Blower Door Testing of Insulated Concrete Form (ICF) HomesMarzena Kasia FYDRYCH1, Michael STREET1,2, Lori FERRIS1,Leslie NORFORD1

1Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave, 02139 Cambridge, United States. 2 Morehouse College ,Atlanta, GAmfydrych@mit.edu

OBJECTIVE

The objective of this part of the project is to evaluate the air tightness of Insulated Concrete Form single-family houses using Blower Door Test.

MOTIVATION

B

CONCRETE SUSTAINABILITY HUB

IMPACT

ACKNOWLEDGEMENTS

This work has been supported by the Concrete Sustainability

Hub at MIT, with sponsorship provided by the Portland

Cement Association (PCA) and the RMC Research &

Education Foundation.

REFERENCES

[1] ASTM E1827-96 Determining Airtightness of Buildings Using an Orifice Blower Door

[2] ASTM E779-03 Standard Test Method for Determining Air Leakage Rate by Fan Pressurization

[3] ASHRAE 438RP-92 Evaluation of the Techniques for the Measurement of Air Leakage of Building Components, D.G.Colliver, W.E.Murphy, W.Sun

[4] ASHRAE Fundamentals - 2009

• Infiltration of air through the building envelope is often a major variable in a system’s heating and cooling loads.

• Air flows through building elements such as walls, roofs, windows, doors and bathroom and kitchen vents. The choice of walls, windows and doors materials and the quality of construction affect the total leakage area of the envelope. Air flow depends on the envelope’s leakage area and the pressures generated by buoyancy forces (associated with indoor-outdoor temperature differences) and wind. These natural forces vary with building location.

• ICF walls consist of a solid, continuous and seamless unit that suggests tighter construction than framed walls.

• Infiltration is very difficult to predict and is better estimated with house-specific air tightness tests. Inadequate field tests have been done to evaluate the general potential for reduced air infiltration of ICF homes.

MIT in cooperation with

the concrete industry

has scheduled air

tightness tests of 40 ICF

houses across the

United States.

To date,15 blower door experiments have been carried out in:• Mississippi – 10 houses• Florida – 2 houses• Connecticut – 2 houses• New Hampshire – 1 house

House floor area varies from 800 to 7300ft2

METHODOLOGY

BLOWER DOOR TESTBlower door tests have been performed by certified home auditors according to ASTM E1827-96[1] or ASTM E779-03[2] using the Minneapolis Blower Door with TECTITE software.

Blower Door Methodology[3]

• A powerful variable speed fan is placed in an opening in the building envelope

• The air is blown into (pressurization) or out of (depressurization) the building.

• A uniform, artificial, static pressure is imposed across the entire building envelope and the amount of air being moved by the fan to create this pressure differential is determined.

• The air flow rate through the fan is usually determined from:

a) measurements of the pressure drop across a known flow restriction, or b) the fan rotational speed and a calibration curve.

Building Data1782.5 ft2 floor area14082.1 ft3 volume3962 ft2 exposed surface

KEY FINDINGS

Construction Classification Based on Unit Leakage Area[4]

• Tightness of tested ICF houses varied from good to tight.

• Mean unit leakage area was 0.016in2/ft2

Leakage area normalized by exposed surface area is a useful metric for evaluating air tightness, based on ASHRAE ratings.

• Measurement-based air tightness metrics indicate that ICF houses are subject to lower amounts of uncontrolled outdoor airflow than typical production housing.

• Tighter construction facilitates the use of mechanical ventilation with heat recovery for low-cost and low-environmental-impact building ventilation.

• Air tightness measurements allow us to quantify energy use and carbon emissions associated with air leakage for houses in different climate regions using building energy simulation programs.

Building Leakage Curve

Airflow at 50 Pascals

CalculationsAir Change per Hour

Test Data Flow at 4Pa

AL total leakage area of the building

Unit leakage area

(per ft2 of exposed surface)

Example Blower Door Data