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BACKGROUND

North Star Housing Group is a housing association which owns around 4,000 properties in the North East of England. Around 900 of these properties are traditional, pre-1920s, back of pavement terraced houses that are inherently thermally inefficient and difficult to decarbonise.

North Star were keen to experiment and understand what was the art of the possible, so in 2021 North Star embarked on a project to explore solutions to treat and decarbonise a typical late Victorian terraced property.

North Star were presented with a void property on Montrose Street in Central Middlesbrough, the property was in a very poor state of repair and needed full refurbishment. With so much investment required it provided the ideal opportunity to experiment and explore carbon zero options.

This three storey property had single glazed timber windows, brick solid walls, solid concrete floors and inefficient gas central heating. The second floor incorporated a habitable room, with inadequate loft insulation. An independent energy assessor confirmed the Energy Performance Certificate (EPC) rating of F – the poorest performing of the housing association’s property portfolio.

As part of the review of options to treat the property, a number of more traditional measures were explored and discounted including:

External Wall Insulation (EWI) – Montrose Street is aesthetically pretty, with the terraced houses incorporating intricate brickwork detail. Not only would EWI detract from the visual appearance of the street scape, based on North Star’s experience, overlaying masonry with cladding and render could be more susceptible to cold bridging, and have a tendency to look tired after a short period of time.

Air Source Heat Pump – The initial proposal was to incorporate an Air Source Heat pump system. Given the limited space, the very small rear yard and in such close proximity to other properties, it was felt this to be an inappropriate solution in this location.

Infra-Red Heating – although used in more commercial settings or at scale, through research North Star had little confidence that this system was right for this domestic property.

ACTION

Once stripped back to brick and internal floors had been removed, the first phase was to heavily insulate the property. This included insulating floors at ground floor and first floor and incorporating insulation to stud partition walls, allowing us to compartmentalise each room to retain heat and reduce heat loss on a room-by-room basis. Loft insulation and rafter insulation was added, with additional insulation backed plasterboard to ceilings. Internal wall insulation was added to each internal wall, being cognisant of the need to correctly join and seal to prevent cold bridging.

In addition, new double-glazed windows and composite external doors were fitted to complete the external envelope.

Working with energy contractor Cara Ltd, heating solutions were pursued, with a proposal to incorporate the innovative Photonomi HONES system – a prototype developed in the Republic of Ireland.

The HONES thermal / electric panel system uses proprietary pyramidic semiconductors to generate hot water, heat and electricity, by harvesting daylight instead of sunlight. Unlike more traditional photovoltaic (PV) systems requiring optimum orientation, the HONE Electric technology is designed to maximise thermal performance and operate with high kWh outputs – even in winter months and poor weather. This technology is known to generate six times more kWh than a solar PV per sqm.

The overall design of insulation and the HONE system meant that an electric radiator heating system would be capable of adequately heating the home at low costs. Radiators and room temperatures could be controlled individually by SMART Wifi technology, allowing remote monitoring and control of the system via a mobile App.

Mechanical and natural ventilation were built into the design to ensure air circulation within the home is adequate to reduce the risk of damp and mould. In addition, Aico smart hub monitors have been installed which allow North Star to monitor humidity and moisture levels within the property remotely. This further assists us in assessing the performance of the property and the measures installed.

IMPACT

The full refurbishment and redesign of the project concluded in August 2023 at a cost of £80,000 and is now occupied by a tenant of North Star. Although it is in the early stages of measuring the success and performance of the new technology, early indicators show that the system can generate 12.5 Kw per day, with excess energy created and fed into the grid via agile feed in tariffs. The house is likely to powered for as little as £500/year, if not less.

The Energy Assessment has been revised with the property now achieving an EPC performance rating of A, with SAP score of 109.

Ongoing monitoring is underway and a full review of the outcomes and learning from the project will be concluded in August 2024 and shared widely.