Oxfordshire County Library – a potential battery

This trial aims to learn if it’s possible to use buildings as batteries to provide flexibility to the electricity network.


Project LEO is investigating how buildings can be used as batteries to provide flexibility in a low carbon future. LEO partners, Oxfordshire County Council and the University of Oxford, are working together to test this technology at the Oxfordshire County Library. The Library is the main public library in central Oxford and holds over 500,000 items available for loan. The Library is owned and run by Oxfordshire County Council.

This building is of particular interest to LEO as libraries tend to have relatively low, non-critical, uniform use throughout the week and as such, presents an ideal environment for testing the provision of flexibility services. Secondly, a library, through the very nature of the building and its contents, has a high thermal inertia (acting as a heat battery) which affords the building internal resistance to temperature and air-specific changes. This presents the potential opportunity for providing flexibility with minimal disruption to the building’s services and users. 

Aim of the trial

We are running MVS trials at the Oxfordshire County Library, testing how a building can provide flexibility to the electricity network by altering the time of use of electricity (by changing the demand for air conditioning) within the building. The trials will explore and unlock the potential of the building to play a part in delivering flexible energy. 

The core idea is to temporarily shift (or modulate) the use of air conditioning, for example, making sure that demand does not occur at times when the grid is congested. Coordinating this operation to make use of the buildings thermal mass, even if the chiller is switched off in the summer, the temperature inside the building should not rise immediately due to the energy stored within the walls and contents of the building. 

Switching off the air conditioning can bring about a large reduction in the electricity consumed by the building. This contributes to relieving the stress on the electricity grid, helping to maintain stability of the network in a way that removes or delays the need for network upgrades. 

What we hope to do

Through the trials being conducted on this building, we hope to increase our understanding of just how much flexibility this building – and others alike – could provide the electricity network with. The trials will allow the team to develop a business case for enabling similar assets to provide a flex market services. 

Initial trials are also trying to understand the amount of data, metering and monitoring required throughout the building in order for any potential flexibility service to be appropriately managed and validated. 

The team also hope to learn if altering the temperature set points of the building will affect building users and if so, understand the upper and lower limits of any temperature changes to minimise impact on users whilst still being able to provide a flexibility service.

How the trial works?

The trials undertaken at the Library will involve a series of tests which turn up and down the energy demand of the building through either changing the temperature set point (increasing/decreasing air conditioning use), or fully deferring the air conditioning load for some time intervals during the day. 

The team have collected data from the Building Management System (BMS) as well as from additional ad-hoc prepared temperature and electrical load sensors to understand patterns of energy use of the building and to synthesise and validate a theoretical building model to be use in the optimisation of the flexibility service delivery. 

Who is involved?

Oxford University is running this trial with the support of Oxfordshire County Council.