System 02 · Hot and cold
Two pools, one step apart: 38 °C and 4 °C
A warm pool and a cold plunge share a wall, a step and a plant room. Guests move between them in seconds, and the building pays for one set of services instead of two.
A warm pool next to a cold one changes how people use a spa deck. Nobody has to walk to another room to reverse the temperature, so the cycle can be repeated without anyone leaving the deck. For a hotel, a club or a villa that entertains, the arrangement keeps the whole routine in one place.
Where it works, and in which months
Indoors, the warm pool is a year-round feature. Outdoors in the Gulf it follows the season: in the cooler months, evenings are cool enough for a 38 °C pool to be welcome, and in the hottest months the same deck runs the cold side hard and keeps the warm side switched off or lightly tempered. Plan the first conversation with the guests' calendar in mind, not the brochure's.
What is shared and what is not
- One plant room. The chiller for the cold side and the heater for the warm side live together, which means one set of power, drains, ventilation and service access.
- Separate water. Two circuits, two filters, never mixed: the warm pool's sanitiser is watched more closely than the cold pool's.
- One step and one wet edge. A stone step between the pools keeps the walking distance to a stride and the wet area compact.
- Two temperature panels. Each pool carries its own small display at the rim.
Whether the cold side's rejected heat can warm the other pool is a fair question to put to the project engineer: the physics invites it, and on an indoor pair running all year the saving could be real. We settle it in the layout, not in the brochure.
Sizes and footprint
| Warm pool | Cold pool | |
|---|---|---|
| Size | 1.6 × 1.2 m warm pool | 1.2 × 1.2 m cold pool |
| Set point | 38 °C | 3–5 °C, ±0.3 °C |
| Seats | two or three adults | two adults, one on the edge |
| Use | soaking, resting between rounds | short dips, then back to the warm side or the cabin |
The two pools add up to about 3.4 m² of water; allow the shared step and a working margin of 600 mm on the open sides, and a few square metres of plant room within reach.
How many guests a pair can serve
Take the stays as assumptions and the arithmetic is simple. If a guest spends about ten minutes in the warm pool and two in the cold one, the warm pool (three seats) serves about eighteen guests an hour and the cold pool (two seats) about sixty dips an hour. The warm pool is the bottleneck, so a deck that expects thirty guests an hour at its peak adds a second warm pool or a glass cabin beside the pair rather than a bigger cold pool. Change the stay times and the answer changes; the layout asks you for yours.
Who orders pairs
Hotel spas and resort decks (hotels and resorts); padel and fitness clubs that want members to stay and spend (fitness and padel clubs); residential towers adding an amenity floor (developers and residences); and large villas with a guest wing. A pair beside a glass sauna is the layout in the Riyadh padel club profile.
What a pair costs
Indicative range for a complete pair, both pools lined and finished, with its plant: $27.7–48k (SAR 104–180k). Civil works, utility connections, permits, shade and any duties are quoted separately; the price guide lists what each range assumes.
Does the warm pool need a separate heater?
Yes. It has its own heater and circulation, because warm water needs closer attention to sanitising and puts a different load on the filter than cold water does. Both sit in the same plant room.
Can the warm pool be run in July?
It can, but outdoors it is rarely wanted from June to September; it can be set to a mild temperature or switched off, and the deck used as a cold deck. Indoors it runs all year.
Can a pair be added to an existing deck?
Often yes, if the slab can take the recess and a plant room or niche can be found within a few metres. Send photos and a plan, and we will mark what has to change.
Do both pools need to be the same finish?
No, but matching finishes read as one object. A darker tile on the cold pool makes the water look cooler, which suits it.
Other systems
What usually stands behind a pair
Built-in cold plunge pools
Round or square, flush or with a seat edge, 3–5 °C all year. Built into the floor, with the plant out of sight.
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Panoramic glass saunas
Full-height glass on one or two walls, 1 to 12 seats, Harvia heaters. Cut to the room and the heat load.
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Terrace and rooftop saunas
Free-standing cabins with one or two glass faces, flat roof, screens and shade. Made for 45 °C summers and cool winter evenings.
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Send the deck plan: we place both pools, the step and the plant room
The pair is drawn as one object, so the plant room, the drains and the shade are decided together.
One message starts the layout
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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