Receptacle Energy

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I am trying to model a 2-story college going for LEED. The building
contains several differernt lab rooms which includes a lof of
equipment (Approximately 26W/ft^2 for half of the building). After running
the simulation, the preliminary report states that the annual TDV Energy Use
Summary for the entire building is 847.95 TDV-kBtu/sqft-yr with 684.71
towards the receptacle energy. Trying to get the minimum 14% energy cost
savings is almost impossible with this receptacle energy. What options do I
have to reduce the Receptacle Energy in order to meet criteria for LEED
points? Is there somewhere I can input this heat load so it does not have
such a great impact on the energy use summary report and still have an
accurate model of the building?
-Steven Rutter

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sounds like you're modeling the peak energy use of the equipment. If so,
you can develop a schedule, which has the equipment on at part load all days
except cooling design days. You'll need to do some research to figure out
what the appropriate part load is. If the building is complete, or if there
is a similar building currently in operation, I recommend obtaining
electricity use data, and monitoring a few sub-panels for a period of a few
days. In many labs, the high-energy equipment is not used at full load most
of the time.
--
Karen

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Joined: 2011-09-30
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Good advice, and I agree based on my own measurements of printers, computers, refrigerators, consumer electronics, etc.

The hard part is finding good data. I've had some luck (& fun) with a simple "Kill-A-Watt" plug power meter (available from Amazon for about $25). Over time I take measurements and get a good feel for what things use. For example, I recently measured a typical large office printer for about 600 hours and found the average watts to be about 75 though the nameplate was about 1100. That was interesting because I had no idea how much those used.

I would expect a similiar relationship for the lab equipment in that the average usage will be on the order of between 5 to 30% of nameplate power.

You can also check the EnergyStar or Labs21 websites to see if they have any useful data.

If you are going to measure some panels to get better data, an excellent data logging power meter to do that is the ElitePro by Dent Instruments (a favorite of energy engineers).

Hope this helps!

Regards,

James Hess

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For lab plug load info, go to http://www.epa.gov/lab21gov/toolkit/bp_guide.htm and download the "Measured Peak ....pdf, and "Right Sizing....pdf."
And at http://www.epa.gov/lab21gov/toolkit/index.htm see the "Benchmarking " link for end-use site energy, and the "Laboratory Equipment Efficiency Wiki," if you have any influence over purchasing the equipment.

If the building is half lab I would be very surprised if the non-receptacle TDV energy is only 170 Btu/sf even in balmy CA. (TDV is a type of power plant input energy for the non-CA reader.)

Note that modeling lab airflow and exhaust fans is a bit tricky in DOE2 and its not hard to underpredict. There are a few different approaches and the appropriate one is dependent on the proposed and baseline designs.

In particular, even if the lab exhaust airflow is VAV, these exhaust fans are usually CV/bypass which is not the DOE2/eQuest default. And the exhaust fan power should be derived from manufacturer's sheets or the fan hp on the mech schedules. Using static pressure and assumed typical fan efficiency may underpredict fan power in many cases because of the nozzle losses, particularly if "high plume dilution" fans is used.

Fred

I am trying to model a 2-story college going for LEED. The building contains several differernt lab rooms which includes a lof of equipment (Approximately 26W/ft^2 for half of the building). After running the simulation, the preliminary report states that the annual TDV Energy Use Summary for the entire building is 847.95 TDV-kBtu/sqft-yr with 684.71 towards the receptacle energy. Trying to get the minimum 14% energy cost savings is almost impossible with this receptacle energy. What options do I have to reduce the Receptacle Energy in order to meet criteria for LEED points? Is there somewhere I can input this heat load so it does not have such a great impact on the energy use summary report and still have an accurate model of the building?
-Steven Rutter

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