A challenging Retrofit

Cannington Court started life in 1138 as Cannington Priory. After being returned to the Crown during the Reformation of the 16th century, it became a Catholic boys’ school and then an agricultural college. In 2012, EDF Energy signed a long lease on the building, and started a multi-million pound restoration project to create a new training facility: Campus.

The project achieved BREEAM Excellent standard with minimal impact on the environment and local community.

Cannington Court opened for business on the first June. This unique facility is a major training centre which will help connect all the different parts of EDF Energy and our key partners.

It boasts 50 en-suite bedrooms, a wide range of learning and meeting spaces, plus pioneering learning technology throughout. This is a place where our employees can discover new ways of learning that will appeal to all different styles and help grow in their personal development.

A challenging building

Working with a Grade I building held its particular challenges; the restoration had to be sympathetic to the original style, while integrating the best energy efficiency measures possible.

Additional challenges included dealing with archaeological remains and a number of protected species such as bees, bats and wisteria.

English Heritage and the architects both specified that no renewables could be installed on the original building. Carports were therefore built over the car park to create the necessary roof space for the solar thermal and PV panels. An additional benefit is that cars are not visible from neighbouring houses. Together with the heat pumps, which are very quiet, and the lack of emissions from the site, this means the finished project is very unobtrusive.

State of the art energy performance

The building is fitted with an integrated energy system which has been optimised for efficient operation revolving around a renewable energy centre using ground-source heat pumps, solar thermal, and solar PV, as well as heat recovery.

This provides Cannington Court with renewable energy for all its heating, cooling and hot water needs, as well as part of the electricity needed to run the building and electric vehicle charging points.

The solar PV array in itself will generate in excess of 26MWh per year of renewable electricity, saving over 12 tonnes of CO2 a year.

Integrated Energy Solution

Integrated Energy Solution
  1. Ground-source heat pumps: using heat recovery, drilling deeper and larger boreholes than usual, and using a more efficient coaxial design means only eight boreholes were needed, instead of the 40-50 a building this size would normally require. The pumps extract low-grade heat from the ground and concentrate it into a heat exchange, bringing the temperature up to over 40° C).
  2. Solar thermal panels: these sit on top of carports in the car park, absorbing ambient heat from the air, and directing it into the heat pumps. If we have enough heat to run the buildings already, we can redirect into the ground for storage and later extraction.

Together, the heat pumps and solar thermal provide all the cooling, space heating and hot water for the building. This is the first system to integrate heat pumps with solar thermal in this way. EDF R&D has added this intellectual property and patents to its extensive portfolio of low carbon innovations.

  1. Solar PV panels: these produce electricity, which is used to power the heat pumps and electric car charge points, as well as supplying the building. The 30kWp installed capacity provides part of the electricity used at Cannington Court. The remainder comes from EDF Energy’s nuclear-backed Blue tariff, meaning no fossil fuels are consumed on site
  2. Thermal storage: this is a very efficient way of storing heat (as opposed to batteries, which store electricity). Excess heat produced by solar thermal, and recovered from the building cooling system is returned to the ground for later re-extraction. This means the ground is kept at near constant temperature despite the heat taken out by the heat pumps. In simpler terms, recovering heat allows the ground to be ‘recharged’, and to reduce the number of boreholes needed to feed the heat pumps.
  3. Super-efficient all-electric heating and cooling system: for every 1kWh electricity consumed, the system produces up to 5.5kWh of heat (this means the system is 550% efficient or operates with a sCOP of 5.5). This is because more ‘free’ renewable energy is harvested from the site by the heat pumps and solar panels than is required to run the system, making it extremely efficient.

For comparison, a very efficient condensing gas boiler would use 1kWh of gas to produce 0.9kWh of heat (making it 90% efficient), and conventional electric heating such as storage or immersion is around 95% efficient.

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