Sites / Ark Elstree campus (former Mercure Hotel)
Ark Elstree campus (former Mercure Hotel)
Ark Data Centres · proposed · Hertsmere Borough Council
Proposed redevelopment of the former Mercure Hotel / Hilfield Park site near Watford–Elstree. Operator cites 250 MVA from 2028; trade reporting about 200 MW campus. Held at proposed until a lasting Hertsmere Public Access URL is linked.
Stated size
200 MW
biggest size stated for this site Operator
Source: Ark Elstree: about 200 MW (trade reporting)
The largest megawatt figure on the public record for this one site (planning docs or operator materials). It may include stages that are not built yet. Not everyday electricity use; the source sits with the number. Stated size is not electricity use.
Site area
Unknown
ex-industrial / brownfield
What was here: Former Mercure Hotel / Hilfield Park
Water
Not disclosed
No annual water figure in materials reviewed
Equivalences
No operator on this map discloses expected load factor (the share of peak power used on average), so yearly electricity figures are shown as a range, not as a known total.
-
66,667 kettles running at once
ⓘ Arithmetic and sources
66,667 kettles running at once (at biggest size stated for this site; power size, not annual use)
- Nameplate 200 MW treated as continuous power for a power-to-power comparison only.
- One kettle = 3 kW.
Figure type: biggest size stated for this site · stated
-
259,556-454,222 homes' annual electricity
ⓘ Arithmetic and sources
259,556-454,222 homes' annual electricity (at 40%-70% load factor)
- Uses biggest size stated for this site = 200 MW.
- Assumed average load = nameplate × 40%-70%.
- Home use = 2700 kilowatt-hours/year.
- No operator discloses load factor; this is a bound, not a measurement.
-
Local geography (load-factor range): about 1.2-2.1× Barking and Dagenham's annual electricity (the lowest-consumption local authority we compare against)
ⓘ Arithmetic and sources
At 40%-70% load factor: about 1.2-2.1× Barking and Dagenham's annual electricity (the lowest-consumption local authority we compare against) (annual electricity)
701-1,226 gigawatt-hours per year assumed
- Uses biggest size stated for this site = 200 MW.
- Energy = MW × 8760 h × load factor / 1000 → GWh/year.
- Compared to Department for Energy Security and Net Zero local-authority total metered electricity (all sectors).
- No operator discloses load factor; this is a bound, not a measurement.
- Water: Water use: not disclosed
Claims on record
None recorded yet.
Disclosure checklist
- Stated size (MW): disclosed
- Water: not disclosed
- Power usage effectiveness (PUE): not disclosed
- Energy source claim: none on record
- Load factor: not disclosed
Plain checklist, no aggregate score.
Right of reply
Right of reply: open; no response received. Email marco@prismaticlabs.ai. Subject is prefilled. Or see methodology.
Sources
No live planning application link recorded yet. We do not upgrade a site past “proposed” without one.
Map point: longitude -0.33, latitude 51.655. Last reviewed 2026-07-20.