located in the tatami adjacent to the host's tatami, for use in the cold months; this hearth is covered with a plain tatami and is not visible in the warm months, when a portable brazier ( furo) is used instead. There will be a tokonoma (scroll alcove) holding a scroll of calligraphy or brush painting, and perhaps a small, simple, flower arrangement called a chabana (), but no other decoration. Chashitsu are broadly classified according to whether they have a floor area larger or smaller than 4.5 tatami, a differentiation which affects the style of ceremony that can be conducted, the specific type of equipment and decoration that can be used, the placement of various architectural features and the hearth, and the number of guests that can be accommodated. Chashitsu which are larger than 4.5 mats are called hiroma ("big room"), while those that are smaller are called koma ("small room"). Hiroma often are shoin style rooms, and for the most part are not limited to use for chanoyu. Other factors that affect the tea room are architectural constraints such as the location of windows, entrances, the sunken hearth and the tokonoma, particularly when the tea room is not located within a purpose-built structure. The other factors that influence the construction of the chashitsu as a space in the iemoto are the iconography of the past and the memory of particular individuals. Not all tea rooms can be made to conform to the ideal seen in the image. Typical names It is usual for chashitsu to be given a name after their owners or benefactors. Names usually include the character for "hut", "hall", or "arbour", and reflect the spirit of rustic simplicity of the tea ceremony and the teachings of Zen Buddhism. Characteristic names include: Mugai-an (, Introvert Hut) Mokurai-an (, Silent Thunder Hut) Tōkyū-dō (, East-Seeking Hall) (note: the at Ginkaku-ji is pronounced Tōgu-dō, and is a private Buddhist hall, not a chashitsu) Shō-an (, Pine Hut) Ichimoku-an (, One Tree Hut) Rokusō-an (, Six Window Hut) Bōji-tei (, Forgotten Path Arbour) Notable chashitsu Tai-an () built in 1582, is the only extant chashitsu designed by Sen no Rikyū, representing his concept of wabi-cha. Located at Myōki-an temple in Yamazaki, Kyoto. Designated a National Treasure. Jo-an () was built in Kyoto in 1618 by Urakusai, the younger brother of Oda Nobunaga, and was moved to Inuyama in Aichi in