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Domestic Energy Efficiency Upgrades, Netherfield, Milton Keynes City Council

The Social Housing Decarbonisation Funding (SHDF) provided an opportunity for Milton Keynes City Council to develop a methodology for energy efficiency upgrades that would be scalable whilst utilising a street-level approach with Mears Group plc.

The challenge

The Social Housing Decarbonisation Funding (SHDF) provided an opportunity for Milton Keynes City Council to develop a methodology for energy efficiency upgrades that would be scalable whilst utilising a street-level approach with Mears Group plc.

A key challenge for domestic retrofit work is delivering on a ‘least regrets’ basis and to avoid unintended consequences for homes, as set out in PAS-2035. It is recognised that even before the work has started residents would have been visited several times, so getting it right first time and being consistent and transparent with the process and information matters. It is disruptive to return in later years and need to overhaul or alter earlier retrofit work to do more upgrades. This project was based on providing benefits now and setting a workable basis for any future work. Perhaps unexpectedly, Milton Keynes does not have coherent property archetypes but rather has a mosaic of building techniques and heritage that needs to be well considered.

Delivering the scale of work that is required across the Milton Keynes housing stock required a bold approach to the investment and works pipeline. The council wanted to avoid limiting their ability to do work further down the line in other areas. This involved pre-empting further funding, being able and prepared to meet financial gaps and smooth the investment plan and having schemes ‘oven-ready’ in advance of funding announcements. This was based on not seeing grant funding as the answer but having the ability and willingness to re-think the housing capital investment approach and embed the council’s decarbonisation strategy.

The solution

The solution to date has consisted of thermal upgrades being designed for 304 properties in Netherfield as a phase 1. This covers three streets in turn, with eight different property archetypes that each have a different design. Work will start on-site in September 2022, and is due to finish August 2023, following a meticulous design process. This follows the PAS-2035 specification, with a number of independent organisations and roles recruited as retrofit assessors, coordinators, designers, advisors and evaluators.

The project has employed an estate-based methodology, without pre-ordained decisions on what the measures should be. The project started from an energy conservation basis and then built-up wider benefits across people, property, place, and the planet. The retrofit process is summarised as follows:

  • individual retrofit assessment – all properties have their own survey and BIM modelling
  • pre-works air tightness testing
  • design stage
  • planning and consultation
  • construction phase
  • handover to residents
  • post works air tightness testing
  • monitoring
  • evaluation of the works.

The work for all properties includes warm roof upgrades, external wall insulation, high performance windows and doors, replacement of window fins, and ventilation upgrades; whilst some will also receive high performance garage doors and internal wall insulation. These measures reduce heat loss and solar gain – to keep homes cooler in higher temperatures. A principle was to complete the energy efficiency works alongside planned maintenance work for the social housing, meaning issues including poor internal air quality, dampness and mould could be addressed in parallel.

The design has considered the appeal and aesthetic upgrade of homes including facades and cladding. This is about returning the kerb-side appeal and pride of place in the community, giving properties a full aesthetic lift alongside the carbon and fuel cost savings as a holistic approach. The design also incorporated Netherfield’s legacy style and colour palette.

A challenge has been realising a whole street upgrade, where the funding allows for the full works on council-owned stock but this can leave gaps where there are Housing Association, private landlord or owner-occupied homes in the street. This can be addressed with further investment by Milton Keynes but emphasises the need to future proof, consider the wider street aesthetic and ensure work is done in a way that is suitable and easy for future maintenance and building upgrades.

The impact

The project’s upgrade designs are anticipated to deliver energy savings, which will be crucial for residents as the energy cost crisis continues. Based upon previous gas prices the project was estimated to provide a £304 saving per annum for a terraced household. However, the reality of the current energy price cap is that what was presented in March 2022 as savings in pockets is now about stabilisation and lessening bill increases. The empathetic communication of what the project outcomes are for residents is really important.

Devices and modelling will be used to measure the upgraded homes performance, including air tightness testing, BIM modelling and thermal heat mapping. The monitoring framework for the project will also capture residents’ perceptions and satisfaction, and mental health outcomes.

Netherfield is seen as planting the seeds for wave 2, and in starting the delivery of Milton Keynes’s ambition for every home to be modelled and upgraded as necessary.

This work also has an impact on, and increasing demands of, the supply chain. It is recognised that meeting retrofit targets, for the regions and nation as a whole, will create a significant peak in materials and supplier demand that is quite beyond current capacity, whilst it may then drop off significantly causing further problems. The supply chain needs greater consideration, management and foresight, from education through the assessment pipeline and evaluation.

Lessons learned

  • Effective pre-work is extensive and there is a need for some acceleration - the retrofit pre-works have been significant to get it right and follow PAS-2035, including pre-application engagement with planning, detailed assessments and full residential engagement. Issues such as uncertainty on what is allowed under the latest Permitted Development Rights (PDR) only adds delays.
  • It is recommended that some elements, and best practices, of the SHDF process should now be streamlined and accelerated as enablers, given the scale of need.
  • Clear and transparent communication with the community matters - this project experienced how an incorrect assumption, in this case on the cost of new extractor fans that were being installed in houses, can spread very quickly over social media. This impacted residents’ views and trust in the intervention, where the project team engaged effectively with the community, and provided an online calculator, to dispel the myth.
  • Effective engagement included working with key figures in the community; sharing information with resident groups and parish councils; and the provision of local estate surgeries that have built trust and now effectively provide advice to residents. Intervention Information such as designs should be shared at the right time, managing expectations until there is clarity on the technical solutions.
  • Current grant funding is only part of the answer for retrofit - Milton Keynes is fortunate to have alignment between funding streams and its wider strategy for the housing stock and investment. It is important to bring decarbonisation goals into the wider capital spend pipeline, which may also focus on safety and decent homes standards, whilst a holistic and ‘one hit’ approach for social home upgrades is more effective.