Numerical code AGLA allows the simulation of muti-layered facades including advanced elements, such as transparent insulation (TIM) and liquid-based collectors-accumulators im­plemented as layers of a facade. It is based in the one-dimensional discretization of all the domain in the predominant direction (horizontal for heat transfer from outdoors to indoor building) and vertical for heat transfer occured in air channel (at a double envelope facade). Empirical heat transfer coefficients are introduced to solve convective heat exchange. Ther­mal radiation is solved applying the radiosity method.

Outdoor conditions are introduced as mean monthly values of horizontal global radiation, minimum and maximum air temperatures, wind velocity and direction, and relative humidi­ty. From these data, instantaneous values are calculated considering for solar radiation an isotropic diffuse model. Outdoor conditions over the surface of the facade are calculated, and all the heat transfer mechanisms are solved by means of a transient implicit algorithm. Thermal balances are performed for each component, and global heat transfer balances must be satisfied for the whole facade in order to pass to solve the following time step. The period of simulation is typically of one year, and time step varies from five to ten minutes depending on the case to simulate.

Solar collectors including transparent insulation are treated as multi-layered semi-trans­parent walls, TIM is solved by means of a discrete ordinate method [10]. A multi-node model is applied to accounts for stratification in the water accumulator [4]. More detail about the mathematical models implemented in AGLA code can be found in [6].