RimWorld Airlock Fix: Beat Freezer Meltdowns
Table of Contents
Quick-Start: Build a Freezer Airlock in 5 Easy Steps
Need the quick recipe for a working freezer? Here's a no-nonsense step-by-step guide:
Construct a Proper Freezer Room
Build an enclosed room with walls and a roof, adjacent to your kitchen if possible. Install at least one Cooler (two if in a hot biome). Set the cooler's target temperature to around -5°C for a buffer. Ensure the hot side faces outdoors with no roof so heat can vent properly. For comprehensive base layout strategies and optimal room placement, check out our colony layout guide.
Place the First Door (Freezer Entrance)
In the wall where you want the entrance, put a door. This will be the inner door, connecting directly to the freezer interior. Use a solid door (wood, steel, etc.) or an Autodoor if you have the research.
Build a 1-Tile Hallway
Immediately outside that inner door, leave one tile of space enclosed by walls. This tiny room is the airlock chamber. The walls should be the same material as your freezer. This acts as a buffer between the freezer and outside.
Place the Second Door (to Outside)
In the outer wall of that one-tile chamber, add the outer door leading outside. Now you have a door → one tile chamber → another door sequence. Add a roof over the airlock chamber. Congratulations, you've created a basic airlock!
Optional Optimizations
Use slower-opening materials for doors (like stone), add an extra tile for a larger airlock, or double-wall your freezer for extreme climates. Set up a stockpile zone in the freezer for foods only, and consider using shelves for better organization.
Quick Tip: Remember to disable "hold open" on your doors – an airlock door that's accidentally left open defeats the purpose!
Step-by-step airlock construction: Building the double-door system that prevents temperature loss in your freezer
Freezer Spoilage Woes: Why You Need an Airlock
The Problem
Each time a colonist opens a freezer door, warm air rushes in and cold air rushes out. RimWorld's temperature system tries to equalize connected rooms when a door is open.
With enough traffic, your "freezer" can easily climb above 0°C, causing food to un-freeze. Just a few degrees matters – remember, 0°C (32°F) is the cutoff for items to be "Frozen (won't spoil)."
The Airlock Solution
An airlock is essentially double-door insulation. By adding a small chamber with another door, you ensure your freezer isn't exposed to the full brunt of outside air whenever someone enters.
Instead, the warm air only fills the tiny chamber, and only then does the inner door open, mixing a much smaller amount of air with the freezer. The temperature spike is far smaller – often just a degree or two.
Airlock Freezer Layout
╔═══════════════════════════════════════╗
║ ❄️ ❄️ ❄️ FREEZER ROOM ❄️ ❄️ ❄️ ║
║ ║
║ 🥩 🍖 🥕 🌽 🍞 [COOLER] ←─ COLD ║
║ 🧀 🥛 🍎 🥔 🥩 ↓ ║
║ 🍗 🥓 🥬 🍅 🥖 [COOLER] ←─ COLD ║
║ ║
║ ║
╚═══════════════════╤═══════════════════╝
│ INNER DOOR
│
┌───────────────┴───────────────┐
│ AIRLOCK CHAMBER │ ← Small buffer room
│ │
└───────────────┬───────────────┘
│ OUTER DOOR
│
═══════════════
OUTSIDE WORLD
(Hot/Cold Air)
A RimWorld airlock freezer example: This large food storage room is double-walled and has a two-door airlock at the bottom. When colonists go through, one door closes before the next opens, trapping most of the heat in the small entryway.
How Temperature Equalization Works
RimWorld doesn't instantly homogenize room temperatures; it does it over a few ticks (each tick is 1/60th of a second in game time). When a door is opened, the game performs equalization calculations between connected areas.
With an airlock, you split that into two separate exchanges: outside ↔ airlock chamber, then chamber ↔ freezer. The result is a much smaller temperature change in the freezer.
Even if both doors of an airlock are open briefly, the temperature of a freezer with an airlock still doesn't rise as high as a freezer with a single door, because the intermediate air cools a bit before mixing.
A Degree or Two Can Save Your Food
Even a short period above 0°C will progress the food rot timer. Having a buffer of a few degrees (keeping things at -5°C or lower) means even with minor spikes, you stay below 0°C. As one guide concluded, "Unless you are running a really mild climate, an airlock will probably only save you a degree or two... It's good practice, and it discourages pawns from unnecessary trips."
Advanced temperature management: Demonstrating how proper airlock design maintains consistent freezer temperatures even with frequent access
Why Freezers Get Warm: Common Mistakes
Single Door to Outdoors
A lone door to outside allows too much heat exchange. Solution: add an airlock (our main topic here!).
Roofed Hot Exhaust
If the hot side of coolers is in an enclosed or roofed space, the heat has nowhere to dissipate. Always unroof or vent the red side of coolers to open air.
Oversized Freezer, Too Few Coolers
If your room is very large, one cooler might not suffice. Add more coolers, reduce room size, or divide into two freezers.
Frequent Door Use / High Traffic
If your freezer is a pass-through or main thoroughfare, you'll get constant door activity. Redesign so it's not the main traffic route.
Power Outages / Events
Solar flares or power failures will turn off coolers. An airlock slows warming but can't prevent it indefinitely during extended outages. Learn comprehensive solar flare survival strategies to protect your colony during power outages.
Is the Airlock Trick Really Worth It?
Some players swear by always building freezer airlocks and double-thick walls. Others claim it's overkill unless you're in a scorching biome. So, how much difference do airlocks and other insulation really make?
Heat Exchange and Power Savings: The Data
To quantify the benefit of an airlock, consider results from community tests in an extreme desert (50°C ambient):
| Freezer Design | Stabilized Internal Temp | Power Usage | Notes |
|---|---|---|---|
| Single wall, single door | +6°C (not frozen) | High (cooler runs often) | Frequent temperature spikes. Food would spoil here. |
| Add Airlock + Single Wall | -2°C (frozen) | Medium | The airlock alone improved cooling by ~8°C. |
| Double-Thick Walls + Airlock | -6°C (well frozen) | Low-Med | Double walls gave another few degrees benefit. |
| Under Mountain + Airlock + Double Walls | -29°C (deeply frozen) | Low | Mountain roof provides excellent insulation. |
Power Savings
An often overlooked benefit is reduced power consumption. When your freezer stays colder and fluctuates less, coolers spend more time in their low-power state (20W standby vs. 200W active). One player reasoned: "Walls and doors are cheaper than another generator" – it's more resource-efficient to build an extra door than to build additional power sources.
When Can You Skip the Airlock?
- Cold Biomes: If you live on an ice sheet or tundra, the outside is often below freezing anyway. For comprehensive cold weather survival strategies, see our cold survival guide.
- Early Game Rush: It's fine to start with a single door freezer, but plan to add the airlock soon after.
- If You Use RimFridge mod: Smaller refrigerated cabinets reduce the need for a large walk-in freezer.
- Aesthetic Concerns: Some players skip airlocks for looks, but will need extra coolers to compensate.
Extreme Climate Strategies
Dealing with Scorching Heat
In extremely hot biomes (like equatorial jungles or deserts) and during summer heat waves, temperatures can soar to 40–50°C or higher. Here's how to manage:
Multiple Coolers
Use two, three, or more coolers for one freezer. Many desert base builders dedicate 2–4 coolers for a decent-sized freezer to ensure it stays frozen even in a 50°C heat wave.
Double-Wall the Whole Freezer
Double-layer walls slow heat leakage. In a hot desert, this can make several degrees difference and helps maintain temperature during power outages.
Insulate the Door Too
Even closed, a door conducts heat more than a wall. Your airlock isn't just for when doors open; having two doors between freezer and outside provides better insulation.
Pre-cool Before a Heat Wave
If you see a heat wave coming, temporarily set your coolers to an even lower target (like -19°C) to "bank" extra cold. When the heat hits, you'll have more buffer. For comprehensive cold weather survival strategies and temperature management, see our cold survival guide.
Managing Foot Traffic
Even with an airlock and plenty of cooling, how you use your freezer day-to-day affects its efficiency. This section addresses minimizing unnecessary door openings.
Base Layout & Freezer Placement
Adjacent to the Kitchen
Build your freezer touching your kitchen or dining area for shorter trips. Consider making the only access to the freezer through the kitchen to keep all freezer traffic in an already cool area. For more advanced base layout strategies and room optimization, check out our optimal colony layout guide.
Avoid Using Freezer as a Hallway
Don't design your base such that the fastest route from point A to B is "through the freezer." If colonists are pathing through the freezer to get somewhere unrelated, you'll have unnecessary door opens.
Dedicated Haulers
You can reduce traffic by controlling who goes into the freezer. Only allow your cooks and dedicated haulers to access the freezer using Zone restrictions.
Stockpile Organization
Create higher priority stockpiles near the door for frequently accessed items. Put a small stockpile for meals right by the inner door so colonists only take a few steps in to grab food. For detailed room design principles and space optimization, see our room impressiveness guide.
Convenience Tools: Shelves, Policies, and Small Fridges
Shelves in Freezer
Shelves allow stacking of 3 items on one tile. Using shelves in your freezer means you can store the same amount of food in 1/3 the space. A smaller freezer is easier to keep cold and requires fewer steps in/out.
"Thanks to the advent of shelves. You can have a massive stash in a relatively small freezer."
RimFridge Mod
The RimFridge mod adds buildable refrigerators that you can place anywhere. Many players use these in the kitchen or dining room so pawns never go into the walk-in freezer except when stocking it.
For example, keep 10 meals in a fridge in the mess hall. Everyone grabs meals from there (zero trips into freezer), while a hauler periodically refills it from the main freezer.
Traffic Management Summary
Keep the freezer near those who need it, keep others out, and consider using game mechanics like shelves or mods to reduce how often items need to go in or out. A well-designed base might only have the freezer door opened a handful of times a day rather than every few minutes.
Advanced freezer layout: Multiple airlocks, optimized traffic flow, and strategic placement for maximum efficiency in large colonies
Mods & Wild Experiments
Experimental Designs: The Door Chimney Exploit
Door Chimney Exploit
╔═══════════════════════════════════╗
║ ❄️ ❄️ ❄️ FREEZER ❄️ ❄️ ❄️ ║
║ ║
║ 🥩 🍖 🥕 [COOLER] ←─ COLD ║
║ 🧀 🥛 🍎 [COOLER] ←─ COLD ║
║ ║
╚═══════════════╤═══════════════════╝
│ INNER DOOR (OPEN)
│
┌───────────┴───────────┐
│ AIRLOCK ROOM │
│ │ ← UNROOFED TILE
│ [ ] │ (CHIMNEY)
└───────────┬───────────┘
│ OUTER DOOR
│
═══════════════
OUTSIDE WORLD
EXPLOIT: Open inner door + unroofed tile
creates temperature averaging glitch
This exploit (sometimes called the "open door chimney") allows ridiculously efficient cooling beyond normal game limits.
The setup involves an airlock with an inner door held open and one tile unroofed. The unroofed door tile acts as a vent to outdoors, while the door's mechanics still average temperatures in a unique way.
In practice, players achieved a freezer at -30°C in a 50°C heat wave with just two coolers – essentially beating the normal limits of coolers. Some even reached -85°C with mountain roofs!
Note: You don't need to use this exploit for normal gameplay. It's mostly for fun or if you like breaking the game's physics. These designs are also finicky – if a door is accidentally closed, it stops working.
Action Step Recap
We've covered a ton of information. Here's a concise recap of the most important actionable steps for your RimWorld freezer:
Build an Airlock
Always add that second door and small chamber. It's cheap and immensely helpful. One tile between doors is enough in most cases.
Double Up Walls in Hot Biomes
If you're regularly above 30°C, make your freezer walls double-thick for insulation. It saves power and keeps things stable during heat spikes.
Unroof the Hot Side
Ensure the area where your coolers vent (red side) is open to sky or very well ventilated. Otherwise, your coolers' own heat will fight you.
Watch that Thermostat
Set your cooler to around -5°C (or lower if you can afford power) to give a buffer. Don't set it exactly at 0 – you want leeway so it doesn't hover at the edge.
Limit Door Traffic
Design your base so that only people with a reason go into the freezer. Use internal doors to the kitchen, stockpile meals separately, etc. The less often the door opens, the better.
By following these steps, you'll drastically reduce food spoilage problems in your colony. A well-designed freezer means one less thing to worry about, allowing you to focus on beating back raids, managing colonist moods, and expanding your base. For comprehensive defense strategies to protect your colony, check out our combat and defense guide.