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Consider the air handled! With AHU upgrades

The project

Over the yearlong course from winter 2021-2022, we have successfully upgraded components of several Air Handling Units (AHUs) across our university campuses (Whiteknights, Greenland’s and London Road) in order to save huge amounts of energy and carbon. This sustainability project was funded by the Department for Energy and Net Zero, under the Public Sector Decarbonisation Scheme (PSDS) and delivered by Salix. The upgrades oversaw ten inverters and ten fan motors replaced within five older, inefficient AHUs. The units were replaced on a like for like basis, with more modern fittings and higher efficiencies where appropriate. All the AHUs were also internally cleaned, including a thorough scrubbing of the coils, amendments of existing coils, and new data loggers were installed so that we can track energy outages more accurately on a permanent basis.

What are Air Handling Units?

AHUs or air handling units are big industrial machines with numerous functions, that work to condition and distribute clean hot or cool air throughout buildings. The AHUs take in air from outside, and then clean, cool or heat the air appropriately from which the air is then circulated around indoor spaces providing ventilation, heating or cooling as required. The reason for this process is to ensure a clean and temperature-controlled environment for those using buildings on campus. AHUs are usually installed in out of the way places such as under floors, basements and roofs due to their large size. Unfortunately, these big units use an awful lot of energy to run, especially when they are running continuously and at a fixed fan speed, which is why the new and more efficient fan motor upgrades have been necessary.

Fantastic energy saving results

Dr. Sam Mudie, who works as an energy officer in sustainability services at The University, oversaw the process of this project and calculated the savings outcome of the AHU upgrades. Overall, the AHU upgrades used more electricity than initially anticipated in the pre-project application; however, the upgrades are still using less than half the energy of the old ones. In addition, a great financial saving of £58,840 per year was achieved, along with an annual carbon saving of 5422 tCO2e (which is 30 tonnes more than expected). The total cost of the project also came in under budget at £24,032 per year which is very favourable. The table below summarises the total savings for this successful AHU project.

Table below: The pre- project and post project energy, carbon and financial saving calculations


Julia Cope, Sustainability Services

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