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NC-v4 EAp2:Minimum energy performance

ASHRAE 90.1-2010 Mandatory Provision 6.4.3.3.3

Dear Everyone,

I am writting to enquire about ASHRAE 90.1-2010 Mandatory Provision 6.4.3.3.3 which regards to Optimum Start Controls. It states that heating&cooling air distribution systems shall have control algorithm. 

Typically air handling unit which terminal conditioning system is used in our country. 

My questions are:

1. Does that requirement regards to terminal unit system - fan coil where it may be hard to estimate capacity of 5000L/s or makeup air system, or only for fresh air (rooftop) system which is not our case.

2. I understand that algorithm should evaluate the warmup time based on actual temperature difference. So for each day for different actual indoor condition warmup time must be evaluated separately. Am I right?

3. Usually warmup time is set as fixed with fixed setback temperature. In that case this requirement is not meet, right?

Best Regards

2
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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
4454 thumbs up

Mon, 03/18/2019 - 19:51

1. This only applies to single pieces of equipment over 5000 l/s. 2. Yes each day. 3. Correct. A fixed schedule is not optimal start/stop.

Tue, 03/19/2019 - 09:05

Thanks Marcus, so in that case what about AHU which are not designed to heat spaces, but only to provide constant volume of fresh air with fixed temperature. Am I right that they can be excluded from this requirement? Best Regards
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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
4454 thumbs up

Tue, 03/19/2019 - 17:01

What you describe sounds like an a heating/cooling air distribution system to me. So no I do not think it can be excluded.

Wed, 03/20/2019 - 10:26

Thanks Marcus, This is Dedicated Outdoor Air System. AHU suppiles fresh air for ventilation purposes with supply temperature equals to room thermostat setpoint. That means AHU has no impact in heat balance in normal building operation. Warm up process is met by fan coil units. In that case is it heating/cooling air distribution system? 
Profile picture for user sheffer
Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
4454 thumbs up

Wed, 03/20/2019 - 13:00

Thanks for the more thorough explanation of the system.  We agree that 6.4.3.3.3 does not apply to this system. This system is required to be turned off prior to occupancy by another mandatory provision so optimum start/stop does not make any sense.

Thu, 03/21/2019 - 08:47

Thanks Marcus!  

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