[TRNSYS-users] Ground heat transfer calculation

I recently performed a comparison between a simplified approach (as specified in ISO 13370 annex D) and a detailed one (as implemented in Type49 from Trnsys standard library, simulation over 3 years) for ground heat transfer calculation.

The case study is a 2 storeys office building, floor area nearing 1500 m2, slab on grade with 2 m horizontal peripheral insulation (R=1.7 m2.K/W).

I get the results shown in attachment:

· TAirInocc.pdf: air temperature during the first week-ends of the year (numbered from 7 to 18, building unoccupied, HVAC systems off) for the ground floor thermal zones (numbered 2, 3, 6 and 8): discrepancy around 2°C between the simplified calculation ('0Ref') and the detailed one ('1Sol').

· PuisMoy0.pdf: mean heating power during a typical day of the week (negative as a convention) for the two water loops heating the ground floor premises: discrepancy between 20% and 50%, the main impact being observed during morning restart.

· Another comparison has been performed with continuous insulation under the slab (R=1.7 m2.K/W) and leads to similar discrepancies.

Has anyone amid you ever noticed such a gap between these two kinds of calculation. Or perhaps somebody has further information regarding the qualification of the simplified approach presented in the international standard ISO 13370 or the detailed one implemented in Type49?

Thanks a lot for any insight regarding this issue.

Best

Antoine Gautier

Solamen

+33 6 58 24 02 60

antoine.gautier@solamen.fr