Understanding Condensation on Refrigerated Display Cabinets

Refrigerated display cabinets are essential in cafés, restaurants, pubs, and retail outlets to keep food chilled and visually appealing. However, condensation on glass doors and surfaces can be a common challenge, affecting both food presentation and energy efficiency. Understanding why condensation forms and how to prevent it is key to maintaining optimal performance and hygiene.

Key Terms You Need to Know

Before exploring condensation, it's important to understand a few basic scientific terms:

• Dew Point – The temperature at which air moisture begins to condense.
• Relative Humidity – The ratio of water in the air to the maximum water the air can hold at a given temperature.
• Absolute Humidity – The actual weight of water in the air, measured in grams per cubic metre (g/m³).
• Surface Temperature – Condensation forms on a surface only when it falls at or below the dew point.
• Heat Transfer Principle – Heat moves from warm areas to cold areas, which explains why warmer room air forms condensation on colder cabinet surfaces.

How Condensation Happens

Imagine this scenario:

• Room temperature: 20°C
• Relative humidity: 60%
• Absolute humidity: 10.4 g/m³
• Dew point: 12°C
• Cabinet internal temperature: 3–5°C
• Cabinet door surface: 12.5°C

In this case, no condensation occurs.

Now, if the cabinet temperature is lowered to 2°C, the door surface drops below the dew point. Warm room air contacting the cold surface can no longer hold the same moisture, and condensation begins to form. Over time, droplets may run down the glass, obscuring the view of your displayed products.

Where Humidity Comes From

The level of moisture in your kitchen or retail environment is influenced by multiple factors.

External Weather & Environment

• Open doors and windows
• Rainy days can increase relative humidity to 90–95%
• Staff entering with wet clothing or shoes

Building Construction

• Modern buildings are usually drier
• Older buildings may have naturally higher humidity

Occupancy & Activity

• People emit moisture through breathing and perspiration
• Activities involving water or steam, like cooking or dishwashing

Equipment & Appliances

• Steam from hot serveries, dishwashers, glass washers, coffee machines, and boilers
• Refrigerators and freezers themselves contribute moisture

Ventilation

• Extraction fans remove moisture but intake vents can bring it in
• Temperature differences between inside and outside influence moisture movement
• Air currents can carry moisture across the room, leading to condensation on cold surfaces

How to Combat Condensation

Preventing condensation often requires a combination of adjustments and monitoring. Here's how to tackle it effectively:

• Adjust Cabinet Temperature – Slightly increasing the setpoint can raise surface temperatures above the dew point.
• Reduce Moisture Sources – Identify areas generating humidity and minimise exposure to the cabinet.
• Use Dehumidifiers – In rooms with high natural humidity or persistent condensation, portable dehumidifiers can help maintain ideal moisture levels.
• Check Ventilation – Ensure proper air circulation and ventilation around the cabinet. Avoid placing cabinets in direct airflow paths that carry moisture.
• Regular Maintenance – Clean and inspect door seals and glass panels to ensure optimal performance.

Tip: Monitor conditions over several days to identify patterns and optimise settings for your specific kitchen or retail environment.

Summary

Condensation on refrigerated display cabinets is largely a result of temperature differences, air humidity, and room conditions. By understanding dew point, humidity, and the sources of moisture, you can maintain clear, appealing displays while protecting food quality.

Do

• Adjust cabinet temperature carefully
• Reduce environmental humidity where possible
• Use dehumidifiers if needed
• Maintain proper ventilation

Don't

• Ignore persistent condensation
• Block airflow around cabinets
• Rely solely on trial-and-error without monitoring room conditions

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