Infiltration
user-6652724
| Posted in Mechanicals on
i am trying to understand the design, or expected infiltration, after a house passes a 3ach50
blower door test
can result be used to determine a seasonal infiltration rate for the house to see if
additional ventilation or combustion air is needed for equipment
how do you understand impact of household appliances ie dryer, bathroom exhaust fan, kitchen hood
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Replies
Kevin,
In Climate Zones 4 through 8, a blower door test result of 3 ach50 represents the maximum allowed by the building code.
Actual infiltration and exfiltration rates depend on factors that vary from house to house. One major factor is wind exposure. Houses exposed to the wind have higher infiltration and exfiltration rates than houses in sheltered locations.
Infiltration and exfiltration rates are higher in cold weather than in warm weather (due to the stack effect), and higher in two-story and three-story homes than in one-story homes (also due to the stack effect).
For a new homes, you want to try to beat the code maximum level of 3 ach 50 if possible. I would say that 1 ach50 is a good goal. All new homes (those striving for airtightness) need a mechanical ventilation system.
I wouldn't worry about your clothes dryer unless you get close to the Passivhaus goal of 0.6 ach50. Your bathroom exhaust fan will be fine. Range hood fans are an entirely different matter; for more information on range hood fans, see Makeup Air for Range Hoods.
-- Martin Holladay