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New technology leads to significant carbon savings at CUH

Cambridge University Hospitals is helping the NHS lead the fight against climate change with ground-breaking new technology designed to cut carbon emissions.


The Trust has become the first in the country to use sophisticated technology which chooses between solar, battery and mains energy. This is used to deliver the lowest possible carbon heating and air-conditioning for mums and babies at The Rosie hospital.

It’s led to a 60 per cent carbon reduction1 and represents a major step towards the Trust’s highly ambitious, net-zero carbon future.

Developed by Arriba Technologies on St John’s Innovation Park in Cambridge, the new technology combines photovoltaic (solar) roof panels, cooling, heating and the power of huge lithium batteries with unique computer-controlled electronics in a single unit.

It’s innovative because it can flip between the three different sources of power – sun, batteries and electricity from the national grid – and chooses whichever is the most green at the time.

For example, if there is low demand on the grid it may decide to draw energy from the mains supply, a proportion of which is renewable, allowing the sun’s energy to recharge the batteries ready for the night time.

Or, if the batteries are fully charged and the sun is shining, it would choose to power the unit directly from the sun.

We are trying to make sure we squeeze every bit of value out of low carbon kilowatt hours. This direct connection and clever power management between PV panels, batteries, mains supplies and heating/cooling plant hasn’t been done anywhere quite like this before, as far as we’re aware.

Richard Hales, Energy and Sustainability Manager at CUH

Maintaining the right temperature at the Rosie Hospital is vital for the welfare of mums and babies. Water has to be heated to high temperatures to ensure it is safely pasteurised. But the environment also has to be cool enough to be safe for patients and provide valued air conditioning on hotter days.

The new system is one of many measures being adopted by CUH in its ambition to halve its carbon emissions over the next 10 years and become net-zero carbon by 2045.

Richard added: “Being a 24/7 major acute hospital means CUH is a very intense consumer of energy, water, goods and materials.

“Front-line patient care, and all the associated support functions and campus infrastructure mean that each day CUH consumes the same amount of gas and water as a small town, and three times as much electricity.

“Our plan is to keep refining the technology whilst replicating and scaling up across our buildings in order to decarbonise our estate. For the past decade the Trust has had a rolling fund to reinvest energy savings in green infrastructure. This has allowed us (together with the decarbonisation of the national grid) to lower our on-site building carbon footprint – even though demands on the hospital have grown.

“We have made significant progress in the more conventional energy efficiency areas of lighting, heating and control systems. Our overall ambition is to become net-zero carbon by 2045, with a very challenging interim target of halving emissions in the next 10 years.”

Other measures adopted by the Trust to date include:
  • Encouraging staff to adopt more sustainable means of travelling to the site, such as buses or cycles. Since 1993 the proportion of staff travelling to the site by car has halved, and will be further improved with a new South Cambridge railway station, due to open in 2025. Bicycle racks are available for 2100 cycles and the Trust provides a dedicated Campus Cycle Hub offering repairs and servicing 5-days a week (alongside two self-service repair posts with pumps for quick fixes out-of-hours.)
  • Ensuring waste generated by the Trust is recycled where possible with 24 different waste recycling streams. The hospital currently generates 11 tonnes of waste per day. Just under half of this requires high temperature disposal and is burned onsite in the Trust’s very carefully controlled and regulated incineration plant. The heat generated from this is converted to steam and used to help heat the hospital. The majority of the rest of the waste is either specifically recycled or subject to recovery off-site (again including incineration with heat recovery).
  • Setting up a regional pilot project to look at ways we can recycle plastics used in clinical applications, for example, syringes. These products are made with high grade plastics which often end up being incinerated or disposed of via low-value domestic recycling. From a very detailed analysis of its top 200 clinical plastic items, the Trust is hoping to establish new routes directly back into the manufacturing chain.
  • Establishing a new clinically lead multi-disciplinary team to drive down the use of certain anaesthetic gasses which can directly contribute to climate change.
  • Using a pair of specialist biodigesters units to breakdown food waste. The food waste is turned into grey water, thereby avoiding food waste going to landfill or disposed of into the waste water drain. The biodigesters weigh and log where all the leftovers have come from. This allows the patient catering teams to understand how it can reduce the amount of food wasted in the first place.
  • Using hybrid and low emission pool and lease cars. The organisation’s ‘car club’ pool of cars for business generate on average around 100g of carbon dioxide per kilometre. The Trust is looking to replace these with Ultra Low Emission or all-electric vehicles (with emissions of 75g CO2/km or less) and install charging points in car parks to support this transition.
  • Taking trouble to try and keep a very limited supply of green space as biodiverse as possible.

As well as working to lower the carbon emissions from its existing estate, the Trust is pushing exceptionally hard with the plans for its new buildings, such as the Cambridge Children’s Hospital and the Cambridge Cancer Research Hospital. Both will meet the requirements of the NHS’s new Net-Zero Carbon Building Standard and the principles of Passivhaus design.

1When compared to the previous conventional chiller unit