If you’re looking for an affordable way to improve energy efficiency in your home, window insulating film might seem like an attractive option to prevent heat loss.
While double glazing is definitely a more expensive option, how does the effectiveness of window insulating film compare? In this guide, we’ll explore the benefits and drawbacks of window film, and share practical installation tips.
What is insulating film for windows?
Insulating window film is a thin, transparent or tinted layer of polyester, combined with an adhesive layer.
It sticks to the interior side of your windows and is designed to improve thermal insulation by reducing heat loss in the winter. In the summer months, thermal insulation film blocks solar heat, reducing indoor temperature and minimising the need for air conditioning.
Some films for insulating windows also offer UV protection and glare reduction, making them a versatile option for home improvement.
How much does window insulating film cost?
The cost of installing window film to improve energy efficiency will vary on:
- The size of your windows
- How many windows are in your home or business premises
- The quality of the window film you purchase
Some brands sell window insulation kits for single-pane windows for approximately £4-£4.50.
Brands that offer ‘secondary’ glazing films that claim to boost the energy efficiency of windows that are already double glazed, typically retail between £1.50-£2 per square metre.
You can buy cheap insulating film for under £1-£1.50 per square metre. These secondary insulating films are often applied during winter months to optimise the thermal retention properties of existing double glazing.
Does window insulating film work?
If you have single-pane windows, insulating window film is likely to improve the energy efficiency of your windows. Applying this additional layer of thermal protection within the home can be a cheaper alternative to investing in double glazing.
Here are the benefits:
- It improves energy efficiency – According to Energy Saving Trust, insulating film can help reduce heat loss by up to 70%, leading to lower energy bills in winter and improved indoor comfort in summer.
- Some offer UV protection – Many films block up to 99% of harmful UV rays, which prevents the fading of furniture, flooring, and curtains.
- It’s a cost-effective alternative to double glazing – If you have single-glazed windows, insulating film can be a budget-friendly way to improve thermal efficiency without the high cost of replacing windows.
- It’s easy to install – Unlike replacing windows, applying insulating film is a simple DIY project.
- It reduces glare – Some window films can help reduce glare, making rooms more comfortable, especially in bright sunlight.
What are the drawbacks?
- It offers limited insulation compared to double glazing – While insulating window film does improve energy efficiency to some extent, it won’t achieve the same level of insulation as double or triple glazing.
- It has a shorter lifespan – Typically, insulating window film lasts for approximately 5 years. Over time, window films degrade, bubble, or peel, especially if exposed to moisture or direct sunlight for long periods of time. This means you will have to remove and replace the film.
- It can be difficult to remove – If window film is not installed properly, removing the film later can be tricky and leave a sticky adhesive residue. As mentioned above, you’ll need to replace your window film every 5 years or so.
- It alters window appearance – Depending on the type of film, it can slightly alter the appearance of your windows, which some homeowners may not like
How to install insulating window film
Installing insulating film is a straightforward process, but following these steps will ensure the best results:
- Step 1: Prepare the window surface
Clean your window thoroughly to remove dust, dirt, and grease. Any dirt or particles left behind on the surface can cause air bubbles. Clean your windows with a mixture of water and mild dish soap. Avoid ammonia-based cleaning products, as they can affect the adhesive quality of the film. Dry the window completely with a lint-free cloth or paper towel.
- Step 2: Measure and cut the window film
Measure your window precisely but cut the film slightly larger than the glass area so you have room for adjustments. Use a sharp, straightedge utility knife or scissors for a clean, precise cut. And, if you’re applying film to multiple windows, be sure to label each piece so they don’t get mixed up during installation.
- Step 3: Apply a soapy water solution
Top tip - if you lightly spray the window with a mixture of water and a small amount of dish soap, it stops the window film from sticking too soon. This gives you more time to position the film.
- Step 4: Apply the window film
Peel off the backing and gently place the film on the window, smoothing it out with a squeegee to remove any air bubbles. Work from the centre outward to avoid trapping air. If you don’t have a squeegee, use a plastic card (such as a credit card) wrapped in a soft cloth. Be careful not to press too hard as this can potentially tear the window film.
- Step 5: Trim any excess film
Use a sharp utility knife to carefully trim any left over window film along the edges of the window frame. Be sure to hold the blade at a slight angle for a clean cut. Apply gentle, consistent pressure to avoid damaging the film or scratching the glass. Wipe away any loose trimmings with a lint-free cloth.
- Step 6: Let the window film cure
Leave the window film to set for at least 24-48 hours before touching it so it sticks to the glass properly. During this period, don’t touch the film and reduce any exposure to extreme temperatures and humidity. If you notice bubbles start to appear, gently smooth them out with a squeegee or soft cloth before the adhesive fully sets.
Applying insulating window film can help reduce cold draughts, but it’s not the only solution. For more ways to keep your home warm, check out our guide on draught proofing windows with easy DIY fixes.
Is insulating window film the best option?
| Feature | Insulating window film | Double glazing | Thermal curtains |
| Cost | Low | High | Medium |
| Installation | DIY | Professional | DIY |
| Energy Efficiency | Moderate | High | Moderate |
| Durability | 5-10 years | 20+ years | 5-10 years |
| UV Protection | Yes | Yes | No |
| Appearance Impact | Minimal | None | High |
If you are here to weigh up the pros and cons between insulating film and double glazing for energy efficiency purposes, your best option is always going to be double glazing. After all, a thin sheet of plastic will never offer the same insulating benefits as double glazing.
While window film offers some insulation, it doesn’t compare to the long-term benefits of double glazing, which provides superior heat retention and energy savings.
However, the cost of insulating window film is significantly cheaper. And, if you have single panes, you may notice some impact.
If you do already have double glazed windows and want to ‘top up’ their efficiency for winter, the effectiveness of ‘secondary’ glazing films is still debatable.
For a more effective long-term solution that can help you save thousands on your energy bills whilst adding value to your home, go for double glazing instead of insulating film!
Get in touch
With Cloudy2Clear, we offer quality double glazing replacements and window repairs you can rely on. Our 25-year guarantee ensures you are spending your money wisely, as we’ll repair any of our double glazing installations or upgrades that may fail within this time. We offer this guarantee as we know our double glazing experts get it right the first time, every time.
If you would like to book a consultation, call us now on 0800 880 7012. Our engineers will provide a non-obligation quote so you can decide the best way to insulate your home throughout the year.
