90.1 - Enclosed Spaces

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Supriya and Mike,

We had a discussion a few weeks ago about the definition of an enclosed space 
related to the classification of spaces:

Section 3 of 90.1 under the definition of Space says:
"...Crawlspaces, attics, and parking garages with natural or mechanical 
ventilation are not considered enclosed spaces."

All three space conditioning types under the definition of Space (Conditioned, 
Indirectly Conditioned, Semiheated, and Unconditioned) specify that the space 
must be enclosed to qualify.

Here our recommendation:

1. A SpcFunc = "Parking Garage - Garage Area" currently exists in 90.1, and we 
feel that all parking garages will either be naturally or mechanically 
ventilated.  If the user model specifies the SpcFunc = "Parking Garage - Garage 
Area" then the Proposed model will match the User model's CondgType.  That same 
space in the Baseline model will be simulated as CondgType = "Unconditioned".

2. For ventilated attics and crawlspaces we are recommending that we trust that 
the user will specify SpcFunc = "Unnocupied-Exclude from Gross Floor Area" for 
these two space types.  Baseline = Proposed for both SpcFunc and CondgType.

Noah

Original issue reported on code.google.com by ncz...@archenergy.com on 14 Nov 2014 at 6:28

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If the user identifies the parking garage as conditioned then the baseline will 
be unconditioned? I don't think that is good. Maybe we just default parking 
garage to unconditioned in the proposed as well?

Original comment by bikerose...@gmail.com on 14 Nov 2014 at 6:53

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I would argue that space conditioning a parking garage is unnecessary (i.e., a 
waste) and the proposed design should be penalized accordingly. 

Original comment by rhedr...@archenergy.com on 14 Nov 2014 at 7:38

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Based on my discussion of parking garages with the 90.1 committee, here is the 
suggested implementation. Since parking garages are not considered enclosed 
spaces, there are no exterior wall, floor or roof requirements for the parking 
garage exterior walls and other exterior envelope components. The baseline will 
have exterior assemblies “same as proposed”. If a parking garage is 
adjacent to a conditioned or semi-conditioned space the components separating 
them should be treated as exterior walls (not semi-exterior walls. It also 
means that the area of the parking garage should not be included in conditioned 
floor area (used to define baseline HVAC systems) regardless of whether it is 
conditioned or not. And finally, the baseline parking garage HVAC system should 
not map to the table for conditioned space HVAC baseline systems, but instead 
be “same as proposed”. Hope that makes sense. 

Original comment by bikerose...@gmail.com on 4 Dec 2014 at 1:09

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This makes sense to me. A few things questions/clarifications:

You indicated:

If a parking garage is adjacent to a conditioned or semi-conditioned space the 
components separating them should be treated as exterior walls.

1) Is it also assumed the same rules apply to roofs and floor surfaces of 
conditioned/semi-conditioned space adjacent to unenclosed space (parking 
garage, crawlspaces, and attics).

2) It is this wall and roof area classified as "exterior" that is included in 
the window-to-wall ratio (WWR) and skylight-to-roof ratio (SRR) calculations, 
not walls and roof surface area of the unenclosed (conditioned or 
unconditioned) space. 

3) Can the bounding surfaces of an attic and/or crawlspace be insulated and 
therefore, become part of the enclosed, conditioned building volume?  It seems 
appropriate that they can, but I don't think it would be appropriate to include 
these spaces in the floor area since they are typically not "occupied" space. 
It is for this reason we included an "Unoccupied-Exclude from Gross Floor Area" 
space function, but the user can still define that space as 
IndirectlyConditioned or DirectlyConditioned, and the exterior envelope rules 
apply to the other surfaces of those spaces, not the surfaces separating from 
the conditioned, occupied space.

Original comment by da...@360-analytics.com on 4 Dec 2014 at 6:39

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One more question that occured to me when setting up a test model:

If a proposed multizone HVAC system serves BOTH conditioned enclosed space and 
parking garage (for example, an automobile dealership with both a conditioned 
repair shop and an adjacent, parking garage), what should the tool do?  

Some possible options:

1) Stop analysis and say this is not allowed. This is what I propose for Phase 1
2) Remove terminals serving the conditioned space and otherwise model the 
proposed system as-is in the baseline
3) Apply a baseline system type per the map. We talked briefly about this as an 
option; would likely be System 9/10 if it was heating only and you modified the 
PRMRM to allow parking garage as an applicable space function for this system 
type. 

Original comment by da...@360-analytics.com on 5 Dec 2014 at 12:01

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1. Yes, if a conditioned or semi-conditioned space sits on top of parking 
garage, the floor of the space above would be considered that same as if it 
were above an exterior area (fore example raised on posts above open surface 
parking. Similar if the parking garage was over a conditioned space. 
2. Yes, I agree that since these walls and roofs are exterior walls they would 
be counted in SRR or WWR. 
3. I think according to 90.1 and attic or crawlspace is ventilated, and not 
considered an enclosed space, like the parking garage. Even if they did 
insulate these spaces the ventilation would keep the temperature close to the 
ambient. If either of these spaces are not ventilated they probably should not 
be considered an attic or crawlspace, but rather indirectly conditioned or 
unconditioned based on rules we have already established. Perhaps the space 
types should be called ventilated attic and ventilated crawlspace to limit 
confusion. 

Original comment by bikerose...@gmail.com on 5 Dec 2014 at 12:52

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I don't think it would be that common, but I worry about the case where a 
boiler servers an entire building and provides some hydronic heat or OA 
tempering for the parking garage and the building maps out to one without a 
boiler. I don't like option 3. Option 2 makes the most sense long term, but 
option 1 is probably practical for phase 1. 

Original comment by bikerose...@gmail.com on 5 Dec 2014 at 12:56

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Re comment #7, I'll proceed with option 1, and look for PRMRM updates that 
describe how to implement option #2.

Re: comment #6, 3) What if the ventilation to the insulated attic or crawlspace 
is supplied by an HRV or other system that pre-conditions the ventilation air, 
or the ventilation rate is a very minimal amount? If there is no insulation 
between the conditioned occupied space and an insulated, unoccupied space, I 
think in most cases the unoccupied space will not be that close to the ambient 
temperature.

These considerations are more applicable to higher-efficiency SF residential 
buildings, so perhaps we drop that as an example.

In any case, yes, it seems whether the space is naturally or mechanically 
ventilated is the key criteria for correctly classifying unconditioned and 
indirectly conditioned spaces. Currently we can tell in the data model if the 
space is mechanically ventilated since the ThrmlZn would have VentSrc = 
'Forced' and a VentSys or ExhSys defined. Therefore, what we need to know is if 
the space is naturally ventilated to determine if it is an enclosed space. 
Since ventilation is defined at the thermal zone, I plan to incorporate an 
additional ThrmlZn:VentSrc specification of 'Natural' (currently the options 
are 'None' and 'Forced'). This is actually already addressed in in both the 
NACM and PRMRM (3.6.5.4 Ventilation Source), but CBECC currently doesn't 
support this as an option. Once added, at least in the near term, VentSrc = 
'Natural' is only with respect to not having forced ventilation, as opposed to 
using mechanical/non-mechanical strategies to "passively" cool a space; that 
will be dealt with separately in the future. If you want to have rule that 
prescribes different infiltration rates for zones with "Natural" ventilation, 
you could add that rule to this issue or create a new one.  Otherwise, 
infiltration will all be user-defined.

Does this work? 

Original comment by da...@360-analytics.com on 5 Dec 2014 at 1:35

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I'll also add an indicator at the Space whether it is an "Enclosed" space and 
default based on the 90.1 rules.

Original comment by da...@360-analytics.com on 5 Dec 2014 at 1:40

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I am not sure I understand all of the comment 6 response. You are right that if 
the space is insulated and conditioned (not in the 90. definition) it will not 
be close to ambient. However, I don't think it matters from a 90.1 perspective 
if the ventilation is mechanical or not. The parking garage will almost always 
be mechanically ventilated, but 90.1 is clear about it no being an enclosed 
space and by that virtue not requiring insulation. Since it is not an enclosed 
space the surfaces between it and any conditioned space (including semi-heated 
and indirectly conditioned) will need to be insulated. Maybe there need to be 
changes made to 90.1, there certainly were some members of the envelope 
subcommittee who thought there needed to be when we discussed this. But for 
now, I think we have to go with the 90.1 requirement especially since there 
were some long term members who say this was done purposely. 

Original comment by bikerose...@gmail.com on 5 Dec 2014 at 1:46

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Luke and I talked a bit more about this offline and brainstormed a few more 
common examples of UNCONDITIONED spaces that could or are likely to be 
naturally or mechanically ventilated. In all the examples, consider the spaces 
enclosed by surfaces with the exception of louvers or other openings in walls. 

Applying the exceptions for unconditioned, unenclosed spaces literally; i.e. 
limited only to crawlspaces, attics, and parking garages with natural or 
mechanical ventilation, these examples would be considered enclosed, and 
therefore the baseline envelope for the wall separating this space from 
conditioned space would need to meet the semi-exterior requirement.

Trashroom (typically on exterior of building or in parking garage) -> SpcFunc = 
"Storage"
Meter Rooms (typically on exterior of building or in parking garage) -> SpcFunc 
= "Electrical/Mechanical"
Stairwell (typically on exterior of building and/or in parking garage) -> 
SpcFunc = "Stairway"
Breezeway (typically on exterior of building) -> SpcFunc = "Corridor"
Enclosed Dining Porch (typically on exterior of building) -> SpcFunc = "Dining 
Area"

In these examples, it is the semi-exterior surface BETWEEN the unconditioned 
space and the conditioned space that would be included in fenestration area 
calculations, right?

Original comment by da...@360-analytics.com on 10 Dec 2014 at 1:37

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Assuming that those spaces are unconditioned, I agree that the surfaces 
separating them from conditioned spaces would be semi-exterior and considered 
in the fenestration area calculations for semi-exterior walls. 

Original comment by bikerose...@gmail.com on 10 Dec 2014 at 1:51

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From a thermal envelope and space conditioning system perspective, I don't 
understand the rationale for defining exceptions between the three "unenclosed" 
space types and the other examples in #11. That said, I'll leave it be. Summary 
of resolution to follow...

Original comment by da...@360-analytics.com on 10 Dec 2014 at 2:06

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Summary of resolution I think we reached on today's call:

1) Add two additional space functions (feel free to recommend alternate 
language):
   - "Attic or Crawlspace (Naturally or Mechanically Ventilated)"
   - "Attic or Crawlspace (Not Ventilated)"

2) Maintain the existence of the "Unoccupied-Include in Gross Floor Area" and 
"Unoccupied-Exclude from Gross Floor Area" in the SpaceFunction enumerated list.

3) The following space functions will always be defined as unenclosed spaces, 
and therfore be treated as being part of the exterior environment for the 
purposes of envelope and have no space conditioning requirements or baselines.
   - "Attic or Crawlspace (Naturally or Mechanically Ventilated)"
   - "Parking Garage - Garage Area"
Therefore, the following applies:
a) If these unenclosed spaces happen to have space conditioning or a mechanical 
ventilation system, the systems are assumed to be the same in both proposed and 
baseline model (unless other rules apply). 
b) The baseline envelope of IndirectlyConditioned, DirectlyConditioned or 
Plenum spaces adjacent to these unenclosed spaces would be exterior. 
Fenestration on these surfaces would be included in the fenestration area 
calculations for "exterior" surfaces.
c) The baseline envelope of IndirectlyConditioned, DirectlyConditioned, or 
Plenum space adjacent to any other "Unconditioned" enclosed space would be 
semi-exterior. Fenestration on these surfaces would be included in the 
fenestration area calculations for "semi-exterior" surfaces.

5) The following space functions will have 0 W/ft2 baseline SpaceBySpace 
lighting power allowance.
   - "Attic or Crawlspace (Naturally or Mechanically Ventilated)"
   - "Attic or Crawlspace (Not Ventilated)"
   - "Unoccupied-Include in Gross Floor Area"
   - "Unoccupied-Exclude from Gross Floor Area"

6) The following space functions will always be excluded from the floor area 
used to determine the baseline HVAC system.
   - "Attic or Crawlspace (Naturally or Mechanically Ventilated)"
   - "Attic or Crawlspace (Not Ventilated)"
   - "Parking Garage - Garage Area"
   - "Unoccupied-Exclude from Gross Floor Area"
   - Any space function that is defined as Spc:CondgType = "Unconditioned" or "Plenum"

Let me know if I missed anything for phase 1 or add comments for future 
reference

Original comment by da...@360-analytics.com on 10 Dec 2014 at 2:10

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That all makes sense to me. 

Original comment by bikerose...@gmail.com on 10 Dec 2014 at 2:16

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Thanks for reviewing. I thought should add one point already touched on in #3:

7) All other surfaces in the following spaces EXCEPT those that classified as 
"semi-exterior" or "exterior" by the rules above will be modeled "same as the 
proposed"
   - "Attic or Crawlspace (Naturally or Mechanically Ventilated)"
   - "Parking Garage - Garage Area"
   - Any space that is defined as Spc:CondgType = "Unconditioned"

Original comment by da...@360-analytics.com on 10 Dec 2014 at 2:33

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Agreed. 

Original comment by bikerose...@gmail.com on 10 Dec 2014 at 3:25