The Architecture Billings Index (ABI) closed 2015 in positive territory. Demand for design services increased in eight out of 12 months last year.

“As has been the case for the past several years, there continues to be a mix of business conditions that architecture firms are experiencing,” said AIA Chief Economist Kermit Baker in a statement.  “Overall, however, ABI scores for 2015 averaged just below the strong showing in 2014, which points to another healthy year for construction this year.”

The ABI is the leading indicator of construction activities that reflects the approximately nine to 12 month lead time between architecture billings and construction spending. The December ABI score was 50.9, up from 49.3 in November. As Kermit Baker will have you know, any score above 50 means an increase in billings.

The December new projects inquiry index was 60.2, up 1.6 points from November, while the design contracts index was down 2.5 points, to 51.0, over the same period. The national, new projects inquiry, and design contracts indices are calculated monthly.

Except for the Northeast with 46.7 (a 0.5 increase over November), the regional numbers were down for December. The West was at 53.7; the South, 53.3; and the Midwest 46.1. (That’s a decline from 54.5, 55.4, and 47.8, respectively.)

The sector index breakdown fared similarly. At 46.5, mixed practice was down 1.1 points from November. Multi-family residential fell 0.9 points to 52.9, whilecommercial/industrial billings fell to 47.3, from 51.0 in November. Institutional billings saw a gain of 0.2, to 52.2, for December. The regional and sector categories are calculated as a three month moving average.