What to look for when buying a portable AC.
1. Real compressor cooling vs evaporative cooling
A compressor air conditioner uses refrigerant to absorb heat indoors and pump it outside. It works in any humidity and actually lowers the air temperature.
An evaporative cooler (sometimes called a "swamp cooler") only blows air through water. It feels nice in dry climates, but in damp Irish weather it adds humidity and does little to cool a room.
For Irish vans, caravans, lofts and garden rooms, a compressor unit is the only option that delivers real cooling.
2. Power options: mains, battery, solar or 12V
Most portable ACs in Ireland are mains-only. That is fine for a house or permanent cabin, but useless off-grid. The Zero Breeze Mark 3 gives you all three options:
- Mains 240V
- Plug into a standard Irish socket. Best for garden rooms, site cabins and home use.
- Battery 48V
- True off-grid cooling. One battery runs the Mark 3 for 3–5 hours; chain two or more for all-night use.
- Solar / 12V
- Charge the battery from a solar panel or vehicle dual-battery system via the Anderson input.
3. BTU sizing guide
BTU tells you how much cooling power a unit has. Too small and it runs constantly without reaching the target temperature; too large and it cycles on and off too quickly, wasting power and dehumidifying poorly.
| Space | Recommended BTU | Notes |
|---|---|---|
| Rooftop tent / small pod | 3,000–5,000 BTU | Rapid cool-down of a small sleeping space. |
| Camper van / caravan | 5,000–6,000 BTU | Comfortable temperature in a converted van or medium caravan. |
| Garden room / loft bedroom | 5,000–7,000 BTU | Handles poorly insulated attic or studio spaces. |
| Market stall / site cabin | 5,000–6,000 BTU | Spot cooling for staff and customers in a partially open area. |
The Zero Breeze Mark 3 produces 5,280 BTU of cooling — right in the sweet spot for vans, caravans, loft bedrooms and garden rooms up to roughly 15–20 m².
4. Key buying checks
Compressor vs evaporative
A compressor AC removes heat and vents it outside. An evaporative cooler only blows moist air and struggles in humid Irish weather. For real cooling, choose a compressor.
Single-hose vs dual-hose
Dual-hose units pull outside air through one hose to cool the compressor and exhaust hot air through the second. They are more efficient, especially in vans and small rooms.
Noise level
Look for 45–55 dB if you plan to sleep nearby. The Zero Breeze Mark 3 runs at around 46 dB, similar to a quiet office.
Weight and portability
A 10 kg unit can be carried by one person and stowed in a camper cupboard. Heavier units need two people and permanent floor space.
Heating mode
A heat-pump mode gives you year-round value — cool in summer, warm in spring and autumn.
Venting
Every real AC needs a hot-air exhaust. Check that window kits or a universal venting option are available for your setup.
