The Architecture Billings Index (ABI) concluded the year in positive terrain, with the December reading capping off three straight months of growth in design billings.

The American Institute of Architects (AIA) reported the December ABI score was 52.9, down from a score of 55.0 in the previous month. This score still reflects an increase in design services provided by U.S. architecture firms (any score above 50 indicates an increase in billings).

The new projects inquiry index was 61.9, up from a reading of 61.1 the previous month, while the new design contracts index decreased slightly from 53.2 to 52.7.

“Overall, 2017 turned out to be a strong year for architecture firms. All but two months saw ABI scores in positive territory,” said AIA Chief Economist, Kermit Baker, Hon. AIA, PhD. “Additionally, the overall strength of the fourth quarter lays a good foundation for healthy growth in construction activity in 2018.”

Key December ABI highlights:

• Regional averages: South (56.3), West (53.0), Midwest (52.9), Northeast (49.4)
• Sector index breakdown: multi-family residential (55.4), commercial / industrial (54.8), institutional (51.2), mixed practice (50.4)
• Project inquiries index: 61.9
• Design contracts index: 53.2

(The regional and sector categories are calculated as a 3-month moving average, whereas the national index, design contracts and inquiries are monthly numbers.)