Transparent Insulation System for Passive Solar Energy Utilization in Buildings

A new concept for the passive use of solar energy, transparent insulation, is described together with the first experimental results. Transparent insulation material has the property of being transparent or translucent to solar radiation while at the same time acting as heat insulation. Elements made of this material can be attached to the walls of buildings and thus permit the utilization of solar energy for heating. Relations are given for the dependence of heat flux and conversion efficiency of radiation into useful heat on the thermal resistance of the components. Calculations using meteorological data show that with material-parameters achievable with present technology not only south but also west/east and possibly even north orientations can lead to significant contributions to heating. In order to avoid overheating in summer, control of radiation must be provided. Experiments with two different materials on two buildings showed promising results. In sunny periods in wintertime a heat flux into the house was measured for south and west orientated walls. The mean heat flux is reduced drastically depending on the material and orientation used.