Ontario · Energy · checked September 28, 2026

Duct leakage and ductwork pressure testing in London

If some rooms never get warm in winter or cool in summer, the problem is often the ductwork, not the furnace or air conditioner. In the London area, 73% of households heat with a forced-air furnace, so duct losses affect many London homes.

Get matched in London → Duct leakage and airflow testing
A duct-testing fan on a basement floor connected by flexible duct to a furnace, a pressure gauge hanging from a joist

Typical cost

$200–$450

Forced-air furnaces

73%

Homes with ducts that can leak

Electric baseboards

Not published

Houses built before 1991

66%

Older houses usually leak more and have less insulation

How London is built

London's houses by when they were built Ten house shapes, one for each tenth of London's 119,295 houses. Before 1961: 25%, 1961–1990: 41%, 1991–2000: 11%, 2001 or later: 24%. Older houses glow hotter.
  • Before 1961 25%
  • 1961–1990 41%
  • 1991–2000 11%
  • 2001 or later 24%
Each house stands for one in ten of London's 119,295 houses (single-detached, semi-detached, row and duplex), drawn by when it was built. The glow shows the usual pattern: older houses tend to be leakier and less insulated. More snow in the drawing means more heating degree-days: a longer, colder heating season. Sources: Statistics Canada 2021 Census (table 98-10-0233-01), NRCan HOT2000 climate data.

Who needs it in London

In the London area, 73% of households heat mainly with a forced-air furnace; natural gas is the main heating energy for 61% of households and electricity for 24% (Statistics Canada, 2023).

Of London's 119,295 houses (single-detached, semi-detached, row houses and duplexes), 25% were built before 1961 and 66% before 1991, according to the 2021 Census. Ducts in older houses often run through unheated spaces with taped or unsealed joints, and supply runs to the far rooms are the first to suffer.

The same leaks cost you in summer when the ducts carry cooling: air from a central air conditioner or heat pump that escapes into an attic, garage or crawlspace is cooling you paid for, and leaky return ducts can pull in humid air. Sealing and balancing the ducts helps in both seasons, and it's worth doing before a new heat pump goes onto old ductwork.

What the test shows

  • Total duct leakage, as a share of the system's airflow, measured by pressure-testing the ductwork with a calibrated duct-pressurization fan.
  • Airflow at each register, which explains why one bedroom is always cold.
  • Whether sealing and balancing will fix comfort problems before you buy bigger equipment.

Duct leakage testing in detail.

What it costs

About $200–$450 (a September 2026 planning range; quotes vary). It isn't part of a standard EnerGuide evaluation, so ask for it when you book if comfort is your main complaint.

Great Lakes–St. Lawrence Southern Ontario and southern Quebec

What this means in London’s climate

Cold winters and hot, humid summers: seal the attic, dry the basement, plan cooling.

This region has real winters and hot, humid summers, so bills come from both heating and cooling. Natural gas heats most Ontario homes, while most Quebec homes use low-cost electricity. An EnerGuide evaluation here should cover air sealing and the attic, cooling and dehumidification, and keeping the basement dry before insulating it.

  • Right-size cooling to control humidity. In humid summers, an oversized air conditioner or heat pump cools quickly but shuts off before removing moisture, leaving rooms clammy. A heat pump replacing the air conditioner also covers much of the heating. Ask: Ask for a room-by-room heat-loss calculation and a duct and airflow check before replacing your air conditioner or furnace.

What else homes in London need →

Sources for this climate guide · checked October 26, 2026

NRCan-licensed service organizations serving London

A service organization is a company that Natural Resources Canada (NRCan) licenses to deliver EnerGuide evaluations; its registered energy advisors do the home visit. Duct leakage testing isn't part of a standard EnerGuide evaluation. Some of these organizations offer it, as do HVAC contractors with duct-testing equipment, so ask when you call.

Only assessments from the seven HRSP-approved organizations qualify for the $600 Home Renovation Savings rebate and its assessment-path upgrade rebates; each listing below says whether it's one of them.

Source: NRCan list of licensed service organizations, checked September 28, 2026. Call to confirm your street is covered and ask about wait times.

Programs in London

Provincial · needs an evaluation Home Renovation Savings — Home Energy Assessment path Up to $10,000 per home ($5,000 if heated with Enbridge gas), including $600 back on your two assessments, for insulation, windows, air sealing and more — if the follow-up assessment is done by December 31, 2026 Open · deadline Provincial Home Renovation Savings — direct rebates (no assessment) Heat pumps up to $7,500 ($12,000 ground-source), solar with battery up to $10,000, plus attic, thermostat and appliance rebates — no assessment needed Open Federal National Heat Pump Rebate Announced October 8, 2026 and opening early 2027: up to $10,000 below the median income, $2,000 for other eligible homeowners Announced · opens 2027 Federal CMHC Eco Improvement premium refund A 25% energy-efficiency rebate on your CMHC mortgage insurance premium after $20,000 of energy renovations Open Municipal BetterHomes London loan City of London program (FCM Green Municipal Fund-supported) with a free retrofit coach: loans up to $40,000 at a 2.5% fixed rate, terms up to 20 years, repaid through property taxes, with up to 50% of approved costs paid up front. The project must cut energy use by at least 25% (typically a $20,000-$30,000 investment); at least 80% of costs must be energy efficiency. For detached, semi, townhomes, duplexes and triplexes used as a full-time primary residence. Participants usually pay for the initial energy assessment ($500-$700) before financing approval; EnerGuide assessment costs are eligible for financing. Site updated Sept 2026. Municipal BetterHomes London income-qualified incentives Grants that do not have to be repaid, deducted from the loan balance after renovations. Paid on a sliding scale by energy savings: $2,500 at 25%, $3,000 at 30%, $4,000 at 40%, $5,000 at 50%, $6,000 at 60%, $7,500 at 75%, up to $10,000 at 100%. Household income must be under $95,000 for one person or under $115,000 for two to five people. Rental properties are not eligible.

Duct leakage testing in London: common questions

How much does duct leakage testing cost in London?

Plan on about $200–$450. It is usually a separate service from an EnerGuide evaluation.

Is duct cleaning the same thing?

No. Cleaning removes dust; it doesn't find or seal leaks. A leakage test measures where air is lost.

What is ductwork pressure testing?

The same thing as a duct leakage test: registers are sealed, a calibrated fan pressurizes the ducts, and the airflow needed to hold the test pressure shows how leaky they are.

Should I close vents in unused rooms?

Usually not. Closing registers raises duct pressure and can increase leakage elsewhere in the system.

Duct leakage testing near London

Duct leakage testing in Waterloo79 kmDuct leakage testing in Kitchener81 kmDuct leakage testing in Brantford82 kmDuct leakage testing in Cambridge90 kmDuct leakage testing in Chatham-Kent98 km All 70 cities →

Sources

Checked September 28, 2026. Census figures are for the municipality (Ontario); climate data is NRCan's HOT2000 station London (10 km away).

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