Architect and Builder Magazine South Africa Dec 2017 / Jan 2018 - Page 79

The roof space is treated as a ‘fifth elevation’ and a usable space. It is landscaped and utilised as breakaway space for the office users. Challenges One of the challenges was achieving the fire escape capacities required. An unusual feature is that the public ‘street’ is actually a pressurised fire escape. All the wood is treated with a fire retardant and there is fire separation between the ‘street’ and the office and retail spaces. All glass shop and office fronts are protected by drenchers aimed directly onto the glass, thus separating them from the ‘street’ in case of fire. The main staircase within the ‘street’ also acts as a fire escape. The huge extraction fans form part of the industrial design as well as the fire management system. The building is unusual in terms of its footprint and it was a challenge to work within the geometry of the site. Building on top of an existing parking basement and within the overall design plan of the Silo precinct resulted in what is essentially a triangular design. Stipulated pedestrian routes and public spaces as well as the relationship to the historical core of the district, the Grain Silo complex, further defined the building design. Façade The façade, engineered by Arup’s façade engineering team, plays an important role in the No 5 Silo successful performance of the building. It is a practical design when it comes to the window to wall ratio and the balance between glass and opaque surfaces. The façade responds very directly to orientation. For instance the north façade, where sun control is relatively easy, is entirely glazed with the addition of fritted glass fins that control the amount of sunlight coming into the building. The East and West façades, which are harder to control in terms of light entering the building, consist of a high ratio of opaque to glass areas. Angled towards Table Mountain, the south façade, with the least sun exposure, is entirely glazed, bringing a high level of daylight into the building and playing a large role in supported the sustainability aspirations. The façades respond intimately to their surroundings and make the most of the expan- sive views of the harbour, mountains and sur- rounding buildings. High performance double glazing reduces solar gain in to the building and ensures excellent acoustics, removing the majority of noise produced by a busy working harbour environment. Solar and thermal performance requirements were set at a high level to meet the stringent energy requirements from within the building. The tile chosen to clad the façade gives the impression of oxidised steel, supporting the industrial architectural aesthetic. 79