Although ENR’s indexes measure the costs of non-residential buildings, the recovery in the housing market is having a major impact on index movement. After a long decline, ENR’s 20-city average price for 2x4 lumber is up 12.2% this year, following a 4.1% and 5.7% increase during the previous two years, respectively. ENR’s prices for structural steel and cement in the cost indexes posted more modest gains. Labor costs have pushed back the materials price increase, keeping ENR’s cost indexes relatively flat.
结果，去年增长了2.2％，该建筑成本指数在一年中增长了3.9％。在过去两年中，施工成本指数分别增加了2.7％和2.8％。
下面解释了驱动器索引的机制。新利18备用
新利18备用Enr从1909年开始系统地报告材料价格和工资，但直到1921年才建立CCI。该指数被设计为绘制基本成本趋势的通用工具。如今，它仍然是恒定数量的结构钢，波特兰水泥，木材和普通劳动力的加权汇总指数。这种商品包的价值为100美元，使用1913年的价格。
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CCI中普通劳动的最初用途旨在反映所有建筑工人的工资率活动。然而，在1930年代，工资和边缘效益的率比熟练的行业相比，以百分比的速度上升的速度要快得多。为了应对这一趋势，ENR在1938年引入了其建筑成本指新利18备用数，以权衡熟练的交易对成本的影响。新利18备用官网登录
The BCI labor component is the average union wage rate, plus fringes, for carpenters, bricklayers and ironworkers. The materials component is the same as the CCI’s. The BCI also represents a hypothetical package of these construction items, valued at $100 in 1913.
这两个指数旨在指出美国建筑成本的基本潜在趋势，因此，组件基于对当地条件影响较小的建筑材料；新利18备用官网登录新利18备用Enr选择钢，水泥和木材，因为它们与美国经济有稳定的关系，并在建筑中起主要作用。
实际上，ENR选择了这些材料，因为所有三个材料新利18备用都可以使用可靠的价格报价，从而确保可以及时计算两个索引。尽管基于有限数量的组件，任何指数中可能存在一些弱点，但ENR认为，大量要素会增加验证价格和发布指数之间的时间滞后。新利18备用同样，与包括许多组成的价格变化更少的组件的指数对价格变化更敏感。
缺点是,辊筒的使用y a few cost components makes indexes for individual cities more vulnerable to source changes. These aberrations tend to average out for the 20-city indexes, which ENR recommends for general use.
Since the indexes are computed with real prices, the proportion a given component has in the index will vary with its relative escalation rate. In the late 1970s, labor’s share of the index dropped because materials prices were in the grip of hyperinflation. For example, in 1979, lumber prices increased 16%, cement prices increased 13%, and steel prices jumped 11%, but labor rose only 8%. These events resulted in materials gaining a larger percentage of the index.
In the original CCI, the components were weighted at 38% for labor, 38% for steel, 17% for lumber and 7% for portland cement. The shifting tide of inflation changed the weight of the CCI components, making labor 81%, steel 13%, lumber 5% and cement 1%. This shift was less dramatic for the BCI, which is now 66% for labor, 23% for steel, 9% for lumber and 2% for cement.
两项指数均未根据生产率，承包商的开销或利润进行调整。但是，这些索引可以解决这些因素。通常，当生产率较低时，售价将相对较高，高于ENR指数。新利18备用通常，当竞争激烈时，完成建筑的售价将低于Enr的指数。新利18备用
