[TRNSYS-users] Estimating sensible and latent loads

[David BRADLEY]

Ali,

   As far as the initial temperature is concerned, set it in between the 
heating setpoint and cooling setpoint temperature and it won't have any 
impact on what your peak heating and cooling loads are. When the zone 
temperature is between the heating and cooling setpoint then by 
definition there is no load on the space.

   As a side note, I would caution against sizing HVAC equipment based 
on a short term simulation. I mention it becuase in long term 
simulations the initial value has little impact and if your initial zone 
temperature does have a significant impact then it might be that your 
simulation is short. In any case, I'd recommend running a year or two or 
at least december plus a year so that any initial values that the 
simulation starts with aren't impacting your results. If you're running 
a case in which you have a lot of thermal coupling with the ground and 
are modeling the ground temperature as impacted by the presence of the 
building (using Type49 for example) then you should be running a 5-10 
year long simulation so as to get away from any initial value bias.

  As for your second question if you impose a humidity setpoint on your 
building then as with temperature, Type56 will limit the building's 
humidity and report the amount of latent energy that had to be added or 
removed in order to keep it between the setpoints.

kind regards,

  David


On 1/9/2023 4:21 PM, Ali Shahrouzian via TRNSYS-users wrote:
>
> Dear all TRNSYS user,
>
> Hi,
>
> I have two questions about estimating the size of HVAC system of a 
> building.
>
> My 1^st question:
>
> As you know, there is a good explanation in 09-Tutorial document 
> regarding estimating the size of HVAC equipment of a building by using 
> the printegrator component (setting its parameter #4 to 15 min and 
> determining the peak 15-minute heating and cooling load for building). 
> However, it is evident that the maximum 15-minute heating and cooling 
> load for the building is highly dependent on the initial temperature 
> of the building, which is set on TRNBuild. When starting a simulation, 
> what should the initial temperature be?
>
> My 2^nd question:
>
> How can I estimate the size of humidifier or dehumidifier in the HVAC 
> equipment?
>
> I’d be glad if someone could help me out.
>
> Best regards,
>
> Ali
>
>
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-- 
***************************
David BRADLEY
Principal
Thermal Energy System Specialists, LLC
3 North Pinckney Street - suite 202
Madison, WI  53703 USA

P:+1.608.274.2577
d.bradley at tess-inc.com

http://www.tess-inc.com
http://www.trnsys.com
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