[Bldg-sim] 90.1 and infiltration/air-tightness?

[Karen Walkerman]

I believe RESNET allows for credit for infiltration reduction below 0.35 ACH
for confirmed construction (blower door tested).

In my opinion, leaving out infiltration is a major fault of ASHRAE 90.1 and
Appendix G (and LEED).  Reducing infiltration through good building
techniques and attention to detail can have an enormous impact on building
energy use.  Yes, the building must be tested in order to receive credit,
but infiltration needs to be brought to the attention for designers and
owners.  Also, ensuring that the air barrier is OUTSIDE the insulation (not
the interior sheetrock) is essential to ensuring the performance of the
insulation.

I recently completed an evaluation for an existing historic building about
to undergo renovations.  The biggest single potential energy saver?
Infiltration reduction.  Will we get LEED credit for this?  No.

~karen~

On Feb 13, 2008 11:17 AM, Michael Tillou <michael.tillou at gmail.com> wrote:

> Nick,
>
> ASHRAE 90.1 doesn't allow any credit for infiltration savings for
> commercial
> buildings and doesn't have any specific guidance about an allowable air
> tightness value.  When using Appendix G or Chapter 11 ECB you need to keep
> infiltration the same in both the proposed design and the energy budget.
>
> The IECC and RESNET HERS offer a method for infiltration savings in
> Low-Rise/Single Family Residential.  I believe both methods allow a
> minimum
> as-designed infiltration of ACH = 0.35.  The baseline uses weather factors
> from ASHRAE 136 and a Normalized Leakage value of 0.57.  The IECC also
> requires a post-construction blower door test to verify the savings.
>
> You could probably propose an exception calculation for infiltration
> credit
> if it followed the IECC residential method and the proposed building was a
> small building with simple systems.  I certianly don't think it would be
> applicable for a large multi-story building with complex systems.   I
> think
> that you would also need to be able to demonstrate the as-built (post
> construction) infiltration rate, through blower door testing or other
> appropriate means, as part of proposed exception calculation.
>
> Best regards,
>
> Mike
>
>
>
> -----Original Message-----
> From: bldg-sim-bounces at lists.onebuilding.org
> [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Nick Doylend
> Sent: Tuesday, February 12, 2008 3:58 PM
> To: bldg-sim at lists.onebuilding.org
> Subject: [Bldg-sim] 90.1 and infiltration/air-tightness?
>
> Hi, I'm wondering if 90.1 makes any stipulations regarding building air
> infiltration, for example can there be a difference between proposed
> design
> and energy budget building?  I can't seem to find any reference to facade
> air tightness but the standard is a pretty dense document to wade though.
> Is there a more easily digested summary available anywhere?
>
> Thanks,
>
> Nick
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