Blower Door Basics Sim Building info Blower Door

Blower Door Basics -- Sim. Building. info Blower Door Basics THINGS YOU NEED TO KNOW BEFORE YOU PLAY THE GAME

Air Leakage Affects Home Performance Blower Door Basics ___ Sim. Building. Info Photo courtesy of Energy. Star. gov

Air Leakage Requires: A hole. Pressure difference across that hole. The bigger the hole or higher the pressure difference, the more airflow. To reduce airflow, we can reduce the size of the hole or lower the pressure difference. Blower Door Basics ___ Sim. Building. Info Graphic developed for the US DOE WAP Standardized Curricula

Air Leakage: Temperature Winter T = Temperature Difference Summer 70 T=60 Blower Door Basics ___ Sim. Building. Info 10 90 70 T=20 Graphic developed for the US DOE WAP Standardized Curricula

Air Leakage: Pressure P = Pressure Difference Positive Blower Door Basics ___ Sim. Building. Info Negative Graphic developed for the US DOE WAP Standardized Curricula

Measuring Pressure Difference Pascal (metric standard) • 1 Pascal = weight of one Post-It note • 249 Pascals = 1 inch water column (American standard) • 1” water column = pressure required to suck 1” of water up a straw Blower Door Basics ___ Sim. Building. Info

Measuring Building Air Leakage Natural driving forces Blower Door Pressure differences too small to measure reliably. Exaggerates pressure differences so they can be measured reliably and the results are repeatable. Exaggerated air leakage measured with the blower door gives us an idea of the amount of air leakage that would occur under natural conditions. Blower Door Basics ___ Sim. Building. Info

Blower Door Testing Blower door testing is used to quantify and locate air leakage by using a calibrated fan to depressurize a house. Photo courtesy of NRCERT Blower Door Basics ___ Sim. Building. Info

Controlled Driving Force Use a Blower Door as a Controlled Driving Force Using the blower door depressurizes the house, drawing air through all the holes between inside and outside the house. Blower Door Basics ___ Sim. Building. Info Negative pressure Blower Door Graphic developed for the US DOE WAP Standardized Curricula

Units for Measuring Airflow Cubic Feet per Minute (CFM) • Rate of airflow. • Based on the size of a home and the number of occupants, a home should have a certain amount of fresh air when the home is closed up. CFM 50 (standard for blower door) • Blower door measures the rate of airflow in CFM when the pressure difference between the inside of the house with reference to outside is -50 Pascals. Blower Door Basics ___ Sim. Building. Info

Approximate Leakage Area 25” 20” • Divide CFM 50 by 10 • For example: 5, 000 CFM 50/10 = 500 in. 2 Photo courtesy of NRCERT Blower Door Basics ___ Sim. Building. Info

Summary • The blower door is a controlled driving force used to quantify air leakage. • Air leakage is measured in cubic feet per minute at a pressure difference of 50 pascals with reference to another space. • Blower door readings can be converted to air leakage under natural conditions, total size of opening, and more. Blower Door Basics ___ Sim. Building. Info