Glass Skylight Features Made Easy and Simple

If you’re buying cheap Velux skylights, it’s hard to choose the best skylight because of the many features of every product. To be honest, most skylight features are too technical to read. Most people don’t find these features easily understandable.

Let’s say you’re buying an openable skylight. The product says that it is a skylight with a high VLT rating and a low shading coefficient.

Here’s a quick question. Did you understand the description?

If no, then this article will explain to you some skylights features that you might encounter in the future.

Things might get too technical, but everything will be explained in layman’s terms.

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Ratings used in skylight windows

Manufacturers test their products using ratings. These ratings determine the skylight’s performance in light transmission, heat gain, and heat flow.

  • Visual light transmittance (VLT). The VLT is the measure of light entering through a glazing material. The higher the VLT, the more light can pass through the window
  • U-Factor. It is the measure of heat flow by quantifying the convection, conduction, and convection of heat.
  • Shading Coefficient. It is the measure of solar heat gain from direct sunlight that passes through the window.
  • R-Value. It is the measure of a material’s resistance to heat flow.
  • UV Blockage. The material can block ultraviolet rays from the sun.

Using the ratings in buying skylights

Now that you know the technical definitions of the terms, here are the simplified definitions of these ratings.

When you look at cheap Velux skylight features, check the VLT first. If you want more light entering your house, choose a high VLT skylight. However, if you prefer a tinted and non-glazing skylight, a lower VLT skylight must be your choice.

After the VLT rating, check out the U-Factor and the R-Value. If you want your Velux electric opening skylight to keep the heat out, you should choose a higher U-Factor.

Imagine it this way. If you have a low U-Factor, the heat can be trapped inside your house. This rating is beneficial during winter because it can help in warming the house.

On the other hand, the R-Value is the skylight’s insulation factor. A high R-Value means that the material can resist heat flow. In other words, it insulates better.

After that, choose your desired shading coefficient and UV blockage. The shading coefficient filters certain rays of light entering the window.

Imagine a rainbow. If the rainbow passes through a skylight with a high shading coefficient, not all colours in the spectrum will pass through. Some will bounce back.

In effect, it will create a “shade” and reduce the light’s brightness.

Moreover, UV blockage is a filter that blocks harmful ultraviolet rays from the sun. A higher UV blockage rating is preferred in all cases.

Being a wise buyer

Aside from knowing these ratings, knowing where to buy Velux skylights is important. Always buy skylights from legitimate distributors. Avoid counterfeit products.

Your knowledge in these ratings will serve no purpose if you buy fake skylights. Thus, be watchful of sellers and their products.

Now that you know how to interpret the ratings, buy cheap Velux skylights at Skylights Online. Aside from affordable skylights, they sell high-quality and original products. So, visit their site now at