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Retrofit Case Studies

BDR Outstanding 119 Ebury Street, City of Westminster, London.

This listed building was previously a hotel and originally a single family home. The project is developing the building into three duplex apartments for tenants. However, when BREEAM Domestic Refurbishment was released in 2012 the landlord/developer; Grovesnor, expressed a wish to achieve the highest level of sustainability certification, i.e. an ‘Outstanding’, as well as the UK Government’s 2050 target of an 80% reduction in operational CO2 emissions. The purpose of doing so was to test the feasibility of achieving this in a heritage context and to establish the developer as a leader in sustainable conservation of buildings (BRE, 2015).

The average post-refurb SAP rating is 88 and Predicted Energy Demand is 68.1 kWh/m2/year. The space heating and hot water strategy comprising two combi-boilers with flue-gas heat recovery, and one condensing system boiler supported by a solar thermal unit mounted on the roof of the closet wing. As well as the solar thermal system, on site generation comprises 2.08kWp of six roof-mounted 330-Watt monocrystalline panels and 1.40kWp of solar slates – the latter installed to assess their aesthetic impact in a heritage context. MVHR has also been included, which presented a great architectural challenge in terms of integrating the ductwork into the listed fabric. (BRE, 2015). The interventions are summarised in Table 1 Technical specification for BDR Outstanding City of Westminster, London [76], with Figure 1 showing the CO2 reductions that were achieved for the project.

Table 1 Technical specification for BDR Outstanding City of Westminster, London (BRE, 2015) Performance/U-valueDetailDate Completed Incomplete Design StageDescription3 duplex apartmentsGrade II listed buildingClient/DeveloperGrovesnorCommercial rentConstructionSolid Wall masonryVapor-permeable solid internal wall insulation for retained wallsEER/SAP Rating EER BSAP rating 88 (Design Stage)DER 9.67 kgCO2/m2EstimatedPredicted Energy Demand 68.1 kWh/m2/yearIncludes all energy consuming sourcesAir permeability3m³/m².hr @ 50 Pascal’sOver 3x current building regulationsWalls0.15 W/m2kInternal solid wall insulationRoof 0.15 W/m2k Windows1.6 W/m2kVacuum double glazing & triple glazing to extensionsFloor0.20 W/m2k Heating SystemNew condensing gas boiler, with flue gas heat recovery  (FGHRS)FGHRS typically improve condensing boiler efficiency by 3% (EST, 2013)VentilationMVHRImprove air quality and heat retentionSolar thermalSmall arraySize constrained by space availablePV 2.08kWp of six roof-mounted 330-Watt monocrystalline panels and 1.40kWp of solar slatesConstraints due to buildings heritage valueBudget Total refit £2m (total refurbishment cost estimate)434m2 – £4,608/m2

Figure 1 119 Ebury Street – Carbon Emissions Breakdown – 80% reduction (Grovesnor, 2015)


BRE. 2015. BREEAM, Case studies, Residential, 119 Ebury Street [Online]. Building Research Establishment. Available: http://www.breeam.org/podpage.jsp?id=800 [Accessed 11th August 2015].

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

GROVESNOR 2015. 119 Ebury Street Enviornmental Initiatives and Carbon Emissions Breakdown. In: COMBINED, E. S.-. (ed.) Adobe Acrobat. Grovesnor.