and Northern Europe. Every guide is written for homeowners comparing real quotes.

Featured · Air Conditioning Costs

How Much Does Air Conditioning Cost in Ireland? (2026 Prices)

In Ireland, a single-room split air conditioning installation typically costs €2,500 to €4,500 fully fitted. Whole-home multi-split systems commonly range from €6,500 to €12,000. Running costs for a well-sized inverter unit used through an Irish summer usually add €40 to €120 a year to an electricity bill.

Updated 2026-06-01 · 9 min read

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Home Cooling

Is Air Conditioning Worth It in Ireland?

Ireland's climate is mild, yet overheating complaints are rising fast in new builds and apartments. Here is an honest assessment of when air conditioning pays for itself.

Updated 2026-05-30 · 7 min read

Installation Guides

Air Conditioning Installation in Dublin: Complete 2026 Guide

Costs, apartment approvals, planning rules, installation timelines and how to vet installers — everything Dublin homeowners need before booking air conditioning.

Updated 2026-06-05 · 11 min read

Air-to-Air Heat Pumps

Air-to-Air Heat Pump vs Air Conditioning: What's the Difference?

The two terms describe almost the same hardware. Understanding where they genuinely differ helps you buy the right system — and claim the right grants.

Updated 2026-05-20 · 8 min read

Air Conditioning Costs

Home Air Conditioning in the UK: Costs and Options (2026)

UK air conditioning prices by system type, what drives London premiums, permitted development rules and realistic running costs at 2026 electricity rates.

Updated 2026-06-01 · 9 min read

Country Guides

Air Conditioning in Denmark: Costs, Rules and What to Buy

Danish summers are warmer than they were, and reversible air-to-air heat pumps have become the default answer. Costs, approvals and efficiency guidance for 2026.

Updated 2026-06-01 · 8 min read

Home Cooling

What Size Air Conditioner Do I Need? A Room-by-Room Sizing Guide

Oversizing is the most common and most expensive specification mistake. Here is how installers size a unit properly, and how to sanity-check the number you are quoted.

Updated 2026-06-10 · 7 min read

Energy Efficiency

Air Conditioning Running Costs Explained (With Real Examples)

How to work out what your air conditioning actually costs per hour, per season and per year — plus the settings that make the largest difference to the bill.

Updated 2026-06-12 · 8 min read