ASTM E779-19 PDF

Full title and description

ASTM E779-19 — Standard Test Method for Determining Air Leakage Rate by Fan Pressurization. This standard specifies the procedures, equipment, measurement steps and reporting requirements for measuring the air leakage rate of building envelopes using a calibrated fan (blower door) to pressurize and/or depressurize the building and measure flow versus pressure.

Abstract

ASTM E779-19 describes a field test method for quantifying whole‑building air leakage. The method uses a fan to impose a series of pressure differences across the building enclosure, records corresponding flow and pressure data, and derives an air leakage characteristic (flow vs. pressure relationship) from which the leakage rate at reference pressure(s) (commonly 50 Pa) and normalized metrics such as ACH50 can be calculated. The standard covers instrument calibration, test preparation, data collection, basic data reduction and reporting of results and conditions relevant to interpreting the measurements.

General information

• Status: Active (2019 edition).
• Publication date: 2019.
• Publisher: ASTM International.
• ICS / categories: Building performance; air leakage and airtightness; energy efficiency and HVAC testing.
• Edition / version: ASTM E779-19 (2019 edition).
• Number of pages: Approximately 6–10 pages (typical ASTM test method length: 8 pages).

Scope

This test method applies to whole‑building air leakage measurements carried out on site using fan pressurization equipment. It is intended to characterize the aggregate leakage of the building envelope (exterior walls, roof, windows, doors, penetrations) under controlled pressure differences. The method does not address testing of individual components (for example, isolated window or door unit leakage tests) nor ductwork leakage testing. It also provides guidance on test conditions, minimizing the effects of wind and stack (temperature) influences, and on reporting environmental and test setup conditions needed for reliable interpretation.

Key topics and requirements

• Required equipment: calibrated fan/blower door, differential pressure gauges/manometer, flow measurement or fan calibration data, and data logging tools.
• Pre-test preparation: sealing of temporary openings as required, selection of test configuration (single or multi-fan), and documentation of building geometry and environmental conditions.
• Test procedure: sequence of pressurization/depressurization steps, recommended pressure levels and stabilization criteria, and number of data points to establish a reliable flow‑pressure curve.
• Data reduction: deriving leakage characteristic Q = C · (ΔP)^n (or equivalent), computing leakage rates at reference pressures (commonly 50 Pa), and converting to normalized metrics such as equivalent leakage area or air changes per hour at 50 Pa (ACH50).
• Corrections and limitations: minimizing or accounting for wind and stack effects, thermal conditions, and transient influences; suitability for different building sizes and enclosure types.
• Reporting: required test results, uncertainty/precision statements, instruments and calibration references, test configuration, environmental conditions, and any deviations from the standard procedure.

Typical use and users

ASTM E779-19 is used by energy auditors, building performance consultants, home energy raters, architects, mechanical engineers, building envelope contractors, research institutions and code officials. Common applications include diagnostic testing for retrofit and air‑sealing projects, compliance testing for energy codes and green building programs, quality assurance during construction, and research studies of building airtightness and ventilation performance.

Related standards

Standards and guides commonly used with or alongside ASTM E779 include international and national blower‑door and airtightness standards and procedures (for example ISO standards for fan pressurization methods), other ASTM methods and guides addressing component or assembly leakage tests, and industry protocols from building rating programs and energy performance bodies. Practitioners often cross‑reference these documents when selecting test details, conversions and reporting formats.

Keywords

air leakage, blower door, fan pressurization, airtightness, ACH50, building envelope, infiltration, building performance, test method, field measurement

FAQ

Q: What is this standard?

A: ASTM E779-19 is a field test method that defines how to measure whole‑building air leakage using a fan to pressurize or depressurize the building and measure the resulting airflows and pressures.

Q: What does it cover?

A: It covers test setup, required equipment, measurement sequence, data collection and analysis to determine the air leakage characteristic, leakage rates at reference pressures (commonly 50 Pa), and reporting requirements necessary to interpret results reliably.

Q: Who typically uses it?

A: Energy auditors, building scientists, raters, engineers, contractors and code officials use it for diagnostics, retrofit verification, quality assurance during construction, compliance testing and research into building airtightness.

Q: Is it current or superseded?

A: This document refers to the 2019 edition (designated -19). Users should confirm with ASTM International or their organization that no later revision or corrigendum has been issued after 2019 before relying on the version for compliance or formal reporting.

Q: Is it part of a series?

A: It is one of several ASTM standards and guides related to building airtightness, component leakage testing and ventilation measurement; practitioners commonly use it together with complementary ASTM and international standards and with program‑specific protocols.

Q: What are the key keywords?

A: Air leakage, blower door, fan pressurization, airtightness, ACH50, building envelope, infiltration, field test method.