function changeInputs() {
    var id = this.getID();
    var selected = this.getSelected().get('value');
    if (!id || !value) {
        //no id. or no value so quit
        return;
    }
    $$('tr.input_' + id).each(function(input){
        if (input.hasClass ('input_' + id  + '_'+ selected )){
            input.setStyle ('visibility','visible');
        }  else {
            input.setStyle ('visibility','hidden');
        }
    });
}

var e =  $('building_costing_mechanism');
if (e) {
    e.addEvent('change',changeInputs.bind(e));
}