Slovenia FTTH uses hot aisle immersion liquid cooling

There is no publicly available evidence that Slovenia's FTTH network uses hot aisle immersion liquid cooling; however, these cooling technologies are increasingly used in high-density data centers worldwide.

Hot Aisle Containment

Hot aisle containment is a traditional data center cooling method where server racks are arranged in alternating hot and cold aisles. Cold air is supplied to the cold aisle, while hot air exhausts are confined to the hot aisle and returned to cooling units. This method improves energy efficiency and prevents hot and cold air from mixing, but it is generally limited to racks consuming around 15–20 kW per cabinet, which is sufficient for standard enterprise workloads but may be inadequate for high-density AI or GPU clusters .

Immersion Liquid Cooling

Immersion cooling involves submerging servers in non-conductive dielectric liquids. There are two main types:

• Single-phase immersion: The liquid absorbs heat and is circulated through heat exchangers to dissipate it.
• Two-phase immersion: The liquid boils at low temperature, absorbing heat as it vaporizes; the vapor condenses on a heat exchanger and returns to liquid form, creating a highly efficient cooling loop . Benefits of immersion cooling include up to 90% reduction in cooling energy costs, higher rack density, elimination of fans, reduced noise, and extended hardware lifespan. It is particularly effective for AI, HPC, and crypto mining clusters where racks can exceed 80–100 kW .

Relevance to FTTH Infrastructure

FTTH networks typically rely on distributed access nodes, optical line terminals (OLTs), and aggregation points rather than ultra-high-density GPU clusters. These facilities generally do not require immersion cooling or extreme hot aisle containment, as their power densities are much lower than hyperscale AI data centers. Standard air cooling or conventional hot/cold aisle containment is usually sufficient for telecom equipment supporting FTTH deployments .

Conclusion

While hot aisle containment and immersion liquid cooling are advanced solutions for high-density, high-power data centers, there is no indication that Slovenia's FTTH network employs hot aisle immersion liquid cooling. These methods are more relevant to AI, HPC, and hyperscale cloud environments rather than typical fiber access infrastructure .