Re: [EnergyPlus_Support] Re: Comparable Comfort

[Rick Strand <rkstrand@xxxxxxxx>]

Rory:

Your question is an interesting one.  I have done similar work in the past 
using IBLAST (a predecessor of EnergyPlus) in that I was trying to achieve 
equal comfort for both a radiant and a forced air system.  Due to the 
distinct differences between these two system types, there are different 
thermostatic settings that are required to maintain the same level of 
comfort.  I ended up doing the "brute force" method that you 
discussed--varying thermostatic settings in different input files to 
achieve similar levels of comfort between the two system types.  This is 
certainly a possibility for your study, but as you point out, this is 
fairly time consuming.  I was not able to find any other alternatives at 
the time and thus don't have any better suggestions to offer.

To answer your other questions, it is fairly likely that you should see 
"effective temperature" controls in EnergyPlus within the next year.  The 
effective temperature is simply defined as some user specified combination 
of mean air temperature and mean radiant temperature such as ET = (x)(MAT) 
+ (1-x)(MRT) where x is defined by the user.  Such controls would allow you 
to come close to achieving equal comfort for various cases by factoring in 
both radiant and convective contributions to thermal comfort.  The radiant 
systems in EnergyPlus already allow some alternate controlling schemes 
(x=0, X=0.5, and x=1.0 in the above equation).

Regarding whether it is possible to control the building to PMV=0, this is 
not something that is planned for EnergyPlus and there are not any 
buildings I am familiar with that even try to implement such a control 
scheme.  In theory, all buildings should achieve acceptable PMV levels but 
thermostatic settings are usually based on achieving a particular air 
temperature.

This information probably does not help your situation, but I hope that it 
at least sheds some light on what is possible and what has been done in the 
past.

Rick Strand
EnergyPlus Development Team Member


At 10:07 AM 12/14/2005, you wrote:

>Hello
>
>I am an enginnering masters student in University College Dublin.
>I am about to start a series of simulation studies relating to
>thermal mass in office buildings.
>
>I am hoping to asses the energy perormance of a naturally ventilated
>office building as a function of different construction types (of
>increasing weight). Each construction will have the same U-value.
>
>In order to properly rank the annual energy perfomance provided by
>the different constructions I feel that I should try and normalise
>out the comfort conditions experienced in each case. ie. I would
>like each building to be equally comfortable before comparing the
>buildings associated energy perfomance.I will probably measure
>annual comfort using a PMV or PPD index, (possibly "PMVhrs Too Hot"
>and "PMVhrs Too Cold").
>
>At the moment I am looking at winter time heating perfomance, and as
>expected the "PMVhrs Too Cold" is increasing with increasing thermal
>mass, mainly as a function of the low radiant temperatures which are
>experienced following a period of night-setback. I can normalise
>for "PMVhrs Too Cold" by manually using different dry bulb
>temperature setpoints prior to simulation, untill comparable heating
>comfort results are produced, but this is taking a long time.
>
>Does anybody know if there is a better way to do this?
>
>Can radiant temperature setpoints be used instead of dry-bulb
>temperature setpoints in E-plus?
>
>Or would it even be possible to control a buildings heating system
>so that a PMV of zero is always acheived?
>
>I would be interested to know if this would be technically possible
>and if anybody has tried to do something similar in the past.
>
>Best Wishes
>
>Rory Walsh
>Energy Research Group
>University College Dublin
>
>
>
>
>
>
>
>
>
>
>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 not allowed -- please post any files to the appropriate 
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>
>EnergyPlus Documentation is searchable.  Open EPlusMainMenu.idf and press 
>the "search" button.
>
>Yahoo! Groups Links
>
>
>
>



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