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Split-Pack AC for garage

Discussion in 'Residential Energy Codes' started by jar546, May 20, 2020.

  1. jar546

    jar546 *****istrator

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    What are your thoughts on the installation of a split-pack ductless AC unit for an attached garage that is outside of the thermal envelope?
     
  2. Ty J.

    Ty J. Sawhorse

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    In WA, if HVAC is installed, it also must comply with the thermal envelope requirements. The only real exception is if they can demonstrate a peak design rate less than 3.4 BTU/h•sq.ft or 1.0 watt/sq.ft.


    WA R402.1 General (Prescriptive)
    The building thermal envelope shall meet the requirements of Sections R402.1.1 through R402.1.5.

    Exception: The following buildings, or portions thereof, separated from the remainder of the building by building thermal envelope assemblies complying with this code shall be exempt from the building thermal envelope provisions of this code:
    1. Those with a peak design rate of energy usage less than 3.4 Btu/h ft2 (10.7 W/m2) or 1.0 watt/ft2 of floor area for space-conditioning purposes.
    2. Those that do not contain conditioned space.
    3. Greenhouses isolated from any conditioned space and not intended for occupancy

    WA R505.1 Change in Occupancy or Use
    Any space not within the scope of Section R101.2 which is converted to space that is within the scope of Section R101.2 shall be brought into full compliance with this code.
    Spaces undergoing a change in occupancy that would result in an increase in demand for either fossil fuel or electrical energy shall comply with this code.
    Any space that is converted to a dwelling unit or portion thereof from another use or occupancy shall comply with this code.

    Exception: Where the simulated performance option in Section R405 is used to comply with this section, the annual energy use of the proposed design is permitted to be 110 percent of the annual energy use otherwise allowed by Section R405.3.
     
  3. cda

    cda Sawhorse

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    Not sure why you cannot a/c your man cave, without a lot of requirements??

    If you do a portable, no one will ever know??????

    Or you but a BAF in it do they care?
     
  4. ICE

    ICE Moderator

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    Isn’t that why they were invented? The energy code that won’t allow conditioning an un-insulated space was written specifically for garages. Who are we to tell me that I can’t make my garage comfortable? I pay the electric bill.
     
    #4 ICE, May 20, 2020
    Last edited: May 27, 2020 at 10:20 AM
  5. north star

    north star Sawhorse

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    # ~ # ~ #

    Jeff, ...you can certainly install a ductless mini-split
    A\C unit and 1 or 2 air handlers........Just know that
    if you do not have plans to add thermal insulation
    everywhere, you will be losing conditioned air pretty
    quickly.......If money is not an object with you, then
    go ahead.......The mini-splits sure do address the
    desire to condition zones, rather than a whole area.

    FWIW, ...we install a heck of a lot of mini-split units,
    so stay away from the LG brand.......Trane & Mitsubishi
    are the current leaders in the industry, ...around
    here anyway !.........Also, know that the Trane,
    Mitsubishi,
    LG and some others are proprietary in their
    controls..........You must have their access codes to
    be able to work on them, or hire one of their
    proprietary repair technicians.


    # ~ # ~ #
     
    Robert, Enri Code and jar546 like this.
  6. Ty J.

    Ty J. Sawhorse

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    Seeing the comments that followed my post above, I do want to clarify that I was answering Jar with code.

    There is always discretion and a bit of "I was looking the other way". I wont even begin to imagine how many mini-splits are installed without permits, so do I really want to make someone insulate their garage because they were one of the few who actually pulled a permit? I do agree with others here, the energy consumption to partially condition a shop or garage with a mini-split is not going to change the world's global warming issues.
     
    jar546 likes this.
  7. Enri Code

    Enri Code Sawhorse

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    Overall, my thought is that a split-pack ductless AC unit for a garage can work for thermal comfort. Actually quite standard in a lot of European and Asian countries I've been to in structures that don't have much of a thermal envelope to speak of. The better units can do a lot in that they can heat, cool and dehumidify.

    Climate permitting, you may want to look at just using a portable evaporative (swamp) cooler if just any sort of thermal comfort is what you want to achieve.

    It would be more economical in that the cooling of the space is not as dependent on the thermal envelope.

    A PTAC unit can also work.
     
    #7 Enri Code, May 27, 2020 at 10:09 AM
    Last edited: May 27, 2020 at 10:15 AM
    jar546 likes this.
  8. steveray

    steveray Sawhorse

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    (Amd) 104.1 General. The building official is hereby authorized and directed to enforce the provisions of this code.

    Can't do it without insulation...
     
    jar546 likes this.
  9. Enri Code

    Enri Code Sawhorse

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    For sure that seems to be the case where building officials will choose to interpret and enforce the code in a way which considers the garage with AC as now conditioned and not exempt from energy code. .

    Interesting enough, I found that in some parts of the country, like in parts of Texas, Arizona, Florida, etc. where it gets hot as heck, it's quite common to see some form of cooling - or even heating - in garages. Some homes won't even sell if they don't have them.

    In those areas, there seem to be an understanding that the conditioning is permitted because code somehow sees home garages as distinct areas that:

    1. Primarily just need to be air tight and insulated against the other normally conditioned occupied spaces. No penetrations allowed between garage and rest of house.

    2. Aren't conditioned continually but only on occasions say for when someone is working on a project in their garage. No different from instances in non-AC garages when someone plugs in a portable fan and open their garage door to get air moving to work on something in their garage.

    3. People tend to add insulation themselves without the building official needing to tell them once they see their utility bill after running their AC in their garages... since, let's face it, some people will use their garages differently and may stay there longer and not just on occasion. :D

    Personally, I have no idea if I can pull off putting an AC in my garage in my neck of the woods. I'm curious now though and will ask around where I live. It would be cool - no pun intended - if I am able to do so and be able to work on some personal craft projects in my garage when time permits during the hot summers here.
     
  10. mtlogcabin

    mtlogcabin Registered User

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    You could probably meet the 110% limitation if the unit is used on occasions
    Then again when I fire up the welder or plasma cutter in my garage I guarantee they will use more energy than an AC unit
    R503.2 Change in space conditioning.
    Any nonconditioned or low-energy space that is altered to become conditioned space shall be required to be brought into full compliance with this code.
    Exception: Where the simulated performance option in Section R405 is used to comply with this section, the annual energy cost of the proposed design is permitted to be 110 percent of the annual energy cost otherwise allowed by Section R405.3.
     

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