Picture the scene. You have spent weeks planning the perfect summer event, whether it is a wedding breakfast under canvas, a garden festival, a charity fundraiser or a birthday bash your guests will talk about for years. The weather forecast looks promising. The bunting is up. And then, on the morning of the event, that marquee turns into something resembling a greenhouse in the Sahara.
A fully lined marquee on a warm July afternoon can hit temperatures well above 30 degrees Celsius inside, even when it feels pleasant outside. Bodies generate heat. Catering equipment adds more. The sun beats down on the canvas. Without a plan for cooling, a lovely event can quickly become an uncomfortable one.
The good news? Sorting the cooling side of things is genuinely straightforward once you know which piece of kit to go for. At HSS DIY, we offer two types of cooling hire that between them cover almost every marquee and outdoor event scenario: the evaporative cooler and the portable air conditioner. This guide tells you exactly which one you need, how to set it up, and how to make sure your guests are comfortable from the first glass of Pimm's to the last dance.
Quick answer: which do I need?
- Open-sided or well-ventilated marquee, garden party or festival tent: hire an evaporative cooler.
- Sealed, fully lined or enclosed marquee with no airflow: hire a portable air conditioner.
Not sure? Read on, it takes about 7 minutes.
Why marquees and event spaces get so hot
Permanent venues have one big advantage over marquees: built-in ventilation and, often, fixed air conditioning. A marquee has neither. It is essentially a large, lightly insulated tent that collects heat from three different directions.
- Solar gain: canvas absorbs heat from the sun all day and radiates it inward.
- Body heat: a room full of guests generates a surprising amount of warmth. Roughly 80 to 100 watts per person, if you want to get technical about it.
- Catering and equipment: hot food service, coffee machines, DJ rigs and lighting all add to the heat load.
According to the Met Office, UK summers have been trending warmer over recent decades, with 2022 seeing temperatures exceed 40 degrees Celsius in parts of England for the first time on record. Planning for heat at a summer event is no longer a nice-to-have.
External source: Met Office UK climate projections at metoffice.gov.uk.
The one question that decides everything
Before you look at any product, there is a single question that determines which cooling hire is right for your event:
Is your marquee open-sided, well-ventilated or partially open? Or is it fully enclosed and sealed?
Open-sided or ventilated: evaporative cooler is your go-to.
Fully sealed and enclosed: portable air conditioner is the right call.
The reason this matters is that the two machines work on completely different principles, and using the wrong one genuinely will not work.
An evaporative cooler draws warm air over water-saturated pads. As the water evaporates, it removes heat from the air and pushes cooled, slightly moist air into the space. This works brilliantly when there is airflow through the space, because the moist air needs somewhere to escape to. In an open-sided marquee, at a festival, or in a well-ventilated garden structure, this is exactly what happens.
A portable air conditioner uses a refrigerant circuit to extract heat from the air and exhaust it outside via a duct. It works in sealed, enclosed spaces because it actively removes the heat rather than managing it through evaporation. The duct needs to be routed somewhere, typically through a gap in the canvas, a window in an adjacent structure, or a purpose-cut aperture.
Evaporative cooler hire for summer events: open-sided marquees, garden parties and festivals
If your event involves an open-sided marquee, a stretch tent, a festival structure, a garden party with a canopy, or any space that has natural airflow through it, an evaporative cooler is your best choice. It is also the more economical option on running costs, and it needs no exhaust duct, which makes setup a lot simpler.
HSS DIY evaporative cooler hire options
For events with a large open marquee, the Industrial Evaporative Cooler is the one to go for. It delivers 8,000 cubic metres of cooled air per hour and covers spaces up to 150 square metres. It runs from a standard 240V socket, uses around 380W (similar to a vacuum cleaner), and has a 60-litre tank with a hose connection so you can run it continuously without stopping to top it up. Please note: minimum hire on this product is 7 days. Average hire price approximately £192.60.
For smaller events, gazebos or well-ventilated rooms used alongside an outdoor event, the Medium Evaporative Cooler covers up to 40 square metres and is portable enough to reposition easily during setup.
The Small Evaporative Cooler suits smaller sheltered areas or works as a spot-cooling option at a reception table or seating zone.
Browse the full range: Evaporative Cooler Hire at HSS DIY
Portable air conditioner hire for enclosed marquees and sealed event spaces
If your marquee is fully lined, sealed or otherwise enclosed with minimal natural airflow, you need to hire a portable air conditioner. The evaporative cooler will not perform well in a sealed space because the humid air has nowhere to escape, and the temperature reduction will be minimal.
A portable air conditioner needs an exhaust duct routed to the outside. For a marquee, this typically means creating a small opening in the canvas or routing the duct through a side panel. The duct needs to exit properly to avoid the warm air just recirculating inside.
HSS DIY portable air conditioner hire options
The Compact Air Conditioner 3.5kW suits smaller sealed spaces up to 25 square metres. Quiet at 55dB, suitable for use during speeches or live performances. From £58.80 per week including free delivery.
The Commercial Air Conditioner offers over 14,000 BTU of cooling for spaces up to 30 square metres. Well-suited to hospitality spaces, wedding anteroom areas and function rooms within larger event venues. From £95.52 per week.
For larger sealed event spaces, the Medium Air Conditioner 5.3kW covers up to around 40 square metres. It comes with 3m of ducting and three flexible directional cold air outlets with 360-degree swivel, which is useful for directing airflow across a larger table layout. This unit can also act as a spot cooler if you need to focus on a specific area, such as a catering station or bar.
The Semi-Industrial Portable Air Conditioner 6.1kW is the right choice for very large enclosed spaces up to 49 square metres, with a maximum duct length of 9m.
Browse the full range: Air Conditioner Hire at HSS DIY
Which product for which event: a quick reference
- Summer wedding reception — Open-sided marquee or stretch tent — Industrial Evaporative Cooler
- Garden party — Gazebo, canopy or open garden structure — Medium or Large Evaporative Cooler
- Festival stage area — Open-fronted tent or festival structure — Industrial Evaporative Cooler
- Corporate summer event — Fully lined, sealed event marquee — Commercial or Medium Portable Air Con
- Wedding ceremony room — Enclosed venue with windows — Compact 3.5kW Portable Air Con
- Outdoor food market / catering — Open-sided canopy — Medium or Industrial Evaporative Cooler
- School / charity fete — Mixed open and covered areas — Industrial Evap Cooler + Compact AC
Hire vs buy: is it worth purchasing your own cooling unit?
For a one-off summer event, hiring is almost always the smarter choice. Here is a straightforward cost comparison based on current HSS DIY pricing:
- Industrial Evaporative Cooler: Hire £192.60 (7-day min) | Buy approx. £500 to £900+ | Verdict: Hire. Cost-effective for single events.
- Medium Evaporative Cooler: Hire from approx. £96 | Buy £100 to £200 | Verdict: Buy if you use it every summer.
- Compact 3.5kW Portable AC: Hire £58.80 per week | Buy £200 to £400 | Verdict: Hire for events; buy if needed seasonally.
- Commercial Portable AC: Hire £95.52 per week | Buy £500 to £1,200+ | Verdict: Hire. Too expensive to justify for occasional use.
Prices are approximate and subject to change. Always check current hire rates at hss.com before budgeting.
Cooling hire timeline: when to book and what to expect on the day
One of the most common mistakes with event cooling is leaving it too late. Portable air conditioners and industrial evaporative coolers are in very high demand during UK heatwaves, and stock can run low quickly. Here is a sensible planning timeline:
- 4 to 6 weeks before the event: confirm your marquee type and dimensions. Work out whether you need an evaporative cooler or portable AC. Browse the HSS DIY range and provisionally note the products you need.
- 2 to 3 weeks before: place your hire order online at HSS DIY. You can order 24/7. Booking early secures stock, especially for peak summer weekends.
- Day before the event: your hire items are delivered. Note that items in the same order may arrive in separate deliveries, so plan for equipment to arrive throughout the delivery day.
- Morning of the event (1 to 2 hours before guests arrive): position your cooling unit. Fill the evaporative cooler tank or connect the hose. Route any exhaust duct for portable AC units. Run the unit for 20 to 30 minutes before guests arrive to pre-cool the space.
- During the event: check water levels on evaporative coolers every 2 to 3 hours if not using a hose connection. Adjust fan speed as needed.
- After the event: empty and clean any water tanks before the unit is collected. Check the hire terms for return conditions.
Event cooling preparation checklist
- Confirmed marquee type: open-sided or sealed
- Calculated approximate floor area (length x width in metres)
- Selected correct cooling unit from HSS DIY
- Hire order placed online at hss.com
- Confirmed delivery address and date
- Identified where to position the unit for best airflow
- Power source checked: 240V standard socket nearby
- Exhaust duct route planned (portable AC only)
- Water supply or hose connection available (evaporative cooler)
- Unit switched on 30 minutes before guests arrive
Health and safety: what to keep in mind
Cooling equipment is simple to operate, but there are a few sensible precautions worth taking at any event:
- Power supply: both evaporative coolers and portable air conditioners run from standard 240V sockets. Use only properly rated extension leads and avoid daisy-chaining leads or running cables under rugs or across footfall areas without appropriate cable covers.
- Exhaust ducts on portable AC: the duct must be routed outside. A portable air conditioner running without a properly vented duct will push warm air back into the space and raise the temperature. Seal any gap around the duct to prevent warm air re-entering.
- Evaporative cooler water hygiene: fill the tank with clean tap water and empty it if the unit is left unused for more than 24 hours. Do not add ice or other substances to the tank.
- Stability: both unit types are wheeled and free-standing. Position them on a level surface away from footfall routes. In a crowded marquee, consider placing them behind a barrier or in a designated service area.
- Noise levels: the compact 3.5kW portable AC operates at 55dB, suitable for background use during events. Industrial evaporative coolers produce fan noise comparable to a household appliance. Factor this in if positioning near a speaker area or ceremony space.
- Children and vulnerable guests: ensure power cables are secured and units are not accessible to unsupervised children.
Real-world example: a summer wedding in a mixed marquee venue
To give this some proper context, here is a scenario that comes up regularly at HSS DIY: a couple planning a summer wedding with a 200-square-metre open-sided reception marquee adjoining a smaller, fully lined anteroom used for the ceremony.
The open reception marquee uses two Industrial Evaporative Coolers positioned at opposite ends of the space for cross-ventilation. The units cool the air effectively as guests circulate, and the open sides allow the slightly moist air to escape naturally.
The ceremony anteroom, which is fully sealed and lined, uses a Commercial Portable Air Conditioner. The exhaust duct is routed through a small cut in the canvas at the rear of the structure, well away from the guest area. The room reaches a comfortable temperature around 30 minutes before the ceremony begins.
Total hire cost for a long weekend: approximately £550 to £600 depending on hire period. Compare that to the cost of unhappy guests, and it is very much money well spent.
Frequently asked questions
Can I use an evaporative cooler in a fully enclosed marquee?
Not as your main cooling solution. Evaporative coolers work by pushing moist air into the space, which requires that moist air to have somewhere to escape. In a fully sealed marquee, the humidity builds up and the cooling effect reduces significantly over time. For sealed spaces, hire a portable air conditioner instead.
How far in advance should I book cooling hire for an event?
We recommend booking at least two to three weeks ahead for summer events. During heatwaves, demand for air conditioner hire and evaporative cooler hire can outstrip supply quickly. Booking early via hss.com guarantees your kit is reserved.
How much does it cost to hire a portable air conditioner for a weekend event?
HSS DIY hire costs vary by product, but as a guide: the Compact 3.5kW unit is from £58.80 per week, the Commercial Air Conditioner from £95.52 per week, and the Industrial Evaporative Cooler from approximately £192.60 for a seven-day minimum hire. All prices include free delivery. Check current pricing at hss.com as rates are subject to change.
Can I hire an evaporative cooler for just one day?
Hire periods vary by product. The Industrial Evaporative Cooler has a minimum hire period of 7 days. Other products may have shorter minimum periods. Check individual product pages at hss.com for specific hire terms.
Do I need a professional to set up the cooling unit?
No. Both evaporative coolers and portable air conditioners from HSS DIY are plug-and-play. The evaporative cooler requires filling the water tank and switching on. The portable air conditioner requires routing the exhaust duct through an opening and plugging in. Setup typically takes 30 minutes to an hour. Difficulty rating: Beginner.
What if my marquee has both open and enclosed areas?
This is a common setup for larger events. Use an evaporative cooler in the open-sided areas and a portable air conditioner in any fully enclosed rooms or sealed sections. Both types are available to hire in one order at hss.com.
Keep it cool: the short version
A hot marquee does not have to be part of the story. Whether you are planning a wedding, a festival, a charity day or a garden party, getting the cooling right comes down to one question: is the space open or sealed?
Open-sided and ventilated? Hire an evaporative cooler from HSS DIY and enjoy lower running costs, simple setup and no ducting required.
Sealed or fully enclosed? Hire a portable air conditioner, route the exhaust duct outside, and your guests will be comfortable from the moment they walk in.
Both scenarios are well within beginner territory. The kit arrives to your door, sets up in under an hour, and goes back at the end of the hire period. No faff. No specialist knowledge. Just comfortable guests and a great event.
Buy the materials. Hire the tools. One order. All in one place.
Browse cooling hire at HSS DIY, available 24/7 with next day delivery: https://www.hss.com/hire/c/air-con-cooling
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