In supermarket refrigeration, after-hours energy loss is one of the biggest hidden costs—especially for open multideck chillers.
Operators often face a key decision:
Should you install night curtains, glass doors, or both?
This guide breaks down clear design rules, helping you decide which areas should use night curtains and where doors are the better investment.
Why Closing-Hour Strategy Matters
Open display refrigerators rely on an air curtain system, which continuously loses cold air to ambient conditions.
After closing hours:
- No customer interaction
- Store ambient temperature rises (HVAC reduced)
- Air infiltration increases sharply
Result:
- Up to 50% energy waste happens after hours
- Compressor runs longer
- Product temperature becomes unstable
Night Curtains vs Glass Doors: Core Difference
1. Night Curtains (Night Blinds)
How it works:
- Pull-down curtain blocks airflow during non-operating hours
- Reduces cold air escape significantly
Key Advantages:
- 10–22% energy savings
- Low investment cost
- Easy retrofit for existing stores
- No impact on daytime merchandising
Limitations:
- Manual operation (or semi-automatic)
- Staff compliance required
- Not fully sealed
2. Glass Doors (Closed Cabinets)
How it works:
- Fully enclosed cabinet with insulated glass doors
Key Advantages:
- Maximum energy efficiency (30–50% savings)
- Stable temperature control
- Reduced frost and humidity issues
Limitations:
- Higher upfront cost
- Reduced impulse buying
- Requires layout redesign
Design Rules: Where to Use Night Curtains vs Doors
Rule 1: High-Traffic Daytime Zones → Use Night Curtains
Examples:
- Beverage sections
- Dairy aisles
- Grab-and-go zones
Why:
- Open design drives impulse sales
- Doors reduce conversion rate
Strategy:
- Keep open during the day
- Use night curtain after closing
✔ Best balance: sales + energy savings
Rule 2: Low-Traffic / Long-Dwell Zones → Use Glass Doors
Examples:
- Frozen food sections
- Meat storage
- Back-of-store displays
Why:
- Customers already expect doors
- Energy savings outweigh merchandising impact
✔ Best strategy: full enclosure (doors)
Rule 3: Stores with Long Closing Hours → Prioritize Night Curtains First
If your store:
- Closes 10–14 hours/day
- Has many open multidecks
Then night curtains deliver:
- Fast ROI (2–4 years)
- Immediate energy reduction
✔ Especially effective in:
- North America supermarkets
- Middle East (high ambient temp)
Rule 4: Retrofit Projects → Night Curtains Are the Default Choice
For existing stores:
- Installing doors = high CAPEX + downtime
- Night curtains = plug-and-play upgrade
✔ Recommended approach:
- Phase 1: install night curtains
- Phase 2: upgrade selected zones to doors
Rule 5: Hybrid Strategy (Most Recommended)
Top-performing supermarkets don’t choose one—they combine both:
| Area | Solution |
|---|---|
| Front display / beverages | Open + Night Curtain |
| Dairy aisle | Open + Night Curtain |
| Frozen / meat | Glass Door |
| Storage / backroom | Fully enclosed |
This is the optimal energy + sales model
Energy Impact: What You Can Expect
Typical results after implementing night curtains:
- Energy reduction: 10–22%
- Compressor runtime ↓
- Product temperature stability ↑
- Payback period: 2–4 years
With doors:
- Energy reduction: 30–50%
- But higher upfront cost
After-Hours Refrigeration Strategy (Action Plan)
If you’re running a supermarket or chain project, follow this:
Step 1: Audit your display types
- Count open multidecks
- Identify high-loss zones
Step 2: Classify zones
- High traffic vs low traffic
- Day vs night importance
Step 3: Apply design rules
- Open + curtain OR fully enclosed
Step 4: Implement SOP
- Staff must close curtains daily
- Add compliance checklist
Common Mistakes to Avoid
Installing doors everywhere → hurts sales
Ignoring night operation → wasted energy
No staff training → curtains not used
Poor curtain sealing → reduced efficiency
Conclusion
Choosing between night curtains and doors is not a binary decision.
The real optimization comes from:
- Zoning your store correctly
- Applying hybrid strategies
- Aligning with after-hours operation
If done right, you can:
- Cut energy costs significantly
- Maintain high merchandising performance
- Improve long-term ROI
FAQ
Q1: Are night curtains enough for energy saving?
Yes. For most open chillers, they deliver 10–22% savings with low investment.
Q2: Do glass doors always save more energy?
Yes, but they may reduce sales in high-traffic areas.
Q3: Can I retrofit night curtains on existing chillers?
Yes. This is the most cost-effective upgrade for existing supermarkets.
Q4: Which is better for North America supermarkets?
A hybrid approach:
- Open + night curtain (front area)
- Doors (low-traffic zones)
