Minimum House in Toyota

豐田極簡宅

A New Prototype of Urban Housing

A house for a young couple and their two children in Toyota City, Aichi Prefecture. Located on a long and narrow site east to west, there is heavy traffic on the west side of the road, buildings closely adjacent on the north and south sides with a wide opening to the sky in the southeast at the second floor. The massing is a compact box with a frontage of 2 ken(3.6m) x depth of 7.5 ken(13.6m) , 15 tsubo(50m2) x 2 floors = 30 tsubo(100m2) in total, with a height of approximately 6 m. The structure is divided into three levels. A large window on the southeast wall of the living room connects to the urban void.  The covered terrace along the street-side of the dining room and kitchen has a mesh front and translucent walls on the sides to allow full access to the changing light and wind while maintaining a moderate sense of distance from the city.

To ensure year-round comfort and energy efficiency, the exterior skin and mechanical equipment were designed for comfort and energy-efficiency. Within a limited budget, we devised ways to ensure high performance with a combination of thoroughly reduced materials and low-priced equipment. We created a warm wood-filled space by eliminating interior finishes by using exterior insulation, and exposing the wood structure, base, piping, and wiring.  This allows the residents to understand the structure of the building and to make repairs and modifications on their own. This is a proposal for a new prototype of urban housing in an age of global environmental crisis, by providing a delightful house open to the inside (family) and outside (city), full of light, wind, and natural materials, with less construction material and waste. 

Realization of high earthquake resistance, comfortable thermal environment, and healthy soil environment at low cost

By placing load-bearing walls with structural plywood and steel braces at appropriate intervals at both ends of each floor in the short direction, we achieved high earthquake resistance performance (Grade 3) while eliminating deformation differences in the skip floor and suppressing deformation during wind pressure, as well as ensuring spatial flexibility and transparency. The height of the three stories were reduced to under 6 m. The roof was constructed with a reduced number of components, by utilizing 3.5" square timbers on top of the exterior insulation and a folded roof over baseboards and asphalt roofing.  This strategy helped simplify the roof framing and eliminated the need for rafters.

By using exterior insulation, high-performance window sashes, and eaves, the building achieved high envelope performance, with a UA value of 0.49 (ZEH+ standard) and an ηAC value of 2.2 (above the energy conservation standard). A comfortable thermal environment was achieved at low cost by devising ventilation routes and using fans and ducts to distribute warm/cold air from a single under-floor air conditioner to each zone. In addition, the entire site, including the soil, was improved by digging trenches and holes in the exterior, burying organic materials, and allowing water and air to move through the soil in a way that is possible even for amateur builders.

都市住宅的新原型

這座住宅位於日本愛知縣，屋主是年輕夫妻，家中有兩名孩童。住宅坐落於東西向的狹長基地，西側道路車流量大，而南北緊臨其他建築，二樓的東南側有大片窗戶。此建築量體的正面為「2間」（3.6公尺；註：「間」為日本傳統長度單位，1間約為1.8公尺）×深度7.5間（13.6公尺）；15坪（50平方公尺）×2層樓=共30坪（100平方公尺），高度約為6公尺，整體建築區分為三層。客廳東南牆的大型窗能連接都會的虛空間。面向街道的餐廳與廚房外則設有陽台，且佈有雨遮蔽與網狀立面。側面的半透明牆體完全將光線與風的變化引進屋內，同時又與城市保持適當距離。

為確保全年節能且居住舒適，建築皮層與機械設備著重能源效率。在有條件的預算前提下，建築師設法簡化材料、省去不必要的室內裝飾、善用物美價廉的設備，以達到室外隔熱高效能，築構了溫暖木質空間，裸露的木結構、地基、管線與線路，利於屋主暸解建築結構於日後自行修繕與維護。這幢建築是在全球面臨環境危機的時代下，給予都市建築新原型的提案，建築師盼能藉此打造出對內（家庭）、對外（城市）開放，同時充滿陽光、微風、天然原始材料且令人欣喜的建築，節省施工原料及不必要的廢棄物。

實現高抗震舒適條件，以及健康的土壤環境

本建築以結構式合板來打造承重牆，每層樓的短邊在適當間隔會設置鋼斜撐，達到高抗震效能（三級），同時消除地板高低差與風壓所產生的變形，並確保空間彈性與透明度。三層樓的高度降低到6公尺以下，而屋頂構造元件數量也較少，室外隔熱層上方採用3.5吋的方形木材，在護板與瀝青頂層地面上則有折疊式屋頂。此一手法有助於簡化屋頂框架，減少梁的需求。建築物採用室外隔熱、高效能窗框與屋簷設計，因此外層可達到極高效能：熱傳導係數UA値0.49（零耗能住宅標準〔ZEH+ standard〕）、玻璃日射透過率（ηAC value）為2.2（優於節能標準）。本屋採用位於地板下的單一空調，並建構通風路徑，運用風扇和導管，即可把冷暖氣送到各個區域，以低成本打造舒適的溫度環境。此外，整體基地在室外（包括泥土）挖掘溝與洞、埋設有機材料，讓水與空氣能在泥土中移動，藉以改善環境，即使是業餘建築者也做得到。