A guide to cavity wall insulation
A guide to help you understand all about cavity wall insulation
Knowledge Article4 min read
Felix O’Hare & Co Ltd managed the construction of this brand-new facility. As the building is situated within the University’s South Belfast campus near the Grade II listed Riddel Hall, it was important that the new building complimented its heritage surroundings. The building features a red brick façade that references the architectural language of Riddel Hall, whilst also introducing a modern understated aesthetic.
The new business school building delivers a variety of facilities for the Russell Group University, with a range of teaching and learning accommodation for undergraduate and post-graduate students. With the University committed to achieving net zero carbon emissions by 2040, it was also important that the building uses energy efficiently. The project team targeted a BREEAM ‘Excellent’ rating for the development and implemented an innovative geothermal heat system, extracting heat from the sandstone substrate below.
LOCATIONBelfast, Northern Ireland
They also looked to ensure excellent fabric performance with a specification including Kooltherm K8 Cavity Board and Kingspan GreenGuard GG300.
Kooltherm K8 phenolic insulation has thermal conductivities as low as 0.021 W/mK. This thermal performance made it possible for the project team to achieve an ambitious U-value for the cavity walls, with a slimmer overall construction depth than would have been possible with a lower performing insulation material. The 100 mm thick partial fill insulation boards were installed with a 50 mm clear cavity, providing long-term resistance against moisture penetration.
The Kooltherm K8 boards are lightweight, making them easy for the installers to manually handle and fit on site. They could also be simply cut to size with a standard fine-toothed saw supporting a fast installation process on the new business school building, ensuring it was completed in time for the start of the new academic year.
The geothermal heating system is linked to an underfloor heating system across the ground floor of the building. As this provides a constant but low level of heat, it was important to ensure that the building fabric retained this effectively. To achieve this, two 100 mm layers of Kingspan GreenGuard GG300 were fitted beneath the underfloor heating system across the ground floor area. The XPS boards offer a high compressive strength, making them ideal for the high traffic floor areas, and achieve a thermal conductivity of as low as 0.033 W/mK. The boards were laid with joints offset to ensure a continuous layer of insulation and support long-term energy savings.
This careful specification of building materials, combined with the use of renewable technologies has allowed the building to achieve BREEAM Excellent certification. This supported the University’s recent achievement of the prestigious ‘Best Energy Achievement in Third Level Education’ award at the Energy Achievement Awards 2023 in Dublin.
Images: Donal McCann Photography Ltd
Page updated 17/07/2025
Find out about the products
Kooltherm K8 Cavity Board
Partial fill cavity wall insulation
Kingspan GreenGuard GG300
Insulation for heavy duty commercial, industrial and cold store flooring
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