Saunas and cold plunges in Sandton, sized for 1,750 m

Altitude is in the sum

Thinner air carries less heat per kilowatt, so a heater sized from a sea-level chart underperforms here. We add capacity for altitude and say so in the quote, because a cabin that tops out at seventy degrees is a cabin nobody uses twice.

The dry Highveld winter is the other half: cold nights, low humidity, and a sauna that feels excellent from May to August.

Hail

Highveld summer hail is severe. Roofs get heavier gauge, upward-facing glass is specified for impact, and anything fragile lives under an eave. Thin polycarbonate rarely survives a bad storm.

The backup power advantage

Sandton households have among the highest density of inverters, batteries and solar in the country. Load shedding is over — more than 475 days without it — but that hardware is still there, and it is close to ideal: the chiller goes on a backed circuit, and the heater's heat-up window gets scheduled into the solar peak.