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Hello to all equest users,
I have following question.
At e-quest I give the specific Indoor Temperature
via Cool Design Temperature = 75 F
and Heating design Temperature = 70 F (for example)

In my building I have such a load from people that during the Winter (the
heating period) I need cooling energy.

My question is how is this cooling energy calculated?

Based on which indoor temperature? The 70F or the 75F?

Thank you very much
Konstantina Kalliakoudi
Mechanical Engineer M.Sc.

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Hi Konstantina,

The way to figure out the temperature set-point based calculations is as
like-wise the following way.

As you mentioned that there is cooling requirement during the winter period.
The thermostat set-points are like
Cooling set-point- 75 degree Fahrenheit
Heating set-point- 70 degree Fahrenheit.

So the temperature that the building is required to maintain is in between
70 to 75 degree Fahrenheit.

The cooling requirement is as per the cooling thermostat set-point..So if
the temperature is above 75 degree Fahrenheit then HVAC tries to cool it
below 75 degree Fahrenheit.

If the temperature is below 70 degree Fahrenheit then the heating system
tries to heat it above 70 degree Fahrenheit.

So in overall case the space temperature has to be maintained in between
70-75 degree Fahrenheit.

As per in your query the occupancy has heated the space during winter
season such that there is requirement of cooling.

Hence as discussed above your space temperature would be more than 75
degree Fahrenheit.
So the cooling system will try to bring it down below 75 degree Fahrenheit.

In this way it could be figured out in my sense.

Hope this might help..

*Thanks,*
Frellancer
India.
......................................................................................................................................................

---------- Forwarded message ----------
From: Konstantina Kalliakoudi
To: equest-users at lists.onebuilding.org
Cc:
Bcc:
Date: Tue, 21 Apr 2020 15:01:07 +0300
Subject: [Equest-users] Question about Indoor Temperature
Hello to all equest users,
I have following question.
At e-quest I give the specific Indoor Temperature
via Cool Design Temperature = 75 F
and Heating design Temperature = 70 F (for example)

In my building I have such a load from people that during the Winter (the
heating period) I need cooling energy.

My question is how is this cooling energy calculated?

Based on which indoor temperature? The 70F or the 75F?

Thank you very much
Konstantina Kalliakoudi
Mechanical Engineer M.Sc

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Joined: 2015-05-21
Reputation: 0

Each time you simulate your model, the cooling needs for a given zone are calculated twice.

First, during the LOADS portion of the simulation:

* The zonal inputs DESIGN-COOL-TEMP and DESIGN-HEAT-TEMP are used to estimate the ?steady-state? exterior skin loads and intra-zonal loads between walls/floors/ceilings. When I say ?steady-state? I?m describing one or (typically, from wizard-bourne models) a series of calculations for load design conditions defined by your DESIGN-DAY inputs, as occurring.
* If you ever learned to do load calcs by hand/spreadsheet to determine loads present on a system before considering ventilation? this first part of the simulation is pretty analogous to getting that far.
* These loads are used to help auto-size any systems for which you didn?t provide manual inputs for the heating/cooling/airflow capacity?
* Note that all of the SIM reports starting with ?L? are reporting on loads determined during this first LOADS portion of the simulation
Then, during the SYSTEMS portion of the simulation takes over. From here, the hourly (8760) simulation occurs that among others things, distinctly moves to

1. Consider heat transfer hour over hour (and the effects of thermal mass)
2. Consider the effects of SYSTEMS conditioning as well to determine the actual zone temperature each hour (now varying vs the ?steady state? inputs used during the LOADS portion of the simulation)
3. Layer in the effects of ventilation loads (including natural/window ventilation)
4. DESIGN-COOL-TEMP and DESIGN-HEAT-TEMP are no longer used to assert or otherwise ?bound/control? zone temperatures. During this portion of the simulation, zone temperature is calculated independently, and the thermostat inputs/schedules (or lack thereof) are the primary means of defining system heating/cooling behavior.

There?s a lot more discussion in the mailing list archives if you are interested in further reading, but I?m hopeful this helps you understand better the contribution of those zonal DESIGN temp inputs in the scheme of things.

~Nick

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Nick Caton, P.E., BEMP
Senior Energy Engineer
Energy and Sustainability Services
Energy Performance Contracting
D
M
E

913 . 564 . 6361
785 . 410 . 3317
nicholas.caton at se.com
15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219

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