The Summer Heatwave Guide: How to Keep Your Marquee Cool

There is nothing quite like a British summer garden party. But when a heatwave hits, a marquee can quickly go from a breezy sanctuary to a greenhouse. At DIY Marquees, we design our structures to be versatile, but during peak July and August temperatures, you need a strategy to keep your guests (and your cake!) from melting.

Here is your essential guide to marquee climate control, from “opening the walls” strategies to high-tech ventilation.

1. The Art of “Opening the Walls”

The most effective way to cool a marquee is through natural airflow. However, simply unzipping a door isn’t enough during a heatwave.

• The Windward Strategy: Identify the direction of the breeze. Open the side of the marquee facing the wind to “scoop” fresh air in, and open the opposite side to allow hot air to escape. But be careful! doing this should only be in fair weather as marquees perform better in the wide with Sides ON.
• Leg-Only Mode: For DIY Marquees with detachable side panels, consider removing the panels entirely on at least two sides. This transforms the marquee into a “canopy” or “pavilion” style. You keep the vital overhead shade while allowing a 360-degree cross-breeze.
• The “Half-Wall” Trick: If you want to maintain a sense of enclosure (or hide some catering crates!), fold the wall panels down halfway or use half-height barriers. This keeps the ground-level aesthetic while letting air circulate at head height.

2. Strategic Ventilation Techniques

Air inside a marquee becomes “stagnant” when it has nowhere to go. Because heat rises, it often gets trapped in the apex (the roof peak).

• Fan Placement: Don’t just point fans at people. Place large floor fans near the open sides to “pull” the cooler outside air into the marquee. For larger events, “air movers” are more effective than standard pedestal fans as they circulate a much higher volume of air.
• Avoid “Greenhouse” Panels: While window panels are beautiful, they can create a magnifying effect in direct sunlight. If a heatwave is forecast, try to use solid white panels on the sun-facing side to reflect heat, saving the window panels for the shaded side of the structure. Although our Clear Roof Marquees are beautiful they can be very hot in the direct sun.

3. Mastering the Shade

Shade is your best friend. A white PVC marquee roof is excellent at reflecting UV rays, but you can go further:

• Internal Linings: Marquee linings aren’t just for decoration. That layer of fabric between the PVC roof and your guests acts as a thermal barrier, trapping a pocket of air that helps insulate the interior from the sun’s direct heat on the roof.
• External “Island” Shade: If space allows, set up smaller gazebos or sunshades just outside the marquee entrance. This creates a “cooling zone” for guests before they even enter the main structure and prevents the ground right outside the doors from absorbing heat and radiating it inward.
• Natural Shading: When planning your layout, look at the movement of trees or buildings. If you can position the marquee so it falls into natural shade during the “danger zone” (2:00 PM – 4:00 PM), you’ll see a temperature drop of several degrees.

4. High-Tech Options: Coolers & AC

For high-stakes events like weddings, you might need more than a breeze.

• Evaporative Coolers: These are more effective than simple fans. They use the evaporation of water to cool the air and work best in semi-open marquees where there is plenty of fresh air.
• Air Conditioning: If you choose a full AC unit, remember that the marquee must be entirely sealed for it to work. This means keeping all walls on and doors closed—the opposite of the ventilation strategy. Only choose this if you have a high-capacity industrial unit designed for temporary structures.

Summary Checklist for a 30°C Day:

1. Early Morning: Keep the marquee closed to trap the cooler night/morning air inside for as long as possible.
2. Midday: Once the sun is high, open the “leeward” and “windward” sides to start the cross-breeze.
3. Afternoon: Ensure hydration stations (iced water) are placed in the coolest, most shaded corner.
4. Evening: As the sun dips, keep the walls open to let the evening “cool” in, but be ready to close them if the humidity brings in the midges!

Planning your summer event? Check out our range of durable, white roofed, heat-reflective marquees and accessories to ensure your party stays cool no matter what the British weather throws at you.