Seal Tight, Ventilate Right (Part 2)
So last month, we talked about the value, in both comfort and money, of
sealing up all those drafty air leaks in your house – window frames,
door frames, recessed lights, attic hatches, duct registers on exterior
walls, outlets and light switches, pipe penetrations, you name it. But
can a house be too tight? After 40 years of residential building science
research, the answer is a resounding “No”. Houses, the physical
structure itself, cannot be too tight. Houses do not need to “breathe”.
However, people living inside the house, do need to breathe! Therefore,
you want adequate ventilation to provide acceptable indoor air quality.
So, the question is “how much ventilation do I need?”
The minimum level of residential indoor ventilation is determined by ASHRAE Standard 62.2. ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning Engineers) is a building technology society that develops many of the standards and best practices related to the indoor environment (full disclosure, I’m an ASHRAE member). ASHRAE Standard 62.2 states that all residential homes require ventilation. This ventilation can come naturally from openings in the building (doors, windows, drafts), or by mechanical ventilation, such as an electrically powered fan. The amount of ventilation is dependent on two primary factors: 1) conditioned (i.e. heated) floor square feet (which includes heated basements); and 2) the number of occupants. The larger the house or higher the number of occupants, the more minimum ventilation will be required. The exact calculation is too complex for this space (well, what else did you expect from a bunch of engineers!)
So how do you determine if your house needs more ventilation? Step 1 – hire an energy evaluator or qualified contractor to perform a door blower test (discussed in the previous month’s article) to determine your natural ventilation (i.e. air leakage). Step 2 – Have the energy evaluator or qualified contractor calculate the required minimum ventilation based on ASHRAE 62.2. Step 3 – if the natural ventilation is less than the required ventilation, have the energy evaluator write up a scope of work to prove the necessary minimum ventilation. Often, this can be done by simply placing your kitchen or bathroom fans on a timer to run for specific time periods during the day.
ASHRAE Standard 62.2 deals with several other indoor air quality issues not addresses here such as minimum air filtration standards, minimum ventilation levels for kitchens and bathrooms, clothes dryer ventilation, and indoor air pollutants. For more detailed examples, listed of qualified contractors, or information on the different types of mechanical ventilation, please see our website, www.transductiontechnologies.com
The minimum level of residential indoor ventilation is determined by ASHRAE Standard 62.2. ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning Engineers) is a building technology society that develops many of the standards and best practices related to the indoor environment (full disclosure, I’m an ASHRAE member). ASHRAE Standard 62.2 states that all residential homes require ventilation. This ventilation can come naturally from openings in the building (doors, windows, drafts), or by mechanical ventilation, such as an electrically powered fan. The amount of ventilation is dependent on two primary factors: 1) conditioned (i.e. heated) floor square feet (which includes heated basements); and 2) the number of occupants. The larger the house or higher the number of occupants, the more minimum ventilation will be required. The exact calculation is too complex for this space (well, what else did you expect from a bunch of engineers!)
So how do you determine if your house needs more ventilation? Step 1 – hire an energy evaluator or qualified contractor to perform a door blower test (discussed in the previous month’s article) to determine your natural ventilation (i.e. air leakage). Step 2 – Have the energy evaluator or qualified contractor calculate the required minimum ventilation based on ASHRAE 62.2. Step 3 – if the natural ventilation is less than the required ventilation, have the energy evaluator write up a scope of work to prove the necessary minimum ventilation. Often, this can be done by simply placing your kitchen or bathroom fans on a timer to run for specific time periods during the day.
ASHRAE Standard 62.2 deals with several other indoor air quality issues not addresses here such as minimum air filtration standards, minimum ventilation levels for kitchens and bathrooms, clothes dryer ventilation, and indoor air pollutants. For more detailed examples, listed of qualified contractors, or information on the different types of mechanical ventilation, please see our website, www.transductiontechnologies.com
