The Finns know how to do winter. This open-plan Helsinki penthouse is warm and inviting while still being bright and airy. It´s the perfect pad for hunkering down.

Few cities experience such extreme seasons as Helsinki. After the giddiness of summer when the sun barely dips below the horizon and every night is celebration of life outdoors, winter descends like a slushy, bleak punishment for having had it so good. Anyone brought up on Tove Jansson´s Moomins will remember the foreboding of winter with the blocks of black and white etchings, which meant snow, darkness and uneventful hibernation. But Helsinki´s residents are well prepared for both bronzing spells by the Baltic and for Gore-Tex, gloves and gumboot expeditions during winter (remember Nokia began life as a rubber boot maker). And so are its buildings.

On the top of a five-story 1924 apartment building designed by renowned Finnish architect Lars Sonck, we´ve found the perfect place to celebrate winter. Coming in from the cold, you enter an original wood-panelled Kone lift, complete with foldaway bench, concertina grille and brass Kone plaque. It shuttles you smoothly to the top of the building with enough time to remove hat, scarf, gloves and unzip your jacket. This is a shoes-off apartment but the oak floor is warm and there´s a vibrant Alexander Calder painting in the small hallway to admire while you heave off your boots. 

The 180 sq m apartment today is not as Sonck designed it. The current owner, with a little help from an architect friend and some expert Finnish and Estonian workmen, ripped out the six rooms and servant quarters and transformed it into an open-plan penthouse in 2005. Incredibly, this took just eight months. Thanks to Sonck´s experimental structure, in which the roof is supported not on walls but on iron and concrete columns, it is a cavernous space, punctuated only by a couple of columns, a kitchen unit and a bookcase. The clean, white space is like a blank canvas for the owner´s extraordinary collection of Finnish furniture, glassware and ceramics. It´s like an ode to Finnish design, peppered only with a few foreign objects – a low, grey wool Zanotta sofa, a couple of Le Corbusier club chairs and a late 19th-century Russian glass chandelier in the bedroom. There´s plenty of time here in winter to live with these things, to look at them, think about them, use them. After all, what´s the point of collecting such pieces if you don´t spend time with them?

But for all the many beautiful things here the owner describes himself as a minimalist who hates handles. He marvels over the seamless edge of the Corian kitchen sink and bathroom basin. The floor-to-ceiling cupboards (handleless, of course) reveal yet more Wirkkala glassware – this is no place for curious toddlers. He recessed the lights and all electronic into the walls to keep the lines pure and laid a caramel-coloured Canadian oak floor throughout, to soften the effect of the white and give the apartment an earthly warmth. From the balconied bathroom it´s just a short hop to the built-in alder wood sauna.

Life up here is indulgent, surrounded by birds, books and beautiful furniture. When the sun shines outside, the whole apartment, with the white walls and all that brass and glass, glows. The owner puts Bach on the surround sound system and suddenly you could be standing in a cathedral. The apartment has an extraordinarily transcendental and also elemental quality to it.

Asked if he ever feels lonely he says he has friends over for long feasts and sauna sessions – there´s certainly no shortage of Artek chairs and stools for a merry gathering. But many Finns, like the Moomis, admit to bedding down and enjoying solitude in winter. And with a city centre nest like this, who wouldn´t?