There is an unusual sight to be found in the small hamlet of Peka Peka, on the windswept west coast of New Zealandâ€™s North Island. At first, it looks like a series of modest hillocks, but on closer inspection some of them have windows and small white towers rise above the landscape like periscopes.
Friedrich (â€śFritzâ€ť) and Helen Eisenhoferâ€™s idiosyncratic dwelling lies beneath the grass of these knolls; it is a prototype domestic biodome for what Fritz, a modernist architect who was trained at the Kunstakademie in Vienna, has called the Eco Home. Fritz travelled from Austria to the Pacific in 1953 to begin a career there that now spans more than half a century.
The coupleâ€™s work on their shared home began in the late 1980s. While they chose the site for its proximity to the sea, another major factor was that, being among the sand dunes, the terrain lent itself to their dream of creating an earth-sheltered, low-cost, energy-efficient house.
The building is a series of sun-facing, faceted domes designed to store heat and conserve energy. Each was constructed with a thin shell of robust ferro-cement that contains the iron foundation that forms the skeleton of the structure.
The main dome, which covers the living area and â€“ more unusually â€“ an indoor swimming pool, is half submerged in the earth to a depth of 4m.
A closer look reveals two large glass panels, one facing north towards the southern hemisphereâ€™s midday sun, and another facing west to trap the sunlightâ€™s passive heat.
â€śOver the years, Iâ€™ve studied energy conservation and underground development around the world,â€ť says Fritz. â€śItâ€™s a unique way of building and has very low material costs.â€ť
Energy-efficient techniques of generating solar gain are common to many passive or sustainably designed buildings, and they have always been a key feature of Fritzâ€™s architectural exploration.
However, he took it a step further in his own house, creating a system he describes as a â€śrock storeâ€ť containing tonnes of river stones placed under and around the building as both insulation and a heat trap.
The rocks collect heat on warm days and then slowly release it, regulating the temperature inside the house. The system is complemented with rooftop solar panels that provide the two residentsâ€™ basic electricity requirements.
â€śThe heat exchange from the rocks tends to be very slow,â€ť says Fritz. â€śDay to day, we donâ€™t need to heat the dome at all, so our electricity requirements are extremely minimal.â€ť
The circular front door repeats the houseâ€™s dominant visual element and leads directly into the soaring, open-plan main dome. The all-white, jungle-filled interior has a warm microclimate, while the living areas on the ground floor are all oriented in relation to the indoor swimming pool, an unusual central feature that creates an ever-shifting interplay of light, water and foliage.
Fritz has created pools inside many of his projects, and the couple have had one in every house theyâ€™ve lived in. As the weather is highly temperamental on the Pacific coast, and winters can be blustery and cold, the couple rarely swim in the sea. The ozone-treated pool, however, can be used in any season.
Higher than usual humidity levels are one downside of this otherwise happy arrangement, says Helen. However, the glass wall was designed to extend to the base of the dome, so any condensation drains into the garden.
â€śItâ€™s also very calming sitting at the dining table seeing the reflection of the water dancing on the ceiling. Itâ€™s something to wake up to every day,â€ť she adds.
The couple chose plants that are known to be effective at cleansing the air, including peace lilies, banana palms, ferns and palm trees.
â€śOver the years, weâ€™ve tried different things,â€ť says Helen. â€śItâ€™s been a system of trial and error, but weâ€™ve discovered peace lilies are best as theyâ€™re not affected by humidity â€“ and theyâ€™re a lovely white or red, so they make beautiful indoor displays.â€ť
As the curved interior walls arenâ€™t suited to traditional furniture, the leather seating throughout the house was custom-made by the Auckland-based firm UFL to Fritzâ€™s specifications. He then designed and hand-built the dining and coffee tables using recycled and repurposed materials.
The exceptions to this are the Eero Saarinen Tulip dining chairs, and the hardy Corian work surface in the kitchen. â€śWeâ€™ve had the Corian for 20 years and itâ€™s fantastic,â€ť says Helen. â€śIt still looks new and itâ€™s not too cold to the touch.â€ť
Fritz planned the compact, U-shaped kitchen to be simple yet efficient. Divided from the dining room by a breakfast bar, inside the kitchen cooking is arranged on one side, and the fridge on the other, connected with worktops to either side of the sink bench in the middle for economy of movement.
The mezzanine level above holds Fritzâ€™s studio, the coupleâ€™s bedroom and a bathroom. Also, two steps up from the bedroom, is a second living area that can be divided off from the main space with a vertical blind. It has views out over the sea towards Kapiti Island, a nature reserve that sits just off the coastline.
â€śI think the best part of living in such an unusual dwelling is the huge open space we are lucky to spend most of our time in,â€ť says Helen. â€śIn fact, I now find smaller rooms slightly confining. The other key factor is the peace and tranquillity, as so little noise comes into the dome from outside. Playing music is a joy because the whole space fills with sound like a bandshell. After so many years living here I would find it difficult to live in a conventional house.â€ť