Forum discussion
NC-2009 EAp2: Minimum Energy Performance
Hi,
We are Energy modelling a project with 3 types of systems to heat water:
1.- Solar Collector
2.- Electrical Heat Pump
3.- Hot water Boiler - Gas
For the "BASELINE" model, should I model the Solar Collector?
or
Should I just consider it for the PROPOSED model because it´s going to reduce the energy consumption?
Thanks.
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Anthony Hardman
Building Performance AnalystThe Green Engineer
16 thumbs up
May 23, 2013 - 2:34 pm
You would model a gas hot water heater in the baseline and you'd model the proposed as designed.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
May 23, 2013 - 2:43 pm
A slight amendment to Anthony's suggestion - model the baseline for the heat pump as electric water heater and the baseline for the boiler as gas water heater.
The solar is all savings!
Marcio Alberto Casado Pereira
181 thumbs up
May 23, 2013 - 2:48 pm
Anthony,
We had the same question as Fabiano's a few days ago and we found in ASHRAE 90.1-2007, Appendix G, 11-Service Hot-Water Systems that:
"The service hot-water system in the baseline building shall use the same energy source as the corresponding system in the proposed design..."
So we concluded we had to model the solar water heating system in the baseline. I'm confused now...
Steven Beccia
Mechanical EngineerClark Nexsen
6 thumbs up
May 23, 2013 - 2:50 pm
Solar hot water is considered "on-site renewable energy" and should be modeled in the proposed only, as it is a savings. Report the savings in the appropriate section in the EAp2 template. you should be good to go!
Marina Andrade
Sustainability Consultancy ServicesCushman & Wakefield
17 thumbs up
May 23, 2013 - 2:54 pm
Thanks,
I am going considering the heat pump (electrical) and the boiler (gas) for the baseline.
The solar will be the savings for the Proposed then.
Anthony Hardman
Building Performance AnalystThe Green Engineer
16 thumbs up
May 23, 2013 - 3:04 pm
I can't find any LEED Interpretations on the subject, but I've always handled DHW systems similarly to HVAC system types. So for example, if the proposed building had a hybrid (gas/electric) HVAC system, you would use gas in the baseline. Similarly, if my proposed DHW system is a hybrid, I would use gas in the baseline. I agree that the user's manual doesn't really clarify this issue, so my guess is that either approach would be acceptable to GBCI.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
May 23, 2013 - 3:56 pm
The GBCI reviewer will follow the guidance in Table G3.1-11 Baseline that was quoted by Marcio above for the baseline service hot water (SHW) systems. "The service hot-water system in the baseline building shall use the same energy source as the corresponding system in the proposed design..." This language is pretty clear. SHW does not follow the same baseline guidance as the HVAC systems.
The solar hot water is addressed by the Exception to G2.4 which indicates that you use the back up source for the baseline when using an on-site renewable in the Proposed.
Anthony Hardman
Building Performance AnalystThe Green Engineer
16 thumbs up
May 23, 2013 - 4:04 pm
You're right, I started reading at bullet "a" which wasn't helpful.