Double Arches Single Span Greenhouse
Double Arches Single Span Greenhouse
A cold-climate single-span greenhouse featuring a double-arch frame — an outer load-bearing arch and an inner arch separated by a 40–60cm air gap — covered with two layers of agricultural film. The trapped air layer between the films acts as a thermal barrier, cutting winter heat loss by 30–50% compared to a single-film arch tunnel and reducing heating costs substantially. Designed for high-latitude and severe-winter regions where year-round production depends on reliable insulation, without the capital cost of a multi-span glass or polycarbonate greenhouse.
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Key Highlights
· Double-arch frame (outer load-bearing arch + inner arch) with 40–60cm trapped air gap — effective thermal insulation barrier
· Double-layer film covering reduces winter heat loss by 30–50% and cuts heating costs substantially vs. single-film tunnels
· Hot-dip galvanized steel frame, 275g/m² zinc coating, 15+ year service life
· Single-span flexibility with cold-climate insulation — ideal for high-latitude and severe-winter regions
· Double-layer film covering reduces winter heat loss by 30–50% and cuts heating costs substantially vs. single-film tunnels
· Hot-dip galvanized steel frame, 275g/m² zinc coating, 15+ year service life
· Single-span flexibility with cold-climate insulation — ideal for high-latitude and severe-winter regions
Product Overview — Double-Layer Insulation for Cold Climates
The PONSUNO Double Arches Single Span Greenhouse is purpose-built for one challenge: maintaining a stable growing environment through severe winters without excessive heating expenditure. Its defining feature is a double-arch frame — an outer arch that carries the full structural load (wind, snow, film weight) and an inner arch positioned 40–60cm below it. Each arch is covered with its own layer of film, trapping a stationary air layer between the two films. Because air is a poor conductor of heat, this trapped layer functions as an effective insulation barrier, reducing the greenhouse's overall heat transfer coefficient (U-value) to roughly 3.0–4.0 W/m²K — compared to 6.0–7.0 W/m²K for a standard single-film arch tunnel.
- Structure & Materials. The load-bearing frame uses hot-dip galvanized steel with a 275g/m² zinc coating. The outer arch is formed from 25–50mm diameter steel pipe, sized by span and local snow/wind loads. The inner arch uses slightly smaller pipe (20–40mm), as it carries only the inner film weight and does not bear external loads. The two arches are connected by short spacer bars (typically 40–60cm long) that maintain the air gap and transfer some load between layers. Side walls are vertical or slightly curved, with the inner film terminating at the side-wall base to seal the air cavity. All connections are bolted with galvanized hardware; no field welding required.
- Thermal Performance— The Defining Advantage. The double-film air-gap system delivers insulation performance that a single-film greenhouse cannot match. In winter, the outer film is exposed to ambient cold while the inner film stays close to indoor temperature; the stationary air layer between them resists conductive heat flow. Field measurements in cold-climate operations show that double-arch double-film greenhouses maintain indoor temperatures 5–8°C higher than single-film tunnels under identical outdoor conditions and heating input, or achieve the same target temperature with 30–50% less fuel consumption. For growers in regions with prolonged freezing winters, this directly translates to lower operating costs and fewer crop losses during cold snaps.
- Structural Performance. The outer arch carries all external loads (wind, snow, rain) and is engineered to the same standards as a single-arch tunnel. The inner arch is a lighter, non-load-bearing member that primarily supports the inner film. The spacer bars between arches provide lateral stability and help prevent the inner film from sagging. Snow load resistance ranges from 0.25–0.40 kN/m² depending on steel specification — comparable to or slightly better than a single-arch tunnel of the same outer-arch gauge, since the double-layer system adds some rigidity. Wind resistance is up to 130 km/h with reinforced options.
- Trade-Offs. Three considerations. First, the double-arch frame and double-film covering increase material cost by approximately 25–40% over a comparable single-arch tunnel. Second, the inner film and air gap reduce light transmission by roughly 10–15% compared to a single-film greenhouse — a trade-off that is acceptable in cold climates (where heating, not light, is the limiting factor) but may matter for high-light crops in marginal regions. Third, condensation between the two films must be managed; the air gap should be ventilated or the inner film treated with anti-drip coating to prevent droplet buildup that further reduces light and adds weight.
- Covering & Integrated Systems. The outer film is standard 150–200 micron PE/PO/EVA (anti-fog, anti-drip, UV-stabilized). The inner film is typically 100–150 micron PE/PO with anti-drip treatment. Side walls are selectable: double film (for maximum insulation), single film, polycarbonate hollow sheet, or color steel sandwich panel. The structure supports side roll-up ventilation, internal/external shading (30%–85%), heating (hot-water boiler, unit heater, or radiant floor — the primary system in cold climates), drip or spray fertigation, environmental control, and supplemental lighting (often essential in short-day winter months at high latitudes).
Who It's For. Growers in high-latitude or severe-winter regions (Northern Europe, Russia, Canada, northern China, mountainous areas); operations producing warm-season crops through winter where heating cost is the dominant expense; budget-conscious growers who want multi-span-level insulation at single-span capital cost; and any project where winter heat retention is the primary design driver.
| Parameter | Specification |
| Structure Type | Double-arch double-film single-span greenhouse |
| Roof Profile | Double-layer arched roof — outer arch + inner arch, 40–60cm air gap |
| Span Width | 6m / 8m / 10m / 12m — customizable |
| Length | 20m – 100m — customizable |
| Outer Ridge Height | 3.5m – 5.5m (varies by span) |
| Inner Ridge Height | 3.0m – 5.0m (40–60cm below outer ridge) |
| Eave / Side-Wall Height | 2.5m – 4.0m — customizable |
| Air Gap Between Arches | 40 – 60cm (stationary insulation layer) |
| Main Frame Material | Hot-dip galvanized steel, 275g/m² zinc coating |
| Outer Arch Pipe Diameter | 25mm / 32mm / 40mm / 50mm / 60mm (load-bearing, per span & load) |
| Inner Arch Pipe Diameter | 20mm / 25mm / 32mm / 40mm (supports inner film only) |
| Spacer Bars | 40–60cm galvanized steel, connecting outer and inner arches |
| Outer Film | 150–200 micron PE / PO / EVA (anti-fog, anti-drip, UV-stabilized) |
| Inner Film | 100–150 micron PE / PO (anti-drip treated) |
| Side-Wall Covering | Double film / Single film / Polycarbonate hollow sheet / Color steel sandwich panel — selectable |
| Overall U-Value (Insulation) | 3.0 – 4.0 W/m²K (vs. 6.0–7.0 for single-film tunnel) |
| Light Transmission | 75% – 82% (double film, new condition; ~10–15% less than single film) |
| Natural Ventilation | Side roll-up vents (both sides) + optional roof vents |
| Mechanical Cooling | Optional fan & pad evaporative cooling system |
| Shading System | Optional internal / external motorized shade net (30% – 85%) |
| Heating System | Optional hot-water boiler / unit heater / radiant floor (primary system in cold climates) |
| Irrigation & Fertigation | Optional drip / spray / ebb-and-flow with automated dosing |
| Environmental Control | Optional multi-zone sensor + central controller + remote app |
| Supplemental Lighting | Optional LED / HPS grow light system (recommended for high-latitude winters) |
| Snow Load Resistance | 0.25 – 0.40 kN/m² (per steel specification) |
| Wind Load Resistance | Up to 130 km/h (reinforced options available) |
| Door | Double sliding door or hinged door (1.5m × 2.5m standard) |
| Foundation | Concrete strip foundation or independent column foundation |
| Frame Service Life | 15 – 20 years (with proper maintenance) |
| Outer Film Service Life | 3 – 5 years (depending on film grade and climate) |
| Inner Film Service Life | 4 – 6 years (protected from UV by outer film) |