If you're in the process of designing a new building or are simply curious about how to make your home more energy-efficient, you may have heard about SHGC or Solar Heat Gain Coefficient.

In this blog post, we'll take an in-depth look at what SHGC is, its significance, and how it impacts the overall energy efficiency of buildings.

We'll also discuss the differences between SHGC and U-factor, explore the ways to reduce SHGC and wrap up with how SHGC values help determine which windows and doors you should choose for your building.

So, sit back, relax, and discover everything there is to know about SHGC!

What Is SHGC?

The Solar Heat Gain Coefficient (SHGC) is an essential metric used in evaluating the energy efficiency of windows and glazing systems. It measures the amount of solar radiation that enters through windows and other glazing areas like skylights, curtain walls, or glass facades and impacts the ability of a building to both absorb and radiate heat.

A higher SHGC value indicates more heat from solar radiation is entering the building from outside, which can increase cooling loads on air conditioning systems, thereby leading to higher energy bills. Whereas a lower SHGC value indicates less solar heat gain, which means less cooling is required, leading to lower energy consumption and cost savings.

The SHGC value is expressed as a fraction between 0 and 1, where 0 represents no solar heat gain, and 1 represents the maximum amount of solar heat gain. Therefore, architects, engineers, and building designers use this metric to identify the appropriate level of solar control required to help maintain indoor temperature conditions and overall occupant comfort.

Why Is SHGC Important?

SHGC is an important factor to consider while choosing windows or glazing systems for a building or a house. This coefficient is an essential metric that explains how much solar heat is transmitted to the interior space of a building through its windows or glazed surfaces, which is vital for energy efficiency.

If a building has a high SHGC rating, then it is more susceptible to heat gain, especially during the summer months. This leads to an increase in cooling loads on air conditioning systems, which results in higher energy bills. On the other hand, if the SHGC rating is low, then the building will have less solar heat gain, which means less cooling is needed, leading to lower energy consumption and cost savings.

Moreover, SHGC ratings also impact comfort levels for occupants of the building. Higher SHGC values lead to increased heat radiation, making the interior space warmer and less comfortable. Meanwhile, lower SHGC values can create a more comfortable indoor environment by reducing glare and solar heat gain.

Overall, the SHGC rating plays a crucial role in the energy efficiency, economic cost, and general comfort of a building.

What Is The Difference Between U-Factor & SHGC?

U-factor and SHGC are both important metrics used in evaluating the energy efficiency of windows and glazing systems. However, they measure different aspects of energy transfer.

U-factor measures the rate of heat flow through a window or glazing system due to the temperature difference between the indoors and outdoors. A lower U-factor indicates better insulation and energy efficiency.

Meanwhile, SHGC measures the amount of solar radiation that passes through a window or glazing system. The lower the SHGC value, the less solar heat is transmitted into a building. This is important for reducing cooling costs, particularly in hot climates.

In short, U-factor is a measure of heat loss or gain due to temperature difference, while SHGC measures solar heat gain.

How Can The SHGC Value Be Reduced?

In most cases, reducing the SHGC value of a glazing system is done by increasing the window’s ability to reflect solar heat away from the building. This can be achieved in several ways:

First, you can opt for low-emissivity (Low-E) coatings, which are applied to windows and help minimize the amount of heat that enters through them. Low-E coatings have a thin layer of metal oxide on one side that reflects solar energy back outside instead of allowing it to enter the building.

Second, you can also use window films or tinting films to reduce SHGC. These films can block out more than 70% of solar radiation and will help keep your home cooler in hot climates.

Third, using a double or triple-paned system helps insulate and prevent excess heat from entering the building. Double pane and triple pane units are often filled with a gas such as argon or krypton for insulation purposes.

Finally, installing larger windows is another way to reduce SHGC values in buildings. Large, vertical windows draw less heat into rooms than small windows do due to their size and shape, helping reduce cooling costs over time.

Overall, there are a variety of ways you can reduce the SHGC value of your building’s glazing system to improve energy efficiency and save money on cooling costs. By opting for Low-E coatings, window films, double-paned systems, and/or larger windows, you will have a much better chance at keeping your building cool during hot summer days while also saving energy costs in the long run.

How Do These Values Determine Which Window Or Door To Install?

SHGC value helps you decide which windows and doors to install in a building. It is an essential factor that helps to balance natural daylighting and solar control, reduce energy consumption and regulate indoor temperatures.

The SHGC (Solar Heat Gain Coefficient) value of doors is carefully selected by designers and architects to optimize energy efficiency and indoor comfort of buildings depending on the climate conditions of the area.

In warmer climates, doors with low SHGC values (between .06-.31) are preferred as they minimize the amount of solar heat that enters the building, helping to keep indoor temperatures low and to reduce energy consumption.

In colder climates, higher SHGC values (between .45-.57) are chosen as they help to capture and retain the solar heat inside the building, keeping it warm and reducing heating costs.

Therefore, understanding the SHGC value of windows and doors is essential for any building designer looking to improve overall energy efficiency and indoor comfort.

However, the SHGC values vary depending on other factors, such as the orientation of the building, the amount of shading provided by external fixtures, and the temperature within the building itself.

April 17, 2023 — Della Wang