[Bldg-sim] Modelling for retrofit ECM's

Jeff Haberl jhaberl at tamu.edu
Fri Feb 11 11:43:34 PST 2011


Chris. 

I'm a little old fashion. I mainly have used DOE2.1e for 25+ years and taught it for 20+ years. Recently, I've begun to use and teach EQUEST and am familiar with TRNSYS, BLAST  and EnergyPlus, and have use other very old programs like SERIRES, PASOLE, DEROB, FCHART, PVFCHART, some home-rolled FD programs, and others I've forgotten. 

When I teach students about interior walls I always preface the discussion with the question: what is the wall doing? Is it separating two zones at the same temperature? Is there daylighting? Direct gsain?...if not, then it probably contributes little to the heat transfer. 

The exception to this is if it is thermally massive, then it may be acting to dampen loads if the "connection" is strong, I.e., if the combined convection/radiation coefficient has a small resistance and large area (Manke and Hittle talked about this in their paper, and Janet covered it more in her thesis). 

So, if the wall is separating two zones with different temperatures then it plays a stronger role in the zone heat transfer. 

Most programs combine convection and radiation heat transfer into one coefficient. Some have bouyancy in this coefficient, most don't. 

Use of interior walls is more important for simulations considering daylighting, so care needs to be taken to get the surface characteristics and orientation right. 
An airwall itself is just a massless resister between two space temperature nodes, often which is determined, ad hoc, by the user. 

There are cases where interior walls count in thermal simulation, such as passive solar, direct gain, etc. However, the physics of the real passive solar room is probably not well represented by such a simplistic representation in DOE-2, and would be better served by a special purpose program. 

So, a long story short is that I would consider interior walls as a second order effect for buildings with zones all at the same temperature. So simple is better. This allows you to spend your time on the windows, systems, orientation, shading and other things that are first order parameters. 

Hope this helps. 

Jeff

BB 8=!  8=)  :=)  8=)  ;=)  8=)  8=(  8=)  :=')  8=)  8=)  8=? BB

Jeff S. Haberl, Ph.D., P.E., FASHRAE...................jhaberl at tamu.edu

Professor......................................................Office Ph: 979-845-6507

Department of Architecture.......................Lab Ph: 979-845-6065 

Energy Systems Laboratory.......................FAX: 979-862-2457 

Texas A&M University..............................77843-3581

College Station, Texas, USA.......................URL: www-esl.tamu.edu

BB 8=/  8=)  :=)  8=)  ;=)  8=)  8=()  8=) 8=?  8=)  8=)  8= BB
 

----- Original Message -----
From: Chris Yates [mailto:chris.malcolm.yates at gmail.com]
To: Jeff Haberl
Cc: Carol Gardner <cmg750 at gmail.com>; R B <slv3sat at gmail.com>; bldg-sim at lists.onebuilding.org <bldg-sim at lists.onebuilding.org>
Sent: Tue Feb 08 02:24:26 2011
Subject: Re: [Bldg-sim] Modelling for retrofit ECM's

Dear Jeff,



You mention the use of "Real walls or air walls" between zones in your post. I feel this raises a question on this list that I've already enquired on this list. I apologise for raising the issue once more, however I did not feel that the discussion resulted in a clear conclusion of how various simulation programs may treat "Air walls" or "virtual partitions".



I hope you don't mind me asking: 


*	what programs do you use mainly?
*	under normal modelling practice, how would these programs treat "air walls" with respect to:

	*	 Conduction
	*	Long-wave radiation
	*	Short-wave radiation
	*	Air flow

Many thanks

Chris 


 

On 05/02/2011 22:04, Jeff Haberl wrote: 

	ALSO: 

	 

	 

	Here are a few papers that shed light on the ELF/OLF proxy method and other findings, somewhat dated but useful:

	 

	 Haberl, J., Komor, P. 1990. “Improving Commercial Building Energy Audits: How Daily and Hourly Consumption Data Can Help,” ASHRAE Journal, Vol. 32, No. 9, pp. 26 - 36 (September). 

	 

	 Haberl, J., Komor, P. 1990. “Improving Commercial Building Energy Audits: How Annual and Monthly Consumption Data Can Help,” ASHRAE Journal, Vol. 32, No. 8, pp. 26 - 33 (August).

	 

	Haberl, J., Komor, P. 1989. “Status Report on Methods for Using Hourly, Daily and Monthly Data to Provide Useful Information on Building Energy Use,” submitted to the New Jersey Energy Conservation Lab, Center for Energy and Environmental Studies at Princeton University, Princeton, New Jersey (May).

	 

	Haberl, J., Komor, P. 1989. “Investigating An Analytical Basis for Improving Commercial Building Energy Audits: Early Results from a New Jersey Mall,” Thermal Performance of the Exterior Envelopes of Buildings IV, ASHRAE, Atlanta, Georgia, pp. 302 - 331 (December). 

	 

	Haberl, J., Komor, P., Haberl, J. 1989. “Investigating An Analytical Basis for Improving Commercial Building Energy Audits: Results from a New Jersey Mall,” Center for Energy and Environmental Studies Report No. 264 (June).

	 

		________________________________

		From: bldg-sim-bounces at lists.onebuilding.org [bldg-sim-bounces at lists.onebuilding.org] on behalf of Jeff Haberl [jhaberl at tamu.edu]
	Sent: Saturday, February 05, 2011 3:44 PM
	To: Carol Gardner; R B
	Cc: bldg-sim at lists.onebuilding.org
	Subject: Re: [Bldg-sim] Modelling for retrofit ECM's
	
	

	Rohini,

	 

	Zoning a building is still an art form. There are very few papers that have looked into this with any rigor. 

	 

	In one thesis we did on the Zachry building, which was the basis for the Predictor Shootout I and II, we looked at 1, 2, 5 and actual zoning on the building. What we saw was that, in general, the centroid of the "cloud" of data points remained about the same. However, the scatter in the cloud became more  pronounced at we added more zones.

	 

	So, if all the zones in the floor are being operated the same, I'd use 1, 2 or 5 zones per floor, depending on the functions of what's going on in each zone. Real walls or air walls between the zones usually get the job done.

	 

	The quickest way to get the light and receptacle loads on a real building is using "blink" tests, which can be done on a Saturday, with walkie talkies, and a data logger on the whole-building electric feed, possibly some sub feeds. I first heard of this test from Todd Taylor at PNNL. We've used it to help resolved motor loads, lighting loads, receptacles, etc. Seems to work pretty well. 

	 

	There are also several ways to get the plug loads, including: by proxy, by weather-day-type profiles, by daily readings, and a method that uses an energy balance. The proxy methods can use square proxies for for the occupancy based on OLF/ELF ratios, the weather-day-type method was something that I heard about from Don Hadley at PNNL, later adopted by Bou Saada on the Forrestal building and daycare center. The daily readings are just that, read the main meter by eye, daily, especially during weather independent times. The energy balance method is documented in papers by Claridge et al. at the ESL.

	 

	There is also some encouraging work being done by Abushakra and Reddy on ASHRAE RP 1404, now in progress and scheduled for completion later this year. This is based on previous work by Abushakra for his Ph.D. thesis.

	 

	Hope this helps.

	 

	Jeff

	 

	PS: here are some helpful papers:

	 

	Song, S., Haberl, J. 2008. “A Procedure for the Performance Evaluation of a New Commercial Building: Part I – Calibrated As-built Simulation”,  ASHRAE Transactions-Research, Vol. 114, Pt. 2, pp. 375-388 (June ). 

	 

	Song, S., Haberl, J. 2008. “A Procedure for the Performance Evaluation of a New Commercial Building: Part II – Overall Methodology and Comparison of Results”,  ASHRAE Transactions-Research, Vol. 114, Pt. 2, pp. 389 – 403 (June).

	 

	Claridge, D., Abushakra, B., Haberl, J. 2003. “Electricity Diversity Profiles for Energy Simulation of Office Buildings (1093-RP),” ASHRAE Transactions-Research, Vol. 110, Pt. 1 (February), pp. 365-377.

	 

	Haberl, J., Bou-Saada, T. 1998. “Procedures for Calibrating Hourly Simulation Models to Measured Building Energy and Environmental Data,” ASME Journal of Solar Energy Engineering, Vol. 120, pp. 193 - 204 (August). 

	 

	Haberl, J., Bronson, D., O'Neal, D. 1995. “An Evaluation of the Impact of Using Measured Weather Data Versus TMY Weather Data in a DOE-2 Simulation of an Existing Building in Central Texas,” ASHRAE Transactions-Research, Vol. 101, Pt.. 2, pp. 558 - 576 (June). 

	 

	Haberl, J., Bronson, D., Hinchey, S., O'Neal, D. 1993. “Graphical Tools to help Calibrate the DOE-2 Simulation Program to Non-weather Dependent Measured Loads,” ASHRAE Journal, Vol. 35, No. 1, pp. 27 - 32 (January).

	 

	Haberl, J., MacDonald, M., Eden, A. 1988. “An Overview of 3-D Graphical Analysis Using DOE-2 Hourly Simulation Data,” ASHRAE Transactions-Research, Vol. 94, Pt. 1, pp. 212 - 227 (January). 

	 

	Kim, K., Haberl, J. 2010. “Development of a Calibration Methodology for Code-Complaint Simulation With Results From Using a Case-Study House in a Hot and Humid Climate”,  Proceedings of the 17th  Symposium on Improving Building Systems in Hot and Humid Climates, Texas A&M University, Austin, Texas, accepted for publication (May).

	 

	Bronson, D., Hinchey, S., Haberl, J., O'Neal, D. 1992. “A Procedure for Calibrating the DOE-2 Simulation Program to Non-Weather Dependent Loads,” ASHRAE Transactions-Research, Vol. 98, Pt. 1, pp. 636 - 652 (January).

	 

	 

	8=!  8=)  :=)  8=)  ;=)  8=)  8=(  8=)  8=()  8=)  8=|  8=)  :=')  8=)8=?
	
	Jeff S. Haberl, Ph.D.,P.E., FASHRAE..............jhaberl at tamu.edu
	
	Professor............................................................Office Ph: 979-845-6507
	
	Department of Architecture.............................Lab Ph:979-845-6065
	
	Energy Systems Laboratory.............................FAX: 979-862-2457
	
	Texas A&M University.....................................77843-3581
	
	College Station, Texas, USA, 77843..................URL:www.esl.tamu.edu
	
	8=/  8=)  :=)  8=)  ;=)  8=)  8=()  8=)  :=)  8=)  8=!  8=)  8=? 8=)8=0
	
	________________________________

		From: bldg-sim-bounces at lists.onebuilding.org [bldg-sim-bounces at lists.onebuilding.org] on behalf of Carol Gardner [cmg750 at gmail.com]
	Sent: Saturday, February 05, 2011 12:59 PM
	To: R B
	Cc: bldg-sim at lists.onebuilding.org
	Subject: Re: [Bldg-sim] Modelling for retrofit ECM's
	
	
	Hi Rohini, 

	When you are bill matching there are not magical ways of doing things. You pretty much have to put what's in the building in your model. Those things you can control. The tricky part is to figure out how the building is really being operated and to get the most accurate weather data you can for your site.
	
	
	Cheers,
	
	
	Carol
	
	
	On Fri, Feb 4, 2011 at 8:34 AM, R B <slv3sat at gmail.com> wrote:
	


		Hi All, 
		While modelling existing building (with calibration to utility bill), do you model every VAV zone or lump similar ones together? What could be possible disadvantages of lumping down the road? Any ECM's that will be affected by this simplification?
		Is there a magical way to figure the W/sqft for lighting and plug loads without having to count everything on site? 
		Thanks for any insights.
		-Rohini

		_______________________________________________
		Bldg-sim mailing list
		http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org <http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org> 
		To unsubscribe from this mailing list send  a blank message to BLDG-SIM-UNSUBSCRIBE at ONEBUILDING.ORG <mailto:BLDG-SIM-UNSUBSCRIBE at ONEBUILDING.ORG> 
		
		




	-- 
	Carol Gardner PE
	
	
	
	_______________________________________________
	Bldg-sim mailing list
	http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org
	To unsubscribe from this mailing list send  a blank message to BLDG-SIM-UNSUBSCRIBE at ONEBUILDING.ORG
	


-- 


Chris Yates C Eng MCIBSE

Building Physics Consultant

Tel:   +447960731576

Email: chris.malcolm.yates at gmail.com

Skype: christopher.m.yates



More information about the Bldg-sim mailing list