Returning zeros if null

Returning zeros if null

I have a select statement
select
name
,age
from table_employees
where id=@impId;
I want to check if age is null than return zero. I tried following but it
doesn't work
select
name
,age isnull(age,0.00)
from table_employees
where id=@impId;
Please let me know how to fix this. Thanks