When embarking on the exciting journey of building a custom home in Japan, you will likely spend hours poring over housing catalogs and builder websites. Among the beautiful photos of living rooms and kitchens, you will inevitably encounter a series of technical-sounding metrics: UA value, C value, and perhaps Q value. Builders often proudly display these numbers—for instance, "Industry-leading UA value of 0.35!" or "Exceptional C value of 0.5!" It is entirely natural to ass