Summary
- Plans have been formally submitted to replace three former Microsoft office buildings at Thames Valley Park with a data centre.
- Planning documents indicate potential electricity demand of up to 110MW while only 1.8MW of grid capacity is currently available to the site.
- Onsite natural gas generation is proposed while wider electricity network upgrades are brought forward.
Mapeley has formally submitted plans to redevelop three former Microsoft office buildings at Thames Valley Park near Reading as a data centre, with planning documents indicating potential electricity demand of up to 110MW against only 1.8MW currently available to the site from the grid.
The application to Wokingham Borough Council moves the project beyond the consultation stage covered earlier in the summer. The proposal includes data centre buildings, onsite power generation equipment, backup generators and office space, while Microsoft is expected to leave the existing campus when its lease expires at the end of 2027.
The increase in the stated electrical requirement is one of the main changes to track. Earlier consultation material described a 72MW proposal using natural gas fuel cells while additional grid capacity was brought forward. The submitted documents cited in current local reporting now describe demand that could reach 110MW, making the gap between the existing connection and the proposed facility even larger.
The 1.8MW figure is the grid capacity reported as presently available to the site. It is not enough to support anything close to the proposed maximum data centre demand, so electricity supply becomes a development programme in its own right rather than a utility connection added after the buildings are designed.
Gas generation is proposed as a bridge to the grid
Mapeley proposes generating electricity onsite from natural gas while local network upgrades are brought forward. Earlier project material identified fuel cells within that strategy, giving the development a route to produce power without relying entirely on the constrained grid connection during its initial operating period.
That approach can shorten the gap between a completed data hall and a future network reinforcement date, but it transfers more energy infrastructure onto the site. Fuel supply, emissions, noise, maintenance and resilience then become part of the data centre design alongside substations, backup generation and cooling.
The duration of the bridge will be important. A generating system described as temporary can still become a major part of the facility’s operating model if grid reinforcement takes several years. The planning and environmental assessment therefore need to consider the period for which gas generation may actually run rather than assuming a rapid transition to full grid supply.
Earlier consultation documents also referred to potential future use of biomethane or hydrogen. Those options depend on suitable fuel becoming available at workable cost and scale, so they do not change the immediate proposal to rely on natural gas during the period of constrained grid access.
The site’s redevelopment has an obvious land use advantage because it replaces established office buildings inside an existing business park rather than opening an entirely new greenfield campus. The electricity profile, however, is far more intensive than the offices it would replace, which explains why the existing utility provision cannot simply be carried across to the new use.
Cooling and power have to be assessed together
Earlier consultation material proposed air cooled chillers as part of the mechanical design. Air cooled systems can reduce direct dependence on cooling towers and evaporative water use, but they still require substantial electrical power for compressors and fans and have to be designed around ambient temperature and acoustic limits.
That cooling load forms part of the wider facility demand rather than the IT load alone. A planning figure for total electrical requirement can therefore include power used by computing equipment, cooling, pumps, lighting, controls and other supporting systems, depending on how the applicant has defined it.
The submitted plans also contemplate buildings up to around 30.5 metres high. Large data centre structures need space not only for server halls but for electrical rooms, cooling plant and maintenance access, while external power compounds can occupy a significant part of the site.
Heat reuse has also been discussed during the project’s development. The technical availability of waste heat does not guarantee a useful export scheme: a nearby customer, pipework and suitable delivery temperature would be needed, and the quantity available would rise as the data centre fills with operating equipment.
Formal submission gives councillors and statutory consultees a more complete basis on which to test those relationships. The project must now be assessed not simply as a replacement building scheme but as a large energy user with onsite generation operating in parallel with a future grid reinforcement programme.
Consent would still be only one step towards operating capacity. The developer would need to deliver the onsite energy system, build the data centre, secure the required gas and network arrangements and eventually connect the larger grid supply before the full proposed electrical envelope could be used.
Thames Valley Park therefore illustrates the practical effect of the UK’s connection constraint on individual projects. The site can be redeveloped faster than the electricity network can provide the proposed 110MW demand, forcing the applicant to design an interim power system into the scheme from the beginning.
