Paper Conference

Proceedings of ASim Conference 2014: 2nd Asia conference of IBPSA-China, Japan, Korea


Thermal Losses via Large Slabs on Grade

Pascal Brinks, Oliver Kornadt, René Oly

Abstract: Thermal losses via slabs on grade are usually calculated by simplified steady state calculations such as described in ISO 13370 or ASHRAE Fundamentals. In this research such standard methods were compared to transient simulations using a finite difference model coupled with building simulation software. The focus was on large slabs up to 10000 m² to analyze the thermal transport in particular under industrial buildings. To respect real conditions of such buildings also lower inside temperatures than in dwellings were assumed. Moreover different insulation types and soil qualities were compared. The simulations in general showed good accordance with the ISO-method for small horizontally insulated slabs like dwellings at 20 °C inside temperature. For large slabs and in particular for non-insulated slabs the losses seemed to be far overrated by the steady state method, in particular for large low heated buildings such as warehouses. Here a lot of energy from summer overheating of the building is stored under the slab and causes a heat flow from the ground back into the building during the first months of the heating period and not inverse. Therefore short vertical footer insulations appear most energy efficient for most large industrial buildings.
Keywords: Thermal losses via ground, industrial buildings, large slabs, building simulation, transient ground modeling
Pages: 427 - 434