How Do You Specify Curtain Walls for Cold-Climate Projects in Central Asia?

Condensation governs, not the energy calculation.

That is the thing most facade specifications for Astana, Almaty, Tashkent, or Bishkek get wrong. A design team sets a U-value target from the energy code, selects a system that meets it, and then discovers water running down the inside of the mullions through a January where outside temperatures sit below minus 25 degrees Celsius.

The U-value was satisfied. The interior surface temperature was not, and those are different calculations answering different questions.

Central Asian winters are genuinely severe. Astana regularly sees minus 30 degrees Celsius and lower, with continental extremes producing annual temperature swings exceeding 70 degrees. A facade specification that works in Western Europe will not simply transfer. PRANCE manufactures glass facade and curtain wall systems engineered for these conditions.

Curtain Wall U-Value Cold Climate Targets

Assembly U-value, not centre-of-glass, is what matters and what codes check.

• Standard commercial, temperate: 1.4 to 2.0 W/m²K

• Cold climate commercial: 0.9 to 1.5 W/m²K

• Severe cold, continental extremes: 0.7 to 1.1 W/m²K

• High-performance and passive-oriented: below 0.8 W/m²K

Regional codes derive from the Soviet-era SNiP framework, now developed into national standards such as the SP series in Kazakhstan and equivalent documents in Uzbekistan and Kyrgyzstan. Requirements are expressed in terms of heat transfer resistance and vary by region within each country, so the governing document should be confirmed for the specific city.

Reaching below 1.0 W/m²K on an assembly basis generally requires triple glazing, a deep thermal break, and warm-edge spacers working together. No single upgrade achieves it alone.

Curtain Wall Condensation Cold Climate Control

The governing requirement, and the one that drives specification beyond what the energy calculation would demand.

Why Condensation Happens?

Condensation forms when an interior surface falls below the dew point of the interior air. In a heated building at 21 degrees Celsius and 40% relative humidity, the dew point sits around 7 degrees Celsius. At 50% humidity it rises to approximately 10 degrees.

With outside air at minus 30, a poorly broken aluminum mullion can easily hold an interior surface temperature below that threshold. Water forms, runs, pools on sills, and over time damages finishes and supports mould growth.

How It Is Measured?

Two metrics, depending on practice.

• Condensation Resistance Factor, measured under AAMA 1503, expresses the relationship between interior surface temperature and the indoor-outdoor temperature difference. Higher values indicate better resistance.
• Temperature factor fRsi, used in European and increasingly in regional practice, expresses the ratio of the warmest interior surface temperature above outside air to the full temperature difference. A higher value means a warmer interior surface.

Thermal modelling to EN ISO 10077-2 or equivalent produces these figures, and a manufacturer who can run that analysis is in a different category from one quoting catalogue U-values.

What Controls It?

• Thermal break depth, the single largest factor on the frame

• Warm-edge spacers, which lift edge-of-glass surface temperature substantially

• Glazing build-up, since a third pane raises inner surface temperature

• Interior air movement, because stagnant air at the glass line runs colder, which is why perimeter heating placement matters

• Interior humidity, since the dew point moves with it

That last point deserves attention on buildings with high internal moisture generation, such as hotels, residential, and leisure facilities, where the dew point sits higher and the facade requirement rises accordingly.

Curtain Wall Thermal Break Cold Climate Requirements

Deeper than temperate practice, and for condensation rather than energy reasons.

• 20 to 28 mm: standard commercial, generally insufficient for severe cold

• 30 to 40 mm: typical cold-climate specification

• Above 40 mm, multi-chamber with foam inserts: severe continental conditions

Polyamide 6.6 with approximately 25% glass fibre reinforcement remains the standard material, with conductivity around 0.3 W/mK against roughly 160 W/mK for aluminum.

Multi-chamber breaks with insulating foam inserts in the cavity perform better than solid polyamide of the same depth, since they interrupt convection within the break itself. Improving the frame as well as the glass covers the assembly logic.

Glazing for Severe Cold

Triple glazing becomes the default rather than an upgrade.

A typical cold-climate build-up runs two cavities, two low-E coatings, argon or krypton fill, and warm-edge spacers throughout. Centre-of-glass U-values below 0.7 W/m²K are achievable, which is what makes sub-1.0 assembly values possible.

Coating Position

Surface 3 in a double-glazed unit, or surfaces 2 and 5 in a triple-glazed unit. Which coated surface suits a heating climate is the decision that reverses between regions, and getting it wrong here is a genuine specification error rather than a preference.

In a heating-dominated climate the coating should reflect interior heat back into the room. This is the opposite of Gulf practice, where the coating sits on surface 2 to reject solar gain before it enters.

Solar control in cooling-dominated regions explains that inversion. Specifying the wrong surface in Central Asia costs heating energy and reduces inner surface temperature, worsening condensation risk.

Solar Gain Is Useful Here

Worth stating, because it reverses a habit.

In a heating-dominated climate, solar gain through south-facing glazing offsets heating load. A very low SHGC rejects energy the building wants. Typical cold-climate targets sit around 0.40 to 0.55, considerably higher than hot-climate practice.

Summer overheating still needs consideration, particularly in Tashkent and Almaty where summers are genuinely hot, so the balance is a seasonal calculation rather than a single-season optimisation.

Gas Fill

Argon is standard. Krypton performs better in narrow cavities and costs considerably more, which makes it worth considering only where cavity width is constrained by frame depth.

Thermal Bridging at Junctions

Severe cold exposes weaknesses that temperate climates tolerate.

Slab edges. Where the floor slab approaches the facade, concrete conducts heat outward along its full length. Insulation continuity at this junction matters far more at minus 30 than at zero.

Anchors and brackets. Steel anchors penetrate the insulation line. Structural thermal break pads between bracket and structure interrupt that path.

Spandrel zones. Discontinuous insulation or unsealed back pans allow air movement that defeats the insulation entirely, and the consequence in severe cold is a cold spot that attracts condensation.

Perimeter junctions. Head, sill, and jamb details where the facade meets structure. Air leakage here carries moisture into the construction where it freezes and thaws.

These junctions need coordinated detailing and ideally thermal modelling at the design stage, since correcting them afterward usually means compromise.

Installing in Sub-Zero Conditions

Winter construction is normal in the region rather than exceptional, and the method has to account for it.

Sealant application. Most structural and weather sealants have minimum application temperatures around 5 degrees Celsius, with cure times extending substantially below that. Surfaces must be dry and frost-free, which in practice means temporary enclosure and heating.

Gasket behavior. Elastomeric gaskets stiffen in extreme cold, making correct seating harder and increasing the risk of pinching during unit engagement.

Handling and lifting. Wind limits for panel lifting combine with cold to produce narrow working windows.

Programme sequencing. Sealant-dependent work should be scheduled for warmer periods where possible, with the erection sequence planned around it rather than against it.

Installing in sub-zero conditions is as much a planning problem as a technical one, and it belongs in the programme at tender rather than being discovered on site.

Material Considerations

Aluminum performance. Aluminum remains ductile at low temperatures and does not suffer the brittleness that affects some steels, so the alloy choice is not a cold-weather concern in itself.

Thermal movement. Annual temperature swings exceeding 70 degrees Celsius produce substantial movement. Aluminum expands at approximately 23.6 × 10⁻⁶ per degree Celsius, so a 4 metre member moves around 6.6 mm across that range. Movement joints must be sized for the full annual range rather than a typical daily swing.

Glass thermal stress. Large temperature differentials across a pane, particularly where interior blinds trap heat against the glass, create stress that annealed glass may not survive. Heat-strengthened glass is commonly specified.

Completed work across varied climates is documented in our project gallery.

Frequently Asked Questions

1. What U-value should a curtain wall achieve in Central Asia?

Commonly 0.7 to 1.1 W/m²K on an assembly basis for severe continental conditions, with 0.9 to 1.5 adequate in milder parts of the region. Regional codes derived from the SNiP framework set the binding requirement and vary by city, so the governing document should be confirmed per project.

2. Why does condensation control matter more than U-value in cold climates?

Because they measure different things. U-value describes energy transfer across the whole assembly while condensation depends on the temperature of the coldest interior surface. A facade can satisfy an energy target and still drop a mullion surface below the interior dew point, producing visible water.

3. How deep should the thermal break be for severe cold?

Typically 30 to 40 mm, rising above 40 mm with multi-chamber construction and foam inserts in the most extreme conditions. Standard commercial depths of 20 to 28 mm are generally insufficient where outside temperatures reach minus 30 degrees Celsius.

4. Should solar gain be minimised in cold climates?

No. In heating-dominated climates solar gain through south-facing glazing offsets heating load, so SHGC targets sit around 0.40 to 0.55, considerably higher than hot-climate practice. Summer conditions in cities such as Tashkent still require the balance to be calculated seasonally.

5. Can curtain walls be installed during a Central Asian winter?

Yes, with planning. Sealants have minimum application temperatures around 5 degrees Celsius and cure slowly below that, gaskets stiffen and seat less easily, and lifting operations face combined wind and cold limits. Temporary enclosure and heating are common, and sealant-dependent work should be sequenced toward warmer periods.

Specifying for Severe Cold

Run the condensation analysis rather than relying on the U-value alone, because the surface temperature question is what actually governs. Specify a thermal break deep enough for the design condition. Use triple glazing with warm-edge spacers throughout. Put the low-E coatings on the correct surfaces for a heating climate. Resolve the slab edge, anchors, and spandrel insulation with coordinated detailing. Then plan the installation programme around what sealants can actually do in winter.

PRANCE manufactures thermally broken curtain wall systems with triple glazing, deep multi-chamber thermal breaks, condensation risk modelling, and cold-climate installation support. Send your project location, winter design temperatures, and code requirements and request a cold-climate specification.