[esp-r] Amount of energy that passes through the surfaces

[Eduardo Goncalves]

Hello ESP-r world,


I Hope you can help me,

I am trying to determine the amount of energy that passes through a wall. I
have a fairly simple model (square with 10x10 each side and 3m height). I
have a basic control with 25 degrees the whole summer (June till September),
there are no internal gains from occupants or lights and I want to know the
amount of gain/loss through the walls.

Once simulated, if I go through *Enquire about/Zone Energy
Balance/Integrated over time/Gain-Loss* I have the following results,



*                                Gain         Loss*

* Infiltration air load           0.000       0.000*

* Ventilation air load            0.000       0.000*

* Uncontr`d casual Occupt         0.000       0.000*

* Uncontr`d casual Lights         0.000       0.000*

* Uncontr`d casual Equipt         0.000       0.000*

* Thermal bridge (linear)         0.000       0.000*

* Storage at air point            0.925      -0.977*

* Opaque surf convec: ext       233.485     -16.093*

* Opaque surf convec: ptn       157.405     -33.853*

* Transp surf convec: ext         0.000       0.000*

* Transp surf convec: ptn         0.000       0.000*

* Convec portion of plant        44.617    -385.509*

* Totals                        436.433    -436.433*



I suppose that the gains from the walls would be 233.485+157.405= 390.989
Whrs, and losses 16.093+33.853 = 49.946 Whrs. (there’s no other source of
internal gain in the model).

So far so good, nevertheless, if I go through *Surface energy
balance/Integrated over time/Gain-Loss/All Items*, I get something like,



*                         Facing Teste             Facing outside*

*                         Gain       Loss          Gain       Loss*

* Conductive flux     111853.23   -16240.70  1745485.50 -1842903.13*

* Convective flux       3598.84   -53664.82     1333.83 -3128152.00*

* Longwave rad int     15327.17   -60134.77         --          --*

* LW rad ext >bldg          --         --     476125.97  -244280.39*

* LW rad ext >sky           --         --          0.00 -2835801.50*

* LW rad ext >grnd          --         --      27968.51  -643154.69*

* Shortwave rad.           0.00        0.00  6443323.00        0.00*

* Occupt casual gn         0.00        0.00         --          --*

* Lights casual gn         0.00        0.00         --          --*

* Equipt casual gn         0.00        0.00         --          --*

* Controled casual         0.00        0.00         --          --*

* Heat stored          15333.66   -16072.75   720997.19  -720940.69*

* Plant                    0.00        0.00        0.00        0.00*

* Totals              146112.91  -146113.05  9415234.00 -9415233.00*



for each surface of the model (4 walls, ceiling and pavement).

Having those values for each surface, I sum the losses of the surface facing
inside (*392043Whrs*), which would be the convective heat that is
transferred to the zone, i.e., gain and losses that comes from the *Zone
energy balance*, as referred to initially (Gain *390,989 kWhrs*, and losses
49946 Whrs). The problem is that the results are *very* different *
(392043Whrs/390989kWhs)*, and I don’t know why. My suppositions must be
wrong.

How can I actually get the amount of energy that passes through the walls
(gains and losses)?


Thanks for your help
-- 
Eduardo Gonçalves
+ 351 913 310 390
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.strath.ac.uk/archives/esp-r/attachments/20101220/43a3477a/attachment.html