Salix visit sets out lessons from Cardiff University's Welsh Government-funded retrofit

Salix Finance has published lessons from a visit to Cardiff University's Welsh Government-funded decarbonisation works, covering LED lighting, rooftop solar, a replacement air handling unit and window replacement in a conservation area.

Salix said its team members Rachael Holliday and Gbenga Adenaike met Alice Milanese, Cris Lewis, Tessa Lama and Nigel Griffin from the university. The projects they reviewed were funded through the Welsh Government loan programme Salix delivers in Wales and through the Digarbon project, and included heat pumps, solar photovoltaic (PV) panels, LED lighting, upgraded air handling systems and improvements to insulation and windows.

Gbenga Adenaike, Wales programme manager at Salix, said: "The projects demonstrate why successful decarbonisation depends on more than technology alone."

Lighting, solar and air handling

At the Arts and Social Studies Library, Salix said a new LED lighting system with motion sensors and daylight controls had been installed with money from the Wales loan programme. The library also has a rooftop solar PV array of about 438 panels, fitted after a roof replacement so the two jobs were aligned.

Salix reported that some library occupants initially assumed lights switching off automatically indicated a fault, which it cited as showing the need for clear communication when new systems are introduced.

The replacement air handling unit serving the Sir Martin Evans and Cardiff School of Biosciences buildings uses four individual fan-and-motor assemblies rather than a single belt-driven fan, according to Salix. Nigel Griffin of Cardiff University said: "This work has delivered one of our greatest energy savings per unit, demonstrating how targeted investment can deliver benefits beyond reduced energy consumption, including improved reliability and maintainability."

In the Main Building, chemistry laboratory fume cupboards that previously ran at full capacity continuously have been upgraded to reduce airflow when the sash is lowered. Salix said the savings depend partly on users keeping the sash down when a cupboard is not in use.

Windows in a conservation area

Window replacement at the Law and Tower buildings is being delivered through Digarbon. Cris Lewis, Digarbon project manager, said both buildings sit in a conservation area and required careful consideration of planning requirements and replacement materials, with structural limitations, restricted access and the need to keep the buildings operating adding complexity.

The work replaces single-glazed steel-framed windows with double-glazed alternatives. Salix said occupants of the Law Building would be decanted to other spaces during construction, while Tower Building occupants would move floor by floor as work reaches them.

The university also plans to fund the installation of thermostatic radiator valves itself as part of its wider programme of works, Salix said.

Rachael Holliday of Salix said delivering improvements across a live university campus requires careful coordination.

The funding

The visit follows two rounds of Welsh Government-backed loans to the university delivered through Salix.

Loan	Announced	Value
Salix Energy Efficiency Loan Scheme	February 2024	£8.8m
Digarbon	January 2025	£12.2m

In February 2024 Salix said Cardiff University had secured £8.8m through the Salix Energy Efficiency Loan Scheme, funded by the Welsh Government, for low-carbon upgrades to its Cathays campus and Queen's Building. That programme included replacing 22,000 lights at 33 buildings with LED fittings and installing solar PV on six roof areas, with air conditioning refurbishments expected to cut those systems' annual energy use by 22%. The university estimated the programme would save £1.7m and 1,400 tonnes of carbon a year once complete. Salix's January 2025 visit report described it as a £10m loan, of which £8.8m came through Salix.

In January 2025 Salix said the university had been offered a £12.2m Digarbon loan for energy efficiency upgrades to the Tower and Law buildings in the Cathays Park conservation area, and was among the four successful applicants offered Digarbon funding. The Royal Welsh College of Music and Drama was offered £1.7m in the same round, Salix said, with Swansea University and the University of Wales Trinity St David also named. The Digarbon-funded phase at Cardiff is scheduled to run until March 2028.

The Welsh Government announced Digarbon on 25 April 2024. Salix described it as a £20m initiative for higher and further education institutions in Wales, carrying a 2.05% interest rate. In its January 2025 announcement, Huw Irranca-Davies, Deputy First Minister with responsibility for Climate Change, announced £20m of loan funding to higher education establishments. Salix's loan page says the Wales Funding Programme covers 100% of project costs for public sector organisations in Wales at a fixed 2.45% interest rate.

What happens next

Arcadis said in September 2025 it had been appointed to lead the decarbonisation of the 1930s Law School and 1960s Tower building, describing a fabric-first retrofit focused on roof systems and full replacement of the single-glazed windows. Arcadis said the phased works are scheduled for completion in 2028 and that the university targets net zero carbon emissions by 2030.