1IRAC Greenhouse Plastic Explained: How It Retains Heat in Cold Climates

IRAC greenhouse plastic is designed to help reduce nighttime heat loss in colder climates.

What Is IRAC Greenhouse Plastic?

IRAC (Infrared Anti-Condensate) greenhouse plastic is engineered to help retain heat inside the greenhouse at night while still allowing strong daylight transmission. The “IR” additives reduce radiant heat loss by reflecting more infrared energy back toward plants and the growing area instead of letting it escape.

This makes IRAC greenhouse plastic especially useful for cold climates, winter growing, shoulder-season production (early spring / late fall), and any greenhouse that runs heat overnight.

A tight, wrinkle-free installation improves film lifespan and greenhouse performance.

How IRAC Greenhouse Plastic Retains Heat

After sunset, soil, benches, and plants release stored heat as infrared radiation. Standard plastic allows a significant portion of that radiant heat to escape. IRAC film contains infrared-reflective additives that send more of that energy back toward the crop zone, which can reduce how quickly temperatures fall overnight.

What temperature difference can you expect?

In real-world use, many growers report a noticeable improvement in nighttime temperature stability when switching from standard clear plastic, but results vary widely.

Your actual temperature gain depends on factors like greenhouse tightness, wind exposure, heater size, ventilation leaks, and whether you run a double layer system.

What affects IRAC performance most?

If you want the best results from IRAC greenhouse plastic, pay extra attention to these factors:

• Air leaks: gaps around end walls and doors can erase heat gains quickly
• Wind: high wind increases convective heat loss
• Wet surfaces/condensation: moisture can change heat behavior and light
• Double layer inflation: an air layer dramatically improves insulation
• Frame abrasion: rubbing reduces film lifespan and can create weak points

Does IRAC Reduce Heating Costs?

Yes. By slowing heat loss, IRAC plastic can help reduce fuel or electric heating usage, stabilize overnight temperatures, and protect crops during cold snaps.

While IRAC film costs more upfront than clear plastic, many growers recover the difference in one to two heating seasons when heating is a major operating cost.

IRAC vs Clear vs Double Poly

IRAC and “double poly” solve related—but slightly different—problems. IRAC reduces radiant heat loss at night, while a double poly system adds an insulating air barrier. Many growers use both for the best winter performance.

Who Should Use IRAC Greenhouse Film?

IRAC greenhouse plastic is a strong fit for:

• Northern climates and high-elevation regions
• Growers heating at night (propagation, early starts, winter greens)
• High-value crops where temperature swings reduce quality
• Greenhouses or hoop houses where fuel costs matter

If you only grow during warm months and rarely heat, clear greenhouse plastic may be a better value. If you’re in a high-sun region (like FL/CA), also consider Hoop House / Poly Plastic for more diffusion and temperature management.

How to Choose Thickness and Size

Choosing the right thickness and dimensions prevents headaches during installation and helps avoid premature tears.

Thickness basics:

• 6 mil: a common, durable choice for most hoop houses and greenhouses.
• If you need more durability, prioritize a strong fastening system, proper tension, and abrasion protection on frame edges.

Measuring basics (simple method):

1. Measure the width from ground-to-ground over the hoop (the full arc)
2. Add extra length for fastening on both sides (often 1–2 feet per side, depending on your channel/fastener system)
3. Measure the full greenhouse length and add extra for end-wall fastening (commonly 2–4 feet total)

If you’re unsure, size up—extra film can be trimmed, but film that’s too small can’t be stretched safely.

Installation Tips to Get the Most from IRAC Film

Small installation details can make a big difference in lifespan and performance:

• Install on a warm day so the film stretches evenly
• Keep film tight to reduce flapping and abrasion
• Pad or tape sharp frame edges to prevent rubbing
• Use proper fastening hardware for consistent tension
• Seal common leak points (end walls, doors, vents) to preserve heat gains

Proper fastening helps maintain tension and reduces wind damage and abrasion.

Condensation: What IRAC Can and Can’t Fix

Condensation is influenced by humidity, temperature swings, air movement, and how well the greenhouse is sealed. IRAC (and other anti-drip films) can help water sheet and run down instead of dripping, but it won’t eliminate condensation if airflow is poor or humidity remains high.

To reduce condensation:

• Ventilate strategically (even in winter, brief venting can help)
• Improve air circulation with fans
• Avoid large temperature swings when possible
• Keep film clean to maintain light and reduce cold spots

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