Published 2026-09-12 · Event 2026-05-06

Fortum starts Espoo and Kirkkonummi heat plants; Microsoft hall heat is still a 2027 phase-in

On 6 May 2026 Fortum said large heat-pump plants at Hepokorpi in Espoo and Kolabacken in Kirkkonummi had started operations. They currently make district heat from ambient air and electric boilers. Recovery of waste heat from Microsoft’s two data centres on those sites is to begin step by step the following year. A running heat plant is not delivered hall heat, and 40 percent of a 2 TWh Finnish demand is not a Swedish offtake.

Fortum’s 6 May 2026 notice is the dated utility source used here. It says the large-scale heat-pump plants in Kolabacken, Kirkkonummi, and Hepokorpi, Espoo, have started operations. Currently the plants produce district heating with heat pumps using ambient air as a heat source, and with electric boilers. That is a heat-plant commissioning sentence. It is not a sentence that Microsoft’s halls have started delivering waste heat.

The Microsoft clause is scheduled, not delivered. Fortum says recovery of waste heat from the two data-centre sites will begin step by step next year, in line with Microsoft’s construction and commissioning schedule. As new phases of the data centres are completed, increasing volumes of waste heat will be available. Next year from a May 2026 notice is 2027. This article does not treat a later 2027 delivery as documented.

The 40 percent sentence is an expected full-implementation illustration. Once fully implemented, data-centre waste heat is expected to cover approximately 40 percent of the total yearly 2 terawatt-hour district-heat demand of the 250,000 heat users in the area. Expected and approximately are Fortum’s words. Two terawatt-hours is a heat-demand envelope, not IT load. The plant inventory — 40 air-to-water units, 72 water-to-water units producing up to 180 megawatts of district heating, 200 megawatts of electric-boiler capacity and 20,000 cubic metres / 800 megawatt-hours of thermal storage — describes the heat plants. It is not a Microsoft IT-load table.

Geography stays Finnish. Espoo’s Clean Heat programme and the city’s 2030 carbon-neutrality target are named in the notice. They do not become Stockholm Data Parks, Falu Energi & Vatten or Horndal. Fortum’s 9 September 2026 Loviisa nuclear PPA with Google is a different Finnish energy instrument already stored on its own row. A running heat pump is not that PPA.

DataCenterSweden records 6 May 2026 as a Finnish heat-plant start at two named Microsoft-adjacent sites. No Swedish project identifier is attached. The 180 MW heat-pump rating is not written into any Swedish capacity cell. The next update would need a later primary source that names actual waste-heat delivery from a completed hall phase.

Why it matters

A heat-plant start is easy to headline as Microsoft heat in the pipes. The May notice is usable only if ambient-air operation, 2027 phase-in and the 40 percent illustration stay on separate lines from any Swedish offtake.

What remains unknown

The notice does not publish a 2026 delivered megawatt-hour from the Microsoft halls, a Swedish offtaker or an IT-load figure for either campus.

Sources