Dear Joynal Abedin
Thanks for your question because it makes me to think about concepts of building physics.
In highly insulated buildings, passive house or NZEB most of the thermal losses are produced by the ventilation system because the envelope is quite insulated.
The time constant depends on the ratio between thermal losses and thermal inertia in the room. If most of the thermal losses are produced by the ventilation system the thermal inertia of the walls will produce a small effect.
Reduce your ventilation ratio to a value of 0.6 or calculate the minimum required ratio for your house according to your national standards or ashrae.
You can make a quite interesting essay for your house analising the effect over the time constant of different ratios of ventilation.
Good luck with your research.
El 23/03/2014 10:37, "Joynal Abedin" <J.Abedin@lboro.ac.uk> escribió:
>
> Hi,
>
> I’m simulating a domestic building using Type-56 with three thermal zones. All the building fabrics such as the external walls are massive with the correctly defined conductivity, heat capacity and density. However, when I simulate the building the thermal response of the rooms appear to have very low thermal time constant i.e. it changes very rapidly and it seems that the massive walls with specific heat capacity are not having any heat storage impact. The capacity value in the Air Zone Regime gets automatically to 1.2 times the volume of the room. If I manually increase this value the thermal time constant does increase, but should I be increasing this value? The main problem I think is that the thermally massive walls are not having any thermal mass effects on the temperature response of the rooms. What am I doing wrong? Why is the heat capacity of the air zone set to 1.2 times the zone volume? One building in TRNSYS17 Example projects have this set to 3 times the Volume.
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> If anybody as any ideas or suggestions please please email me. Your help will be very much appreciated.
>
>
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> Thanking you in advance.
>
>
>
> Kind regards,
>
>
>
> Joynal Abedin.
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> Loughborough University, UK.
>
>
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