Arguably one of the greatest challenges Britain faces when attempting to reduce its carbon emissions is the vitality of its existing building stock.
Estimates from the Chartered Institute of Building have suggested that 70% of the buildings constructed before 2010 will still be in use by 2050. With many of these buildings built to either weak or no carbon emission standard, this poses a serious issue and makes retrofit applications a priority.
For existing steel and concrete framed buildings, one of the most efficient ways to boost the energy performance of the property is by stripping and replacing the existing cladding. Structural Insulated Panels (SIPs) are well suited to these types of applications. The panels are lightweight, minimising structural load on existing frames. SIPs also support a wide variety of finishes and façade systems and can greatly improve the fabric performance of existing buildings. By fitting the panels in out-board applications, it is possible to achieve these improvements without reducing usable space within the building footprint.
One of the first projects to take advantage of these benefits was the Lowery Centre at Waltham Forest College. The Centre, which houses the College’s engineering and fashion workshops, was constructed in the 1960s and was selected for refurbishment as part of the multi-million pound ‘Heart of the College’ investment programme.
The poorly-insulated original cladding was stripped back to reveal the concrete floor slabs and slotted brackets were secured to the face of the slabs. Screws were drilled through the corners of the SIPs and fixed to brackets. The brackets were then secured to the slotted floor brackets. This double bracket arrangement allowed the panels to be easily manoeuvred to compensate for distortions in the frame. A breather membrane was then stapled to the exterior face of the SIPs.
The pre-cut window entrances within the SIPs were designed to be smaller than those in the original cladding solution, minimising solar gains during summer and heat loss in winter. On the South elevation, brise soleil were also bolted to fixed posts within the SIPs to provide additional solar shading.
Timber battens were screwed outside the breather membrane and particle boards were fixed to these. A grey and white external render system was then applied to the surface of the particle boards. The project was completed on time and on budget for the new academic year with no loss in usable floor space.
In the next article in this series, we will look at a variety of new projects which have benefited from SIPs.