|
Hi Mohannad, Did you check your
orientations? A surface to the north is 180 degrees (check it in type 16)
(instead of 0 degrees) Regards, Mariëlle Nuchelmans Van: Sabine Jansen -
BK [mailto:S.C.Jansen@tudelft.nl] Hello Mohannad, Just to make sure, you didn’t mean the latitude is
MINUS 24.65 (so on the southern hemisphere, in which case the sun will come
from the north)? Otherwise, your latitude is around the
latitude of the tropic of cancer. This is a special location and what I would
do is plot the solar radiation per m2 per orientation just to check if
then you understand. You can also leave out the solar radiation first, to
check if this is really the cause. Qvent is defined as (see
manual): QVENT sensible ventilation energy gain of zone So that negative values are given if
there are ventilation outputs, i.e. LOSSES. This should only occur of your
ventilation air is a lower temperature than you indoor air. Qcool is defined as:
QCOOL sensible cooling demand of zone (positive values) This means POSITIVE values are given for
energy outputs (so this is an opposite definition of Qvent) Qcool can be positive while Qvent is
negative, when solar or internal gains are bigger than the total losses and
thus additional cooling is required. Qcool refers to the cooling demand of your
zone that is needed according to the energy balance of your zone (and your
setpoints). If you use external air at external air temperature (and no other
cooling items, such as a cooling floor), Qcool is your total cooling demand. However, if you use ventilation air at a
temperature different from Toutside, this means additional cooling is required
to produce the air at this temperature. I think in that case you need to
calculate the energy required for cooling down the air (from Toutside to Tair-inlet)
in order to come to the total cooling demand. Qvent is in this case not related
to the cooling demand, only to the energy balance of the zone. I hope this is of any help. Kind regards, Sabine Jansen p.s. The energy balance of the zone is
given in balance output 4, but in the manual there is one small error in the
definition of Qtrans, which should be defined in the opposite way, that is, it
is also included as a GAIN in the balance equation, meaning positive values are
gains to the zone and negative values are losses. Van: Mohannad
Bayoumi [mailto:mohannad.b@gmail.com] Hello, I am simulating the energy demand for a floor in an office building -
Lat 24.65°. The floor has 4 main zones facing the 4 different orientations. U-Outwall: 0.15 Wh/m2.K U-Glass: 0.5 Wh/m2.K G-Glass: 56 % External shading factor: 88% I keep getting a higher cooling demand (QCOOL) for the northern zone
against the eastern and the western ones. I tried many times with and
without inner loads and shading devices. I also tried with mechanical
ventilation - 1- What can be the reason for these surprising results? I still can not understand why the QVENT values are in negative while
the QCOOL are in positive, although the cooling process is to lead the heat
away from the body or the space. 2- If I would like to find out the total cooling demand of a zone,
should I use the QCOOL or QVENT values, or should I add them together?? Thank you Mohannad Bayoumi |