[EnergyPlus_Support] Re: Time Set Point Not Met - Radiant Floor Heating System

["jeannieboef" <jeannieboef@xxxxxxxxx>]

Thanks, James. In my system it's not much, but when a window opens and the air temperature changes by 1.5 Kelvin, the Radiant Floor System just can't keep up because of it's huge thermal capacity. I don't have start up problems because the system is always on (actually read a study on this, which shows very small savings by ramping up and down overnight). Obviously, increasing the capacity of the system can only improve things by a negligable degree. The as designed system is also AS DESIGNED and thereby has this inherent property. It's not so much I'm taking about in any case. 1 Kelvin tolerance instead of 0.2 would probably cut it.

I've posted this question on some diverse blogs to see what people say and will keep you posted.

Thanks again for the input.

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "James V Dirkes II, PE" <jim@...> wrote:
>
> Dear Jeannie,
> 
>  
> 
> This criteria comes from ASHRAE 90.1 ,as you probably know.  ASHRAE 90.1
> does not define this value, although I think perhaps they should.  Since
> they do not, I suspect that it�s up to some interpretation.
> 
>  
> 
> Normally, my �unmet loads� are at startup periods and do not last for more
> than an hour or so.  In my opinion, this is not too important, since you can
> always start the system a bit earlier on the coldest or hottest days.  I
> suspect that ASHRAE�s underlying rationale for not having too many unmet
> load hours was that they did not want the system deliberately undersized.
> If you can justify that it�s not (deliberately undersized), you may be OK.
> 
>  
> 
> p.s., This is my opinion only.  I have not debated the issue on a LEED
> certification!
> 
>  
> 
> The Building Performance Team
> James V. Dirkes II, P.E., LEED AP
> 1631 Acacia Drive NW
> Grand Rapids, MI 49504
> 616 450 8653
> 
>  
> 
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of jeannieboef
> Sent: Wednesday, September 29, 2010 2:25 AM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] Time Set Point Not Met - Radiant Floor Heating
> System
> 
>  
> 
>   
> 
> Time Set Point Not Met Tolerance is 0.2�C ( ... DOE had specified a
> tolerance of +-0.5F for this...energyplus has a default of 0.2 degC). Am I
> justified in relaxing this tolerance on a system that obviously cannot
> respond to fast and so accurately to flux in room temperature? Increasing
> the "Capacity" of the system will not fix this.
> 
> Should I then relax the tolerance on the baseline heating system also?
>




------------------------------------

Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx

The primary EnergyPlus web site is found at:
http://www.energyplus.gov

The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/

Attachments are currently allowed but be mindful that not everyone has a high speed connection.  Limit attachments to small files.

EnergyPlus Documentation is searchable.  Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
Yahoo! Groups Links

<*> To visit your group on the web, go to:
    http://groups.yahoo.com/group/EnergyPlus_Support/

<*> Your email settings:
    Individual Email | Traditional

<*> To change settings online go to:
    http://groups.yahoo.com/group/EnergyPlus_Support/join
    (Yahoo! ID required)

<*> To change settings via email:
    EnergyPlus_Support-digest@xxxxxxxxxxxxxxx 
    EnergyPlus_Support-fullfeatured@xxxxxxxxxxxxxxx

<*> To unsubscribe from this group, send an email to:
    EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx

<*> Your use of Yahoo! Groups is subject to:
    http://docs.yahoo.com/info/terms/