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Basic ventilation questions

jdchess | Posted in General Questions on

I’m sure most of you are familiar with Matt Risinger. In one of his builds where he used ONLY mini-splits, he mentions using a Panasonic WhisperComfort FV-04VE1 “Spot” ERV in the laundry room as the only ventilation for the entire house. Check the 2:09 mark in this video…

https://www.youtube.com/watch?v=U0FFILNuQsM

Panasonic does state in the documentation that the WhisperComfort does meet “whole house ventilation requirements under ASHRAE 62.2.” You can check out the documentation by downloading their PDF sell sheet here…

ftp://ftp.panasonic.com/ventilationfan/fv04ve1/whispercomfort_updated_sellsheet.pdf

I understand the idea of a fully ducted ERV…you exhaust stale air from the bathrooms and supply fresh air back to the bedrooms and/or living areas. How can using a single “spot” ERV in the laundry room as is mentioned in the video above move the fresh air to where it needs to be (i.e. bedrooms) without some sort of distribution system (i.e. central air)? Does this actually work? I’m sure Mr. Risinger had good reasons for going that route, I’m just trying to understand what makes this a viable option.

Panasonic also has a video showing this single “spot” ERV acting as whole house ventilation…

https://www.youtube.com/watch?v=Yn4Eq3ijBl0

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Replies

  1. Jon_R | | #1

    > Does this actually work?

    To meet code or to provide good ventilation to closed door bedrooms? Even many fully ducted systems don't provide the latter. But some people leave all interior doors open making distribution largely a non-issue.

    1. jdchess | | #2

      Jon,

      I'm sure it meets code. The part I'm wondering about is the distribution and/or circulation of the fresh supply air. Seems like even with all interior doors open, it wouldn't be enough to provide hardly any fresh air at all to the bedrooms, unless of course they were directly beside the room where the ERV was located.

      1. Jon_R | | #4

        Open doors move a lot of air. How much depends, but I got 60 and 137 CFM using two different methods. Whether this amount of mixing/exchange provides better or worse bedroom air quality than some much lower CFM delivered directly into a closed door bedroom depends on the specifics. At 20 CFM, the open door will almost certainly outperform.

        "it is clear on a qualitative basis that outside air was fairly well distributed when the doors were open" https://www.buildingscience.com/sites/default/files/migrate/pdf/CP-0802_Field_Test_Room_to_Room.pdf

  2. Expert Member
    MALCOLM TAYLOR | | #3

    Jason,

    As far as I know, the only ways to provide fresh air to bedrooms without ducts, are to either have spot ventilation (something like Lunos) in each room, or have exhaust-only ventilation located somewhere else, and passive fresh-air intakes in the bedrooms. The second option isn't very effective.

  3. GBA Editor
    Martin Holladay | | #5

    Jason,
    Matt Risinger's approach probably complies with ASHRAE 62.2. That said, the members of the ASHRAE 62.2 committee have argued for years on the question of whether the standard should include a distribution requirement rather than simply an airflow rate requirement. As far as I know, ASHRAE 62.2 does not require fresh air distribution.

    The best-performing ventilation system will exceed minimum code requirements. I agree with you that installing a spot ventilation system in a laundry room isn't ideal.

  4. jdchess | | #6

    Martin and Malcolm,

    Thank you both for the input. What do you think about multiple spot ventilators vs fully ducted, such as one in the laundry room and one in the master bedroom?

    1. Expert Member
      MALCOLM TAYLOR | | #7

      Jason,

      I have no direct experience with spot ventilation. From the feedback here people like them. The two downsides appear to be noise and cost.

  5. Expert Member
    Peter Yost | | #8

    The best single proxy for indoor air quality and distribution in my book is CO2. An engineer for the Vermont Energy Investment Corp (which runs our utility energy program, Efficiency Vermont) has done quite a bit of testing of mechanical ventilation systems using a CO2 monitoring device (https://www.efficiencyvermont.com/Media/Default/docs/white-papers/efficiency-vermont-improving-ventilation-cold-climate-homes-white-paper.pdf ). In this study and in conversations I have had with Brian Just, and my own testing using a CO2 monitor: the distribution system is key, especially with doors closed but even with bedroom doors open, just not enough air movement to adequately distribute without dedicated distribution system.

    Also, not surprisingly, our Martin Holladay has a recent blog on ventilation in which he cites/discusses Just's study: https://www.greenbuildingadvisor.com/article/ensuring-fresh-air-in-bedrooms.

    Peter

    1. Jon_R | | #9

      Note that Fig 7B shows that open doors came very close to 1000 ppm - and they would have done better if the homes complied with ASHRAE 62.2 (as Risinger's build does).

      > not enough air movement to adequately distribute without dedicated distribution system.

      It's easy to show that many "best practice" dedicated distribution systems don't provide enough air movement either. For example, with 15 CFM to a closed door, 2 person bedroom, expect ~2000 ppm. Would take more than 30 CFM to beat the Fig 7B results.

      In my opinion, avoid code minimum ventilation and build some type of system that exceeds ASHRAE 62.1 (not just 62.2).

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