What are energy-efficient windows and how do they work?

What are energy-efficient windows and how do they work?

What are energy-efficient windows and how do they work?


Windows improvement over time can be a little bit confusing as they all look the same. People always wonder how they are different and power-saving compared to any other type of window, and what is the benefit of such an upgrade. This brief article addresses the way it works and its advantages.

What are energy-efficient windows?

Thanks to the past 25 years of technological progress and research, energy-efficient windows have become up to 4 times more insulating from heat and cold than the conventional windows.

By providing more insulation to keep the heat contained inside in the winter and out in the summer, this type of windows can reduce the amount of energy lost by up to 75%. By reducing the amount of energy needed to maintain a comfortable temperature inside your home, it is possible to reduce utility bills.

  • what makes a window energy-efficient?

Energy-Efficient Windows Work

Energy-efficient windows are made from various components (Glass, frame, pane spacer) acting together to provide a high level of insulation. Those components are to be considered as energy-efficient. Their substantial protection against the heat gain and heat loss reduces the consumption of energy for the whole house.

  • how energy efficient windows work?

Parts of a Typical Energy-Efficient WindowDouble-paned windows and triple-paned windows are made from multiple sheets of glass sandwiched together separated by a little space between them to create consecutive air gaps that are well sealed. This multiple-layer construction prevents the air from entering or exiting. Air pockets could also be filled with a different type of gas for even increased efficiency and optimal heating bills. A double glazed window combined with one pane coated for Low-E and argon gas sealed in between can reduce the U-value as low as 1.8 compared with about 5 for the traditional single glazed clear window.

  • Low-e Window Coatings

When heat energy is absorbed by the glass, it is convected away by air or re-radiating through the surface of the glass. Emissivity is the ability of a material to radiate energy. By coating the glass surface it helps to block up to 90% of sun’s rays which improves the window insulation.

There are also different glazing options to help improve efficiency and lower the bills such as tints, reflective coatings and gas fill.

Efficient Window materials

There are a wide verity and configurations for energy-efficient windows, from frame material to the style. These materials affect the performance as they will vary according to,

  • How much air can leak in or out?
  • What is the distance that sunlight can travel through the glass?
  • How much can the glass reduce heat radiation on its surface?


  • Frames

Type of Frames

Frames can improve the overall efficiency of the window by affecting its U-factor. Vinyl, Fiberglass, Composite frame materials and Wood, all these types of materials provide a significantly higher thermal resistance than metal. Below describe the following properties.

  • Aluminum or metal frames: Being almost maintenance-free, metal frames are really attempting, plus they are light, strong and durable. When it comes to thermal insulation though, metals are well known for having such a high U-factor. A way of reducing this factor is adding an insulating plastic strip between the outside and the inside of the frame and sash.
  • Vinyl Frames: Polyvinyl chloride is the main material for this type of frame. By applying some Ultra Violet (UV) stabilizers, it is possible to keep the material from breaking down by sunlight. The Vinyl frame has good moister resistance and doesn’t even require any painting job. Its thermal insulation can be better improved by filling hollow cavities with insulation materials.
  • Fiberglass Frame: Fiberglass frames have air cavities that can be filled with insulation materials which make them more efficient than wood and vinyl frames. In addition, they are dimensionally stable.
  • Wood Frames: Thermal insulation of wooden framed windows are relatively good but once a while, their maintenance has to be done. This could be reduced by cladding with aluminum or vinyl.
  • Composite Frames: Composite frames provide more dimensional stability, have better moister resistance and better structural and thermal insulation than the conventional wood frames.


  • Glazing/ Glass

After choosing the adequate frame for the housing requirements, the right glass should be chosen to fit in there. Here also we have a wide verity of windows. The following two factors are basic for all glass materials and they really make the difference in terms of how efficient the window is U-value: U-value is a sum of the thermal resistance of the layers that make up an entire building element – for example, a roof, wall or floor. It also includes adjustments for any fixings or air gaps.

  • Solar heating gain coefficient: this number indicates how much heat can pass through the glass.

It is possible to make this value as low as possible by using some coating. Low emissivity coatings and spectrally selective coatings are the most trending types. 

  • Spectrally selective coatings: It is a special type of Low-E coating. It allows the full amount of light to be transmitted while blocking from 40% to 70% of heat as it is spectrally selective.


  • Spacers / Gas Fills

In double and triple layer windows, something has to keep the distance in-between the glass sheets which in this case is the spacer. This air gap provides accommodation for thermal expansion and minimizes the gas leaks. Air gaps can be filled with other gases such as Argon or Krypton to further improve its insulation. They are non-toxic, odorless and clear.

The benefits of Energy-Efficient Windows

Energy-efficient windows come with many benefits:

  • Less Energy: Having this type of windows along with some other efficient products in a house such as energy-efficient heating systems helps to reduce the amount of energy required to heat or cool the house and it means less energy and less carbon footprint along with low bills.
  • Reduce noise pollution: A sealed double or triple glazing window is really effective for reducing high noisy frequency. It provides a peaceful and quiet environment inside the house.
  • Property value: Energy-efficient Windows will actually increase the value of your property. If you’re in for sale, it could go up by 10% which is totally worth it.


A recent report titled as “Global Energy Efficient Windows Market Analysis, Drivers, Restraints, Opportunities, Threats, Trends, Applications, And Growth Forecast To 2027” has addressed the market trend of this new technology as the following:

“Rapid growth in the construction industry is the primary driving factor of energy-efficient windows market. The increasing popularity of such windows due to cost-effective and eco-friendly nature is boosting the global market demand. Increasing concerns towards carbon emission levels and sustainability have facilitated substantial investments by the government across the world. The target market is strongly motivated by government financial support, favorable initiatives and trade policies. In addition, strict regulations issued by the International Energy Agency to conserve energy is expected to propel the demand for such windows.”

Therefore, based on their high market trend, they are expected to be implemented and extensively used in the near future.

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