How to Test Your Current Windows: A 2026 Guide for Canadian Homeowners

Testing your windows in 2026 helps you quickly determine whether your home is losing heat, where drafts are coming from, and whether your current units still meet modern energy-efficiency standards. These quick checks give you a clear snapshot of your window performance and help you decide whether minor repairs are enough or if a replacement is becoming necessary:

1. Identify drafts by moving your hand around the frame or using a candle or incense stick.
2. Check for fogging between the panes — one of the most reliable signs of seal failure.
3. Compare the glass's temperature to the surrounding wall using an infrared thermometer or a simple touch test.

Key Takeaways

• A window inspection helps identify drafts, heat loss, and structural issues that affect home comfort and energy bills.
• Modern 2026 testing methods include thermal checks, condensation diagnostics, and assessments of glass seal failure.
• Priority signs include drafts, fogging between panes, cold zones, and deteriorated weatherstripping.
• Energy-efficient windows with Low-E coatings, argon gas fills, and tight seals can significantly reduce heat loss.
• A professional assessment offers the most accurate insights if you suspect major leaks or aging windows.

Why Testing Your Windows Matters in 2026

Windows play a significant role in keeping your home warm, quiet, and energy-efficient . Over time, even high-quality units begin to lose performance because of worn seals, shrinking frames, aging glass units, and exposure to Canadian winters. A thorough window inspection helps you determine whether your current windows are still functioning correctly or if it's time to consider repairs or replacement.

This updated 2026 guide uses modern testing techniques and homeowner-friendly steps to help you understand how well your windows are doing—and what to do if they are losing heat or letting in drafts.

"When homeowners test their windows, drafts and seal failure are the most common issues we see. If a window feels noticeably colder than the wall around it, it’s no longer performing the way it should. Modern units built for Canadian winters solve this problem with stronger seals and better insulating glass."
— Tony Wong, Project Manager

How to Test Your Windows for Performance

Below are the most effective and practical ways to evaluate how your windows are performing today. These methods focus on real homeowner symptoms: cold rooms, rising heating bills, and visible wear.

Perform a Window Inspection

A thorough visual inspection reveals most early signs of wear. Use this checklist for each window:

What to look for:

• Cracked or brittle caulking
• Deteriorated weatherstripping
• Drafts around the frame
• Condensation on or between panes
• Difficulty opening or closing
• Visible warping in older wood frames
• Cold spots on the drywall near the window

Simple tools that help:

• A flashlight
• A piece of paper
• An infrared thermometer (optional but helpful)
• A candle or incense stick

How to Check for Drafts Around Windows

Finding drafts is one of the most critical steps because air leakage leads to heat loss and higher energy bills.

DIY methods

• Paper test: Try closing a sheet of paper in the window. If you can pull it out easily, the seal may be failing.
• Back-of-hand test: Move your hand slowly around the edges of the window. If you feel cool air, you have an air leak.
• Candle or incense test: Hold a candle or incense near the frame. If the flame flickers or the smoke shifts, air is moving through gaps.

Common causes of drafts

• Shrunken vinyl frames from extreme cold
• Cracked rubber seals
• Worn weatherstripping
• Improper installation
• Seal failure in double or triple panes

Window Energy Efficiency Test

A window energy efficiency test determines whether the glass and frame are effectively insulating your home.

Use an infrared thermometer

Measure the temperature of:

• The centre of the glass
• the edges of the glass
• the surrounding wall

A difference of more than 3–4°C often indicates poor insulation or gas loss.

What this reveals

• Weak Low-E coating performance
• Heat is escaping through the frame.
• Cold bridging around poorly insulated areas
• Loss of argon gas between panes

"Many people only check their windows when something goes wrong, but early signs—like faint drafts or minor condensation—tell a story. A quick window inspection can help Canadians catch problems early and protect their home’s comfort all year."
— Helen Sin, Consumer Success Manager

Condensation Diagnostics

Condensation helps diagnose hidden problems that may not be obvious during a simple visual inspection.

If condensation appears on:

• Inside surface: excess indoor humidity or weak insulation
• Outside surface: normal and sometimes a sign of sound insulation
• Between panes: seal failure and gas loss, meaning the window is no longer insulating properly

Between-pane condensation is one of the most reliable signs your windows need replacing .

Glass Seal Failure Test

A failing seal breaks the insulating barrier between panes.

Check for

• Fog or moisture between panes
• A milky or dirty appearance that cannot be wiped
• Distorted reflections

Seal failure increases heat loss and makes your window less energy-efficient, even if the frame is in good condition.

Air Leak Test for Windows

While professionals use blower door tests, homeowners can approximate the test indoors.

DIY method

1. Close all windows and doors.
2. Turn on all exhaust fans (kitchen and bathroom).
3. Move an incense stick around each window.

If the smoke moves toward the window, air is leaking in.

How to Know If Your Windows Are Losing Heat

Heat loss is usually noticeable during colder months, especially with older double-pane units.

Signs include

• Cold floors or cold air pockets near windows
• The heating system is running more often.
• Higher energy bills compared to previous years
• Cold drafts even when windows are closed
• Condensation at the bottom of the glass

Advanced indicators:

• Uneven room temperatures
• Frost buildup along the frame
• Ice forming on older wood windows.

Common Window Issues and What They Mean

When Is It Time to Replace Your Windows?

Top signs your windows need replacing:

• Frequent condensation between panes
• Persistent drafts even after sealing
• Cracked, warped, or rotting frames
• Noticeable cold zones
• High energy bills despite efficient heating
• Windows older than 20 years

Modern window systems with Low-E coatings, argon gas fills, and tight multi-point locking offer better protection against Canadian winters and help reduce heating costs.

FAQ About Testing Your Windows

1. What is the most accurate way to test for drafts?

Using incense or an infrared thermometer provides the most reliable results for identifying leaks.

2. How often should I perform a window inspection?

Once a year is recommended, ideally before winter.

3. What does fogging between panes mean?

This indicates seal failure, causing gas loss. The window has lost its insulating properties and may need to be replaced.

4. Can old windows be repaired instead of replaced?

Minor issues like damaged caulking or weatherstripping can be repaired, but aging or inefficient windows often need full replacement.

5. Are Low-E windows worth it in Canada?

Yes. Low-E coatings reduce heat loss, improve comfort, and help manage sunlight year-round.

6. How do I perform a window energy efficiency test?

Use an infrared thermometer to measure temperature differences across the glass and frame.

Upgrade Your Home’s Comfort with Expert Window Solutions

If your window inspection reveals drafts, heat loss, or seal failure, we’re here to help. Canadian Choice Windows & Doors™ offers Canadian-made, energy-efficient solutions designed for your local climate.
Our team provides honest guidance, not pressure, so that you can make the right choice for your home.

Ready for better comfort and lower energy bills? Request your free, no-obligation quote today.

Book a Free Consultation