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CARTIS

Ark Hilfield Park Campus

Elstree, England, United KingdomProposed
Evidence
Planned / design
200 MW
Updated
Oct 29, 2026

Ark proposes Hilfield Park on the former Mercure Hotel site at Tylers Way, Elstree. The December 2025 application describes four buildings, each with two independently operable wings; Ark’s separately marketed 6+ data centres are not a verified physical-building count. The operator targets approximately 200 MW of compute capacity, power delivery from 2028 and service in 2029. Its 250 MVA supply figure is not IT capacity. Application 25/1781/FUL is listed for Hertsmere’s 5 November 2026 committee, not approved by that listing. Current title, delivered power and operating capacity remain unverified.

Capacity

Planned campus capacity MW

Planned / design or future potential

200 MW

Source

Operating IT capacity: Not established in published records

A missing figure does not mean zero. Planned, utility and generation figures are not operating IT capacity.

Development

Proposed Hilfield Park campusPlanned

The December 2025 planning application proposes four buildings (HP1–HP4), each with two independently operable wings. Ark separately markets 6+ data centres; the sources do not establish that marketing count as a physical-building count. 250 MVA power supply is not IT capacity.

Milestones (3)
Applicant planning statement submitted for full redevelopment.

Dec 2025 · Recorded actual event

Completed · Announced

Sources (1)
Operator target for power delivery to begin.

2028 · Forecast / planned record

Forecast · Announced

Sources (1)
Operator ready-for-service target.

2029 · Forecast / planned record

Forecast · Announced

Sources (1)

Participants

Ark Data Centres (UK)

Developer · Operator

Sources by role
Developer / Operator (1)

Site & development

Site location

Reported rounded

Former Mercure Hotel and land southeast, Tylers Way, WD25 8JH; one Hilfield Park campus, also marketed as Elstree. Do not confuse supply substations with site location.

Source

Land and site control context

Reported rounded

Applicant says site held freehold; title not independently inspected.

Source

Additional project facts

Planning and marketing scope

Actual

The December 2025 planning application proposes four buildings (HP1–HP4), each with two independently operable wings. Ark separately markets 6+ data centres; the sources do not establish that marketing count as a physical building count.

Source

Reviewed hilfield committee listing

Reported rounded

As checked on 3 November 2026, Hertsmere lists application 25/1781/FUL as item 5B for its scheduled 5 November 2026 Planning Committee. The listing is not planning approval, and the officer report was not accessible in this review.

Source

Infrastructure & permits

Technical details (3)
Utility service

Reported context

Planning statement identifies secured supply from Letchmore Heath; no MVA-to-MW conversion.

Fiber

Reported context

Planning statement identifies proximity to dark fiber; named carriers unverified.

Utility service

Planned or represented

250 MVA

Operator 250 MVA supply specification, target power delivery from 2028; not 250 MW IT.

Other · Documented

Ark Hilfield Park Campus

Sources (1)

Public-source research. Plans may change. See Evidence for sources and qualifications.