Translucent thermal insulation walls for houses in Japan

Translucent thermal insulation walls forJapanese houses have been designed to allowsolar radiation and daylight to pass through thewalls into the house (Fig. 1) in order to reducethe amount of energy required for heating andlighting and to create a comfortable lightingenvironment. The walls are made of translucentor transparent materials such as glass andthermal insulation material.The walls have been developed withconsideration given to conditions of variousregional climates and housing lots. Computersimulations showed that light transmittanceshould be higher than 20% to reduce daytimelighting energy by half in the case of a smallhousing lot in Tokyo. Total solar energytransmittance is the most important factor forreducing energy required for heating. The highertotal solar energy transmittance is, the greater isthe reduction in energy required for heating.Simulations conducted for the cold region and the moderate climate region in Japan showedthat the use of translucent thermal insulationwalls enables 20%-40% reduction in totalenergy, including energy for heating, coolingand daytime lighting.