Bedfordshire, New-Build Academy Expansion

Brief

The principal aims of the 3-storey new-build project included:

• Creating 90 new places to meet growing local demand for secondary and higher education
• Creating new sports and teaching facilities, including science labs and flexible learning spaces
• Providing working environments with excellent thermal and acoustic insulation
• Meeting the requirements of the DfE Spec 21 specification, which requires ‘Net Zero in Operation’
• To achieve an ‘excellent’ rating to BREEAM standards
• Delivering all this on an active campus, where learning activities would continue

These requirements put an important emphasis on sustainability. Consequently, the design brief encompassed a range of important resource-efficiency measures. The main contractor noted that meeting Net Zero Carbon aspirations required “integrating high-performance insulation, renewable energy, and advanced ventilation systems.” As examples, it listed energy-efficient lighting, natural ventilation strategies to optimise indoor air quality, and creating “a highly insulated building envelope, in order to reduce heat loss and operational energy demands.”

Creating this highly insulated building envelope entailed the use of modern doors and windows but, more particularly, the installation of an external wall insulation system over the property’s steel frame. In line with the DfE Schools Output Specification, the EWI system would have a design life of at least 40 years and would achieve an A2-s1,d0 reaction to fire classification (BS EN 13501-1:2018).

Design and Specification:

The chosen EWI system comprised:

• Permarock Mineral Fibre External Wall Insulation System with insulation boards of 160 mm to 170 mm thickness, all adhesively bonded and mechanically fixed to the substrate;
• Permarock Silicone^Ultra K Finish (textured render).

When combined with Permarock Silicone^Ultra K finish, Permarock Mineral Fibre EWI systems achieve an A2-s1,d0 reaction to fire classification and can be used on buildings of any height. The Schools Output Specification Technical Annex 2C: External Fabric dictates that “cladding on a school building with a storey 18m above ground level shall achieve Class A2-s1, d0 fire resistance or better.”  Similarly, it states that the same rating is required “where school buildings are prone to vandalism… for all special schools,” and for all residential areas of boarding schools.

The Permarock Mineral Fibre Insulation was supplied in boards measuring 1200 mm x 600 mm. They were installed in thicknesses of between 160 and 170 mm, using other thicknesses as necessary to complete the detailed design of the system. All insulation boards were affixed using Permarock’s polymer, cement-based adhesive and Permarock mechanical fixings appropriate to the substrate.

Permarock Silicone^Ultra K Finish is a flexible, vapour-permeable render with an attractive textured finish. It provides effective weather protection and helps to maintain airtight facades that contribute to the building envelope’s overall thermal performance.

In addition, it uses nano-quartz technology to produce a bright, durable finish that resists the accumulation of dirt, which it sheds through the normal actions of weathering. It also actively resists the growth of algae, mould and other organisms, so it tends to stay cleaner and brighter for longer than conventional finishes – a characteristic that helps to reduce routine cleaning and maintenance costs.