[BLDG-SIM] ERV (Energy recovery ventilation) simulation in eQuest

[Brandon Nichols]

Lan,
 
As JL suggests, if yours is a hot and humid climate, you may have better results using a heat wheel (enthalpy wheel) with total enthalpy recovery.  Sensible-only as shown in my example is economical in relatively low humidity, cool-summer climates that don't provide much summertime heat recovery opportunity.  
 
So for your project, calculate the theoretical summertime opportunity value before attempting troubleshooting with eQuest:

*	
	What are the estimated flow rates of the outdoor and exhaust airstreams?
*	
	What are the outdoor air expected summer average conditions in terms of temperature and humidity (i.e. enthalpy)?  
*	
	What is the expected temperature and humidity of the exhaust airstream? 

	*	
		The exhaust airstream in general occupancy applications can be estimated at about 85¡ãF and 35% relative humidity, corresponding to the absolute moisture content at 55¡ãF saturation temperature from a typical cooling coil, plus 2% for people and processes.  

*	
	Now the opportunity value of summertime heat recovery may be estimated:

	*	
		Calculate the enthalpy difference between the outdoor summer average and the estimated exhaust airstream, and multiply by the ratio of the exhaust/OSA flow rates. 

Without significant differential enthalpy between outdoor ambient average and the exhaust airstream, there simply may not be much summertime heat recovery opportunity.
 
Hope that helps...
 
 
Brandon Nichols, PE, LEED(r) AP
Mechanical
HARGIS ENGINEERS

600 Stewart Street

Suite 1000

Seattle, WA 98101

www.hargis.biz

 

d | 206.436.0400  c | 206.228.8707

o | 206.448.3376  f  | 206.448.4450

 
 

  _____  

From: Lan Hu [mailto:hulan199 at yahoo.com] 
Sent: Friday, August 31, 2007 8:54 AM
To: Brandon Nichols
Subject: Re: [BLDG-SIM] ERV (Energy recovery ventilation) simulation in eQuest


Thank you very much, Brandon. After I tried used DT/DH control with rang from 5-30, I still didn't get any saving on the cooling side - the ERV sim report still show heating energy used during summer. Any more suggestion?

Brandon Nichols <BrandonN at Hargis.biz> wrote: 

	Lan, see this post...
	 
	http://elcca-exchange.blogspot.com/2007/04/equest-parametric-sensible-heat.html
	 
	Here's an excerpt:
	 
	$ FLOAT gives maximum heat recovery but recovers even unwanted heat, so
	$ use this setting for temperature control
	ERV-TEMP-CTRL = MIXED-AIR-RESET
	 
	Also, the ÄT between exhaust and OSA is typically not great, even if its 110°F outside and your exhaust/relief is 85°F, the ÄT is only 25°F -- compare that to even a mild winter condition of 35°F, where the ÄT is double at equivalent exhaust temperature (i.e 85 - 35 = 50°F).
	 
	Regards
	 
	
	Brandon Nichols, PE, LEED(r) AP
	Mechanical
	HARGIS ENGINEERS
	600 Stewart Street
	Suite 1000
	Seattle, WA 98101
	www.hargis.biz
	 
	d | 206.436.0400  c | 206.228.8707
	o | 206.448.3376  f  | 206.448.4450
	 
	 

  _____  

	From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Lan Hu
	Sent: Thursday, August 30, 2007 1:54 PM
	To: BLDG-SIM at gard.com
	Subject: [BLDG-SIM] ERV (Energy recovery ventilation) simulation in eQuest
	
	
	Hi, all,
	 
	I have problem simulating ERV in eQUSET. In the program I specified ERV effectiveness around 72%, the results show 64% energy saving in heating but just 5% saving in cooling, even when I cut off all the fan tempetrature increase. Anyone has experience or suggestion?. Thank you very much.
	 
	Lan
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