What is technical insulation?

Technical insulation is the professional term for the insulation of technical installations: all the pipes, ducts, tanks, vessels, valves, pumps and process plant that transport or contain a medium at a particular temperature. It covers both hot and cold media — domestic hot water, district heating, steam, refrigeration plant, ventilation air, chemical process fluids, cryogenic gases and everything in between.

It is important to distinguish technical insulation from building insulation:

• Building insulation is the insulation that sits in external walls, roof structures, ground-bearing slabs and floor separations. It is typically large surfaces, laid by carpenters or bricklayers, and regulated by the building regulations' requirements for the energy frame and U-values. The materials are often the same — mineral wool, EPS, PIR — but in thick boards rather than cylindrical mouldings.
• Technical insulation is what sits on the outside of the installations inside the building, or outdoors on pipe trenches, roof surfaces and industrial plant. It is carried out by technical insulation fitters (a separate vocational trade) and is regulated, among other things, by DS 452 (heat loss from technical installations) and DS 428 (fire protection of ventilation systems).

The standard DS 452 itself draws the line:

"The standard does not apply to the insulation of building structures or cold rooms, nor to the insulation of the district heating supply's pipework. The boundary between the district heating system and the building installation is at the district heating system's main valves, so service connections and main valves belong to the district heating system. The standard does not apply to the insulation of boilers and heat pumps." [DS 452-3, cited in Grundlæggende teknisk isolering, BAI 2025]

In other words: The technical insulation fitter's trade begins where the district heating's main valve enters the basement, and ends where you reach the boiler or the heat pump. Everything in between — the heating plant's pipes, main distributions, risers, ventilation ducts, hot water tanks, hot water circulation, cooling pipes, steam lines, process pipes — is technical insulation.

In practice there are four basic purposes of technical insulation. They almost always appear together, but one of them is typically the governing one.

1. Heat insulation — keeping the heat IN hot media. The most classic role. We wrap an 80 °C hot water pipe so that the energy reaches the radiator instead of seeping out into the basement. It is driven by both economics (less energy consumption) and legislation: BR18 refers to DS 452, which defines the maximum permissible heat loss per m² of outer surface through six insulation classes (class 1 to class 6). Class 1 is the loosest (1.17 W/m²·K), class 6 the strictest (0.22 W/m²·K). [isover-hvac-haandbog.txt; Grundlæggende isolering BAI 2025]

2. Cooling insulation — keeping the heat OUT of cold media. The reverse: cooling pipes in a server room (2–6 °C), air conditioning, frozen storage, freezer rooms, cryogenic pipes. Here the primary function is to minimise unwanted heat ingress. But that is not all — condensation is almost always at least as important:

3. Condensation insulation — ensuring the surface never falls below the dew point. When a cold pipe (e.g. 6 °C) stands in room air (e.g. 22 °C, 60 % RH), the water vapour in the air will condense on any surface colder than the dew point (here about 13.8 °C). That is why cooling pipes are insulated with materials that act as a built-in vapour barrier — typically elastomeric foam or cellular glass with μ-values above 10,000. An open-celled glass wool, by contrast, requires an additional aluminium foil as a vapour barrier. Neglect the vapour barrier and you end up with water inside the insulation, rust on the pipe and mould in the ceiling. [grundlaeggende-isolering.txt; cellegummi.md]

4. Fire insulation — slowing the spread of fire and smoke. Steel pipes and ventilation ducts are fast routes for fire and hot flue gases between fire sections. Insulation with the right material and thickness can maintain the fire resistance of the pipe penetration — e.g. EI 60 (integrity and insulation for 60 min). It can also protect the steel structure from losing load-bearing capacity (passive fire protection). It is regulated, among other things, by DS 428 (fire protection of ventilation systems), EN 13501-1 (fire classes A1 to F) and fire requirements in BR18. [Brand_rørgennemføring.pdf; scandisupply.dk]

Many tasks have several of these purposes at once. A cold water pipe in an unheated attic must both be energy-insulated (class 2 per DS 452) and condensation-insulated with a vapour barrier. A fire-protected ventilation system in an escape route must both maintain the fire class and the energy class per the thermal requirements. A district heating pipe in the ground is a typical heat-first task. A 250 °C steam line in an industrial installation has heat, safety (surface temperature ≤ 50 °C so no one gets burned) and fire as drivers all at once.

Technical installations make up a large part of a building's energy consumption, and uninsulated pipes lose astonishingly much. An example from Grundlæggende teknisk isolering (BAI 2025): even a small 3 mm gap in a longitudinal insulation joint increases the heat loss by 13 % over that section. [grundlaeggende-isolering.txt p. 11]

A concrete worked example from BAI's Faglig regning and the Isover handbook:

• A 12 metre DN 50 line at 80 °C, surrounded by 20 °C room air.
• Uninsulated: about 12,946 kWh/year heat loss (corresponding to about 9.7 tonnes of CO₂ at average Danish district heating intensity).
• Insulated to DS 452 class 4 (typically 40–50 mm mineral wool with aluminium foil): 1,611 kWh/year (about 1.2 tonnes of CO₂).
• Saving: 11,335 kWh and about 8.5 tonnes of CO₂ — per year. Payback time: in the best case about 6 months. [grundlaeggende-isolering.txt p. 4–5]

Scale that up to a hospital, a housing complex or an industrial plant, and it quickly becomes a matter of millions in operating costs and hundreds of tonnes of CO₂. That is why the trade, in a green-transition context, is described by some as "the trade that in all contexts gives the greatest and best result for the green transition, because we are dealing with the very core of the energy frame" [grundlaeggende-isolering.txt p. 4].

Beyond energy, insulation also has three other practical functions: personnel safety (DS 452 and the Danish Working Environment Authority require that accessible surfaces on hot installations do not exceed about 50 °C, so people do not get burned), frost protection (uninsulated pipes outdoors freeze in winter), and operational stability (a well-insulated cooling pipe has a stable temperature and does not condense).