Discharge air
Ventilation/dehumidification — the silent 24/7 load, with heat recovery. Part of the glass family — like our glass BESS, biogas plant and CHP.
Outdoor air → Fresh air → Heat recovery → Heating coil → Hall → Exhaust
Ventilation/dehumidification — the silent 24/7 load, with heat recovery. Part of the glass family — like our glass BESS, biogas plant and CHP.
The discharge air is the air that leaves the building after heat recovery. Its temperature is the key health indicator of the recovery unit: the colder the discharge versus the extract, the more heat was recovered.
At the design point (−12 °C outdoors), 63–65 % recovery leaves the discharge only a few degrees warm. A rising discharge temperature is an early warning: the recovery unit is fouling or the bypass damper is stuck (chain K01).
Dehumidification with heat recovery (DIN 1946-4, 36,000 m3/h):
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Method proven on a live European reference aquatic center; presented anonymously.
Estimate from metered / design values. Zero-grid-import windows are real (metered).
Grounded in DIN 19643, VDI 2089, DGfdB and the German Buildings Energy Act. Same knowledge base as the European reference site; presented anonymously.
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
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
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
DGfdB guideline R 65.10 fixes the order for refurbishments: 1) reduce losses (envelope, pool cover, insulate the surge tank, ventilation heat recovery), 2) recover heat (heat recovery, waste-water heat, filter backwash as a heat-pump source), 3) generate efficiently (heat pump > CHP > gas). This hierarchy is decisive for public grant applications: funders check whether losses were reduced before the generation investment. Concretely: insulate the surge tank, add an outdoor-pool night cover and service the ventilation heat recovery before or together with the heat-pump installation.
Basis: DGfdB R 65.10
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