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Retrofit Case Studies

Enerphit – Barmouth Road, Wandsworth, London


Figure 35 Enerphit – Barmouth Road, Wandsworth, London (LEBD, 2015).

Barmouth Road in Wandsworth, London is a Victorian terraced house retrofitted to the EnerPhit standard. To meet strict planning requirements the building was insulated internally and triple glazed sash look-alike casement windows were installed to retain the original appearance of the façade (LEBD, 2015).

The building featured a comprehensive approach to insulation and airtightness, to maximise savings from the fabric only interventions. The dwelling featured whole house MVHR alongside a high efficiency gas boiler to provide space heating and hot water (LEBD, 2015).

Table 11 Technical specification Enerphit – Barmouth Road, Wandsworth, London (LEBD, 2015) Performance/U-valueDetailDate Completed 2014Description139 m² Mid terraceOwner OccupiedClient/DeveloperGreen Tomato EnergyPrivate OwnerConstructionSolid brick wall insulated internally.Internal solid wall insulation with replacement floor insulation and war, loftkgCO2/m2/yr.20 kgCO2/m2Based on stricter PHPP modellingPrimary Energy Demand 114 kWh/m².yrUsing PHPP methodologyAnnual space heat demand23 kWh/m².yrUsing PHPP methodologyAir permeability0.87m³/m².hr @ 50 Pascal’sOver 10x current building regulationsWallsSolid wall with IWI – 0.17 W/m2 K. Insulated cavity wall – 0.13 W/m2 KInternal solid wall insulationRoof Main house – 0.18 W/m2 K. New extension flat roof – 0.11 W/m2 KConstraints due to space limitationsWindows0.8 W/m2kPassivhaus certified triple glazingFloorMain house suspended timber floor – 0.09. W/m2.K Extension solid concrete floor – 0.15 W/m2.K Heating SystemNew condensing gas boiler, with flue gas heat recovery  (FGHRS)FGHRS typically improve condensing boiler efficiency by 3% (EST, 2013)VentilationMVHR – Passivhaus certifiedImprove air quality and heat retentionBudget Total refit unknown139m2


EST 2013. Review of potential for carbon savings from residential energy efficiency -Final report. Cambridge: Energy Saving Trust.

LEBD 2015. Barmouth Road, Enerphit. In: DATABASE, L. E. B. (ed.). http://www.lowenergybuildings.org.uk/.

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