A homeowner opens a set of exterior-leading plastic windows

Unknown to many people, windows are the most significant source of heat loss and gain in buildings.

Using energy-efficient plastic windows can reduce the amount of solar gain and heat loss, which will also help reduce your utility bills and carbon footprint.

The “plastic” component of plastic windows deters many environmentally-conscious buyers. But contrary to what you may think, plastic windows can be eco-friendly. 

This article will look at if plastic windows are eco-friendly, how you can make your existing windows more energy-efficient, and how to buy plastic windows that offer maximum energy efficiency for your climate. 

Are Plastic Windows Eco-Friendly?

Plastic or vinyl windows are more eco-friendly than conventional aluminum and wood windows. When paired with appropriate treatments, plastic windows can eliminate the need for air-conditioning even in harsh climates and reduce heating needs considerably. These windows also reduce pollution and wastage. 

Why Plastic Windows are Eco-Friendly

Eco-friendly plastic windows are made of unplasticized polyvinyl chloride (uPVC), a stiff and durable material used to make the frames and sills. One of the reasons why plastic windows are eco-friendly is that uPVC is non-toxic and does not contain phthalates or BPA.

These windows are also very energy-efficient and reduce your HVAC system’s heating and cooling load. Reducing your energy needs leads to using less energy coming from fossil fuels.

Plastic windows are also very robust and recyclable, reducing landfill waste. 

They Are Made of uPVC

Standard PVC is a lightweight plastic made more flexible and stretchable by adding plasticizers. 

However, plasticizers are not stable compounds. As a result, they can leach and pollute the environment. 

Besides polluting, phthalates and BPA contained in PVC can also be harmful to humans and have been linked to respiratory diseases.

On the other hand, uPVC does not contain plasticizers, phthalates, or BPA, making uPVC plastic windows safer for both the environment and humans. 

BPA-free uPVC is so safe that it is used to make dental retainers. This makes uPVC windows perfect for installing in homes with children, pets, and older adults. 


The unique properties of uPVC make it an excellent insulator and a highly energy-efficient building material. 

The material has low thermal conductivity, meaning uPVC windows stop most of the sun’s rays from entering your home. As a result, buildings with uPVC windows remain cooler in summer than those with aluminum-framed windows. 

A closeup on slightly-opened plastic windows letting fresh air into a home

Combined with double-glazing, uPVC windows significantly reduce the cooling load of your HVAC system. 

These windows prevent heat inside the building from escaping in winter, keeping interior spaces warm and reducing the heating load. 


Wood and aluminum tend to warp over time and when exposed to extreme temperatures. When distorted, these windows become leaky, letting drafts enter and heat escape.

Escaping air increases the heating and cooling load of the building and makes your utility bills shoot up. 

Meanwhile, uPVC windows are built tough. They retain their structural integrity for long periods and even under extreme weather conditions. No plasticizers are added to soften plastic windows, making them strong and durable.

These windows can last for as long as 40 years, so you don’t have to replace them for a long time.

The less often you have to replace something, the fewer purchases you have to make, which benefits your wallet and the environment—the longer you can use an object, the less landfill waste you generate. 

Almost No Maintenance Required

uPVC windows require minimal maintenance. They are not susceptible to mold, rust, or rot. Unlike wooden or aluminum window frames, you don’t have to clean uPVC windows or coat them with special chemicals to prevent bacterial growth. 

These windows also retain their color for a long time and don’t have to be repainted as often as wooden windows. 

There is no need to coat, repaint, and sand them, as less harmful chemicals are used to maintain uPVC windows, and less waste is generated. 


Another thing that makes uPVC windows eco-friendly is that you can recycle most of their components. For instance, the joinery can be used to create new products when it reaches the end of its life. As you already know, reducing your waste greatly helps reduce your carbon footprint.

How Do I Make Windows Eco-Friendly?

Windows are the most significant source of energy loss in homes that need air conditioning in summer and heating in winter. According to the US Department of Energy (DoE), heat loss and gain through windows contribute to 25-30% of the total energy use in an average American home. 

You can make old windows eco-friendly by sealing air leaks, adding energy-efficient window coverings, installing storm windows, and creating exterior shading.

If you want to replace your old windows, choose models with energy-efficiency certifications. Then, buy windows that suit your particular climate. 

Making Windows Energy-Efficient Without Replacing Them

Here are some tips on how you can make your existing plastic windows more eco-friendly:

Check and Fix Air Leaks 

Check around the frames, caulk, and weatherstripping to find the leaks. Make sure there are no cracks or gaps on the inside or outside. Also, check around window-mounted air conditioners for openings. 

You can usually fix these leaks by applying calk or replacing the weatherstripping.

window caulk at the bottom of a window's interior that has started separating from the seam
Peeling or cracking caulk can create gaps that attribute to home heat loss.

Add Energy-Efficient Window Coverings 

According to the Department of Energy, 76% of the sun’s rays hitting conventional double-pane windows enter a building and heat the interiors. 

Operable window coverings like blinds, screens, drapes, and curtains help you restrict the amount of sunlight that enters your house during the day in summer. During winter, you can open the coverings to let the sunlight warm your house. 

Add Exterior Shading

Exterior shading can prevent solar heat gain during summer and keep the interior of a building cool. Additionally, they prevent drafts from entering the building and keep the interiors warm during winter. 

Here are a few exterior shading options to make your plastic windows more energy-efficient: 

  • Awnings – according to the Department of Energy, awnings reduce solar heat gain by 68% on south-facing windows and 77% on west-facing windows. 
  • Curtains – hanging curtains on your porch or patio can create a cool, shady retreat on a hot day. Make sure it drops all the way to the ground and is made of a heavy fabric that can block out the sun. The curtain should be light-colored to reflect the sun’s rays and prevent them from heating the porch or patio. 
  • Draperiesinsulated draperies can reduce heat loss in winter by 10% and prevent heat gain in summer by up to 33%. Make sure you use draperies with white plastic backings to maximize energy efficiency in summer. 
  • Exterior blinds – wood, steel, aluminum, or vinyl blinds can be used outside to provide shade. Make sure the slats fit tightly together to provide maximum shade on hot days. Remember that blinds are not very effective at preventing heat loss during winter. 
  • Solar mesh screens – solar mesh screens are made of woven fabric that can keep 75-90% of the sun’s rays from entering a building. 
  • Shades – exterior roller shades can be made of metal or synthetic fabric and can be rolled up to let in light. You can find shades in various degrees of transparency to let you enjoy the view outside. However, the more transparent the shades are, the less sunlight they can block. 
  • Shutters – shutters that fit tightly against the window prevent the sun’s rays from entering a room while allowing airflow, creating a comfortable atmosphere inside. Shutters also keep cold drafts from entering a room. They can be rolled up and down or swung open. 
  • Overhangs – overhangs are extensions of the roof that are angled to prevent sunlight from entering the building during summer when the sun is high but let it in during winter to warm the interior. 
Solar panels installed as a window awning to create a more eco-friendly plastic window
Solar panels installed as a window awning can create an even more eco-friendly plastic window.

Add a Solar Control Film

A solar control film is a thin, self-adhesive material that can block up to 88% of the sun’s rays from entering a room. They keep indoor spaces cool, reduce the load on your cooling system, and lessen glare. 

Solar films also reduce the number of UV rays entering a room. This feature reduces fading and keeps your upholstery colors bright, so you’ll need to replace them less often.

If you’re looking for a solar control film, we recommend the KESPEN Window Film. It’s an easy-to-install and energy-efficient addition that prevents solar heat gain and reduces glare.

It prevents 82% of infrared and 89% of ultraviolet rays from entering your living spaces. 

This film has a self-adhesive, static-cling design. You don’t need glue to stick it to the glass, so there is no chance of toxic chemicals being released into the air. To install it, you’ll have to spray plenty of soapy water on the glass and the adhesive side of the film. 

Install Storm Windows

Storm windows can be mounted on the outside or the inside of an already existing window.

If you were thinking of buying storm windows, choose one with a low-emissivity or Low-E coating. A Low-E coating makes them more insulating than traditional clear-glass storm windows. 

Low-E coating storm windows reflect 35% more heat than clear-glass storm windows. As a result, they reduce solar heat gain to keep buildings cool in summer and reflect heat inside to keep rooms warm in winter.

These windows also reduce drafts, making rooms more comfortable and less chilly in winter. They can reduce air leakage in homes by 10% or more. 

Low-E storm windows can reduce your heating and cooling costs by 10-30%, depending on the type of window you already have installed in your home. 

Unlike traditional storm windows, these windows are permanently mounted. However, they’re also available as operable models that let you open or close your existing window. 

Replacing Plastic Windows for Energy Efficiency

If your windows are too old or worn out at the edges, you cannot do much to increase their efficiency. Replacing them will be the best course of action.

Here are some tips on how to replace your windows for greater energy efficiency: 

Check Energy Efficiency Ratings Before Buying

Look for windows with the Energy Star label. This label contains the National Fenestration Rating Council (NFRC) that will help you compare products and choose the most efficient one. 

A label usually contains ratings for the following parameters: 

  • U-Factor – the lower this number, the more energy-efficient a window is. 
  • Solar Heat Gain Coefficient (SHGC) – this number refers to the amount of solar radiation that enters a building and heats a space. The lower this number, the less the solar heat gain, and the less your cooling costs are. If your home has greater heating needs, you might want to install a window with a higher SHGC number to let in more sunlight. 
  • Air Leakage – a lower number indicates a tighter window and less air leakage, assuming the window has been installed correctly.

Go For Multi-Pane Windows

Double-pane windows contain air pockets between the panes. These pockets help reduce solar heat gain in summer and prevent inside heat from escaping in winter. 

Triple-pane windows contain three panes of glass, creating two airlocks. The type of gas used to fill these spaces determines the window’s energy performance. A triple-pane window can improve the performance of standard double glazing by up to 50%.

Consider Buying Windows With Low-E Coating

Windows with Low-E coating cost more than clear-glass windows but reduce heat loss by 30-50%.

So, they can actually be the more economical option in the long run. During summer, they reduce solar heat gain to keep the interiors cool and reflect heat inside the house to keep the building warm during winter. 

These coatings last 10-15 years and help reduce your heating and cooling costs, which leads to a smaller carbon footprint.


Generally, plastic is toxic to the environment, but not all plastic is made equal. When you consider all factors, plastic is often the greener choice, especially when choosing the right type.

But uPVC windows aren’t just better for the environment—they reduce your heating and cooling bills but not your wallet thickness.

If you’re going to buy new plastic windows, choose a model with Energy Star certification. 

However, you can also reduce your HVAC load without replacing your windows. Instead, create shading, increase insulation, and plug leaks to make your existing windows more energy-efficient. 


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