How do you prevent mold in small commercial and residential buildings? By removing the water, according to a speaker at aASHRAEpublic session earlier this year. Simple steps to remove mold in small commercial and residential buildings by decreasing humidity were presented at the public session held here during ASHRAE's Winter Meeting. There needs be a shift in designing buildings in different climates as well as greater attention paid to the rule that water moves from warm temperatures to cold, according to Joe Lstiburek, Ph.D., P.E., Building Science Corp., Westford, MA.