[EnergyPlus_Support] Re: air infiltration questions

["jeannieboef" <jeannieboef@xxxxxxxxx>]

In Germany the average infiltration rate for homes is 0.7 ach. But that's very statistical. you could try run a calculated natural ventilation simulation to see what you get to improve your guess. I believe below 0.3 is pretty good for air tightness (is that a real word?). Otherwise, AM10 is a pretty good guide.

Good luck.
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, <brownstonehomes@...> wrote:
>
> ASHRAE 62.2 2007 requires homes have supplemental fresh air ventilation.
> The number of bedrooms plus 1 = occupants.  The number of occupants X 7.5
> CFM, plus 1% of the area.  A 4 bedroom home with 1350 sq ft. would require
> (5 X 7.5 CFM)+ (1% of 1350)  = 37.5 + 13.5 or 51 CFM.  This is not supposed
> to include infiltration.  The bathroom &  kitchen exhausts must also vent to
> the outdoors.  
> 
>  
> 
> I love runtime vents as a builder in a hot & humid climate.  Because it
> helps prevent negative pressure, air goes through the filter & the coils and
> then is distributed through to the ducts.  The Builder's Challenge program
> requires this ASHRAE 62.2 ventilation before awarding the certification of
> Energy Smart with new homes.  First healthy, durable, and then energy
> efficient.  
> 
>  
> 
> Why don't more Mechanical Engineers provide ACCA manual J & D calcs.  Sizing
> is so important in thermal comfort and efficiency.
> 
>  
> 
>  
> 
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Edward G. Lyon
> Sent: Monday, March 08, 2010 10:28 AM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: RE: [EnergyPlus_Support] air infiltration questions
> 
>  
> 
>   
> 
> Very tight houses often have problems with indoor air quality and may have
> ACH .1 or less.  General US practice targets about .35 ACH as adequate for
> ventilation without any other provisions, but you should consider your
> volume to occupancy ratio and recommended minimum ventilation per occupant.
> This is a application that typically requires a dedicated ventilation
> design.
> 
>  
> 
> Ned Lyon, P.E. (MA)
> Staff Consultant 
> 
> SIMPSON GUMPERTZ & HEGER 
> 781.907.9000 main
> 781.907.9350 direct  
> 781.907.9009 fax
> www.sgh.com
> 
>   
> 
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of ylinenergy
> Sent: Monday, March 08, 2010 9:06 AM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] air infiltration questions
> 
>  
> 
>   
> 
> Hello,
> 
> I wonder if anyone can help me with my Energy+ model. 
> 
> I modelled a small low energy bungalow house in the UK climate with floor
> area around 100m2. The building fabric has very high performance (U value
> <0.13). There are totally three zones in the model. I put ideal loads system
> in the model, and the setpoints for heating is 19C. The results I got it
> much higher than I expected. It is around 350kwh/m2 for heating loads. I
> think I must have done something wrong in the model. 
> 
> I put 0.25ac/h as design flow rate in the Zone infiltration section. I
> assumed 0.25ac/h is reasonable value for an air tight house. However, if I
> changed the figure to 0.5, the heating loads jumped to 780kwh/m2. If I
> changed the figure to 0, the heating loads is just 26kwh/m2. Can anyone
> suggest the reasonable ac/h value for a well air tight house? I assumed the
> input figures in Design Flow rate here is the infiltration rate through air
> leakage and not consider the natural ventilation. Is that right?
> 
> I did free running the model, and the average indoor temperature is about
> 10C, more less the right value, I think. 
> 
> Can anybody suggest what might be wrong here? 
> 
> Many thanks in advance.
> 
> Best Regards,
> Yuan
>




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