Portsmouth Library Extension, Portsmouth

The exposed in-situ concrete structure of the University of Portsmouth library extension is integral to its success. It is a fundamental part of its strategy to reduce energy use (the project has achieved a BREEAM rating of Very Good) and to create a comfortable, stable climate for its users. The strong elemental concrete forms characterise the building's clean, modern design and are a visual connection to the original 1976 building with its coffered concrete soffits. Construction was also simplified by its use.
 
The building has made a new gateway and heart for the University Campus, located in a prominent position in Ravelin Park between the University's North Campus and student lodgings in Southsea. Accessed off a new piazza to the west and from the park to the east, a covered street runs right through the building. From this thoroughfare are accessed IT, seminar spaces and also the library turnstiles that are situated in the three storey main entrance hall. Two storeys of book stacks and study space rise above. The project has exceeded expectations of increased student numbers.
 
The basic orientation of the building, the facade treatment and the use of rooflights maximise opportunities for good day-lighting. The south-west elevation facing the park is an echeloned series of massive concrete fins dividing window bays. Windows thus face due south, making it easier to mitigate solar gain, reducing glare from low east and west sunlight and creating triangular study bays alongside the stacks. The façade flanking the entrance with a series of vertical slot windows acts as a giant, welcoming sign, exposing the inner life of the building.
 
Constructed of cast in situ concrete using reuseable shuttering, the structure of the new building is exposed internally. It is insulated and weatherproofed on the outside and clad in a skin of limestone. A building of quality achieved under a design-and-build contract, the fully exposed, in-situ concrete structure to the new three-storey block simplified the construction process, meaning that the entire superstructure was in place relatively early in the contract, reducing the number of external packages and the need for layers of internal finishes. Service runs are fully integrated to reduce visual clutter.
 
The thermal mass of the exposed internal concrete works with an assisted natural ventilation system to provide a comfortable working environment. Innovative fire and acoustic engineering solutions allow the new library floors, IT area and triple height entrance hall to act as one space. To ventilate this, air is drawn in from the rooftop plant room and introduced at pressure through grilles in the raised access floor.

A simple system of supply pipes under the floor pre-cool or warm the air. Warm air flows naturally from the different spaces out into the main central space and rises into the roof lantern from which it is exhausted, via a heat-recovery system in winter. Dampers in the edge of the floor plates provide secure night-time cooling and ventilation. The project has other sustainable features such as rainwater collection