Project overview
In April 2022, Southern Housing instructed Ambue to carry out Retrofit Assessment, Coordination and Design for energy efficient upgrades to an initial scope of approximately 500 Social Rental Homes, to support Southern’s SHDF Wave 2.1 bid. The 500 dwellings are spread over various locations including London, Essex, Margate, Dover, Brighton, and Isle of Wight. This contract is ongoing, with a current focus on the Isle of Wight.
Ambue’s contract with Southern is structured around providing several retrofit services, covering different aspects of the PAS2035 retrofit process:
Retrofit advice
Ambue has provided comprehensive retrofit advice during project set-up and initial risk assessment of Southern’s property lists. This included an in-depth architectural study of BISF properties on a large estate in Essex.
This study analysed the risks and opportunities for the retrofit of the post-war BISF system build archetype, exploring opportunities for off-site fabrication of external wall insulation EWI and other retrofit measures.
The study identified structural complexities with the proposed loading of the original lightweight steel frame with a new EWI system, with particular note relating to the fixing methodology. The preferred solution sought to add a new external footing, so that the new EWI could bear directly onto the new foundation without surcharging the original footings.
Retrofit assessment
In-depth Retrofit Assessment of each dwelling carried out by qualified retrofit assessors in compliance with PAS 2035:2019, including provision of LIDAR scans. Provision of retrofit assessment reports and energy performance data to the client. Input of data to create a measured building survey. Ambue worked with pre-approved contracted and outsourced Retrofit Assessors to undertake the surveys and data gathering required.
Ambue has been collaborating with Southern Housing’s preferred Main Contractor to upskill and develop the supply chain on the Isle of Wight, to support the retrofit of housing through SHDF Wave 2.1. This has been successful with Ambue training and upskilling local PAS2030 Retrofit Assessors in new technologies and techniques, to support our workflow methodology.
It’s also been liaising with local PAS2030 installers to ensure that they are delivering projects to the correct standard.
Retrofit coordination
Ambue’s in-house PAS 2035 certified retrofit coordinators have provided Southern with oversight and quality assurance of retrofit assessments, design, and installation of designed retrofit measures; and provision of post-completion energy certificates. This has included:
- The use of 3D building information models to show energy performance data and evaluation of options.
- Identifying, assessing, and managing risks associated with implementing retrofit from assessment through to handover of completed works. Providing project coordination and reporting in compliance with PAS 2035.
Ambue has collaborated with Southern Housing and their supply chain, to participate in “Roadshows” in local communities on the Isle of Wight.
These have been to engage with residents and tenants in the community, to demonstrate the techniques and technologies for retrofit. This is important to help demystify the process and to assist in promoting engagement, as “resident drop-out” can be a significant abortive cost.
Retrofit design
Provision of PAS2035 compliant retrofit design by Ambue’s in-house qualified retrofit designers (comprising ARB and RIBA architects and architectural assistants) including:
- Data modelling based on the dynamic thermal model built into the Ambue.com platform. A key benefit of the dynamic modelling on Ambue’s web-platform, is that the data is updated to reflect market conditions, so reports can be re-issued at any time to capture current cost forecasts.
- Provision of a Whole House Medium Term Plan for each dwelling.
- Production of an “Improvement of Option Evaluation” Report for each dwelling, include RdSAP evaluation data and cost assessments of each individual item.
- Obtaining planning permission and historic buildings’ consent as required.
- Preparation and export of documents to comply with PAS 2035. Performance specifications for each measure or package of works includes architectural drawings e.g. elevations or ventilation strategy plans.
The detailing and design of the measures for Southern Housing on the Isle of Wight has been developed to suit the harsh and exposed maritime climate conditions – with particular emphasis on the impact of saturation of failing cavity wall insulation. In many instances the extraction of mineral fibre insulation, to be replaced by impermeable resin bonded insulation has been proposed, following careful analysis. This has included hygrothermal calculations using local weather data.
Retrofit evaluation
Ambue’s retrofit coordinators will be carrying out all required evaluation to comply with PAS 2035, including:
- Verifying the completed works and evaluate the pre and post-works energy performance and heat demand.
- Defining the requirements for Post occupancy Monitoring and Evaluation as required.
Outcomes and impact
Retrofit installation cost increases has required a large-scale project adjustment in scale and scope, with Ambue supporting the client team with data and analysis to inform decision making in SHDF2.1 over the course of the project. Other barriers that contributed to reduction in scope include challenges posed by the SHDF funding and delivery frameworks, PAS challenges, resident dropout rates, compliance challenges and local supply chain limitations.
Discussions on scope, scale and locations for Warm Homes Social Housing Fund Wave 3 have started with the client team. Areas of focus include continuation on the Isle of Wight and exemplar heritage blocks in London. Engagement with key stakeholders around required changes of funding and delivery framework aspects form an important part of ensuring successful delivery of the future Warm Homes Wave 3.