Visitors to Devon can enjoy the complete Passivhaus experience at the fully certified Totness Passivhaus B&B, retrofitted with the help of products from Kingspan Insulation’s premium performance Kooltherm range.
Homeowners Adam Dadeby and Erica Aslett had long dreamed of creating their own low-energy home in the south west of England. The couple settled on a dilapidated 1970s property and worked with Janet Cotterell from CTT Sustainable Architecture (and now also Passivhaus Homes Ltd.) to make their dream a reality, extending and transforming the detached house.
As a refurbishment, Totnes Passivhaus B&B posed challenges above and beyond the standard requirements of a new-build Passivhaus property. In particular, the cost of replacing the existing floor slab proved to be impractical. As a result, insulation had to be laid over the existing slab and needed to deliver a U-value of 0.20 W/m2.K without encroaching on headroom. Kingspan Insulation’s premium performance Kooltherm K3 Floorboard provided the solution.
With thermal conductivities as low as 0.020 W/m.K, Kingspan Kooltherm K3 Floorboard*
allowed the target U-value to be achieved with a minimal build-up thickness. A 10mm plaster layer was applied to the existing slab and then 80mm Kingspan Kooltherm K3 Floorboard was installed by Williams & Partners, along with 20mm wood fibre insulation. Finally a 14.5mm hardwood floor was fitted.
As the final U-value for the floor was still above the Passivhaus target limit of 0.15 W/m2.K, the designers chose to compensate by improving the U-value of the external walls to 0.09 W/m2.K. To achieve this, 180mm thick Kingspan Kooltherm K5 External Wall Board
was fitted to the outside of the existing walls and finished with a white render. The insulation is suitable for use behind traditional and lightweight polymer modified renders and dry cladding systems and minimised thermal bridging through the property walls. The existing wall cavity was also filled with polystyrene bead insulation.
Owner Adam Dadeby acted as the Passivhaus Consultant on the project. He commented:
“The architects and I specified the Kingspan Insulation products for the existing walls and floors because their thermal conductivity was lambda 90/90 CE Mark certified. Without this, we would have had to apply a 20% uplift to the manufacturer’s quoted lambda value.”
Kingspan Insulation Kooltherm K3 Floorboard and K5 External Wall Board have been assigned 2008 Green Guide Summary Ratings of A+ and are certified ‘Very Good’ under BES 6001: Responsible Sourcing of Construction Products standard. The products have a fibre-free core manufactured with a blowing agent, which has zero Ozone Depletion Potential (ODP) and low Global Warming Potential (GWP). The insulation core is also rated Class O as defined by the Building Regulations.
* Please note that Kingspan Kooltherm K3 Floorboard is no longer available for specification. Instead please refer to lower-lambda Kingspan Kooltherm K103 Floorboard.