[TRNSYS-users] transfer function basics differnce in ESP-r and TRNSYS

[NALIN SWAROOP]

Hello all

TRNSYS calculates its conduction process through Transfer functions which
it initially calculates and they are used throughout the simulation
Firstly can someone please tell me in layman's term that what basically is
transfer function and what effect its value has on heat transfer and
conduction.I am sorry for asking about something on which so much
literature is available on the internet but the problem is I have read the
mitalas papers and read the TRNSYS manuals which gives the theoretical
basis behind TYPE 56 (multi zone building)and some other papers related to
Transfer function but the problem is every time too much maths is involved
and no overall idea is given of the effects of transfer function on
heating or cooling load
I am asking all this because I have modeled a (50*15*27) 42 zone building
in both TRNSYS 16 and ESP-r 11.6 but large differences are coming in
cooling load values, for TRNSYS it is around 1400 GJ annual load but for
ESP-r it is around 2200 GJ annual load, at first I thought I made some
mistake in modeling and construction parameters for both softwares, but I
have checked many times and all the details of geometry, heat transfer
coefficients, glazing data,construction data and weather data are exactly
same and I need to come up with explanation as to why these differences
are coming.
I have seen the ANSI/ASHRAE standard 140-2001 which compares bestcases for
different simulation softwares and I have tried to benchmark it and the
results match with those given in the standard but the problem is as I go
on increasing the zones,increase the size of the model add glazings the
total value of heating and cooling loads vary a lot.
Also I found one peculiar thing that in TRNSYS if I model a room with
three glazing orientations i.e west, east, north-south. I get maximum
value for east side window and minimum for north-side but if same room I
model in ESP-r I get maximum value for north-south side I dont why this
difference is there I am using the same weather file.
At last I want to know if some study has been done which gives the
mathematical differences between TRNSYS and ESP-r and tells the effect of
these mathematical differences through an example model, all I know is
ESP-r takes the rigorous heat balance approach and TRNSYS models its long
wave, short wave radiation and convection through star network system.
Sorry to bother you all with a long question

Regards

Nalin