Industry Leader Case Studies: Knauf Whole-House Retrofits, Doncaster

Friday, 12 August 2011 13:59

In 2009, Knauf Insulation undertook a project to internally insulate an 1890’s Victorian mid terrace property. The aim was to work with the landlord and his builder to enable a ‘whole-house, low energy refurbishment to be integrated with the wider renovation of the property as a means of delivering a low ‘marginal cost’ of the insulation measures. The project also aimed to install systems that could be undertaken by any competent builder to enable its replication across the millions of homes in the UK which require improvements to their insulation.

The property’s attractive brick frontage made the property less suitable for external wall insulation (EWI) but ideal for internal wall insulation (IWI) system using Knauf’s patented EcoStud as a replacement for the more traditional timber stud framing. To provide a side by side comparison, a Knauf Insulation insulated metal stud system was also installed in part of the property.

The timber floor of the living room was insulated from below with 150mm of glass mineral wool friction-fitted between the timber floor joists with an additional water repellent slab due to the cellar’s high humidity levels. Insulation was also fitted between the joists and the external wall to ensure continuity between the two levels. Further measures included a new tightly fitting UPVC door fitted at the top of the cellar stairs to prevent drafts, and insulation of the walls of dining room and the underside of the staircase to the first floor. In total, 73m2 of internal wall insulation was installed, with a reduction in floor area of less than 2%.

Before the renovation, the property already had an efficient condensing boiler, UPVC windows and doors and 100mm of glass mineral wool loft insulation, with annual CO2 emissions 3.80 tonnes (excluding appliances). Following the installation, CO2 emissions were reduced to 1.80 tonnes per annum (52 per cent reduction), saving around £400 in annual fuel bills (at current energy prices). The cost of installing the insulation over and above the other work that was required to bring the property up to a decent standard was approximately £2800, giving a payback of approximately 7 years.

The results achieved clearly demonstrate the benefits of combining low-energy retrofit works with wider renovation plans, due to the reduced costs that doing so can bring. The project also provided a good example of a systematic approach to installing internal wall insulation that could be used throughout that UK.

Project summary:

Organisation: Knauf Insulation
Project costs: £2,800 (marginal cost of the insulation measures only).
Measures installed: Installation of Knauf Insulation’s glass-wool internal insulation system; suspended wooden floor/loft insulation; and low energy lighting.
Annual emissions reductions achieved: Reduced CO2 emissions by 1.80T per year (52%), excluding appliances
Annual energy bill reductions achieved: Energy savings of approx. £400 p.a.