[Bldg-sim] 90.1 Appendix G: Daylight Utilization

Shariq_Ali at URSCorp.com Shariq_Ali at URSCorp.com
Tue Jun 30 13:11:28 PDT 2009




Jonathan, welcome to our world. To shed some light on the issue - this is a
"gray" area that is often taken advantage of when conducting energy
analysis. Looking at the IES handbook some lighting levels for particular
rooms range from 50 to 100 fc. This seems ridiculous but lighting is
perceived. It is not a hard science, factors like interior colors, occupant
age and health (glasses ? no classes), etc all contribute to what is an
appropriate lighting level. When conducting an energy analysis engineers
need to be reasonable and set parameters for their buildings that are
within the IES range and correct for their space's use. The engineer should
also have an idea of the interior colors, reflectances, demographic of the
occupants to be using the space, know if shading will be a factor in the
facility (internal or external) etc..

If I know a space will be brightly light (because I asked the electrical
engineer on the project) I'll use the higher level. If I know they will
have task lights, I'll use a lower level. If the space has some task lights
and I am not certain of parameters, I'll use a median value. I'm sure there
are engineers that are conservative and use the upper extreme, and others
that are very loose and want to earn more energy credit and thus will use
the lower extreme. A good rule of thumb when designing parameters for the
programs we use would be give us options. Maybe call them "loose" "median"
and "conservative" and give us a list of all the room types in the IES
handbook. I use Trane Trace  and Revit, not Bentley but with Trace I wish
they had built in templates from IES, from ASHRAE, and from the AIA, for
lighting, for airflow, templates, outdoor air, etc.. it would make
conducting energy analysis a lot faster. Because this was not done by trace
or Revit, we've had to build them our selves as we work on projects. If a
software package designed for the US market had these built in (and were
accurate) it would be a huge selling point. The amount of time it takes to
build in a standards library is substantial. Trane has jumped on board
recently and released ASHRAE 90.1 equipment that meets the baseline
standard, however it does not have room templates or lighting level
templates there yet.

A question - does your energy analysis software interface with GBXML? We're
in the market for new - more accurate - software. Specifically Trace does
not do a building level air balance, and when you are using total energy
wheels your going to either over shoot or under shoot your energy savings.
This is a substantial deficiency when your building has 12+ air handlers
and is located in a very hot humid climate.

Good luck.
-Shariq



                                                                              
 This e-mail and any attachments contain URS Corporation confidential         
 information that may be proprietary or privileged. If you receive this       
 message in error or are not the intended recipient, you should not retain,   
 distribute, disclose or use any of this information and you should destroy   
 the e-mail and any attachments or copies.                                    
                                                                              



-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org/attachments/20090630/d76570a0/attachment-0002.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: C4024246.jpg
Type: image/jpeg
Size: 59935 bytes
Desc: not available
URL: <http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org/attachments/20090630/d76570a0/attachment-0002.jpg>


More information about the Bldg-sim mailing list