Keeping guests cool and comfortable can make or break an event — especially during Cape Town’s hot, dry summers. Whether you’re hosting a wedding, corporate function, film shoot or pop-up event, choosing the correct size evaporative air cooler is key to effective cooling.
Choose too small, and the space won’t cool down.
Choose too big, and you waste energy, water, and money.
This guide breaks down exactly how to choose the right size air cooler, how to calculate the airflow you need (using a simple metric formula), and when to choose Chill Out’s Medium vs Large size Portable Evaporative Air Coolers.
Why Correct Air Cooler Sizing Matters
The size of your cooler determines:
- how quickly your venue cools
- how comfortable your guests feel
- how much water the cooler consumes
- how many units you actually need
If the cooler is too small:
- The venue never reaches a comfortable temperature
- The cooler works non-stop and wastes water
- Humidity builds up, making the space feel sticky
If the cooler is correctly sized:
- Cooling is fast and efficient
- Airflow feels crisp and refreshing
- Guests, staff or crew stay comfortable for hours
How to Choose the Right Size Air Cooler
Evaporative coolers are sized by airflow, measured in CMH (cubic metres per hour).
To cool a venue properly, the cooler must replace the full volume of air 20–30 times per hour.
Here’s the simplest way to calculate the size you need.
Step 1: Measure the floor area
Example:
10m × 15m = 150 m²
Step 2: Measure the ceiling height
Example:
Ceiling height = 3m
Step 3: Calculate the total air volume
150 m² × 3 m = 450 m³
Step 4: Multiply by the recommended air changes per hour
Standard: 25 air changes per hour
(Enough for events, weddings, film sets, tents, etc.)
CMH Required = Venue Volume × 25
450 m³ × 25 = 11,250 CMH needed
✔ That means you need multiple air coolers that can deliver 11,250 CMH of airflow.
Important:
For outdoor, semi-open, or tented venues, increase by 30–50% because cool air escapes faster.
Other Factors That Influence the Cooler Size You Need
1. Climate & Humidity
Evaporative air coolers work exceptionally well in hot, dry climates — exactly what the Western Cape experiences in peak summer.
If humidity rises:
- increase ventilation
- choose a higher-CMH cooler
- consider adding multiple units
2. Venue Type
Each setup has unique heat loads.
- Weddings & corporate events: medium heat from people
- Film sets: cameras & lights create high heat
- Warehouses: large, open volumes need high airflow
- Tents & marquees: hold heat → larger coolers required
3. Number of People
More people = more body heat.
If your venue will be full, increase your CMH by 20–30%.
4. Ventilation
Evaporative coolers need fresh air intake.
If ventilation is limited:
- choose a bigger unit
- OR use multiple air coolers
5. Duration of Event
For full-day or multi-day events, choose air coolers with:
- large water tanks
- strong airflow
- continuous-operation capability
Chill Out’s Air Cooler Options (and When to Use Each)
Once you know your CMH requirement, choosing the correct size becomes simple.
Below is a practical guide for selecting between our Medium and Large coolers.
❄️ Medium-Size Portable Air Cooler 💨
Best for:
- Rooms 30–80 m²
- Small events
- Film shoots
- Offices or backstage areas
- Controlled indoor spaces
Strengths:
- Excellent for targeted cooling
- Lower noise
- Easy to position
- Perfect for rooms with good ventilation
Medium units work extremely well near doors/windows where they can constantly pull in fresh air.
❄️ Large-Size Portable Air Cooler 💨
Best for:
- Venues 100–200+ m²
- Outdoor patios
- Marquees & stretch tents
- Wedding venues
- Warehouses
- Large film sets
- High-traffic or open spaces
Strengths:
- High CMH output
- Long air throw
- Powerful coverage for open or semi-open venues
- Often replaces 2–3 household units
Large coolers are ideal when you need maximum airflow and strong cooling over a wide area.
Placement Tips for Best Cooling
Correct placement can improve cooling by 30–40%.
✔ Position coolers at the edges of the venue (not the centre)
✔ Aim airflow toward people or high-traffic zones
✔ Ensure a fresh air inlet — even a partially opened door is enough
✔ Avoid blowing cool air into walls or blocked spaces
✔ For big venues, use cross-flow with 2–3 units
✔ For tents, direct airflow toward open sides
Still Not Sure Which Size You Need?
Choosing the correct size doesn’t need to be complicated.
Use the CMH formula, consider your space and number of guests, and match it to the right cooler size.
If you want expert guidance, Chill Out can help you choose the perfect cooler based on:
- venue dimensions
- expected occupancy
- event type
- layout and airflow
Contact Chill Out anytime for professional sizing advice — and keep your event cool, comfortable, and unforgettable.
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