Result metrics

What do the results mean?

Pulse test results are presented as various metrics at both 4 Pa and 50 Pa, including:

Air Leakage Rate (Q)

The volume of air that exits the building per hour, when the building is pressurised to the cited pressure difference.

Units: m³/h rounded to nearest whole number

Air Permeability (AP)

The air leakage rate normalized to the envelope area of the building. It represents air leakage rate per hour per square meter of building envelope area at the cited pressure difference.

Units: m³/h.m² rounded to 2 decimal places

Air Permeability (AP) = Air Leakage Rate (Q) ÷ Envelope Area (A)

Air Changes per Hour (N)

The air leakage rate normalized to the building volume. This metric represents the number of times that the total air volume in a room, space or building is completely removed and replaced in an hour when the building is pressurised to the cited pressure difference.

Units: 1/h also known as ACH rounded to 2 decimal places

Air Changes per Hour (N) = Air Leakage Rate (Q) ÷ Volume (V)

Effective Leakage Area (ELA)

An estimate of the area of a hole that would produce the same amount of leakage as the building envelope at the cited pressure difference. This value is calculated in accordance with ISO 9972:2015.

Units: m² rounded to 4 decimal places

Calculation Uncertainty

The uncertainty in the air leakage calculation, excluding instrument and on-site building measurement uncertainty.

Units: ±% rounded to 2 decimal places

What are the calculation details?

The calculation details give advanced diagnostic information about a Pulse result:

Coefficient of Determination (R²)

The coefficient of determination is indicative of the accuracy with which a curve fitting equation can be applied to a set of results.

With high frequency 50Hz data collection, 25 reference points are collected per step and it is recommended that an overall R² value of greater than 0.96 for a test to be deemed valid.

Tests that do not obtain this minimum value may be due to adverse environmental conditions or poor test conditions or techniques.

Rounded to 4 decimal places

Air Flow Exponent (n)

The air flow exponent is used to describe the airflow regime through the gaps and holes in the building fabric. Values must range between 0.5 and 1.0.

An n value approaching 0.5 signifies turbulent flow, representing high flow through large apertures. An n value approaching 1.0 will indicate a more laminar flow, characteristic of more air tight structures or those with much smaller gaps and holes.

Rounded to 2 decimal places, with confidence interval

Air Flow Coefficient (C_ENV)

The air flow coefficient is a measure of the efficiency with which air flows through the gaps, cracks and holes in the structure at an internal to external pressure difference of 1 Pa.

Rounded to 3 decimal places, with confidence interval

Air Leakage Coefficient (C_L)

The air leakage coefficient is obtained by correcting the air flow coefficient to standard conditions (i.e. 20°C and 101,325 Pa).

Rounded to 3 decimal places, with confidence interval