Social housing retrofit designed to create thermally efficient homes with low energy bills.
Ten social housing properties on a street in Enfield, North London, have seen their energy use fall dramatically following a complete modernisation and refurbishment project carried out as part of the Mayor of London’s Retrofit Accelerator programme
Overview
Ten social housing properties on a street in Enfield, North London, have seen their energy use fall dramatically following a complete modernisation and refurbishment project carried out as part of the Mayor of London’s Retrofit Accelerator programme. With new air source heat pumps and whole-house ventilation systems from Viessmann, as well as passive windows, external wall insulation and PV panels, these mid-20th Century three-bed semis are now future-proofed and produce their own electricity to help run the heat pump and other domestic appliances.
Project background
The Retrofit Accelerator initiative is a key part of London’s strategy to become carbon neutral by 2030. Under the scheme, millions of domestic properties will be upgraded with improved insulation and low carbon heat and power solutions to turn them into thermally efficient homes with low energy bills.
To help achieve this mammoth task in a short timeframe, a three-year Innovation Partnership has been created to provide London boroughs with the necessary technical expertise. It connects social housing providers and councils to a network of suppliers with the skills and capacity to hit the ground running.
Two such organisations are social housing building and maintenance experts Osborne, and sustainable home refurbishment specialists Bow Tie Construction, who collaborated for the first time on the ten Enfield homes. They will be working together to retrofit hundreds of similar properties across the capital over the next several years.
Viessmann efficiency
Each home in the Enfield pilot project has been fitted with a Viessmann Vitocal 200-A 4kW air-source heat pump, which converts the latent heat in the outdoor air into heat energy. As well as being exceptionally quiet with a sound power level of 35 dB(A), the A+++ / A++ rated Vitocal is listed in the highest energy efficiency classification in the EPREL product registry. Fitting into the smallest of spaces, the heat pump is ideal for this type of urban residential installation.
Hot water is provided via a Viessmann Vitocell 300-V DHW cylinder. Made from corrosion-resistant stainless steel, the Vitocell gives a rapid heat-up from 10 to 60 degrees in just 20 minutes for the 160-litre cylinder model for a high level of DHW convenience at all times. The cylinders are located under the stairs of each property, pushed as far back as possible to ensure adequate storage space remains.
The fabric of each house has been improved with an 170mm external wall insulation system fitted to the outside of the external walls, 300mm mineral wool insulation in the loft, high performance doors and triple-glazed windows compliant with Passivhaus standards.
“We’ve worked with Viessmann before on similar successful projects with these types of technologies,” recalls Bow Tie’s Technical Director Rafael Delimata, “So we were confident that what we were proposing for the Enfield properties was the right solution package. Viessmann equipment is cost-effective and reliable and comes with support from a global company with a team of engineers.”
Bow Tie has now incorporated the Viessmann Vitovent MVHR system into Ventbox, its new patent-pending ventilation ducting system, which was deployed for the first time in this project. This low impact solution allows ducting to be routed around the outside of a building, instead of between ceiling joists, avoiding the need to lift floorboards and cut holes through internal walls. This approach meant that the Enfield residents were able to remain in their properties throughout the entire eight-week retrofit process, experiencing minimal disruption.
Results
Following the retrofit, the ten houses have all jumped from an EPC rating of D up to B, which is equivalent to an energy-efficient new-build property, and very high for a retrofit. Average heat demand has fallen from 11,000 kWh to 2500 kWh – a drop of 78%.
In an interview published on the council’s website*, Enfield Council’s Cabinet Member for Social Housing, Cllr George Savva, said, “This is a whole house approach where residents will benefit from comfort and thermal efficiency all year round and lower bills. We know our residents are still concerned about their long-term financial futures due to the rising cost of living. This retrofit will go some way to addressing these concerns in regard to energy costs.”
*Source: Haselbury homes become models of sustainability | Enfield Council
System spec
Vitogate 300 gateway
PV Modules
