Outdoor diving pool

Night covers (slatted roll covers, floating blankets) cut in-season evaporation by 85 %, night radiation loss by 90 % and wind convection by 70 %. Material: PVC-laminated (cheap, 5-10 yr life) or polycarbonate slats (15-20 yr, 2-3× the price). For a 1,505 m² water surface at 100-150 €/m² including drive = 150-225 k€ — depending on how many separate systems are needed. A 40 % regional climate grant is possible.

Basis: DGfdB + manufacturers (Grando, Coverstar, Hytex)

Outdoor pools have higher convection and radiation losses. Convection: h_conv = 4 + 11 × v_wind [W/(m²·K)] with v in m/s. At 1 m/s wind: h ≈ 15 W/(m²·K). Night radiation (clear sky): ~60 W/m² over a 10 h night. Solar gain during the day (global radiation × absorptivity 0.82 × 12 h) is a credit — in high summer it can drop the heat demand close to zero. A night cover reduces both evaporation (−85 %) and radiation loss (−90 %).

Basis: VDI 2089 Sheet 2

DGfdB guideline R 60.03 on heating public outdoor pools: heat-up phase in April over 30 days, raising the set-point from 10 to 22 °C; slow heat-up (45 days) or solar absorbers as a pre-heat stage save energy. For 2,508 m³ of water × 12 K × 1.16 kWh/(m³·K) = 34,928 kWh — spread over 30 days that is 1,164 kWh/d of extra load. Recommendation: heat up via a pool heat pump on a warm source (backwash water already at 15 °C before season start) instead of a gas peak boiler. A pool cover shortens the time (solar gain by day, loss reduction by night).

Basis: DGfdB R 60.03

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

This regional climate-protection directive funds municipal climate investments at 40 %. It applies specifically to efficiency measures such as pool covers, LED lighting and pump replacement. It can be combined with ISEK provided the measures differ. Example: an outdoor-pool night cover (80 k€ investment, 17 k€/a saving) is ideal — payback with this grant is 2.8 years.

Basis: Regional climate-protection funding directive