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IECC 2018 and Utility use group

Ana

Registered User
Joined
Feb 22, 2023
Messages
25
Location
USA
I have a small 700 sf private garage building that is considered as utility occupancy. My question is what are the energy code requirements for this structure? I was told that if you heat it then you should comply with IECC climate zone requirements for the building envelope, but if you don't heat it then you don't have to comply with the energy code building envelope requirements. Can anyone point me to the code section that is related to this? I checked everywhere but can't find it. The closest thing I could find was that in COMcheck, there's no Utility classification when you try to choose the building type, but this doesn't confirm the statement that I was told. Thanks in advance!
 
to add to my question in case the answer is that U occupancy needs to comply with IECC requirements whether heated or not; I saw on this forum that for a prefabricated metal building, we can use an alternative method other than COMcheck and its R values. IECC 2018 table 502.1.2 uses the U values which seems to be less stringent for prefab metal buildings, do you think this is a reasonable approach?
 
to add to my question in case the answer is that U occupancy needs to comply with IECC requirements whether heated or not; I saw on this forum that for a prefabricated metal building, we can use an alternative method other than COMcheck and its R values. IECC 2018 table 502.1.2 uses the U values which seems to be less stringent for prefab metal buildings, do you think this is a reasonable approach?

Correction:
It's actually table C402.1.4 IECC 2018
 
2018 IECC C505.1 General
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. Where the use in a space changes from one use in Table C405.3.2(1) or C405.3.2(2) to another use in Table C405.3.2(1) or C405.3.2(2), the installed lighting wattage shall comply with Section C405.3. Where the space undergoing a change in occupancy or use is in a building with a fenestration area that exceeds the limitations of Section C402.4.1, the space is exempt from Section C402.4.1 provided that there is not an increase in fenestration area.
Exceptions:

  1. Where the component performance alternative in Section C402.1.5 is used to comply with this section, the proposed UA shall be not greater than 110 percent of the target UA.
  2. Where the total building performance option in Section C407 is used to comply with this section, the annual energy cost of the proposed design shall be not greater than 110 percent of the annual energy cost otherwise permitted by Section C407.3.
 
C402.1.1 Low-energy buildings and greenhouses. The
following low-energy buildings, or portions thereof separated
from the remainder of the building by building
thermal envelope assemblies complying with this section,
shall be exempt from the building thermal envelope
provisions of Section C402.
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 per
square foot (10.7 W/m2) of floor area for space
conditioning purposes.
2. Those that do not contain conditioned space.
 
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