The site was found as a series of cellular servants rooms in the attic of a Grade II listed 1928 Beaux-arts mansion block in Marylebone, lain empty in disrepair since the 1950s.

The new 45-meter long terrace connects two oak-panelled rooms, occupying two wings. Inhabitable apertures link the panelled rooms to the terrace which are perforated with a forest of holes. The perforations in the apertures and in the skylights create a forest of light through which the apartment breathes; cooling, heating, and lighting itself. Directly below the skylights, bespoke Corian objects, bathed in top light, signify the rooms’ functions.

What was the brief?
Despite the building’s Grade II listed status, Tonkin Liu were able to gain permission from English Heritage to completely remodel the 265 sq m apartment with a contemporary interior. The apartment is arranged in an L-shape, composed of two main wings that look out onto a 45-meter long terrace. Each wing has a timber-paneled room around which all of the other accommodation is arranged. The first room is centered around food and study and is referred to as the refectory.

The second room is centered around relaxing and sleeping and is referred to as the salon. The treatment of the apartment with its controlled rooms surround by subservient spaces is inspired by the beaux-arts suite of rooms in the building’s foyer. Wall paneling has been used in the apartment to conceal the slope of the attic’s mansard roof, creating a cavity for storage around the controlled perimeter of the main rooms. The fixed objects in each wing signify its primary function. The refectory has a kitchen island, a dining table and an octagonal study desk all made in white Corian. Each has a skylight of exactly the same size directly above it to bring in natural day light where it is required and elevate the importance of the domestic rituals that the fixed objects serve. The oak veneered panels in the refectory are vertically hinged panels with vertical grain to reflect how the refectory will be occupied, predominantly as a standing space. The salon, a place for reclining, has horizontal sliding panels with horizontal grain, opening on to rooms for sleeping. The ritual object in the salon is a fireplace, which stands at the entrance to the master bedroom. The fire can also be seen from the master bed and the master bath.

The salon’s sliding panels conceal a library, a study, and guest bedroom as well as building management control room and audiovisual equipment. The salon can be transformed into a cinema with automated sliding panels that reveal a projection screen or plasma screen. Alcoves in the refectory, salon and link gallery feature off-set hinges so that the timber framed doors can fold back against the mansard, providing unhindered views out on to a 180 sq m terrace and beyond to the rooftops of central London. The alcoves are lined with white powder-coated perforated aluminium panels, perforated with a forest of trees.

Why is it called Breathing Forest?
The perforated forest breaths. Its primary function is to ventilate the rooftop apartment. Living on the skyline above the rooftops of Portland Place the apartment is constantly in the eye of the wind. Behind the perforated screens are computer controlled panels that open and close to adjust the internal temperature of the apartment without letting sudden gusts of wind disrupt the tranquil interior. The forest breaths gently as it utilises the principles of the thermal stack effect.

In summer evenings the opening of the lower flaps also brings in the scent of LAVENDER from the terraces that has enjoyed a full days exposure to the sun. The perforated apertures in the wall also supply all the heat to the apartment with flat panel radiators concealed behind the perforated linings. The ceiling is an uninterrupted plane, unpolluted by functional components; the thermostats, smoke detectors, heat detectors, cooker extract and speakers are all hidden behind the perforated branches of the ceiling apertures, allowing the decorative apertures to perform a practical purpose.

How is the project unique?
While the daily and seasonal changes taking place with heating and ventilation are all performed discretely behind the perforated screens, the changing light of day and night becomes a more visual performance. During the day the natural light is balanced by the interplay between skylight and windows and the perforations of the tree patterns become dark holes on a light background. As darkness approaches, LED lights concealed in the wall project light through the perforated panels. The colour of the RGB lights can be controlled to reflect the sky – from blue through to red - or create different mood in the apartment.

The fluorescent tubes concealed in the ceiling panels create a soft reflected glow to the aperture for general illumination while halogen spots on concealed tracks project direct light to the working surfaces below. At night the lighting can be balanced from wall to ceiling apertures and from inside to out by turning on the terrace’s external lights.

Has the project won any awards?
RIBA London Award 2010