Case study.

Cornerstone reduces its carbon footprintCornerstone, the UK’s leading mobile infrastructure services company, is always looking for sharper solutions to ensure services are delivered in the most effective way possible to enable digital connectivity across the UK.

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The challenge

Several thousand sites that we manage and own have large cabins or rooms housing critical electrical, radio, and electronic equipment. These essential pieces of equipment produce heat and need to be kept cool.

When telecom networks first came on the scene a few decades ago, the use of air-conditioning was commonplace because of its ease and simplicity to install. However, the steady increase in energy tariffs, the ‘Montreal Protocol’ followed by the ‘Kigali agreement’ has encouraged the telecommunication industry to radically change how they keep their sites cool, by limiting the use of air-conditioning systems. The Montreal protocol bans the use of ozone-depleting refrigerants, massively contributing to the healthy recovery of our ozone layers. The Kigali agreement limits the use of refrigerants that have higher ‘Global Warming Potential.’

At Cornerstone, we recognised that having an effective cooling strategy would ensure long-term environmental sustainability, business continuity and future-proof our network assets.

“We are proud to help keep the UK connected, while constantly looking for practical ways to reduce and minimise Cornerstone's environmental footprint.”

Jack Price, Project Manager, Cornerstone

The solution

Building on this idea, Cornerstone implemented a free cooling strategy as part of the company’s dedicated cooling project in 2018 with the objectives of:

  • Replacing obsolete infrastructure with new, more efficient cooling technology
  • Providing sustainability for the network
  • Reducing power & energy consumption
  • Ensuring that cabins did not overheat
  • Reducing the carbon footprint
  • Reducing high-temperature issues

The project began with a review of the old units, targeting these first before they became redundant. Once these were identified, Cornerstone created a project plan on how we would get them upgraded.

Collaborating with industry experts, Cornerstone’s suppliers Clarke Telecom and Airedale, went out to all the sites to carry out surveys, with the information analysed back at base by Cornerstone’s Operations team. Every review was specific to each individual site, ensuring that the right plan with the most effective final solution was developed.

The project installation across all the sites were grouped into three categories:

  • Free cooling – a fan unit that forces fresh air from outside the equipment into the room to cool the equipment.
  • Split air-conditioning – these units use refrigerant to cool the room.
  • Packaged air-conditioning – these units use a combination of free-cooling and air-conditioning to assure close temperature control.

Using this approach, 740 installations were completed throughout April 2019-March 2020, delivered as:

  • 78% Free air installations
  • 13% Split air-conditioning installations
  • 9% Packaged air-conditioning installations

Being able to convert almost 80% of the original Cornerstone sites with fresh air cooling (free cooling) is a fantastic achievement given the complexity involved in managing network sites.


The environmental benefits of the Free Cooling Strategy across the upgraded Cornerstone sites has resulted in:

  • 602 old mechanical units removed
  • A net figure of 449.87kg refrigerant removed

Put another way, Cornerstone has removed 798 tons of CO2 “footprint” exposure from our Estate, the equivalent of about 399 cars off* the road for a year.

As well as having a significant environmental benefit, implementing more efficient systems, provides enhanced resilience to the mobile network for tens of millions of people.

*assuming R407C GWP = 1774, and a ‘typical car’ produces 200 grCO2/miles driving 10k miles annually would produce 2,000kg of CO2 annually.