Hello all,
I'm working on an 150,000 sf indoor practice facility with 90 ft
ceilings. Does anyone have any suggestions/tips/heads-up comments that
would be useful in starting this model?
Specifically, I'm wondering if I'll run into issues related to
stratification and need to create 'sub-zones' so eQuest better
represents the proposed distribution system.
Thank you for your time and combined insight,
*Matthew Hein*, P.E.
No direct answers, but I would plan on a long discussion with the HVAC designers to arrive at a mutual understanding of the "conditioned volume" and loads incident on that volume to be addressed by the systems. Approaching this as thermally-connected conditioned/unconditioned zones matching those design parameters makes sense procedurally from an eQuest standpoint.
Time permitting, running an early "test" model to ensure the results agree/ballpark with the designer's calculations would be a good idea as well to nail down the nuts & bolts of your modeling procedure before crunch time (Keeping good notes & written communication will also be helpful later for model documentation).
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NICK CATON, P.E.
Thanks David and Nick. Your advice is much appreciated.
- MRH
Has anyone been able to capture savings from a natural ventilation
design for LEED 2009 NC? (I interpret that G3.1.1.b prevents this.)
Glancing over Appendix G I see something that doesn't seem very
encouraging of 'green' design: (not to say that it discourages)
* G3.1.1.b says, "All conditioned spaces in the proposed design shall
be simulated as being both heated and cooled even if no heating or
cooling system is to be installed ..."
It seems like there should be some way to encourage natural ventilation
design by accounting for the energy savings.
I suspect I'll approach this by setting a high Tstat value (100 F) and
using the exact same cooling configuration for proposed and baseline so
the savings are null. Well, maybe I can get some fan power savings.
- MRH
Matt,
There is an addendum to 90.1 that adds heating-only systems 10 and 11. It's addendum dn. You might check it out, but I'm not sure that your space really fits into that addendum, and I don't think it helps you. When using that addendum, you model no cooling at all in either case. In reality, in the proposed building, you are getting some free cooling from natural ventilation.
I have an idea that's complicated but maybe other people have a simplified method that will accomplish something similar. If you were going to accurately demonstrate what you're saving over the baseline, you need to figure out how much energy your baseline system would use to do what the free cooling with natural ventilation is doing in the proposed model. Maybe you could figure out the space temperature you can achieve for each hour that you're using natural ventilation for free cooling. Then, you could set up a space setpoint schedule in your baseline that would match those temperatures. The mechanical cooling system in your baseline model would cool to those same temperatures. Does that sound crazy?
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Stormy L. Shanks, PE
I don't think this prevents you from taking credit for natural ventilation. It doesn't say you must provide fans, pumps, diffusers, etc. You CAN heat and cool with an open window after all - although cooling is the far more common application of natural ventilation. :)
What you would need is a way to model space temperature and control the windows (plus any other devices to mechanically condition the space when conditions weren't favourable for natural ventilation) to maintain the comfort range. There are tools that allow you to control windows and HVAC systems in this manner - based on space temperature, CO2 level, humidity, etc. So assuming your space type and climate are good fits for this strategy - you can apply the appropriate software and control "sequences" to model a system in accordance with Appendix G - and account for wind speed, wind direction, temperatures, moisture, etc. in a fully dynamic fashion.
While I've never attempted to use eQuest for this, I have taken this approach successfully with tools that are intended to model these types of systems.
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Nathan Kegel