Residential Ventilation Codes

The trend continues to make buildings more energy efficient, which I support 100%.  All commercial building codes require these high performing buildings to ventilate.  The problem is residential building codes, that rarely require mechanical ventilation.  Mechanical ventilation typically uses the HVAC system or supplemental fan to bring in outdoor air.  This is in contrast to natural ventilation that comes in through an open window, and infiltration that comes in through a closed window.

Although homes are being built more for greater energy efficiency, mechanical ventilation is only required in five states that I know of.  These include Washington, Minnesota, California, Vermont and Maine.

My state of Illinois doesn’t require mechanical ventilation in homes.  New efficient homes don’t have the means (other than opening windows), to air out the VOCs from new construction.  Until mechanical ventilation gets adopted into building code, I will remain busy dealing with indoor air quality issues that are totally preventable.

Homes can be both energy efficient and well ventilated.  I would like to see more homes installing mechanical ventilation, but I’m afraid that won’t happen until codes force people to have improved IAQ.

Does your state require residential mechanical ventilation?  Have you seen similar problems in your area?  Please make a comment on my blog!

2 thoughts on “Residential Ventilation Codes

  1. Hey Ian,
    Brent here, grad student from UT-Austin.
    Been keeping up with your blog and really appreciate what you do!

    No residential ventilation requirement that I’m aware of here in Texas, but we do have a local green building program with the city’s electric utility, Austin Energy. Unfortunately they don’t make their point system readily available online anymore so I’m not sure if they have a requirement either.

    Regardless, I’m reminded of a study from a couple of years ago by some good researchers at Lawrence Berkeley Lab (Iain Walker and Max Sherman). WIth any introduction of outdoor air for ventilation, there will be some additional heating and cooling energy requirements to condition that air. And if mechanical ventilation is intentionally provided, there is some additional fan energy required to bring in that air. But what kind of energy penalty are we talking about? I don’t think we’ve seen many measurements, but these guys modeled the energy implications of meeting ASHRAE’s residential ventilation standard (ASHRAE Standard 62.2) in several climates (http://eetd.lbl.gov/ie/pdf/LBNL-62446.pdf).

    They concluded that exhaust-only systems are generally the most energy efficient method, with small, low-power fans that don’t introduce all that much outdoor air to be conditioned. Typically, the energy requirements were ~5% of the total heating and cooling energy of the systems.

    I still think there is a big gap in knowledge on how mechanical ventilation systems actually operate (I’ve seen some evidence in papers reporting the answer is “poorly”) and what their real energy requirements are in the field. Something to think about!

    Cheers,
    Brent

    1. Brent,
      Thanks for the comment! From an energy perspective, I’m not surprised a negative system came out on top. The outdoor air gets pre-cooled or pre-heated as it is pulled through the building envelope. The downside to the exhaust system is that the outdoor air comes into the space unconditioned. For humid climates, that means humidity is brought in. For urban areas, that may mean elevated particulate.
      I will read that LBNL article to learn more. Things are never as simple as they seem on the surface.
      I hope to see you at Indoor Air 2011!
      Ian

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