Forum discussion
NC-2009 EAp2: Minimum Energy Performance
This applies to cooling only type systems? That means if the proposed system can heat and cool and is in said climate zone, then this exception may not be applied. Right?
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Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
November 24, 2012 - 3:40 pm
If the system does both heating and cooling - I would say this exception can be applied. My logic is that it is still a cooling system. Certainly could be confusing - any other thoughts?
Jean Marais
b.i.g. Bechtold DesignBuilder Expert832 thumbs up
November 27, 2012 - 2:49 pm
kW savings from the heat recovery device is usually more in the heating case than in the cooling case, therefor my logic was that in milder climates where more focus floats to the cooling side, using heat recovery becomes less important. If your building was needing cooling facilities only, then the heat recovery device may fall away due to first costs and payback times. Current project is not using this exception because (although in the climate) it has both heating and cooling facilities. I err on the side of caution.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
November 28, 2012 - 9:59 am
We agree that your approach is conservative and cautious.
Check out the User's Manual as it provides some clarity (see page 6-81). If you have a combined system both must be exempt to apply the exception (only happens in CZ 3C) across the board. So in a combined system both exemptions d and e must apply to be exempt across the board. If only one exemption applies and the other does not then the exemption cannot be claimed. Note that a bypass is required in many cases so you should bypass in cooling mode if exemption e applies.
The milder climate zones on the list are marine so probably exempted due to humidity issues. The others are the colder climates.
Jean Marais
b.i.g. Bechtold DesignBuilder Expert832 thumbs up
November 29, 2012 - 5:35 am
Bypass is required for the heat recoverer an any event. We control the bypass per enthalpy both in cooling and heating modes.