Maybe you could try running each month (or group of months) with each
month's simulation having it's own maximum outdoor dry-bulb temp. Then
append the data from each csv.
Sherif Ezzeldin wrote:
>
>
> Lixing,
>
> Thank you for your prompt reply
>
> The alternative way works with only one annual CSP but, in my case, I
> have several Monthly CSP. Therefore, I have to select one of those CSP
> values which is not ideal.
>
> Concerning the wish list, in order to solve the problem ideally, I
> could suggest that:
> 1) The hybrid ventilation control may need to have the opportunity of
> adding a schedule for the maximum and the minimum outdoor temperatures
> instead of just values.
> 2) The hybrid control mode 4 (ventilation rate) could firstly compare
> the calculated ventilation rate from the airflow network model with
> the
minimum value (as it does), secondly, compare the zone temperature
> with the CSP, and then predict the hybrid status.
> 3) As well, one of my colleagues suggested that the "System
> Availability Manager: High Temperature Turn On" could be used as an
> alternative only if an "availability schedule name" is added to it as
> in "System Availability Manager: Low Temperature Turn Off"
>
> I don't know how difficult / important these suggestions could be but
> I hope IAQ will be considered soon
>
> Kind regards,
> Sherif
>
>
>
> ------------ --------- --------- --------- --------- --------- -
> *From:* Lixing Gu <gu@xxxxxxxx. edu>
> *To:* EnergyPlus_Support@ yahoogroups. com
> *Sent:* Friday, May 8, 2009 2:12:34 PM
> *Subject:* Re: [EnergyPlus_ Support] Hybrid Ventilation Control
>
> Sherif:
>
> The hybrid ventilation control is mainly used to save energy and
> prevent simultaneous natural ventilation and HVAC operation. The
> IAQ control was not considered when the object was developed. We need
> to reconsider a possible combination to let user make IAQ control. I
> will write this one into a wish list. Do you have more suggestions?
>
> The alternative way you mentioned is to make scheduled maximum and
> minimum outdoor temperature, such as scheduled CSP. Does this meet
> your needs for the time being?
>
> Lixing
>
>
> ----- Original Message -----
> *From:* Sherif Ezzeldin <mailto:shezzeldin@yahoo. com>
> *To:* EnergyPlus_Support@ yahoogroups. com
> <mailto:EnergyPlus_Support@ yahoogroups. com>
> *Sent:* Friday, May 08, 2009 6:39 AM
> *Subject:* Re: [EnergyPlus_ Support] Hybrid Ventilation Control
>
> Hi,
>
> Thank you Lixing, Richard, Linda and Fabio for your concern and
> support
>
> I've looked through the detailed report variables as recommended
> It was very helpful to understand more the performance of the
> system and the control logic
>
> Through different timesteps in an hour, the hybrid status is
> alternating from 1 (allowing natural ventilation) to 2 (mechanical
>
ventilation) according to the cooling setpoint temperature (CSP)
> and the cooling demand. Once the air temperature reached the CSP
> (27C), the mechanical cooling system is operating in order to keep
> the air temperature just below the CSP while the supplied fresh
> air exceeds the minimum requirements (no problem).
>
> My problem summarizes in that, after several timesteps of HVAC
> operation, the hybrid status changes to 1 as the outdoor
> temperature (30C) is between the min.& max. values (15-35C) while
> natural ventilation is not permitted as the outdoor temperature is
> higher than the indoor temperature (27C). At these moments, the
> airflow is below the minimum ventilation rate. Accordingly,
> the hourly supplied amount of fresh air (by both HVAC and Natural
> Ventilation) doesn't match the minimum requirements which affect
> the Indoor Air
Quality.
>
> Since the ventilation rate due to natural ventilation is below the
> minimum requirements at the critical moments, the system should
> then switch to mechanical ventilation with minimum ventilation
> rate to maintain acceptable Indoor Air Quality. Therefore, a
> combined control mode will be helpful at these circumstances, am I
> right?
>
> Another alternative could solve the problem by matching the
> maximum outdoor temperature with the CSP but we can only specify
> just one max. outdoor temp. for the whole year. In that case,
> Which value could be used when we use different seasonal/monthly
> CSP (which is my situtation as well)?
>
> I appreciate very much your help
>
> Kind regards,
> Sherif
>
>
> ------------ --------- --------- --------- --------- --------- -
> *From:* Lixing Gu <gu@xxxxxxxx. edu>
> *To:* EnergyPlus_Support@ yahoogroups. com
> *Sent:* Wednesday, May 6, 2009 8:47:23 PM
> *Subject:* Re: [EnergyPlus_ Support] Hybrid Ventilation Control
>
> Sherif:
>
> I think Rich answers your question regarding the hybrid status
> value between 1 and 2. I am trying to clarify the control logic.
> When the control mode is temperature, the control will check
> whether the outdoor temperature is between min and max temperature
> specified in the inputs, such as 15 and 35C you mentioned. If it
> OK, the control also check whether HVAC system is required to turn
> on or not, by checking indoor temperature. For example, if the
> indoor temperature in the controlled zone is above the cooling
> setpoint. HVAC system turns on.
>
> The control
mode 4 is only working with the AirflowNetwork model.
> If the infiltration by opening windows is above the scheduled
> input. HVAC system turns off and windows are open, regardless of
> other conditions.
>
> Hope this helps.
>
> Lixing
>
> ----- Original Message -----
> *From:* Sherif Ezzeldin <mailto:shezzeldin@yahoo. com>
> *To:* EnergyPlus_Support@ yahoogroups. com
> <mailto:EnergyPlus_Support@ yahoogroups. com>
> *Sent:* Wednesday, May 06, 2009 11:40 AM
> *Subject:* Re: [EnergyPlus_ Support] Hybrid Ventilation Control
>
> Lixing,
>
> Thanks for your concern
>
> The main
concern is designing an acceptable indoor environment
> is to maintain both Thermal Comfort and Indoor Air Quality
> requirements.
>
> Concerning Indoor Air Quality requirements, a minimum
> ventilation rate (10l/s/person= 1.29ACH) is required to
> maintain acceptable level of CO2 in an office space. A
> successful hybrid design should provide that ventilation rate
> by natural ventilation and switch to mechanical ventilation
> just when the minimum value couldn't be met.
>
> At the same time, the zone operative temperature should lie
> within the upper & lower thermal comfort boundaries. A
> successful hybrid design should maintain natural ventilation
> as long as the zone operative temperature is within the
> comfort boundaries, once it reaches the upper comfort boundary
> temperature (cooling setpoint temperature CSP), the system
> should
switch to mechanical cooling
> In EnergyPlus, if I set the control mode to 1 (temperature)
> and the min. and max. outdoor temp. to 15C and 35C as in the
> example file, when the outdoor temp. reaches 32C and the
> indoor temp is 28C and the CSP is 26C , in that case the
> mechanical system should operate and the hybrid status should
> be equal to 2 but the hybrid status value is between 1 and 2.
> My explanation could be that since the outside lies between
> 15C and 35C, then hybrid control allows natural ventilation,
> and since the outdoor temp is higher than the indoor temp,
> then natural ventilation is not allowed.
>
> Alternatively, if I set the control mode to 4 (Ventilation
> rate), the system just compare the predicted ventilation rate
> with the minimum value regardless to the cooling setpoint,
> therefore, during summer, the indoor temperature exceeds
the
> upper comfort boundary temperature but with acceptable
> ventilation rate.
>
> Could you please help me may be there is something I
> miss-understood?
>
> Kind regards,
> Sherif
>
> ------------ --------- --------- --------- --------- --------- -
> *From:* Lixing Gu <gu@xxxxxxxx. edu>
> *To:* EnergyPlus_Support@ yahoogroups. com
> *Sent:* Wednesday, May 6, 2009 2:24:48 PM
> *Subject:* Re: [EnergyPlus_ Support] Hybrid Ventilation Control
>
> Sherif:
>
> The existing EnergyPlus only allows one of controls at the
> same time. Any combination is not allowed. Could you provide
> your control in detail, so that possible enhancement will be
> considered?
>
> Thanks.
>
> Lixing
>
> -----
Original Message -----
> *From:* Sherif Ezzeldin <mailto:shezzeldin@yahoo. com>
> *To:* EnergyPlus_Support@ yahoogroups. com
> <mailto:EnergyPlus_Support@ yahoogroups. com>
> *Sent:* Wednesday, May 06, 2009 6:26 AM
> *Subject:* [EnergyPlus_ Support] Hybrid Ventilation Control
>
> Hi,
>
>
>
> I'm trying to improve the performance of a hybrid
> ventilation scheme in an office space
>
>
>
> I'm using EnergyPlus version 2.2
>
>
>
> Concerning the control mode in the "Hybrid Ventilation
> control" model, we have to specify either to control
> natural and mechanical
ventilation by temperature (control
> mode=1) or by ventilation rate (control mode=4)
>
>
>
> Is there a way to combine these two control modes together
> and to let the program first to calculate the
> temperature (compare it with the acceptable temperature
> ranges) and the ventilation rate (compare it with the
> minimum ventilation rate) all together and then decide
> whether to provide natural or mechanical ventilation?
>
>
>
> Thanks for your support
>
>
>
> Kind regards,
>
> Sherif
>
>
>
>
>
>
>
>
--
Richard A. Raustad
Senior Research Engineer
Florida Solar Energy Center
University of Central Florida
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Phone: (321) 638-1454
Fax: (321) 638-1439 or 1010
Visit our web site at: http://www.fsec. ucf.edu
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