if you have 1/2w 1ohm resistors. paralleling them will obtain 1w 1/2ohm resistor, so if you want the resistance back 1ohm, you need another 2 parallelled resistors and put them in series, so in order to get 1w 1ohm resistor, you need 4 of 1/2w 1ohm resistors.
--\/\/\/-- = 1/2w, 1 ohm
|--\/\/\/--|
-| |- = 1w, 1/2 ohm
|--\/\/\/--|
|--\/\/\/--.--\/\/\/--|
-| |- = 1w, 1 ohm
|--\/\/\/--.--\/\/\/--|