SHGC & U-Values Explained

SHGC & U-Values Explained

# Information


The SHGC or Solar Heat Gain Coefficient is a measure of the amount of heat that can be gained through your windows at times of direct solar contact. The SHGC is important as during summer the SHGC can add large amounts of unwanted heat to your house. Equally in winter the SHGC can be utilised to provide cost and pollution free heat from the sun. The Solar heat gain is measure as a coefficient and indicates the amount of direct solar heat that will penetrate your house.

The SHGC is mainly affected by the glazing type. Products like tinted glass and applied films can help to reduce the SHGC. It is important that when selecting windows and doors the orientation, location and house design are all considered to achieve the best outcomes. In cooler climates it is often advantageous to have a higher SHGC and in hotter climates a lower SHGC is better. To comply with the Energy Efficiency Report, the SHGC must be within 10% of the set value.


The U-Value or Uw is a measure of conductivity of the whole window (glass and frame included). It is a number calculated to return an amount of energy flowing through the product at a given temperature difference per meter squared of window. The Uw is a number that indicates how well a window or door will retain heat in the winter and reject heat during summer. The lower the U-value the better the insulation properties of the aluminium window – the better it is at keeping the heat or cold out. In all cases regardless of climate zone an aluminium window with good insulation properties will help to improve the comfort of your home. To comply with energy reports U values must be Lower than or equal to that specified in the Energy Efficiency Report.

LOW-E Glass

Low-E (low-emissivity) glass is a type of energy-efficient glass that is coated with a thin, transparent layer of metal or metallic oxide. This coating helps to reduce the amount of heat that can pass through the glass, making it more effective at keeping a building cool in summer and warm in winter. Low-E coatings work by reflecting long-wave infrared radiation (heat) back into a building, while allowing short-wave solar radiation (light) to pass through. This can help to reduce energy consumption and costs associated with heating and cooling a building.

Double-Glazing (IGUs)

Double Glazing also known as an Insulated Glass Unit (IGU) utilises 2 panels of glass, which can be different types or thickness including Low-E, are bonded together as a single unit incorporating a moisture-inhibiting spacer block and structural glazing silicon. In the space between the panels of glass, the air is replaced with Argon gas. This inert gas further reduces the ability for heat to transfer through from the exterior glass to the interior glass, helping it to achieve a better energy and acoustic performance rating for the building. This not only makes the building more comfortable for the occupants but also reduces the need to actively heat and cool the building in turn reducing running costs and demand on the power network.

All of our window and door products and feature IGUs and our recently released ComfortEDGE product series provides a minimal frame to house the IGU in thermally efficient and cost effective solution. This range is on display at our Milton Showroom.

When selecting aluminium windows and aluminium doors for your home or building project you will often be required to comply with certain performance values for energy efficiency. That is – you may be asked to select windows and doors with a specific Uw Value or Solar Heat Gain Co-efficient. In order to comply the window system must perform to the set parameters. It’s important to note, that these values are “whole window values”, not glass alone. These values are available for all AWS/Vantage aluminum windows and aluminium door products as part of their WERS rating.