Coupled simulations for hygrothermal investigation of subterranean car parks and similar spaces

Abstract

To investigate the hygrothermal conditions in subterranean car parks a twodimensional simulation procedure has been used, based on coupling the transient heat transfer programme HEAT with the dynamic thermal building simulation program TRNSYS. The likelihood of condensation and the rate of water deposition on surfaces were calculated with a new moisture model KOND. To estimate the consequence of moisture adsorption in materials in the hygroscopic range below saturation, the TRNSYS moisture capacitance model (buffer storage model) was used. A parametric study of the internal temperatures and the annual hours of condensation risk in underground car parks were conducted using German and UK climate data. The simulations indicate the relative risk of condensation occurring for different earth conditions, levels of insulation and air change rates, in spaces covered by earth and spaces covered by a heated building. It is shown that increased ventilation rates in summer can reduce condensation risk in underground car parks below heated buildings.

Practical application: In the design of cellars, storerooms and underground car parks etc., it is important to know whether condensation is likely to occur, how much moisture is likely to accumulate and whether such an accumulation could lead to damage. The designers of underground spaces need to know whether insulation measures, or ventilation controls are necessary. In addition, the wintertime temperature conditions in subterranian spaces below heated buildings are of particular interest when assessing the problem of heat bridges at the pillars and walls which support the overlying building.