Pool hall climate

VDI 2089 Sheet 1 defines the target hall climate: air temperature 30 °C ± 2 K, relative humidity 55 % ± 5 %. Outdoor-air rate at least 30 m³/h per person at full occupancy, at least 4 L/(s·m² of water surface) in base mode. For a hall with 355 m² water surface: 4 × 355 × 3.6 = 5,112 m³/h minimum; in practice VDI recommends ~16,000 m³/h for comfort and pollutant removal (trihalomethanes). Heat recovery via plate exchanger at 65-75 % efficiency is standard.

Basis: VDI 2089 Sheet 1

Evaporation from the water surface is the dominant heat loss in an indoor pool (60-80 %). Smith/Löf variant of the Carrier formula: m_evap [kg/h] = β × A [m²] × (p_w_pool − p_w_hall) [kPa]. β-coefficient per VDI 2089 Sheet 2 Tab. 4: 0.013 unused pool (covered), 0.040 normal use, 0.080 wave/diving pool. Evaporation enthalpy at 30 °C: 0.694 kWh/kg. Pool saturation vapour pressure via the Magnus formula: 611.2 × exp(17.62 × t / (243.12 + t)) Pa.

Basis: VDI 2089 Sheet 2

The German Buildings Energy Act GEG 2024 treats pools as non-residential buildings. Mandatory air-conditioning inspection every 4 years (ventilation > 12 kW). On change of ownership or major refurbishment, tighter envelope U-values apply (external wall U ≤ 0.24 W/(m²·K)). A demand-based energy certificate is required above 250 m² of heated floor area. A hall pool with 1,800 m² of envelope at U=0.8 does not meet new-build standards — so grant funding for envelope refurbishment (up to 35 % rate) is available.

Basis: GEG 2024 (German Buildings Energy Act)

When hall humidity is too high (rH > 65 %) the traditional fix is raising the outdoor-air rate — which doubles the heat loss in winter. The modern approach is a dehumidifying heat pump (sorption wheel or reversible compressor) that removes water directly from the hall air without raising outdoor air. Investment 30-80 k€ depending on size, payback 4-7 years. On a hall running 16,000 m³/h in cold winters a sorption wheel can save 30-50 % of the ventilation heating energy.

Basis: VDI 2089 Sheet 1

DIN 1946-4 governs ventilation with hygiene requirements. For pool halls: filter class F7 minimum, 6-month service interval. Plate heat-recovery exchangers must be able to drain condensate. Hygiene inspection every 2 years (logged in the maintenance record). Pool-specific: because of chloramines, corrosion-resistant materials (V4A stainless, plastic) are required in the exhaust stream; aluminium exchangers are not permitted in the pool-hall exhaust air.

Basis: DIN 1946-4