Frequently Asked Questions

Question 5: Do I need insulated windows in Florida?

The Short answer is YES! We all know the value of insulating our homes here in Florida. Our windows are not any different. However, for some reason, there is a lot of confusing information out there on the internet. When you google this, you will definitely get conflicting answers. We understand that many of our customers want all of the information to allow them to make an informed decision.

Florida’s Climate Considerations Florida has a hot and humid climate, with high solar heat gain. Here’s why Insulated Low-E windows are particularly beneficial:

Reduction of Solar Heat Gain: The Low-E coating reflects much of the sun’s infrared radiation (heat) keeping it away from the house and keeping indoor temperatures cooler. This helps reduce the need for (Load on) air conditioning.

Thermal Insulation: The sealed air gap or gas between the panes (usually argon or krypton) is a poor conductor of heat, further reducing heat transfer by conduction. This helps to keep the glass inside from getting hot and giving off more heat inside your house.

Prevention of Heat Loss or Gain: During the hot months here in Florida, both the insulation and Low-E help to reduce the amount of that outside heat that is allowed to come in. During cooler months, these same factors help reflect the heat generated inside the home back inside and keep the cold out, improving energy efficiency.

Still not sure? We can explore deeper to see how insulated low-emissivity (Low-E) windows are best for thermal regulation in a Florida home, if we use the principals of physics. We can explore how they reduce heat transfer, taking into account the following concepts: conduction, convection, and radiation.

Heat Transfer Mechanisms

1. Conduction:

Conduction is the process by which heat travels through solid materials.

The rate of heat conduction Q through a window can be described by

Fourier's Law of Heat Conduction:

Q = kA(Ti​−To​)​

d

Where:

k = thermal conductivity of the window material (The most commonly used silicate glasses have values between 0.9 and 1.2 W/(m·K) (watts per meter per degree Kelvin).

A = area of the window.

Ti = Temp Inside

To = Temp Outside

d = thickness of the window.

Insulated windows typically have double or triple glazing, which introduces layers of air or inert gas (such as argon) between panes. These gases have lower thermal conductivity than glass, reducing conduction.

Low-E Glass and Conduction:

Low-E coatings further minimize heat transfer by acting as a barrier to infrared radiation while allowing visible light to pass through. This means less energy is lost or gained via conduction.

2. Convection:

Convection refers to heat transfer due to the movement of fluids (such as air). In the case of windows, convection occurs in air leaks and between the window panes. The sealed air or gas-filled space between panes in insulated windows reduces convective currents.

Q convection​ = hA(Tglass1​−Tglass2​)

Where:

h = convective heat transfer coefficient (low in the case of insulated windows).

A = area of the window.

Tglass1 and Tglass2​ = temperatures of the inner and outer panes.

In Low-E windows, the convective currents between panes are minimized, thus reducing heat transfer through convection.

3. Radiation:

Radiative heat transfer occurs when energy is emitted by one surface and absorbed by another. Low-E (Low Emissivity) coatings are designed to reduce the radiative transfer of heat. The coating reflects infrared radiation (longwave radiation) back into the home during the winter and reflects outside heat (shortwave solar radiation) away during the summer.

The Stefan-Boltzmann Law describes radiative heat transfer:

Q radiation ​= ϵσAT4

Where:

ϵ = emissivity of the surface (lower for Low-E coatings).

σ = Stefan-Boltzmann constant.

A = area of the window.

T = temperature of the surface.

Since Low-E coatings lower the emissivity (ϵ) of the glass, they effectively reduce the amount of heat that radiates into the home in Florida’s hot climate.

4. Quantitative Example

Let’s assume: A single-pane glass window without a Low-E coating allows 85% of the sun's infrared radiation to pass through. A Low-E window with double glazing and argon gas fill only allows 10−20% of the same radiation to pass through. The reduction in solar heat gain translates into a significant decrease in cooling load for the house. In Florida, where temperatures can exceed 95°F, minimizing this heat input reduces the energy required for air conditioning.

Conclusion

Insulated Low-E windows are best for thermal regulation in Florida because they:

1) Reduce conductive heat transfer through multiple panes and gas-filled spaces (Insulated).

2) Minimize convective heat transfer from leaks and between panes (Insulated).

3) Reflect infrared radiation, decreasing the amount of solar heat entering the home (Low-E).

These factors help maintain a more consistent indoor temperature and significantly reduce the energy needed for cooling in Florida's hot climate, leading to improved thermal comfort and lower energy bills.

Question 6: What is U-Factor?

The U-factor (also called U-value) is a key measure of a window's thermal performance, specifically how well it insulates against heat loss or gain. It tells you how much heat flows through the window, frame, and glazing combined.

How U-Factor Works:

- The U-factor measures the rate of heat transfer (how well the window conducts heat) and is expressed in BTUs per square foot per degree Fahrenheit (BTU/h·ft²·°F).

- It ranges from 0.20 to 1.20 for most residential windows, with lower numbers being better for insulation.

What It Means:

- Lower U-factor = Better insulation: A lower U-factor means less heat escapes through the window, making it more energy-efficient. This is particularly important in colder climates, where you want to retain as much heat as possible inside your home.

- Higher U-factor = Poor insulation: A higher U-factor indicates the window is less effective at preventing heat loss, meaning more heat can escape in the winter or enter in the summer.

U-Factor in Different Climates:

- Colder climates: Look for a window with a low U-factor (e.g., 0.25 or below) to keep your home warm and reduce heating costs.

- Warmer climates: While U-factor is still important, you may prioritize other factors like Solar Heat Gain Coefficient (SHGC) to prevent excess heat from entering your home.

Example:

If you're comparing two windows:

- Window A has a U-factor of 0.30.

- Window B has a U-factor of 0.50.

Window A is better at keeping heat inside your home, meaning it's more energy-efficient and will help lower your heating bills.

In summary, the U-factor is a crucial metric for understanding a window’s ability to insulate. For optimal energy efficiency, especially in colder climates, choose windows with a lower U-factor. You can find more info here https://www.energystar.gov/products/storm_windows_0

Question 7: What is SHGC (Solar Heat Gain Coefficient)?

Solar Heat Gain Coefficient (SHGC) is a measure of how much solar radiation (or heat from the sun) a window allows to pass through. It is an important factor for assessing the energy efficiency of windows, especially in warm climates where minimizing heat gain is a priority.

How SHGC Works:

- SHGC is expressed as a value between 0 and 1.

- A lower SHGC means the window allows less solar heat to enter your home.

- A higher SHGC means more solar heat is transmitted through the window (like a green house).

What SHGC Means:

- Low SHGC - Warm climates: (around 0.25–0.40 or less): Ideal for hot, sunny climates. A lower SHGC is better, as it minimizes the amount of heat from the sun that enters your home, making your living space more comfortable and energy-efficient. These windows reduce the amount of heat entering your home, which helps keep it cooler and reduces air conditioning costs.

- High SHGC - Cold climates: (around 0.50–0.70): Beneficial in colder climates where you want to capture heat from the sun to naturally warm your home and reduce heating costs. A higher SHGC is advantageous, as it allows more solar heat to come through, helping to reduce heating costs by naturally warming your home.

Example:

- Window A has an SHGC of 0.30: This window blocks 70% of solar heat, allowing only 30% to pass through. Ideal for keeping your home cooler in hot climates.

- Window B has an SHGC of 0.60: This window allows 60% of solar heat to enter, which might be beneficial in colder climates.

Summary:

SHGC is a key factor in controlling how much heat from sunlight passes through your windows. In warm regions, look for windows with a low SHGC to minimize heat gain and reduce cooling costs. In colder regions, a higher SHGC can help take advantage of the sun's warmth to lower heating costs.

Question 8: What is NEAT Glass?

Neat Glass is a type of low-maintenance glass that features a special coating designed to keep windows cleaner for longer periods. It is primarily used in residential windows to reduce the need for frequent cleaning and improve visibility.

How Neat Glass Works:

- Coating: Neat Glass has a thin, invisible coating of titanium dioxide, a naturally occurring compound that is activated by sunlight. This coating is usually applied to the outer surface of the glass.

- Self-Cleaning: When exposed to UV light from the sun, the coating breaks down organic dirt and debris on the glass.

- Hydrophilic Surface: The surface of Neat Glass is hydrophilic (water-attracting). Instead of forming water droplets that leave behind spots or streaks, water spreads out evenly across the glass and quickly rinses away dirt. Rainwater or a simple rinse with water can clean the glass more effectively than on traditional windows.

Benefits of Neat Glass:

1. Reduces Cleaning Effort: The self-cleaning properties of Neat Glass can greatly reduce the frequency and effort required for cleaning, making it ideal for hard-to-reach windows.

2. Clearer Views: Because it helps prevent dirt and water spots from accumulating, Neat Glass maintains clearer views through your windows.

3. Durability: The coating is designed to be long-lasting and does not require reapplication or special maintenance.

4. Energy Efficiency: Neat Glass can also be combined with other energy-efficient technologies, such as Low-E coatings, to provide both low maintenance and enhanced insulation.

Summary:

Neat Glass simplifies window maintenance by using a sunlight-activated coating that breaks down dirt and allows water to rinse it away without leaving streaks. This low-maintenance, self-cleaning feature makes it an excellent choice for homes, especially in areas where keeping windows clean can be a challenge.