Residential housing had a good year in 2012, but Brooklyn’s commercial market may be doing even better. According to a new report out from Brooklyn commercial real estate firm TerraCRG, there were 40 percent more commercial sales in 2012 than in 2011. The $4.38 billion in sales was double that of 2011. Development sites zoned for residential buildings were in the most demand. Investors spent $695 million on these sites, up 221 percent from 2011. Mutifamily sales accounted for $1.3 billion and 585 transactions — the most of any category. Bed-Stuy, Bushwick and Crown Heights (which the report lumps into a single zone) had more commercial transactions than any other area considered by the report — 529 in total. Investors may also be getting more comfortable with larger purchases: there were 59 sales topping $10 million, about twice the number in 2011.