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CARTIS

DayOne Lahti Data Center Campus

Lahti / Kiveriö, FinlandUnder construction
Evidence
Headline capacity
Not established in published records
Updated
Oct 28, 2026
Utility
Lahti Energy

DayOne began construction of its Kiveriö campus in April 2026. The first building is planned for 50 MW of IT load within a 128 MW potential campus, with TikTok confirmed as principal tenant.

Capacity

Planned IT capacity

Planned / design or future potential

50 MW

Lahti first 50 MW building · Phase

Phase scope; not a whole-site figure

Source

Potential IT capacity

Planned / design or future potential

128 MW

Lahti full campus potential · Phase

Phase scope; not a whole-site figure

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

Lahti permit and site preparationAnnounced or preconstruction

1 building

Application covered a two-story data hall and ancillary buildings; construction later began.

Lahti first 50 MW buildingUnder construction

1 building

50 MW IT design within the larger 128 MW potential site.

Lahti full campus potentialPlanned

Future envelope only; no completed or contracted full-site capacity inferred.

Milestones (5)
DayOne announces €1.2B Lahti campus

Aug 14, 2025 · Recorded actual event

Completed · Announced

Source not linked
Lahti publishes building-permit application scope

Oct 2, 2025 · Recorded actual event

Completed · Permit filed

Source not linked
SRV launches Lahti construction

Apr 7, 2026 · Recorded actual event

Completed · Construction started

Source not linked
TikTok confirms Lahti investment

Apr 7, 2026 · Recorded actual event

Completed · Customer commitment

Source not linked
First Lahti building targeted for operation

2027 · Forecast / planned record

Forecast · Ready for service

Source not linked

Participants

DayOne Data Centers

Operator

Sources by role
Operator (1)
Operator (1)
Kiinteistö Oy Lahden Ilmarisentie 3

Owner

Sources by role
Owner (1)
TikTok

Tenant

Sources by role
Tenant (1)
Tenant (1)
Other participants (4)
City of Lahti

Government authority

Sources by role
Government authority (1)
Government authority (1)
Government authority (1)
Eltel Networks

Contractor

Sources by role
Contractor (1)
Lahti Energy

Utility provider

Sources by role
Utility provider (1)
SRV Group Plc

Contractor

Sources by role
Contractor (1)
Contractor (1)

Capital & incentives

Capital claims and financing records may overlap. Their amounts are not added together.

Capital claims

Dayone announced investment

Forecast

€1,200,000,000

Source

Tiktok announced investment

Transaction scope

€1,000,000,000

Source

Grid connection contract value

Transaction scope

€38,000,000

Source

Financing records

Investment commitment

€1,200,000,000

Aug 14, 2025

DayOne aggregate project estimate; no financing sources or spend schedule disclosed.

Parties & sources

DayOne Data Centers (Sponsor)

Sources (2)

Investment commitment

€1,000,000,000

Apr 7, 2026

TikTok investment/customer scope; not additive to DayOne's project estimate and not site financing.

Parties & sources

TikTok (Sponsor)

Sources (2)

Site & development

Site area

Actual

98,901 square metres

Source

Site location

Actual

Kiveriö; Ilmarisentie 3 / Väinämöisentie 2a

Source

Permit application floor area

Reported rounded

40,000 square metres

Lahti permit and site preparation · Phase

Source

Construction start

Actual

Launched immediately after 2026-04-07 contractor announcement

Lahti first 50 MW building · Phase

Source

Grid connection completion target

Forecast

2027 Q1

Source

Peak construction workers

Forecast

1,000 workers

Source

Technical specifications

Power connection agreement

Actual

Executed with Lahti Energy

Source

Cooling design

Design

Air cooled chiller; no freshwater cooling

Source

Additional project facts

Current status

Actual

Under construction

Source

Data hall storeys

Proposal

2 storeys

Lahti permit and site preparation · Phase

Source

Ready for service target

Forecast

2027

Lahti first 50 MW building · Phase

Source

Principal tenant

Actual

TikTok

Source

Waste heat reuse

Design

Under exploration with local partners

Source

Projected operational jobs

Forecast

100 jobs

Source

Infrastructure & permits

Technical details (6)
Electric grid

Under construction

50 MW IT

First-building planned IT load; no operating capacity.

Electric grid

Planned or represented

128 MW IT

Full campus potential only.

Electric grid

Under construction

Power connection agreement and Eltel delivery contract; rating undisclosed.

Electric grid

Secured or contracted

€38,000,000 contract value

Contract value is not capacity, capex total or financing.

Cooling system

Planned or represented

Design claim not operating performance.

Heat reuse

Potential or planned

Integration under exploration; no executed heat-offtake terms captured.

Building · Under review

Lahti first data center building and ancillary works

City of Lahti

Oct 2, 2025

Sources (1)

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