A sauna with a view: designing with glass, light and landscape

Start with the view, not the window

The traditional Finnish sauna was a dim room with, at most, a small window. Heat was precious, and the darkness was part of the calm. A panoramic sauna reverses that inheritance, so the first design question is not how much glass is possible but which single view deserves to be framed.

Most successful examples commit to one direction. At the River Sauna by Jensen & Skodvin at the Juvet Landscape Hotel in Gudbrandsjuvet, western Norway (2009), the building has one tall glass opening towards the river while the other three sides are covered in earth. The saunas are lined up along that glass facade and the changing rooms sit at the back. The result feels sheltered, almost cave-like, yet the river is always in front of you.

Orientation: view, sun and privacy

Three forces pull the window in different directions. The view sets the main axis. The sun path decides how the room behaves: a west-facing pane brings evening light and late warmth, while a south-facing one can overheat the benches and dazzle on a clear afternoon. Privacy depends on who might look back, from a neighbouring house, a footpath or the water.

Because people sit still on benches at different heights, it pays to check sightlines from each tier. A window that frames the horizon from the upper bench may show only the deck from the lower one. A sill set just above bench height usually lets the eye travel outwards while keeping bodies out of view from below. Low northern sun in winter reaches far into a room, which is welcome at the end of a dark afternoon but worth testing against glare.

Glass that holds the heat

Glass is the weakest thermal element in a sauna wall. Even a good insulated glazing unit loses far more heat per square metre than an insulated timber wall, so a large window changes the heating calculation. In practice the heater is sized for the real room, glass included, and the glazing is specified as a sealed double or triple unit rather than a single pane.

Comfort matters as much as energy. Research on windows and thermal comfort by Huizenga and colleagues at the University of California, Berkeley, shows that a cold glass surface draws radiant heat from the body and can set up a cool downdraught along the pane. In a sauna on a winter night, this can be felt as one cold side of the body, or as cooler air sliding down onto the lower bench. Better-insulated glazing keeps the inner pane warmer, which reduces that effect and also lowers the risk of condensation running down the glass and onto the timber below. Careful detailing of the frame, a drip edge and a sill that can tolerate moisture are part of the same task.

Safety near the heater and the benches

Glass in a sauna sees large temperature differences between the hot inner face and a cold exterior, and people sit and move close to it. For this reason glazing in sauna rooms is normally thermally toughened (tempered) safety glass. Glass made to the European standard EN 12150 is heat-treated to tolerate much larger temperature differences than ordinary float glass and, if it does break, it shatters into small, relatively blunt fragments rather than long shards.

Placement is the second layer of safety. Large panes are best kept out of the heater's direct radiant zone, and the heater manufacturer's minimum safety distances must be respected; the European heater standard EN 60335-2-53 requires installation instructions to state those clearances. Where glass runs down close to a bench or a step, laminated or toughened glass, a solid upstand or a handrail keeps knees and feet from meeting the pane directly.

Placing the sauna in the landscape

The site shapes the glazing as much as the brief does. By a lake, the view is usually low and wide, and the building often steps down the slope towards the water. At the Sauna in Ranco by Panorama Arquitectos on Lake Ranco in southern Chile (2009), the interior is arranged so that the joints in the timber lining lead the eye towards the large windows and out over the lake, while the exterior oak cladding is left to weather to grey.

In mountains and valleys, enclosure becomes the point: Jensen & Skodvin's earth-covered River Sauna offers one opening and lets the valley do the rest. In a garden, the scale is smaller and the view more intimate. Madeiguincho's 22 m² Sauna Garden Studio in Cascais, Portugal (2023), built in cryptomeria wood from the Azores, rises from a slope with two windows looking out over the landscape and an elevated platform on the rock beside it. On the coast, exposure to wind, salt and passers-by tends to push designers towards robust frames and an outer layer of screening.

Evening and winter light

A panoramic sauna is used most when daylight is short. After dark, an illuminated window turns into a mirror for those inside and a lantern for those outside, so the lighting plan decides whether the view survives the evening. Low, warm, indirect light below bench level or behind backrests keeps reflections in the glass to a minimum and lets the eye adjust to the snow, water or sky outside.

Exterior lighting should be modest and aimed at the ground or a single tree, never back at the window. In winter, a view of snow under moonlight or an ice hole lit by a lantern can be as strong as any summer panorama, provided the interior stays dim enough to see it.

Timber louvres and the route to cooling

Screening can give privacy without giving up the view. At Löyly in Helsinki's Hernesaari district by Avanto Architects (completed 2016), a free-form timber cloak of around 4,000 individually cut planks wraps the building. The lamellas work like venetian blinds: from inside they leave the sea in view, while from outside they block the view into the saunas. The same idea, at the scale of a single cabin, can be achieved with vertical or angled timber louvres set in front of the glass.

The window and the cooling area belong to one sequence. At Löyly, the saunas open onto a terrace and the sea, with swimming possible all year and an ice hole in winter. In a private sauna, placing the door and the glass so that the view continues from bench to deck to water makes the cool-down part of the same experience. A sheltered, screened terrace on the view side, reached in a few steps, is often more valuable than another square metre of glass.

AUREFJORD designs architectural outdoor saunas in which these questions of glass, light and landscape are part of the brief from the start.

Frequently asked questions

Sources

1. Löyly Sauna – Danish Architecture Center
2. Löyly – MyHelsinki
3. River Sauna by Jensen & Skodvin – Archello
4. Sauna in Ranco / Panorama Arquitectos – ArchDaily
5. Sauna Garden Studio / Madeiguincho – ArchDaily
6. Huizenga et al., Window performance for human thermal comfort – UC Berkeley eScholarship
7. BS EN 12150-1: Thermally toughened soda lime silicate safety glass – BSI
8. EN 60335-2-53: Safety of sauna heating appliances – iTeh Standards