Guide Contents
- 1. What is a sandwich panel and why it is the core of any cold room?
- 2. Insulation core types: PUR vs PIR vs EPS
- 3. Thickness selection table by temperature and Saudi climate
- 4. U-value and practical calculation method
- 5. External cladding options and applications
- 6. Panel joints and thermal leakage control
- 7. Floor panel special requirements and loads
- 8. Saudi and Gulf environment design considerations
- 9. Required quality standards and certificates
- 10. How to choose the right panel for your project
What is a sandwich panel and why it is the core of any cold room?
A sandwich panel is a composite building element with two metal skins and a rigid thermal insulation core in between. In refrigeration projects, this assembly forms the building envelope that controls heat gain and moisture behavior.
In Saudi summer conditions, external air temperature may approach 50 C while the room can operate at -30 C. This very high delta temperature means panel specification directly affects compressor run hours, electricity cost, and long-term system reliability.
Choosing low-grade panel systems can cause progressive efficiency loss, condensation risk, and shorter plant life. A specification-based approach is essential.
Basic engineering principle: with large temperature difference, every additional centimeter of effective insulation reduces total thermal load and operating cost over the full life cycle of the facility.
Insulation core types: PUR vs PIR vs EPS
Insulation core performance drives the panel thermal behavior. Three common options are used in the market, with distinct fire, moisture, and long-term stability characteristics.
A. PUR (Polyurethane)
Widely used with good thermal conductivity and balanced cost. Suitable for standard cooling and medium freezing in many projects.
B. PIR (Polyisocyanurate)
Improved chemistry relative to PUR, usually offering better fire behavior and thermal stability. It is commonly preferred for deep-freeze and higher compliance projects.
C. EPS (Expanded Polystyrene)
Lower-cost option with weaker thermal performance and higher moisture sensitivity over time. Usually not recommended for serious industrial freezing applications.
| Property | PUR | PIR | EPS |
|---|---|---|---|
| Thermal conductivity lambda (W/m.K) | 0.022-0.025 | 0.020-0.023 | 0.035-0.040 |
| Density (kg/m3) | 38-42 | 40-45 | 15-25 |
| Fire behavior | Medium | Better | Weak |
| Moisture absorption | Very low | Very low | Medium to high |
| Temperature range | +80 to -40 C | +120 to -50 C | +70 to -20 C |
| Relative cost | Medium | Medium to high | Low |
| Typical use | General cooling and freezing | Deep and industrial freezing | Light cooling only |
Elfarida Ice recommendation: for industrial freezer rooms, PIR in walls and ceiling with higher-density floor system provides a practical performance and durability balance.
Thickness selection table by temperature and Saudi climate
Required thickness must be selected using target room temperature, ambient conditions, and insulation thermal conductivity, not generic catalog values.
| Room Type | Temperature Range | PUR Thickness | PIR Thickness | Target U-Value |
|---|---|---|---|---|
| Fruit and vegetable cooling | +2 to +8 C | 80-100 mm | 80 mm | <= 0.28 W/m2.K |
| Meat and dairy cooling | 0 to +4 C | 100 mm | 100 mm | <= 0.25 W/m2.K |
| Pre-cooling | -2 to +2 C | 120 mm | 100 mm | <= 0.22 W/m2.K |
| Medium freezing | -18 to -20 C | 150 mm | 120 mm | <= 0.18 W/m2.K |
| Deep freeze | -25 to -30 C | 200 mm | 150-180 mm | <= 0.14 W/m2.K |
| Blast freezing | -35 to -40 C | 250 mm | 200 mm | <= 0.11 W/m2.K |
| Floor system | As per room class | +25-50 mm extra | +20-40 mm extra | Load-adjusted |
Saudi design note: very hot ambient conditions typically require thicker or better-performing panel systems than many mild-climate reference tables.
U-value and practical calculation method
U-value represents total heat transfer through one square meter per degree of temperature difference. Lower U-value means better insulation and lower energy use.
The simplified model uses serial thermal resistance terms.
R_total = R_si + R_facing1 + R_core + R_facing2 + R_se
// Core resistance:
R_core = t_insulation / lambda_insulation
In practice the core term dominates: the two metal facings and the surface films contribute very little resistance compared with the insulation itself, so U-value is governed almost entirely by thickness divided by lambda. That is why a quotation stating a thickness without stating a lambda is not a specification — the same 100 mm can deliver anything from a good U-value to a poor one depending on the core actually supplied.
Typical declared lambda values sit near 0.022 W/m·K for PIR and 0.023 W/m·K for good PUR, so a 100 mm panel lands around 0.22 W/m²·K and a 150 mm PIR panel around 0.14 W/m²·K. Ask for the declared value and the standard it was measured to; an undeclared lambda is the most common place for a cheaper core to hide.
Daily heat loss calculation
The envelope gain follows directly from U-value, area and temperature difference:
Daily energy (kWh) = Q_loss × 24 ÷ 1000
// Worked case: 100 m² freezer room (10 × 10 × 5 m)
A_total = (2 × 10 × 10) + (4 × 10 × 5) = 200 + 200 = 400 m²
ΔT = 48 °C ambient − (−20 °C) internal = 68 K
// 150 mm PIR, U = 0.143 W/m²·K:
Q_loss = 0.143 × 400 × 68 = 3,890 W ≈ 3.89 kW → 93.4 kWh/day
// 100 mm PUR, U ≈ 0.23 W/m²·K:
Q_loss = 0.23 × 400 × 68 = 6,256 W → 150 kWh/day
// Difference = 57 kWh/day × 365 = 20,805 kWh/year
// ≈ SAR 4,160/year at 0.20 SAR/kWh — ≈ SAR 6,240/year at 0.30 SAR/kWh
// those are the published commercial brackets; the industrial tariff is lower. Use your own tariff from the bill
What the numbers mean: a 57 kWh/day
difference in envelope gain is roughly 20,800 kWh a year for a
freezer room of this specification — about SAR 4,200 to 6,200
annually depending on the commercial bracket applied, and less
again on the industrial tariff. Over fifteen years, assuming a
stable tariff and stable operating conditions, the cumulative
difference falls in the region of SAR 62,000 to 94,000, which
usually exceeds the cost of upgrading panel thickness at the start
of the project.
Limits of this example: it assumes continuous
24-hour operation, a constant 68 K difference across the whole
envelope, and a fixed system coefficient of performance. It ignores
infiltration and door-opening load, solar gain on the roof
(sol-air) and insulation ageing over time. The real figure moves
with any of those inputs, and should only be adopted after a
detailed load calculation
using your own site data.
External cladding options and applications
Cladding selection controls corrosion resistance, cleanability, and long-term durability under project conditions.
| Cladding Type | Typical Thickness | Applications | Main Benefits | Limitations |
|---|---|---|---|---|
| Painted galvanized steel | 0.4-0.6 mm | General cold rooms | Competitive cost | Lower chemical resistance |
| Polyester-coated steel | 0.5 mm | Food and general cooling | Good corrosion performance | Requires careful handling |
| PVDF-coated steel | 0.5-0.6 mm | Harsh and coastal environments | High UV and salt resistance | Higher cost |
| Stainless steel | 0.4-0.5 mm | Hygienic plants and healthcare | Excellent hygiene and corrosion resistance | Highest cost |
| Aluminum | 0.4-0.5 mm | Roofs and wet environments | Lightweight and rust-free | Lower structural strength |
| FRP | 1.0-1.5 mm | Chemically aggressive plants | Strong chemical resistance | Heavier, less structural stiffness |
Coastal note: in high-salinity zones, PVDF or stainless options on exposed faces significantly improve service life.
Panel joints and thermal leakage control
Joint lines are the most exposed part of the thermal envelope. One untreated thermal bridge cancels much of the benefit of the high-specification panel around it, which is why installation quality is not secondary to panel quality — it decides whether the U-value you paid for is the U-value you get in service.
A. Tongue and groove / cam lock systems
The best joint system for industrial rooms. The profiles interlock mechanically with an integral air-sealing gasket, leaving virtually no air gap, so the assembled envelope performs close to the theoretical U-value of the core rather than well below it. This is the industry standard on any professional cold-room project, and it is worth confirming that the quotation actually includes it rather than a simple butt joint sealed on site.
B. Expanding foam sealant strategy
Foam is used as a secondary seal at joints, corners and penetrations for pipework and cabling. Specify closed-cell foam: open-cell foam absorbs water, and once wet it loses most of its insulating value while holding moisture against the panel facing. The failure is invisible from inside the room and shows up years later as corrosion at the joint.
C. Corners and penetrations detailing
Internal and external corners, and every point where a pipe or cable crosses the envelope, each need their own engineered detail. Neglecting them is the most common cause of invisible heat loss in cold rooms — loss that a visual inspection will not reveal but a thermal camera will. Commissioning a thermal survey of the finished envelope, before the room is loaded, is the cheapest way to catch this while the installer is still on site.
Common mistake: using screws or fasteners that pass right through the panel from the outer face to the inner face creates a direct metal thermal bridge between the two skins. Steel conducts roughly a thousand times better than the core, so each fastener becomes a cold spot that attracts condensation and, in freezer rooms, a point of visible frost on the outside. Always use fixing methods designed for insulated panels, or fix through the internal structural frame without penetrating the core.
Floor panels face a completely different problem from walls and roof: heavy loads from forklifts and stock, continuous mechanical impact, and moisture accumulating from below. The specification changes accordingly — thicker core, a heavier-gauge or reinforced top facing, and a stated distributed and point load capacity rather than a generic panel rating.
Below −25 °C, under-floor heating stops being optional. Without it, the ground beneath the slab freezes progressively, the ice expands, and it lifts the slab — producing structural cracking that can damage the whole building, not merely the room. The standard remedy is layered: rigid insulation beneath the panel (XPS or rigid PIR), a damp-proof membrane, and electric or warm-water heating pipes embedded during construction. All three have to be installed at build stage; retrofitting them means taking the floor out.
Floor panel special requirements and loads
Floor systems see heavy point loads, dynamic traffic, and moisture exposure. Their design criteria differ substantially from wall and ceiling panels.
| Criterion | Cooling Floor (+2 C) | Freezing Floor (-18 C) | Deep-Freezing Floor (-30 C) |
|---|---|---|---|
| Panel thickness | 120-150 mm | 150-200 mm | 200-250 mm |
| Top face | 0.5 mm galvanized steel | 0.6 mm reinforced galvanized steel | Reinforced steel or FRP |
| Distributed load | 5 kN/m2 | 7.5 kN/m2 | 10 kN/m2 |
| Forklift wheel point load | 7 kN | 10 kN | 15 kN |
| Sub-floor requirement | Moisture control | Extra thermal layer + moisture barrier | Under-floor heating + insulation |
For deep-freeze projects, under-floor heating is often mandatory to prevent frost heave and structural damage beneath the slab.
Integrated floor solution: combine thermal insulation layer, moisture barrier, and controlled under-floor heating in deep-freeze rooms.
Saudi and Gulf environment design considerations
Regional climate introduces constraints beyond standard temperate-climate references.
A. High ambient temperature impact
Large temperature differences raise heat gain substantially, requiring stricter envelope design.
B. Coastal humidity and salt exposure
Elevated humidity with chloride exposure accelerates corrosion on insufficiently protected cladding.
C. Solar radiation on external faces
Light exterior colors and suitable coatings reduce absorbed heat under high summer sun.
D. Outdoor installation constraints
UV-resistant gaskets and exposed-joint protection are required for many freestanding outdoor rooms.
| Condition | Recommended Technical Response | Cost Impact |
|---|---|---|
| Ambient >= 45 C | Increase envelope performance relative to standard tables | Panel premium |
| Coastal environment | PVDF or aluminum on exposed outer faces | Moderate premium |
| Outdoor installation | UV-resistant gaskets and edge protection | Low to moderate premium |
| Deep freeze with high ambient | Higher-performance panel and floor heating strategy | High premium |
🧱 Reviewing a panel quotation before you sign: The costliest item in panel projects is rarely the price per square metre - it is a loosely worded specification: no density stated, no thermal conductivity quoted, or a metal facing unsuited to a coastal environment. Initial review scope: a free desk review capped at one office hour, matching the offered thickness to the required operating temperature, verifying that density, thermal conductivity and fire classification are actually stated in the offer, checking that the metal facing suits the site's distance from the coast, and listing the missing items to be completed before signing. Data required: the quotation or specification you have been offered, target operating temperature, room dimensions and height, distance from the coast, and any floor loading requirements. Limits: the review is desk-based and relies on the data you send, excludes any site visit, field measurement, calibration or certification, and issues no guaranteed figure; it relies on the documents you send as they are, excludes sample testing and verification of supplier certificates, is not an approval of a construction specification, and is not a judgement on any particular supplier. Send the quotation for review, and see cooling load calculation, cold room door types and energy reduction measures.
Required quality standards and certificates
Real panel quality must be proven by standards compliance and documented test performance, not catalog claims only.
A. European standards (EN)
- EN 14509: sandwich panel product standard and key thermal/mechanical properties.
- EN 13501-1: fire classification reference for panel systems.
- EN 10169: organic coated steel requirements.
- EN 15715: installation and field-performance related practices.
B. Additional certificates for food facilities
- HACCP compliance: cleanability and hygiene suitability.
- Food-grade declaration: where direct food-area suitability is needed.
- GCC/SASO alignment: where required by project authority or scope.
C. Field quality verification tests
On receipt of any panel shipment, carry out — or demand the results of — three checks, because these are the properties a cheaper core actually differs in:
- Density test: as a working benchmark, not below roughly 38 kg/m³ for PUR and 40 kg/m³ for PIR. Density below the declared figure is the single most common substitution, and it reduces real insulating value while the panel looks identical.
- Thermal conductivity test: confirming that lambda does not exceed the declared value, measured to the standard the declaration cites.
- Pull-off test: verifying bond strength between the metal facing and the core. Weak bonding shows up years later as delamination and panel bowing under thermal cycling.
Market caution: a significant share of the cheaper panel circulating in the Saudi market does not match its declared specification, with actual core density below the published figure — which cuts real insulating performance substantially while the paperwork still reads correctly. Always request accredited laboratory certificates issued against the specific shipment, and do not accept a generic catalogue specification as evidence.
How to choose the right panel for your project
A reliable panel decision follows engineering sequence, not purchase price alone.
- Define operating temperature class with clear room duty profile.
- Set target U-value based on thermal load and refrigeration design margin.
- Select insulation core type based on performance and safety priorities.
- Select cladding system for the specific project environment.
- Verify certificates and test reports before procurement commitment.
- Evaluate life-cycle cost using purchase plus long-term energy impact.
Elfarida Ice service: we provide engineering support for panel specification, U-value targeting, supplier offer review, and practical life-cycle optimization. Contact us for a free consultation.
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Engineering disclaimer: The U-values, thicknesses and cost comparisons in this guide are indicative and assume continuous operation, a fixed temperature difference across the whole envelope and a constant system coefficient of performance. They ignore infiltration, door openings, solar gain on the roof and insulation ageing. Final panel specification must follow a load calculated with site data and review by a qualified engineer, and the electricity tariff used in any payback estimate must be your own actual tariff.