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NC-2009 EAp2:Minimum Energy Performance

Baseline hot water generation

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Ciaran McCabe
Director
Passive Dynamics Sustainability Consultants
LEEDuser Basic Member
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The Design Preliminary Review has been completed on one of my projects and we have one query from EAp2 which appears unclear. It states that ‘heating equipment should be heat pumps in both Baseline and Proposed Case’. The building has been designed with heat pumps for heating and hot water generation. My query is; does the Baseline hot water generation need to be heat pumps? I have checked ASHRAE 90.1 Table 7.8 Performance Requirements for Water Heating Equipment and ‘electric water heater’ seems to be the only Baseline hot water heating equipment that I can select. Whether I use a heat pump or electric water heater for the Baseline has a big impact on energy consumption so would appreciate advice on this.

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Jean Marais
b.i.g. Bechtold DesignBuilder Expert
LEEDuser Basic Member
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Wed, 03/02/2016 - 12:09

2 things come to mind: - Your HVAC is not yet designed, in which case the HVAC for the two models is the same - Your system type for the baseline is System 1 because this is a residential (includes hotel) project (Table G3.1.1A)
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Ciaran McCabe
Director
Passive Dynamics Sustainability Consultants
LEEDuser Basic Member
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Wed, 03/02/2016 - 12:27

Hi Jean, thanks for your reply. Just to add further clarity the HVAC systems have been fully designed for this new building. We are using a heat pump for space heating and service hot water. Also the building type is a commercial motorway fuel / gas station. Based on this should the baseline hot water system use a heat pump OR electric water heater ? Many thanks in advance.
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Jean Marais
b.i.g. Bechtold DesignBuilder Expert
LEEDuser Basic Member
581 thumbs up

Wed, 03/02/2016 - 13:28

(correction to previous comment -- System 2 PTHP for Residential, as in your case your proposed case heating fuel type is "electric" HP) - If the predominant ft² is "motel" then it will count as residential. - if the project ft² < 2300 m² (SI) & Nonres. and the preposed case has electric HP then you're looking at System 4 -- PSZ-HP
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Ciaran McCabe
Director
Passive Dynamics Sustainability Consultants
LEEDuser Basic Member
12 thumbs up

Wed, 03/02/2016 - 15:22

So is it correct to say that the DHW / service hot water should be fueled via heat pump as per the proposed. I am just referring to the hot water element of the model and not the HVAC system. Could you clarify please.
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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
4454 thumbs up

Wed, 03/02/2016 - 16:10

Technically the baseline hot water system is a heat pump according to Table 7.8. However, the performance required for the "heat pump" is the same formula as for a small electric water heater. This is a bit confusing. The bottom line is that if you have a heat pump water heater in the proposed the baseline efficiency is calculated as if it was an electric resistance water heater. You should be able to claim the significant savings associated with a heat pump water heater.
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Ciaran McCabe
Director
Passive Dynamics Sustainability Consultants
LEEDuser Basic Member
12 thumbs up

Fri, 03/04/2016 - 17:39

Thanks all for your guidance above.

Thu, 01/09/2020 - 11:10

I have a great deal of involvement in these and here's my interpretation of it.  By and large the warmth siphon water radiators can undoubtedly slice your water warming bill down the middle and some of the time by as much as 75%. The key here is the way cool it gets in your general vicinity. The coldest these units will run is 20 degrees. After that they return into dinosaur mode. Ordinary electric tanks pull around 5000 kw's nevertheless some warmth siphon units pull as meager as 900 at this point.  Furthermore you can't have it depend on inside air. It should ALWAYS get outside air.  Rheem really makes an extremely decent 50 gallon model now with a COP rating of about 3.2 It highlights 6 inch associations so it tends to be ducted to the outside, and it even has a break sensor that will turn it off if the floor gets wet.  In the event that you think the temperature outside remains over 20 more often than not than that is the one I would introduce. --------------------

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