Blog > Category > Posted: 2024-Sep-10, Updated: 2024-Sep-11

What is Air Leakage (AL)?

Air leakage (AL) is becoming an increasingly important factor when selecting windows and doors, especially for homeowners in cold climates like Ottawa. With rising energy costs and a focus on energy efficiency, understanding AL can help you choose products that reduce drafts and maintain indoor comfort. But what exactly is air leakage, and why should you care?

The invisible hit to your energy bill

Feeling drafts near your windows or noticing inconsistent room temperatures? That could be air leakage. Air Leakage (AL) measures how much air passes through small openings and gaps in the window assembly. Even the smallest of gaps can significantly impact your home's heating and cooling needs, making your HVAC system work harder and raising your energy costs.

Why air leakage matters in Ottawa

In a city like Ottawa, where winters are long and cold, and summers are hot and humid, controlling airflow through windows is essential for energy efficiency. High AL rates can lead to heat loss in winter and heat gain in summer, making it harder to maintain a comfortable indoor environment. By choosing windows with low air leakage ratings, you can prevent drafts, reduce strain on your HVAC system, and lower energy costs.

How is AL measured?

Air leakage is measured in cubic feet per minute (cfm) per square foot of window area. The highest possible Air Leakage (AL) unit for residential windows and doors is 1.0 cfm/ft² or more, but building codes require much lower limits. Most quality products have AL ratings below 0.3 cfm/ft².

The lower the AL rating, the better the window, or door at preventing air from passing through.

Benefits of low air leakage windows

1. Reduced Drafts: A window with a low AL rating keeps cold air out during Ottawa’s freezing winters and prevents hot air from seeping in during summer.

2. Improved Comfort: Consistent indoor temperatures mean fewer cold spots near windows and a more comfortable home year-round.

3. Lower Energy Bills: Less air leakage means your heating and cooling systems won’t have to work as hard, reducing energy consumption and saving you money.

4. Better Indoor Air Quality: Controlling air leakage can also help improve indoor air quality by reducing the entry of outdoor pollutants and allergens.

Air Leakage vs U-value vs R-value: What's the difference?

While air leakage measures the amount of air passing through a window, the U-value and R-value focus on heat transfer.

Air leakage

Measures the amount of air infiltration through the window assembly
- lower rating unit is better.

U-Value

Measures how much heat escapes through the window
- lower rating unit is better.

R-Value

Measures the window's resistance to heat transfer
- higher rating unit is better.

Together, these ratings provide a comprehensive picture of a window’s energy performance.

Choosing the right AL for your home

For Ottawa homes, selecting windows with a low AL rating is essential for year-round comfort. The perfect energy-efficient window will not only have a low air leakage rating but also perform well in U-value and R-value measurements.

Need help reducing drafts?

If you're not sure how to select the right windows with a low AL rating, our team can help. Contact us today or visit our showroom for expert guidance on energy-efficient windows that will keep your home cozy in winter and cool in summer.

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