Freezer cabinets
Transparent doors for vertical freezers in stores and supermarkets. Heating prevents fogging after door opening and in high retail humidity.
TEC Heat Glass
Anti-condensation heated glass
Transparent electrically heated glass for refrigerated display cases, freezers, wine-storage doors, vending machines, and equipment that operates across temperature and humidity differentials.
Octoglass manufactures glass with a transparent TEC conductive coating and designs the heating system for the specific pane size, insulating-glass construction, and operating conditions.
On this page
What it is for
Glass without condensation and fogging
A refrigerated display case constantly operates between two environments with a large temperature difference.
For example, inside freezer equipment the temperature may be −18…−25 °C, while the retail space is +20…+27 °C.
The outer glass surface cools. If its temperature falls below the dew point of the surrounding air, condensation and fogging appear on the surface.
This leads to several problems:
- product visibility deteriorates;
- water droplets form on the glass;
- frost may form;
- the appearance of retail equipment suffers;
- constant additional heating is required.
Anti-condensation glass solves this with uniform transparent electrical heating.
With a correctly calculated system the glass should not become hot. Its temperature rises only enough to keep the surface above the dew point.
How it works
The entire pane becomes a transparent heater
A transparent electrically conductive FTO coating — fluorine-doped tin oxide — is applied to the glass surface by a pyrolytic process.
The coating is nearly transparent in the visible range while providing controlled electrical resistance.
Conductive busbars run along opposite edges of the glass.
When voltage is applied, current spreads across the conductive coating, which acts as a large flat resistive heater.
Unlike solutions with metal wire or mesh:
- the heating element is invisible in the optical range;
- heat is distributed across the full surface;
- there are no visible wire tracks;
- the product keeps the look of ordinary glass.
As a base material Octoglass primarily uses 3 mm sheet glass with an FTO coating. Other glass thicknesses may be used for some projects.
Applications
Refrigerated display cases
Confectionery, deli, meat, dairy, and other chilled display cases. Glass clarity is maintained even with a substantial temperature difference.
Vending machines
Machines with chilled drinks, food, and ready meals. Low-voltage supply enables a compact and safe heating system.
Wine and refrigeration cabinets
Equipment for restaurants, hotels, stores, and residential interiors where appearance matters. Transparent heating removes the need for visible heating elements.
Pharmaceutical refrigerators
Cabinets for medicines, vaccines, and laboratory materials. Heated glass keeps contents visible without opening the door and prevents fogging during temperature swings.
Cold rooms and airlocks
Viewing windows and glazed doors for cold and freezer rooms. Glass heating prevents condensation and icing on the warm, humid room side.
Ice arenas and cold zones
Glazing between spaces with a large temperature difference — ice arenas, cold halls, and warm public zones. Transparent heating keeps the glass dry and clear without visible heating elements.
Special equipment
Climate chambers, laboratory setups, refrigeration units, process windows, and other equipment operating across temperature and humidity swings.
Glass construction
Single- or double-chamber insulating glass
For freezers with a large temperature differential, a single- or double-chamber construction may be used.
Additional Low-E coatings may be used to reduce heat loss and lower the required heating power.
Recommended configuration
Single pane
FTO-coated glass can also be used as a single heated pane. In that construction you must separately provide:
- protection of the conductive coating;
- electrical insulation;
- protection of electrical leads;
- no user access to live parts;
- protection of the coating from washing and mechanical damage.
For refrigerator doors and display cases, an insulating glass unit is the preferred option. When an IGU cannot be used, the conductive surface must face away from people.
Power supply
Low-voltage heating
The FTO coating itself is an ordinary resistive load and can be heated from either AC or DC voltage.
For new developments Octoglass prefers low-voltage DC supply, because using high voltages — especially AC — can be unsafe both for electric shock risk and for electromagnetic emission from glass powered by alternating current.
Typical project options:
24 V DC
for smaller panes, vending, and constructions with a short distance between current busbars.
48 V DC
for large doors and display cases where current through wiring, connectors, and hinges must be reduced.
Operating voltage is not a fixed product characteristic. It is determined individually depending on:
- glass size;
- busbar layout;
- TEC sheet resistance;
- required power;
- equipment construction (busbar orientation affects the power of the same pane).
Calculation example
Vertical busbars
- Busbars run along the 1700 mm sides.
- Distance between them: 800 mm.
- Calculated resistance: about 6.1 Ω.
- At 24 V: power ≈ 94 W, current ≈ 3.9 A.
Horizontal busbars
- Busbars run along the 800 mm sides.
- Distance between them: 1700 mm.
- Calculated resistance: about 27.6 Ω.
- At 48 V: power ≈ 83 W, current ≈ 1.7 A.
The calculation is an example only. Electrical parameters of a serial product are determined from the actual resistance of the specific FTO sheet and operating conditions.
Control
Heating only when it is truly needed
FTO glass does not have to run at maximum power continuously. A dedicated controller manages optimal operation and includes:
- a glass temperature sensor;
- an air temperature sensor;
- a relative humidity sensor.
The controller provides:
- dew-point calculation;
- power regulation;
- maximum temperature control;
- current monitoring;
- open-circuit diagnostics (for example if the glass is broken or a short circuit occurs).
The controller can integrate with other retail or process equipment. The exact controller implementation depends on the customer’s project requirements.
Key technical specifications
| Configuration | Single- or double-chamber IGU, single pane |
|---|---|
| Coating type | FTO, Low-E |
| Sheet resistance | about 13 Ω/□ |
| Preferred supply | 24/48 V DC |
| Heating element | transparent FTO coating |
| Visible wires on the glass area | none |
| Regulation | electronic |
| Temperature control | optional |
| Humidity control | optional |
| Product size | custom |
| Geometry | per project |
| Current busbars | concealed in the edge zone |
| Connection | per equipment design |
- ConfigurationSingle- or double-chamber IGU, single pane
- Coating typeFTO, Low-E
- Sheet resistanceabout 13 Ω/□
- Preferred supply24/48 V DC
- Heating elementtransparent FTO coating
- Visible wires on the glass areanone
- Regulationelectronic
- Temperature controloptional
- Humidity controloptional
- Product sizecustom
- Geometryper project
- Current busbarsconcealed in the edge zone
- Connectionper equipment design
Power and operating voltage are calculated individually for each glass size.
Safety
For large products, 24 or 48 V DC is preferred. The system may include:
- an individual fuse;
- maximum current limiting;
- glass temperature monitoring;
- overheating protection;
- short-circuit monitoring;
- load open-circuit diagnostics;
- protection if the temperature sensor fails;
- a galvanically isolated power supply.
Conductive busbars must be insulated from:
- the metal frame;
- the aluminium spacer;
- the equipment enclosure;
- other accessible metal elements.
Product development
01
Input data
The customer provides:
- glass dimensions;
- a drawing;
- temperature inside the equipment;
- room temperature;
- expected humidity;
- frame construction;
- available power supply.
02
Electrical and thermal calculation
Octoglass determines:
- busbar orientation;
- resistance;
- operating voltage;
- required power;
- IGU construction.
03
Prototype
A TEC glass pane or IGU is manufactured with leads and a temperature measurement system.
04
Testing
The following are checked:
- electrical power;
- current;
- temperature;
- heating uniformity;
- local hot spots;
- operation under cooling;
- operation at high humidity.
05
Serial construction preparation
Based on testing results, the following are refined:
- current busbar dimensions;
- the controller;
- power;
- the protection system;
- assembly technology.
What we need for calculation
- Glass sizeWidth, height, thickness, shape.
- Equipment temperatureOperating and minimum temperature inside the cold chamber.
- Room temperatureNominal and maximum possible.
- HumidityNominal and maximum possible relative humidity.
- ConstructionSingle pane, single- or double-chamber IGU.
- Power supplyAvailable 12, 24, 48, or 230 V. Available power. Whether control must integrate with other systems.
- Operating modeContinuous operation, periodic opening, washing and maintenance specifics.
FAQ
Will heating wires be visible on the anti-condensation glass?
No. The heater is the transparent FTO coating itself. Metal current busbars run only along the glass edge and can be concealed by the product frame.
How hot does the anti-condensation glass get?
The glass does not need to be heated to a high temperature. The main goal is to keep its surface slightly above the dew point of the surrounding air.
Can the power consumed by the anto-condensation glass be regulated?
Yes. Heating can be regulated by an electronic controller based on glass temperature, air temperature, and humidity.
Can the anti-condensation glass be connected directly to 230 V?
Technically FTO glass is a resistive load, but voltage depends on the resistance of the specific pane. For new developments Octoglass recommends considering low-voltage 24 or 48 V DC systems.
Why not just connect a wire to the coating directly at the surface of anti-condensation glass?
A point contact creates uneven current distribution and local heating. That is why a distributed conductive busbar along the glass edge is used.
Can an anti-condensation insulating glass unit be manufactured?
Yes. For refrigerated and freezer display cases this is the main recommended option. The FTO coating is located inside a sealed insulating glass unit.
Can non-standard anti-condensation glass sizes be manufactured?
Yes. Product geometry, current busbars, and operating power are calculated individually.
Can control of the anti-condensation glass be integrated into refrigerator/equipment automation?
Yes. A dedicated controller can be used, or control can come from the equipment automation.
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