A STUDY ON A PASSIVELY HEATED SINGLE-ZONE BUILDING USING A THERMAL STORAGE WALL ABDUL-JABBAR N. KHALIFA Solar Energy Research Center, Jadiriya, P.O. Box 13026, Baghdad, Iraq (Received 16 July 1997) Abstract—The thermal performance of a passively heated zone is predicted by calculating the transient temperature variation of each node in the system using a finite-dierence model. The sensitivity of the zone air temperature to the change in some of the zone features is examined. Some of these parameters included the thickness of the walls, using constant and variable heat transfer coecients, having con- trolled and uncontrolled thermocirculation in a vented storage wall. # 1998 Elsevier Science Ltd. All rights reserved Passive systems Thermal storage wall Simulation NOMENCLATURE C p =Specific heat (J/kgK) d=Characteristic dimension (m) Gr=Grashof number k=Thermal conductivity (W/mK) L=Characteristic dimension (m) Nu=Nusselt number N=Node number Q aux =Auxiliary heat (W) Q solc =Solar radiation absorbed by glazing (W) Q solw =Solar radiation absorbed by thermal storage wall (W) Ra=Rayleigh number T amb =Ambient temperature (K) T gap =Gap air temperature (K) T grd =Ground temperature (K) u=Wind speed (m/s) UA c =Conductance of glazing (W/K) UA grd1 =Conductance of floor through ground (W/K) UA grd2 =Conductance of floor through walls (W/K) UA inf =Conductance due to infiltration (W/K) UA sw =Conductance between thermal storage walls and zone air (W/K) UA w =Conductance between thermal storage walls and gap air (W/K) UA walls =Conductance through walls of zone (W/K) a b , a d =Absorptivity for beam and diuse radiation, respectively e=Emissivity r=Density (kg/m 3 )/reflectivity r b , r d =Reflectivity for beam and diuse radiation, respectively t b , t d =Transmissivity for beam and diuse radiation, respectively INTRODUCTION A passive system is one which uses the design features, such as shading, orientation, insulation, thermal mass, etc., of the building to reduce or eliminate the heating and cooling requirements of the zone. In contrast to the active system, a passive system doesn’t need any active devices (such as pump, blower, etc.) to achieve the heating or cooling process. One of the most common methods used in passive heating is the utilization of a massive wall for heat storage. The per- formance of the wall is aected by many factors, such as the thickness of the wall and the media used for heat storage. The present study aims at examining analytically the performance Energy Convers. Mgmt Vol. 39, No. 15, pp. 1597–1605, 1998 # 1998 Elsevier Science Ltd. All rights reserved Printed in Great Britain 0196-8904/98 $19.00 + 0.00 PII: S0196-8904(98)00026-0 1597