Sutton Energiesprong 6

Energiesprong Retrofit of 6 Terraced Properties
Bow Tie Construction
Contract Value
circa £450k
Project Description

Bow Tie Construction were selected by EnergieSprong UK and Sutton Housing Partnership to deliver an Ofgem Eco funded deep retrofit of a terrace of four and a terrace of two houses. Bow Tie’s designers were responsible for all design elements and construction was undertaken by Bow Tie’s builders. The residents received the retrofit at no cost to themselves.

The project had to be delivered within a guaranteed maximum price per unit and would target an annual space heating performance of 50 kwh/m2/annum with an airtightness of 1 air change per hour. The houses would be taken off gas. All heating and hot water would be provided by the Ventive compact unit comprising exhaust air heat pump, MVHR and thermal store. Electricity from the PV panels would first go to the Ventive unit to charge the thermal store, then be used by the house, any surplus would be exported to the grid with residents receiving the benefit.

Bow Tie undertook PAS 2035 inspired retrofit assessments and 360 photographs and point cloud laser scans of interiors and exteriors. These were then developed into 3D models of the existing buildings which were edited to create the proposed drawings.

Retrofit Measures include:

Passivhaus Grade Triple Glazed Windows, thermal bridge free installation

Passivhaus Grade Entry doors, thermal bridge free installation

Cavities insulated with high performance expanding foam

Lofts topped up to 300mm of Insulation

YESporch to house Air Source Heat Pump, MVHR, thermal store and ventilation manifold

Photovoltaic Panels

Li-Ion batteries in two properties

Bow Tie Construction were awarded ‘Retrofit Installer of the Year 2022‘ by the Retrofit Academy in recognition of their commitment to retrofit excellence. The project was recognised by an article in the American magazine Passive House Accelerator.

30+ data points are being collected from each property and we look forward to sharing our findings on their ongoing energy performance.

  • “We’re expecting a dramatic reduction in costs. We now know how much energy we’ve used (in March) and we rarely have the heating on compared to this time last year in our old house.”

    – Toni M
  • “Bow Tie Construction were very professional, they did things to a very high standard and paid a lot of attention to detail. When small issues were flagged here or there they were always keen to investigate and fix them.”

    – Francis M
  • “Rafael is very familiar with the latest building technologies and is always on hand to offer suggestions and advice on the practicalities of achieving the desired end product.”

    – Brian A
  • “My projects with Bow Tie are the only ones where I’ve left the contractor to follow my airtightness details and the projects have passed the 1st airtightness test.”

    – Justin Bere
  • “I did get the benefit of regular updates and involvement in the project so I could see the quality of the work.”

    – Raza Rizvi

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