Energy Saving

“Of all the components in a building, it is through the windows that most heat is lost. This is because glass allows heat to escape more readily than most other building materials.

For example, given the same area of wall and window, the window will allow up to eight times more heat to escape.  For this reason, it is important that your windows are as efficient as possible”

Source SEAI “ Guide to Insulating Your Home”

Windows provide our homes with light, warmth, and ventilation, but they can also negatively impact a home's energy efficiency. You can reduce energy costs by installing  Dalgan Ultartherm energy-efficient windows in your home.

You'll find that you have several options to consider when selecting what type of windows you should use in your home.
When selecting windows for energy efficiency, it's important to first consider their  Window energy performance ratings.

Window Energy Performance (WEP) explained
By using the information contained on the label, builders and consumers can reliably compare one product with another and make informed decisions regarding the energy performance of window products.
The basic label lists the manufacturer, describes the product, includes the essential energy performance data and provides a source for additional information. The BFRC Window Energy Rating System (or NSAI Window Energy Performance)  lets you know that you are buying the right products. It helps you to quickly select energy efficient windows for your home by comparing window ratings. To view our products Energy Ratings NSAI WEP

  • Ratings
  • Ratings

Thermal Transmittance (U-value)

This measures how well a product prevents heat escaping.
The energy rating value is based on a standard window to enable comparison of product.

Solar Factor (g-value)

This measures how well a product blocks heat caused by sunlight. The Solar Factor is expressed as a number between 0 and 1. A lower Solar Factor means less heat gain.

Air Leakage (L50 value)

The factor L50 in the formula is an air leakage factor. For good quality windows, air leakage makes little difference to energy performance, for leaky windows, the impact is significant.


A window's energy efficiency is dependent upon all of its components. Window frames conduct heat, contributing to a window's overall energy efficiency, particularly its U-factor. Glazing or glass technologies have become very sophisticated, and designers often specify different types of glazing  for different windows, based on orientation, climate, building design, etc.
Another important consideration is how the windows operate, because some operating types have lower air leakage rates than others, which will improve your home's energy efficiency. Common operating types include: (see Window types) Casement,Bay,,French, Sash,Tilt&Turn