Planning note · Outdoors
An outdoor sauna and a wooden tub at 45 °C: plan the year, not the product
In the Gulf an outdoor suite has two lives: the cooler months, when the cabin is the reason to be outside, and the hot ones, when the cold tub carries the terrace. Plan both, and the equipment choices follow.
The first question to put to outdoor equipment in the Gulf is whether it can survive August. The better one is when it will be used. A suite designed for the hours people actually go outside will be smaller, cheaper and calmer than one designed to defy the sun at noon.
Two seasons, two jobs
The table gives published climate normals, the mean daily maximum in the two hottest months and the mean daily minimum and maximum in January, from each country's meteorological service via the WMO World Weather Information Service. The normal periods differ by station and some are old, so read them as the shape of the year rather than the weather of one summer.
| City | Hottest months: mean daily maximum | Coolest month: mean daily minimum and maximum |
|---|---|---|
| Riyadh | 43.7 °C in July and August | January: 6.9 °C at night, 20.1 °C by day |
| Jeddah | 39.4 °C in July, 38.7 °C in August | January: 18.2 °C at night, 28.9 °C by day |
| Dammam | 45.0 °C in July, 44.7 °C in August | January: 9.6 °C at night, 21.0 °C by day |
| Doha | 41.5 °C in July, 40.7 °C in August | January: 12.8 °C at night, 21.7 °C by day |
| Kuwait City | 46.7 °C in July, 46.9 °C in August | January: 8.5 °C at night, 19.5 °C by day |
| Bahrain | 37.9 °C in July, 38.0 °C in August | January: 14.1 °C at night, 20.0 °C by day |
| Muscat (Seeb) | 38.0 °C in July | January: 16.7 °C at night, 25.1 °C by day |
In the cooler months a cabin ready in about 40 minutes is a pleasure on a terrace and a warm pool is a reason to stay out. In the hot months the cabin is a night and early-morning feature and the cold tub or pool is the daytime one. A layout should say which is which.
What sun does to a tub
A 520 L round timber tub has a water surface of about 1.1 m². Midday sun delivers close to 1 kW to each square metre and the water absorbs most of it, so an uncovered tub in full sun takes in roughly 0.8 kW from the sun alone, before the heat from the air and from the shell. Cooling a 520 L tub from 30 °C to 4 °C means removing about 16 kWh of heat; a chiller that also has to fight the sun on a bare surface runs almost without a break.
| Cover | What it does | Effect on the load |
|---|---|---|
| Nothing | full sun and moving hot air on the water | highest; the chiller never rests |
| Shade cloth or a tree | stops the sun, not the hot air | removes the largest single gain |
| A slatted pergola | shade with airflow | close to shade cloth, and it looks better |
| An insulated lid | stops sun, air and evaporation | lowest; the chiller idles in short cycles |
| Pergola and lid | shade by day, lid by night | what we draw for a tub in direct sun |
The cabin outdoors
- Heat loss. An outdoor cabin loses less heat on a hot night than an indoor cabin next to cold air conditioning, because the temperature difference is smaller. It still needs insulation and sealed joints against dust.
- Surfaces. A timber exterior in full sun can be hot to touch; handles, steps and rails are shaded or built from materials that do not hold heat.
- Glass. Faces that look at the afternoon sun need shade; see glass-front saunas in desert heat.
- Wind and sand. On a roof the cabin is anchored to the structure; door seals and a cleaning path matter more than they do indoors.
The cabins are described under terrace and rooftop saunas and the tubs under wooden cold tubs; how a hot, dry inland site differs from a humid coast is on the Riyadh and Jeddah pages.
A day in July, a day in January
| July | January | |
|---|---|---|
| Cabin | switched on after sunset, used late | switched on in the early evening, the main event |
| Cold tub | used at dawn and after dark, lid on between uses | used between rounds in the cabin, lid still on at night |
| Shade | pergola and lid both in place | pergola stays, lid optional |
| Chiller | short cycles on a covered tub | barely works |
Materials that cope with sun
Timber for a tub's staves is thermally modified ash, which is stable in heat and takes outdoor oil; the liner is smooth white fibreglass, which does not weather and is easy to wipe. Both are oiled or wiped on the schedule in the care sheet. A rim that lies in direct sun gets shade because a surface at 60 °C is not a comfort feature.
A season-by-season check
| Season | Cabin | Cold tub or pool | Shade and cover |
|---|---|---|---|
| Spring | service the heater and seals before the heat | service the chiller, clean the filter, check hoses | inspect the pergola and the lid |
| Summer | evening and night use; keep glass shaded | dawn and night use; lid on between uses | lid on whenever the tub is not in use |
| Autumn | first heavy use as nights cool | chiller idles more; rinse the filter | lid optional at night |
| Winter | the main season; check ventilation | cold tub between rounds | shade stays; lid for dust |
Dust storms and the day after
Keep the lid on the tub when sand is in the air, rinse the filter after a storm and wipe the glass before the heater is switched on, not after. A tub that is covered by habit loses very little during a storm and needs only a rinse.
Sensible limits
Outdoor sessions follow the same safety rules as indoor ones: adults only, seated stays in the cold, no use alone, plenty of water to drink, and a doctor's advice first for anyone with a heart or blood-pressure condition. The layout lists the points where a person can sit, hold on and get out.
Can I use a cold tub at noon in July?
You can, if it is shaded and covered. In the sun with no cover the water warms faster than the chiller can cool it, which is why the tub comes with a pergola and a lid.
Is an outdoor sauna worth it if I only use it in winter?
A cabin used from October to April is a perfectly good purchase. Combine it with a plunge so the terrace has a feature in summer too.
What happens to the timber in the sun?
Thermally modified ash is stable and takes oil well; it needs oiling on the schedule in the care sheet and shade for the rim.
More from the journal
Further notes from the plant room
Glass saunas in desert heat
Toughened glass, heat loss in kilowatts, sun and thermal stress, and what the air-conditioning engineer needs to know.
Open the page
Chiller sizing at 45 °C
Three loads, two worked examples and the reason a plunge in the sun needs a different machine from one in the shade.
Open the page
Sauna, steam or hammam
Four rooms that buyers order with one word: plain definitions, what the Arabic phrase for steam sauna really asks for, and how to write the brief.
Open the pageFrom the note to your site
Tell us the terrace and the hours you want to use it: we plan the shade and the plant to match
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Send a plan or three photographs of the space and say who will use it. The project desk answers with questions first, then a 3D layout and an indicative range.
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