Moisture and fog in the ice rink? Start with the simple measures.

Have you started the ice season and already run into problems with fog, condensation, or high humidity? Warm and humid August weather can place a significant load on both the dehumidifier and the refrigeration system.

The first measure is simple: limit the amount of warm, humid air entering the arena.

Why do fog and condensation occur?

An ice rink contains a large, cold surface. When warm, humid air enters through doors, gates, ventilation systems, or leaks in the building envelope, it cools down. If a surface is colder than the air’s dew point, moisture can condense.

• fog above the ice

• condensation on glass, ceilings, and other cold surfaces

• poorer ice quality

• corrosion and moisture damage

• risk of mould growth

• increased energy use for dehumidification and refrigeration

The moisture problem therefore needs to be addressed in two ways: limit the amount of moisture entering the building and make sure the dehumidification system is controlled correctly.

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Keep doors and gates closed

Open doors and gates can quickly allow large amounts of moisture into the arena. This is particularly important for openings directly to outdoor air and passages between the arena and warmer parts of the building.

Check that:

• doors and ice-resurfacer gates are kept closed

• door closers are working properly

• seals and weatherstripping are intact

• fan dampers close properly

• there are no other obvious leaks in the building envelope

• airlocks or vestibules are used where possible

The ice-resurfacer passage is particularly important. If the gate is left open while snow is being emptied outdoors, large amounts of warm, humid air can enter the arena. Self-closing gates or alarms that activate when a gate has been open for too long can be effective solutions.

Check the dehumidifier

The dehumidifier should maintain a stable indoor climate without drying the air more than necessary. Before the start of the season, check:

• filters

• desiccant rotor

• motor and belts

• temperature and humidity sensors

• airflow rates

• setpoints and control functions

In a typical ice rink with an indoor temperature of between 5 and 10 °C, dehumidification can normally be controlled to maintain a dew point of approximately 0–2 °C. A lower dew point may cause the dehumidifier to operate unnecessarily. A higher dew point increases the risk of condensation problems.

Dew-point control often provides better conditions than control based solely on relative humidity. Relative humidity changes as the temperature changes and can therefore cause the arena to be over-dried even when there is no actual need for dehumidification.

The correct settings must always be adapted to the arena’s temperature, construction, and operation.

Do not bring in more outdoor air than necessary

Outdoor air brings both heat and moisture into the building. During warm and humid periods, unnecessary outdoor-air intake therefore increases the load on the ventilation system, refrigeration system, and dehumidifier.

Ventilation should be demand-controlled. In the arena, the ventilation system can normally operate with recirculated air and only bring in outdoor air when occupancy levels, carbon dioxide concentrations, or other requirements make it necessary.

Uncontrolled air leakage, however, should not be regarded as ventilation. The goal should be a tight building envelope combined with a controlled, demand-based outdoor-air supply.

Separate ventilation and dehumidification

Ventilation and dehumidification serve different purposes and should, where possible, have separate air-distribution systems.

Warm ventilation air should be directed towards the spectator stands and areas occupied by people. Dry air from the dehumidifier should be distributed over the ice, preferably from a centrally located duct above the ice surface.

If warm ventilation air is blown towards the ice, the heat load increases. The refrigeration system then has to work harder, while ice conditions may also deteriorate.

Make use of recovered heat

Desiccant dehumidification is common in Nordic ice rinks. Most of the dehumidifier’s energy demand is used to heat the regeneration air.

If the facility’s technical systems allow it, recovered heat from the refrigeration system can be used for this process. This can reduce the need for purchased energy. The feasibility depends, among other things, on the design of the dehumidifier, the available temperature level, and how the refrigeration system’s heat-recovery system is configured.

Start with a walk-through of the arena

A quick inspection can reveal many unnecessary sources of moisture:

1. Close all gates and doors.

2. Check seals, dampers, and door closers.

3. Review the dehumidifier’s maintenance status and settings.

4. Check when and why outdoor air is brought into the building.

5. Make sure warm air is directed towards the spectator stands and dry air over the ice.

6. Monitor the dew point and energy use over time.

To remind everyone using the facility, EKA has produced free signs for cold and dehumidified zones.

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Download the signs here:https://www.ekanalys.se/fukthantering-ishall-avfuktning

If you experience recurring problems with fog, condensation, or high energy use, EKA can help analyse the interaction between the building envelope, ventilation, dehumidification, and refrigeration system.