Planning an indoor swimming pool:
Costs, technology & design
Swim all year round, whatever the weather! Is an indoor swimming pool worthwhile for your home? The answer depends less on the size of the pool than on the quality of the planning. The decisive factor is that architecture and technology are considered as a unit: A diffusion-proof building envelope with few thermal bridges meets precisely controlled dehumidification with heat recovery, plus quiet and draught-free air routing on glass surfaces. This results in pleasant temperatures, clear panes and permanently dry building components, the basis for comfort and value retention.
What really matters in everyday life? A stable room climate and efficient operation. In practice, 28-30 °C water temperature, an air temperature just above this and around 55-60 % relative humidity have proven their worth. We achieve this balance with duct-guided dehumidification systems and an underfloor cover that massively reduces evaporation. In addition, speed-controlled pumps, demand-based control and, if desired, PV self-consumption ensure noticeably lower operating costs.
To help you plan realistically, we provide reliable guide values: for an indoor project of around 3×8 m, a total investment of around €180,000-320,000 is typical, depending on the structure, pool material and proportion of glazing. The monthly energy costs for a consistently closed cover are usually around €250-500; water, chemicals and maintenance cost around €50-120. These margins are not an end in themselves, but the result of clear priorities: a good shell, clean dehumidification, harmonious hydraulics.
- Oliver Range
- 28. August 2025
Why an indoor swimming pool?
If you want to swim all year round, an indoor swimming pool brings real quality of life into your home: 365 days of exercise, regeneration and stress relief, regardless of the weather. At the same time, the private retreat creates maximum planning flexibility and security for the family. With high-quality planning and a technically sound design, an indoor swimming pool also increases the value of the property and becomes an architectural highlight.
Space & structure: the basis for comfort
An indoor swimming pool is a room-in-room system: construction, waterproofing and insulation work together with the building technology. For a 3×8 m pool with edge zones, you should calculate with 40-60 m² of hall area and a clear height of at least 2.6 m – so there is enough space for the technology and air flow.
The building construction follows the principle of diffusion-tight levels with thermal bridge-free connections and moisture-resistant materials (e.g. XPS and mineral systems). Generous glazing is possible if triple insulating glass and heated edge zones or an air circulation curtain prevent condensation on cold surfaces. Acoustics are just as important: absorber ceilings and wall-side panels dampen reverberation and ensure a quiet, feel-good atmosphere.
Pools & materials: GRP, concrete or stainless steel?
The choice of material determines the installation time, design scope and budget. GRP monolithic pools impress with their quick installation and very homogeneous surfaces. In-situ concrete with tiles offers maximum freedom for shapes as well as overflow or infinity solutions and is extremely durable when professionally sealed. Stainless steel pools are considered the premium option: durable, hygienic and visually very clear – usually with a higher investment. For comfortable lane swimming, widths from 3 m and lengths from 8-10 m make sense. Comfortable steps, benches and an optional counter-current system increase the utility value. The underfloor roller shutter cover is standard in the interior: it ensures safety, a calm water surface and, above all, significantly less evaporation and energy loss.
Indoor climate & dehumidification: Feel good without condensation
Comfort and building protection depend on stable climate values. A water temperature of 28-30 °C(therapy up to 32 °C), an air temperature just above this(+1-2 K) and a relative humidity of around 55-60 % have proven to be effective. This balance keeps surfaces warm, prevents condensation and avoids draughts.
In practice, we rely on duct-guided dehumidification systems with heat recovery. They push tempered supply air along large glass surfaces and return humid air to the ceiling area, keeping windows clear and components protected. Recirculating air dehumidifiers can be useful in smaller halls or as a supplement. For a pleasant background noise level, devices are decoupled, ducts are insulated and low-flow grilles are used – the result is a conversational volume instead of technical noise.
Water treatment & technical room
Clear, skin-friendly water is the result of the interplay between filtration, disinfection and control. Multi-layer or glass filters remove particles, speed-controlled pumps keep the hydraulics running efficiently at the optimum level. The dosing technology takes care of pH correction and disinfection, either classically with chlorine, by salt electrolysis or in combination with UV/ozone to significantly reduce bound chlorine. For systems containing salt, we pay attention to consistent corrosion protection, from fasteners to dehumidification. A clearly planned technical room with good access, drainage and sound insulation facilitates maintenance and keeps operation quiet. Smart Control with sensors for temperature, humidity, COâ‚‚ and VOC controls ventilation and cover logic as required and saves energy.
Energy & operation: Efficient swimming
A consistently used underfloor cover, heat recovery inthe ventilation system and demand-based control have the greatest influence on efficiency. Heat is supplied by a heat pump or, if there is an existing heating system, a heat exchanger; PV self-generated electricity can significantly reduce the annual costs. For a 3×8 m pool with 30 °C water and a consistent cover, the monthly energy costs are typically around €250-500, plus around €50-120 for water, chemicals and maintenance, depending on the building envelope, usage profile and energy prices.
Operation & service: Water care, maintenance, spare parts
Everyday life with an indoor swimming pool should be simple and plannable. Automated measuring and dosing technology keeps the water values stable; visual and functional checks can be integrated into weekly routines. Filter maintenance, leak and safety checks and updates to the control strategy are carried out at longer intervals. In the event of a malfunction, accessibility and availability of spare parts are important to ensure that operations are quickly restored to a stable state. A regional partner from our bluegardens network often takes over the complete service, from instruction and seasonal inspections to the optimization of the heat pump, dehumidification and cover logic.
Cost overview
As a guide value for the structure of an indoor swimming pool with 40-80 m², thermally separated and moisture-optimized – a quality level of around € 2,000-3,000 per m² applies. This means that the pure hall construction usually ranges between around € 80,000 and € 240,000. The pool itself is determined by the material and equipment: GRP/PP pools in common sizes (approx. 3.3-4.0×8 m) are often around €25,000-40,000, concrete/tile around €30,000-50,000, while stainless steel as a premium solution starts at around €55,000-60,000 and can be higher depending on special details.
You should budget around €15,000-35,000for ventilation technology including heat recovery, ducts and installation. For water heating (heat pump or heat exchanger), around € 2,000-8,000 is sufficient in many projects. Depending on the design, an underfloor cover costs around €15,000-23,000 and saves energy during operation. Experience has shown that planning, statics and construction coordination account for around 5-12% of the total of construction and technical trades.
These building blocks result in a valid total corridor of around €180,000-320,000 (net) for a high-quality 3×8 m reference project with heat recovery ventilation and cover. The region, proportion of glazing and individual design can shift these ranges up or down.
bluegarden’s network partners (indoor swimming pool – selection)
Depending on the location, we work together with specialized members.
Backers Zwembaden & Wellness in the Netherlands realizes private swimming pools with wellness, including sophisticated inland pools with planning, installation and service from a single source.
In Luxembourg Delvaux supplies turnkey pool and wellness projects and has extensive experience in cover systems (e.g. Coverseal) and design integration.
In Germany, the ENOP GmbH as an independent institute for energy, building physics, sealing and acoustics, supports the planning phase, ideal for reliable moisture and efficiency certificates.
For planning and realization in southern Germany Poolbau Hirsch (Möglingen, Stuttgart region) is available with strong implementation expertise. Customized PP pools from Carropools as well as solutions from GRP to stainless steel. Accessories and maintenance are also offered.
In addition Well Solutions based in Eich (Rhineland-Palatinate) takes care of ongoing operations: water care, maintenance, spare parts and chemical supply as well as the optimization of technology (e.g. dosing, heat pump, cover), with on-site service and showroom advice on request.
Service areas & coordination
bluegardens coordinates indoor pool projects in Germany, Luxembourg and the Netherlands. Depending on the project profile, we match the right team from planning, construction, technology and operation, from preliminary planning to commissioning and ongoing support.
What does an indoor swimming pool cost?
For a reference project with approx. 3×8 m, duct-guided dehumidification with heat recovery and an underfloor cover, the total investment is usually around € 180,000-320,000 (net). Location, proportion of glazing and equipment shift the corridor.
How high are the operating costs of an indoor swimming pool?
With a water temperature of 30 °C and a consistently closed cover, we calculate around € 250-500 per month for electricity/heat plus around € 50-120 for water, chemicals and maintenance. The cover, control strategy and energy prices have a direct impact.
Do I need planning permission for an indoor swimming pool?
As a rule, yes – especially for extensions or conversions. We take care of the preliminary inquiry, documentation and coordination of clearances, fire protection and moisture protection certificates.
Is salt water in the interior uncritical?
Yes, provided that materials, fasteners and dehumidification are selected and designed to be corrosion-resistant. Salt electrolysis reduces bound chlorine; the air flow protects components and glass surfaces.
How loud is the dehumidification?
With decoupled installation, insulated ducts and low-flow grilles, we achieve a pleasant conversation volume – technical noise is avoided.
