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Radiant Heating - Baseline?

asked 2016-02-16 22:18:34 -0600


I am curious to learn about others' approaches for handling baseline radiant heating AND cooling; when if comes time to build the baseline model. Whether this be radiant gas heating at an outdoor stadium or restaurant or a radiant slab for cool. While a several software can account for the energy usage in a proposed design, either directly or approximately; I haven't see and don't know of any guidance on how this should be reflected for baseline models. For example, California Energy Code and ASHRAE 90.1-2010 define conditioning of 'enclosed areas; but with radiant conditioning this isn't a requirement. It also has applications where forced air conditioned would be impractical. So, how are appropriate baseline systems created ?

As an extension to this, how has it been handled within your chosen software package? Thanks in advance for your thoughts.

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To fully understand the question, you are talking exclusively about OUTDOOR conditioning right?

Julien Marrec gravatar image Julien Marrec  ( 2016-02-17 01:15:22 -0600 )edit

It was vaguely both. For indoor, its more obvious & apparent what the baseline systems should/could be. Though, doing Radiant heating vs. forced air in a warehouse does feel a bit like apples and oranges.

But yes, am very curious about outdoor radiant as well.

dradair gravatar image dradair  ( 2016-02-17 07:33:05 -0600 )edit

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answered 2016-02-17 07:21:56 -0600

updated 2016-02-17 07:40:13 -0600

In my opinion, for 90.1-2010 appendix G, the baseline systems are created for each "thermal block" a term that is defined in the standard which references another defined term "zone, HVAC" which is about a "a space or group of spaces within a building..." so if your radiant system is not within the building than you cannot define a baseline system for it. For anything in a building model that does not have specific rules in Appendix G, the baseline and proposed models should be identical and so no credit or deduction should be made related to the radiant system not within the building. On the other hand, if the radiant system is within the building and used as all of or part of the conditioning for a thermal block, than the normal rules apply and one of the 10 baseline systems would be chosen which would replace the radiant system. Please note that this is just my opinion as an individual and is NOT an ASHRAE official interpretation.

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This is exactly the type of info/discussion I was hoping for. Very well put. This especially true with thermal block > Zone > space > 'within building'. I agree with this line of logic for ASHRAE Appendix G.

For an ECB/Chapter 11 model though, I can see arguments to include/exclude exterior radiant. The inclusion is that it uses energy and would follow the Apdx G logic above. Though, exterior lighting is excluded [per the UserManual], and Part 13 of Table 11.3.1 exception A might provide just cause to exclude exterior radiant as well.

dradair gravatar image dradair  ( 2016-02-17 07:49:19 -0600 )edit

Now, for California/CBECC-com, it could also be a bit tricky....because it has many similar definitions to the ASHRAE, but the breakdown, especially for exterior radiant, it that it uses the word 'enclosed'. Maybe this isn't an issue at all since, from what I can tell, Radiant Systems cant be included natively. If done by exception calculation, how would the baseline be adjusted [as I don't think it can be per CA code]....any one have any insight?

dradair gravatar image dradair  ( 2016-02-17 07:51:48 -0600 )edit

For CA Code compliance, my (unofficial) interpretation is:

  • For Exterior Systems: this would be considered a process load and therefore it is not required to be modeled. If there is a boiler or other system used to generate HW for the radiant loop, that system would still need to comply with any mandatory or prescriptive requirements
  • For Interior Systems: radiant systems are not natively supported, so if you were to do an exceptional calculation, it would only impact the Proposed Design. The Baseline would still use the ACM system map to define its HVAC system.
Dimitri C gravatar image Dimitri C  ( 2016-02-19 12:05:13 -0600 )edit

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Asked: 2016-02-16 22:18:34 -0600

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Last updated: Feb 17 '16