Why infiltration is such a big load
Cold air is denser than warm air, so the moment a door opens it starts to pour out at the bottom and draw warm air in at the top. In a hot, humid Indian kitchen, the incoming air carries both heat and a lot of moisture. The heat has to be removed, and the moisture has to be condensed or frozen on the coil, which takes a great deal of energy and leads to frost and more defrosts.
The larger the opening, the longer it stays open and the bigger the temperature difference, the larger the load. Walk-in freezers with doors propped open during deliveries are the extreme case.
Reducing openings on cabinets
- Organise shelves so staff know where things are and do not search with the door open.
- Put the most-used ingredients in undercounter or drawer units at the station, so the big reach-in opens less.
- Use drawers rather than doors on undercounters where possible; a drawer lets out less cold air.
- Plan prep so several items come out in one opening.
- Fit self-closing hinges and check that doors close on their own from a partly open position.
- Level cabinets so doors do not swing open by themselves.
Strip curtains for walk-ins and cold rooms
Strip curtains are overlapping vertical strips of flexible PVC hung inside a cold-room doorway. They let people and trolleys pass while blocking most of the air exchange when the main door is open. They are cheap, easy to fit and one of the most effective measures for cold rooms with frequent traffic.
They need care to work. Strips should overlap properly, reach the floor and be replaced when torn, stiff or cloudy. Staff should not tie them back for convenience, which defeats the purpose.
Options for doorways compared
| Measure | How it helps | Points to watch |
|---|---|---|
| Strip curtain | Blocks most air exchange while the door is open | Replace damaged strips; keep them clean |
| Self-closing door | Ensures the door does not stay open | Check closers and hinges regularly |
| Door-open alarm | Alerts staff when a door is left open | Set a sensible delay |
| Fast-acting door | Opens and closes quickly for traffic | Higher cost; suits heavy traffic |
| Air curtain | Fan-driven air barrier over the doorway | Uses power; must be correctly set up |
| Anteroom or chilled lobby | Buffers between warm area and freezer | Needs space; best planned at design |
Managing deliveries and restocking
Deliveries are when doors are most likely to be propped open. Stage incoming stock on a trolley, then move it in quickly in one go with the door closed behind. Unload in the coolest part of the day where possible. For display cabinets, restock from the back or during quiet hours, and avoid leaving glass doors open while a whole crate is unpacked.
Do not forget the seal when the door is shut
A closed door only stops infiltration if the gasket seals. A torn or flattened gasket leaks warm, humid air all day and all night, which can add up to more than the openings themselves. Check gaskets with the paper test regularly, clean them so they stay flexible, and replace them when they no longer seal.
Frequently asked questions
- How can I tell how often my fridge doors are opened?
- A simple door sensor connected to a monitoring system counts openings and open time. Without one, have someone tally openings on a busy shift; the count often surprises owners and points to layout changes.
- Do chest freezers lose less cold when opened than upright ones?
- Yes. Cold air is heavy and tends to stay in a top-opening chest freezer when the lid is lifted, whereas it pours out of an upright door. That is one reason chest freezers are efficient for bulk frozen storage.
- Are strip curtains hygienic in a food area?
- They can be, if they are cleaned regularly and replaced when damaged or discoloured. Choose food-safe material and include them in the cleaning schedule.
- Do glass-door coolers lose more cold than solid doors?
- When closed, glass doors let in more heat than insulated solid doors, mainly by radiation and conduction. When it comes to openings, glass doors can help, because customers decide before they open and keep the door open for less time.
