15 Alice Lane Annex

This is the sixth building in the Alice Lane Precinct and the context of this project had a profound impact on its design. The building has achieved a 4-Star Green Star SA Design V1 rating. While the construction period was a tight 19 months, it finished on schedule, and the project won the Construction World Projects Awards 2014.

The 15 Alice Lane Annex project is located in Sandton and was developed by Zenprop Property Holdings together with Growthpoint. An early decision was made to rehabilitate rather than demolish the structure, which complicated structural issues somewhat both vertically and horizontally. The original plan was stepped and this subsequently required the accommodation of 3 different grid systems across the building and into the interstitial surrounding spaces. Three of the existing five levels were retained and converted to parking. Combined with the existing super-basement below the precinct, this will provide 3500 parking bays.

An additional parking level and transfer structure were added as well as 5 storeys of office plates, each measuring between 3500 and 4200m². The length and width of these plates initiated the need for a single internal atrium running the length of the building that brings natural light into the spaces and reduces the plates to a more manageable size.  The transfer structure sits above P zero level and acts as a junction for the transfer of forces from one grid system to another.

The long narrow atrium accentuates the vertical circulation provided by two scenic elevators.  The ends of the building are softened with curved glazed ends which contrast with the concrete that flanks the main entrance. The resulting structure complements the plan, which is a parallelogram that accommodates all the geometric conflicts. External planting and cascading levels reduce the elevated scale of the entrance and provide a softer environment.

Sketch showing change of building plan

The building form is further softened and layered with the addition of aluminium screens, suspended off the full height glazing on the east and west elevations, to shade the building from the morning and afternoon sun. In addition to their functional role, the screens provide a powerful aesthetic to the building, expressing circular perforations on a regular grid to form a tree motif.

The concept of the tree motif continues into the building, informing the interior design. Tree patterns in various materials were added to the lobbies and ablutions to give an illusion of space. Back lit forest screens in the bathrooms illuminate the areas; and playful mirrors dot the walls and introduce movement throughout the space.