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Five ACH50 sits close to the middle of the pre-1960 homes in this study. For homes built from 2010 onward, it stands well above the usual range in the same archive. A whole-home airtightness result becomes much more useful when you put it beside results from comparable homes.
We reviewed archived baseline evaluations for 1,127 individual detached homes in Alberta, evaluated between 2021 and 2026. The aim was practical: replace loose rules about what an older or newer house “should” test at with a transparent comparison from actual evaluation records.
These are results from homes in this practice’s archive, not a representative survey of every Alberta home. They give a useful reference point for a conversation about your house, with the scope kept in view.
What the whole-home result tells us
A blower-door test gives us a controlled way to compare how readily air moves through a home’s leaks. ACH50 expresses that leakage relative to the home’s volume at a test pressure of 50 pascals. Lower results mean less leakage per unit of volume under those test conditions.
That makes ACH50 a useful starting point for assessing the home as a whole. It helps answer whether a result is ordinary for comparable houses, whether it stands out enough to investigate, and whether a repeat test after sealing shows an improvement. It does not need to identify each individual crack to be useful.
Everyday leakage also responds to wind, temperature differences and operating equipment. NRCan explains those driving forces here. The test result is a whole-home airtightness measure; annual heat loss and dollar savings require further analysis.
How the construction periods compare
| Construction period | Homes | Mean | Median | Middle 50% |
|---|---|---|---|---|
| pre-1960 | 126 | 5.97 | 5.40 | 4.15–7.09 |
| 1960–1979 | 283 | 4.04 | 3.75 | 3.00–4.64 |
| 1980–1999 | 314 | 3.81 | 3.56 | 2.84–4.50 |
| 2000–2009 | 173 | 3.16 | 2.97 | 2.38–3.83 |
| 2010 onward | 231 | 1.91 | 1.72 | 1.31–2.17 |
The mean is the arithmetic average. The median is the middle result when the homes are ranked. The middle 50% shows the spread from the 25th to the 75th percentile. Showing all three avoids letting a few very leaky houses define the whole group.
So, is 5 ACH50 typical?
For a pre-1960 detached home: 5 ACH50 falls within the middle half of these results and slightly below the median of 5.40. It would not stand out as unusually leaky within that group.
For a home built from 1960 through 1999: 5 ACH50 is above the middle-half band. It is on the leakier side of this archive’s comparison, although the groups overlap and some homes tested higher.
For a home built from 2000 onward: the same result is further from the centre of its comparison group. In the 2010-onward group, only 4 of 231 homes were above 5 ACH50. That makes a result around 5 a good reason for a closer look at leakage paths and the home’s history.
“Typical” describes a comparison. It does not make a leaky house efficient, set a code limit or establish a retrofit target. An older home can have worthwhile sealing opportunities even when its result is ordinary for its age.
What to do with your result
Use the comparison to frame the next question: where is the air moving, and which leaks are worth addressing? Ask the advisor to connect the whole-home result with the leak locations, access, repair effort and comfort complaints observed at the house.
A home above its comparison range deserves investigation, but the number alone does not identify the cause. A result below the range can still hide a concentrated leak near an occupied room. Whole-home performance and a particular draft are related questions at different scales.
NRCan’s air-sealing guidance supports systematic leak identification alongside attention to ventilation and combustion air. Preserve required air supplies, check ventilation needs, and use comparable before-and-after tests to evaluate sealing work.
The vintage pattern is clear in these records, but it does not prove that age itself caused the differences. Construction methods, later renovations, condition, home geometry and who sought an evaluation all vary. A baseline evaluation also does not mean the house had never been renovated.
How this comparison was assembled
The study used a reproducible, evenly spaced selection across the available baseline-assessment sequences, rather than choosing files because of their ACH50 result. Records were checked for house identity, construction year, house type, positive ACH50 and volume, and supporting pressure-test observations. Duplicate versions and repeat baseline assessments were reconciled so each confidently identified dwelling contributes once.
The table is restricted to detached homes. Rowhouses were kept separate because a whole-unit test can include leakage to neighbouring units. Post-retrofit evaluations and the separate young-home evaluation category were not pooled into the baseline comparison. Records with unresolved identity, version or test-scope questions, or insufficient retained test evidence, were excluded.
The figures describe this selected archive, not Alberta-wide prevalence or a national benchmark. Checking stored results and supporting records is not the same as repeating the tests or certifying that every historical test meets a current standard. No energy savings, renovation effects or cause of an individual result are inferred here.
Analysis prepared October 6, 2026. Source: privately held evaluation records; only aggregate results are presented. Client identifiers and individual property records are not disclosed.
Is 5 ACH50 typical for a house like mine?
