Helsinki satellites track the city's winter heat
New thermal maps are helping planners find waste heat, drafty blocks, and public buildings that need faster retrofits.
2 min read
The thermal images look like a fault map. Long bright seams run under streets where nothing on the surface suggests anything is wrong, and clusters glow around buildings whose owners believed they had solved their heating years ago.
What the survey found
Helsinki’s district heating network loses heat everywhere — that is physics, not failure. What the satellite passes established is that the losses are wildly uneven, and that a small share of the network accounts for a large share of the total.
That distribution is what makes the survey useful. A uniform loss rate would mean replacing everything eventually. A concentrated one means a targeted programme can capture most of the benefit for a fraction of the cost, provided you know where to dig.
The survey did not find new problems. It found which of the known problems were worth the excavation.
From image to work order
Turning thermal imagery into maintenance is less automatic than it sounds. A warm signature can be a leaking pipe, a poorly insulated culvert, a car park that held the day’s sun, or a building venting into a service void.
The city’s utility now treats an anomaly as a candidate rather than a finding. Candidates are cross-checked against pressure telemetry and network age before anyone books an excavation, and roughly two in five survive that filter. The rest are logged, because a signature that recurs across three winters is a different proposition from one that appears once.
The privacy line
Thermal imagery at building resolution says something about how a building is used, and at high enough resolution about how a home is occupied. The utility has capped published resolution at block level and holds finer data under the same regime as metering records.
That satisfied the data protection authority. It did not entirely satisfy the residents’ associations, whose objection is that “held under a regime” is a statement about intent rather than architecture.
What to watch
Watch the conversion rate from anomaly to confirmed fault, which is the honest measure of whether the survey is guiding spending or just decorating it. Watch whether repeat-signature sites get priority over new ones. And watch what happens to the block-level cap the first time an insurer asks for building-level data.
