[Bldg-sim] Negative pressure for EQ cr 5

[Karen Walkerman]

Obtaining a negative pressure difference also requires sealing the space.
 Door seals, and sealing walls.  If you exhaust 0.5 cfm/sf from a room with
chicken wire walls, you won't achieve any kind of measurable pressure
difference.

I usually steer clients away from this credit for this very reason
(difficulty coupled with measurability)

--
Karen

On Wed, Oct 6, 2010 at 3:36 PM, James V Dirkes II, PE <jvd2pe at tds.net>wrote:

>  Personal opinion:
>
> ·         5 Pa is difficult to (accurately) measure
>
> ·         1 Pa is impossible outside of a lab
>
>
>
> I don’t know what they were thinking when making these requirements, since
> they’re not too clear, but I suspect that if you demonstrate .5cfm / sq.ft.
> and no recirculation you’ll be OK.
>
>
>
>
>
> *The Building Performance Team
> **James V. Dirkes II, P.E., LEED AP
> *1631 Acacia Drive NW
> Grand Rapids, MI 49504
> 616 450 8653
>
>
>
> *From:* bldg-sim-bounces at lists.onebuilding.org [mailto:
> bldg-sim-bounces at lists.onebuilding.org] *On Behalf Of *Deepa
> *Sent:* Wednesday, October 06, 2010 2:59 PM
> *To:* Bldg-Sim
> *Subject:* [Bldg-sim] Negative pressure for EQ cr 5
>
>
>
> Hello all,
>
>
>
> One of the requirements for EQ Credit 5 is to prove that the areas such as
> the janitor's closet need to be negatively pressurized to a minimum
> of 5Pa when doors are closed and 1Pa when doors are open. Generally, in
> mechanical drawings, the cfm values are mentioned for exhaust fans.
>
>
>
> I wanted some insight as to how this pressure difference information can be
> obtained for both cases. Is there a straightforward calculation?
>
>
>
>
>
> Thanks,
>
> Deepa
>
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