[Bldg-sim] Unexpected heating results and envelope sensitivity.

Zabaneh, Christopher czabaneh at halsall.com
Wed Aug 1 12:54:51 PDT 2012

Hi all - we're encountering unexpected heating results and envelope sensitivity in our model of a typical Core & Shell office building in Montreal, Canada (ASHRAE Climate Zone 6A).

The building is modeled as fan powered underfloor air distribution from compartmental units fed by makeup air units on the roof. The heating plant has a modulating boiler, HRV, and the envelope has 53% WWR. We're using EE4 (DOE2.1E) vs the MNECB code. The proposed building has a worse envelope than the auto-generated baseline case.

Out two questions:

1.       We think our heating savings are lower than expected (only 10% savings) while are cooling/fans/pumps savings are as expected (60%-80% savings) vs the MNECB baseline case.

2.       We don't understand why reducing the envelope performance has a greater than expected impact on our overall savings (15% worse). Given our experience with similar eQuest models in similar climate zones, we would expect similar envelope performance reduction to have only an overall performance impact of around 3%.

To give a reasonable code comparison, LEED NC 2009 give EAc1 points for between 12% and 48% savings vs ASHRAE 90.1-2007 and 25% to 56% savings vs the MNECB.

I would appreciate your insight as to why the model may be performing as such. I can provide more information if it would help.

Thanks kindly,

Christopher Zabaneh, P.E., LEED AP BD+C, CEPE
Halsall Associates
Tel: 416.644.0416 * Toll Free: 1.888.425.7255 ext. 258* www.halsall.com<http://www.halsall.com/>
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