Clarion, Borehamwood Retrofit

ENGIE Zero delivers the UKs First Housing Association Pilot of Energiesprong retrofit to properties in Essex

As an early adopter of renewable energy and energy efficiency installations, ENGIE has an established Energy and Innovation Team dedicated to the identification of efficiency measures and funding sources. The team, and the projects they deliver, contribute to ENGIE’s strategy to be the leader in the global transition to zero carbon. 

In September 2018, Daniel Archard, Clarion’s Asset Sustainability Manager, approached ENGIE’s Energy and Innovation team and tasked them with putting together a retrofit plan for three of their properties in Borehamwood. These three properties had previously been identified for an Energiesprong approach, however this was later deemed not to be a financially viable option for Clarion at the time. With the residents already engaged, and with Clarion still enthusiastic to pilot innovative energy saving measures for their housing stock, ENGIE designed a whole-house retrofit solution.

With specific complications with each location, ENGIE’s Energy & Innovation team provided solutions to benefit the resident whilst minimising disruption.


The works to the three properties – two adjacent to each other and one separate, larger, four bedroom property– presented several challenges. All three properties remained occupied throughout the works, requiring consideration about how best to mitigate impact on residents whilst works were being carried out.

To address this, the site team communicated with the residents to ascertain their availability and worked flexibly; undertaking works requiring internal access at times which fitted around their other commitments. Additionally, there were more specific complications with each of the locations:

Firstly, the larger property was extremely cluttered, initially causing difficulties with access. In response to this, we provided a skip to allow the resident to clear the loft and excess items; resolving the access issues, whist supporting the resident to declutter their home. The site team also carried out some supplementary remedial works as added value, including laying a new path, removing the existing porch due to a potential asbestos risk, installing new external lighting and replacing the back door.

Furthermore, the house had some issues with condensation and mould. With a potential consequence of improving thermal performance and air tightness being an increase in condensation, this was something that needed consideration.

ENGIE’s Senior Energy and Innovation Advisor, Clive Rowland, carried out ventilation calculations based on Part F of the Building Regulations and suggested installing an additional extractor fan to run continuously and provide adequate ventilation. Relative humidity monitors, installed in each room, will provide ongoing information about the efficacy of this approach.

Secondly, the other two properties are adjacent to each other and this has allowed installation of one continuous set of integrated PV panels which, although each on their own independent systems, offers a more streamlined aesthetic. However, there was no internal space to store the batteries at these properties. Having ruled out the option of storing the
batteries in the lofts due to potential fire risks, we proposed housing these systems externally.

With the batteries requiring specific conditions and temperatures to work most efficiently, we have built bespoke weatherproof shelters to house them in the back garden of the properties.


Working Towards a Shared Vision

With the successful delivery of the initial project, Clarion is demonstrating its ongoing commitment to sustainability and social responsibility by sourcing and delivering energy solutions which tackle fuel poverty and reduce carbon emissions. This objective is in harmony with ENGIE’s aim to be the leader in the global transition to zero carbon. A key factor in the success of this project has been the design and implementation of a bespoke ‘retrofit delivery plan’. This approach has been pivotal to ensuring a joined-up ‘whole house retrofit’ rather than just a collection of measures.

Combined Expertise

A significant advantage for developing and maximising these approaches in the future, has been one of ENGIE’s staff, Senior Energy and Innovation Advisor, Clive Rowland, achieving his Retrofit Coordinator qualification. The Open College Network Level 5 Diploma in Retrofit Coordination and Risk Management is a new qualification, delivered through the Retrofit Academy. The nationally accredited qualification provides retrofit industry with the knowledge and skills to deliver PAS2030 and PAS2035 compliant
retrofit energy solutions.

This perfectly positions ENGIE, ahead of the curve, to meet new standards being introduced in 2019 that will transform the way energy efficiency projects are delivered, providing enhanced peace of mind and confidence to clients about our compliance and expertise in delivering high quality, appropriate solutions and will improve access to relevant government funding.

With one of Clarion’s own team members also successfully achieving the qualification, there is a mutual understanding and appreciation of the benefit this improved expertise brings.

Thermal Performance Improvements

By applying the right thermal insulation correctly, alongside other thermal performance improvements, we’re able to achieve reduced energy bills and warm, dry homes for tenants. These measures are essential for tackling fuel poverty and delivering the government’s Clean Growth Strategy to get all housing up to a minimum Energy Performance
Certificate (EPC) Band C by 2030. At the larger property, the windows were substandard due to ageing and we replaced these under the existing framework agreement to ensure that the benefits of any new thermal performance measures can be maximised. Here, we’ve also taken the External Wall Insulation to below Damp Proof Course (DPC) level. Although a more expensive approach due to the additional trenching, including requiring us to reroute pipework, this is considered best practice as, in effect, the whole house is then enveloped. Unfortunately, this was not a viable option for the two other adjacent properties due to space limitations but does mean we will be able to make comparisons and draw conclusions about the additional impact of this element on increased thermal performance.

Despite the small differences in retrofit works, the improvements have increased the EPC rating of all three properties. From our surveys before the works began, the two smaller properties started at a D rating and the larger property scored an E rating. Re-evaluations of the properties after the work scores all three properties now at a B rating. This should translate into lower energy bills and improved thermal comfort for the tenants.

Innovative Technology

The residential solar landscape has changed considerably in recent years and, with fewer government subsidies available, it’s been sensible to explore ways to maximise the benefits of self sufficient energy generation and supply from solar PV. By installing battery storage, alongside GoodWe’s Smart Photovoltaic Inverter, ENGIE is delivering benefits for both Clarion and their residents.

Residents will have more control over their energy use, with optimum PV energy generation being stored efficiently for times of higher energy use, usually in the evenings. With the system’s interactive user interface, the resident, Clarion and ENGIE’s Energy and Innovation team are able to monitor and track performance and usage. One significant benefit of this is the increased understanding and awareness of how much energy is being saved, used and fed back to the grid and helping to identify where any energy efficiency improvements might be made.

Monitoring data will enable us to properly evaluate the impact of the energy storage technology in increasing the amount of usable power from the PV panel and it’s also hoped that the increased knowledge will effect a conscious, positive change in energy use behaviours and habits for residents. Additionally, by installing the battery, invertor and PV panels
simultaneously, we’re delivering a whole, fully integrated and synchronised system that can better track the complete return on investment for Clarion. When ENGIE installed the PV, we did so alongside the planned roof renewal. This allowed us to fully integrate the panels into the roof, sitting flush with the tiles as opposed to being mounted on a protruding frame, thus engendering an improved aesthetic. Complementing the solar energy generation, we have installed relative humidity sensors and Switchee units will also be fitted
to each home. Switchee is an innovative smart thermostat device, capable of ‘learning’ and automatically responding to a property’s occupancy and thermal profile by sensing temperature, light, motion, humidity and air pressure. The system monitors the ambient environment and collects data on energy consumption habits, enabling it to intelligently optimise heating settings remotely, including switching off automatically when no one is at home. The data produced translates into a dashboard, providing key information relating to performance and potential maintenance and welfare issues such as poor insulation or mould. As well as saving money on heating bills, Switchee saves on average 180kg of CO2 for every year it’s installed.

Ongoing Monitoring and Learning to Shape Future Delivery

Moving forward, after completion of works, ENGIE has developed a detailed monitoring strategy and is offering ongoing support to interpret and analyse data for the next two years and provide meaningful reports back to Clarion. This information will help to support the environmental, social and financial arguments for the wider deployment of these technologies across Clarion’s stock through retrofit packages. In addition to the data from the PV panels, battery and Switchee systems, monitoring and evaluation will include
the following:

With the lifestyle of tenants playing a significant part in energy use and how any savings can be achieved, ENGIE has also designed bespoke resident behaviour questionnaires. Residents completed these prior to the start of the project and will complete them again at both six month and 12 month intervals after the works have been completed. Interestingly, this feedback will also identify how perceptions of behaviour correspond with the data gleaned from the smart technologies installed. By the end of the monitoring
phase, ENGIE will be able to gauge the compound benefits of these technologies and building fabric improvements working in synergy and provide information to Clarion
on appropriate scalable solutions for managing their properties. The results will also work towards tackling fuel poverty and meeting government targets to reduce carbon emissions.