Noortje,
The time base has to do with how often the
wall transfer functions are updated. The time base is distinct
from the simulation time step and while it is ideal to have the
time base and the time step be equal, it is rarely possible.
Ventilation and occupancy changes occur as a function of the
simulation time step. You'll see some stepwise behavior in the
room air temperature if your time step and time base are
different but in my experience this does not lead to significant
problems in computing either the comfort or the energy
consumption of the building. I often have situations in which I
use a 1-5 minute time step and have to use a 1 hour wall time
base in the building.
kind regards,
David
On 09/11/2018 03:12, Noortje Alders via
TRNSYS-users wrote:
Dear TRNSYS users,
I want to analyze the thermal behaviour of
a dwelling with floor heating in detail. Attatched is a
drawing of the floor construction. The time-base is set by 1
hour by default. I would like to set this time-base to a lower
value (eg 15 minutes or less) to be able to analyse the
reaction to change in occupancy with accordingly changing
ventilation, heating setpoint and internal gain. However, the
high thermla mass and high insulation value doesn't allow me
to because the stability criteria are not fullfilled. ("Error
creating the wall transfer coefficients: Stability criteria
not fullfilled"). In a previous thread of the forum (
http://lists.onebuilding.org/pipermail/trnsys-users-onebuilding.org/2012-November/024387.html
) I read that there is a "trick" for this. You can devide
one layer in the ground floor (e.g. the concrete slab) with
an active layer. However, if I try I get the message that
only one active layer is allowed. Is there another way to
tackle this problem?
Kind regards,
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David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
3 North Pinckney Street - suite 202
Madison, WI 53703 USA
P:+1.608.274.2577
F:+1.608.278.1475
d.bradley@tess-inc.com
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