臺北市住宅興建決定因素：市場特性、開發政策與土地產權的整合觀點

The Adjustment of Housing Stock in Taipei- Market Characters, Government Policies and Land Ownership

臺北市在住宅市場景氣之時，出現住宅價格明顯上漲但是新建數量緩慢的現象。不僅造成難以負擔的房價，也可能影響都市發展型態、甚至減弱都市競爭力。雖然存在地理條件以及規劃管制造成的土地總供給限制，但是這不應該影響住宅市場的供需反應。然而，臺北市卻長期出現高房價以及低供給同時存在的現象。過往住宅興建相關研究認為，建商決定是否興建住宅時，應該會比較現存住宅價格與新建住宅成本。這個簡單的決策原則，背後包含許多住宅需求和供給面的考量因素；例如所得水準、人口數量、土地使用管制、現存住宅數量、維護成本、利率、財產稅率以及房屋興建成本等。本文也希望了解政府推動的土地開發相關政策，例如市地重劃、區段徵收以及都市更新，是否影響住宅的興建。此外，以往研究往往忽略土地細碎以及共有土地產權造成的住宅供給限制，這些特徵卻又是臺北市土地市場的常態。本文因此也特別考量這些土地條件對於住宅興建的影響。本文透過臺北市民國九十四年到一○三年的使用執照和拆除執照，以里為分析單元，實證影響住宅興建的重要因素。透過傳統迴歸以及空間延遲模型（Spatial Lag Model, SLM），我們的研究結果顯示，人口增加以及所得較高，都會透過市場機能吸引較多的住宅投資。此外，政府給予都市更新地區的容積獎勵，也相當程度引導住宅的興建區位。然而，屋齡較高的地區較難以吸引新的住宅投資，這對於許多老屋亟待重建的臺北市，形成政策上的挑戰。最後，本文也發現早期發展地區未必無法吸引住宅投資，但是複雜的土地產權卻是必須解決的難題。

Taipei has observed that in the market boom period housing construction was significantly lagged behind the ever-rising housing price. The co-existence of a high-price and small-supply at first glance seems to be an anomaly. New houses are expected to be supplied into the market as a response to a price rise. The majority of previous studies placed a heavy attention on the housing market. Those studies implicitly assumed that the land market is perfect and sites will be developed once new housing is needed. The land market is in fact far from being efficient. We are therefore prompted in our analysis to integrate the land market into the production of new houses, hoping to better explain the high-price/small supply phenomenon. We expand the model previously proposed that a developer will supply new housing if the price of an existing house is lower than the price of a similar but undeveloped site. We also take account of other institutional factors that are deemed important to housing supply in Taipei. Both of OLS and spatial-lag regression models show that neighborhoods with a higher growth rate of population and wealthier residents tended to attract more housing investment. In addition, neighborhoods where the designated urban regeneration projects were located also saw a higher level of housing construction. It was likely due to the floor area bonus granted to those regeneration projects. Moreover, neighborhoods where aged buildings cluster saw less new housing investment. However, those neighborhoods were areas where new housing additions were needed. In addition, early-developed neighborhoods in the City were able to attract housing investment. Finally, complicated ownership on land continued to be a hurdle to supply building sites.