Indoor Swimming Pool HVAC for Indian Hospitality — Dehumidification + Heat Recovery
By MEPVAULT Editorial Team · MEP Consultant · HVAC / Hospitality · 11 May 2026
Reading time ~ 9 min · Originally published: 04 May 2026 · Last revised: 11 May 2026
For a 25 m × 12.5 m hotel pool with 200 swimmers/day peak, the cooling load reaches 49 TR — 30 % of which is latent dehumidification from continuous water evaporation. DOAS + heat-recovery cuts annual HVAC energy 25-35 % vs standalone packaged dehumidifier. Three pool-hall failures we audit: RH > 65 % causing chloride corrosion, drafty pool deck, pool cover not deployed off-hours. Five non-negotiables — stainless-steel ductwork, independent pool AHU, heat recovery, dehumidification on emergency power, 24×365 operation.
Indoor swimming pool HVAC — the most complex sub-system in luxury hospitality
Indoor pool halls combine high latent load (continuous water evaporation), warm humid air (28-30 °C dewpoint), corrosive atmosphere (chlorine + bromine), elevated occupant comfort expectations (no draft, no chill), and 24×365 operating profile. For a 25 m × 12.5 m hotel pool with 200 occupants/day peak, the cooling load on a Mumbai summer day reaches 49 TR — 30 % of which is latent dehumidification.
Pool hall HVAC architecture — what works for Indian hospitality
| System type | Latent control | Sensible control | Energy efficiency | Capex (₹ lakh) | Best fit |
|---|---|---|---|---|---|
| Standalone packaged dehumidifier (PoolPak) | Excellent | OK | Moderate | 40-60 | Mid-tier hospitality, no central plant |
| DOAS + chilled-water FCU | Excellent | Excellent | Moderate | 55-70 | Luxury hospitality with central plant |
| DOAS + chilled-water FCU + heat-recovery | Excellent | Excellent | Best (25-35 % saving) | 75-95 | Luxury 5★ + sustainability target |
| Conventional FCU only | Poor | Excellent | Poor | 30-40 | Avoid — humidity issues guaranteed |
A 25 × 12.5 m hotel pool — DOAS + heat-recovery design walkthrough
| Parameter | Value | Source |
|---|---|---|
| Pool water surface area | 312.5 m² | geometry |
| Pool water temperature | 28 °C | spa/hotel typical |
| Pool hall design indoor air | 28 °C DBT / 55 % RH | ASHRAE Apps Ch 6 |
| Dewpoint | 17.6 °C | psychrometric |
| Evaporation rate (occupied, 200 swimmers/day peak) | 12 kg/hr | ASHRAE empirical formula |
| Evaporation latent load | 8.4 kW per swimmer hour + base 60 kW | calc |
| Outdoor air at 24 m³/hr/occupant | 4,800 m³/hr peak | ASHRAE 62.1 §6.2.2.1 |
| Outdoor air load at 35 °C/65 % RH | 55 kW | psychrometric |
| Heat recovery from pool exhaust → OA preheat | 35 kW recovered | design |
| Net OA load after HR | 20 kW | calc |
| Pool hall sensible internal load | 30 kW (lights + occupants + structure) | calc |
| Total cooling at design | 155 kW = 44 TR | calc |
| DOAS air flow | 18,000 m³/hr (3 ACH pool hall + 4,800 OA) | design |
| DOAS unit | 15 TR dehumidification + 5 TR sensible | vendor |
| FCU per zone | 3 × 5 TR distributed | design |
| Chiller plant tap | 50 TR dedicated (or shared with hotel) | design |
| Pool dehumidification + sensible at design 49 TR | — | — |
Three Indian hospitality pool HVAC failures — what we audit
- Pool hall RH > 65 % — water stains on ceiling, glass + fittings, chlorine corrosion of structural steel. Specify DOAS dehumidification + room dewpoint control feedback to BMS.
- Drafty pool deck — wrong supply diffuser selection. Cold air dumping at swimmer ear level. Use linear bar diffusers along pool edge at low velocity (1.5 m/s), or jet diffusers high-mounted at ≥ 4 m above pool surface.
- Pool cover not deployed off-hours — uncovered pool loses 4-5 kW evaporation continuously through the night. Automated retractable cover saves ₹4-6 lakh/year on dehumidification. Spec it.
Five non-negotiable design choices
- Stainless-steel ductwork in pool hall — chloride corrosion destroys galvanised steel in 2-4 years.
- Independent pool hall AHU — never shared with adjacent occupied spaces.
- Heat recovery from pool exhaust to OA preheat — 30 % HVAC energy saving.
- Pool dehumidification on emergency power — humidity excursion damages structure permanently.
- Active dehumidification 24×365 — never bypass during off-hours; humid air destroys finishes.
References
- ASHRAE Handbook — HVAC Applications 2023 Chapter 6 (Natatoriums + Indoor Swimming Pools).
- CDC Aquatic Health Programs — Recommendations for Indoor Pool HVAC 2018.
- Indian Pool Builders Association — Indoor Pool HVAC Guidelines 2024.
- ASHRAE 62.1-2022 §6.2.2.1 — Outdoor air for Natatoriums.
- ISHRAE Handbook 2024 — Section on Specialty Cooling Applications.
- FGI Guidelines for Design and Construction of Hospitals (referenced for spa/wellness areas).
- BS EN 13779:2007 — Ventilation for Non-Residential Buildings (referenced for natatoria).
- IGBC Green New Buildings v3.0 — IEQ + EE credits applicable to pool areas.
// About the Authors
MEPVAULT Editorial Team — A team of practising MEP consultants based in India. ISHRAE-affiliated; FSAI-aligned.