in case anyone is intrested:
$('#Type').change(function (e) {
var val = e.target.value;
var ddL = $('#Units').data("kendoDropDownList").dataSource;
var length = ddL._data.length;
if (length != 0) {
for (var i = length; i >= 0; i--) {
ddL._data.remove(ddL._data[i]);
}
}
if (val == "Electric") {
ddL.add({Text:"-", value:"null"});
ddL.add({Text:"kW", value:"kW"});
ddL.add({ Text: "GJ", value: "GJ" });
}
else if (val == "Natural Gas" || val == "Fuel Oil") {
ddL.add({ Text: "-", value: "null" });
ddL.add({ Text: "ft³", value: "CubicFeet" });
ddL.add({ Text: "therms", value: "therms" });
}
else if (val == "Water") {
ddL.add({Text:"-", value:"null"});
ddL.add({Text:"Gal", value:"Gallons"});
ddL.add({ Text: "L", value: "Liters" });
}
})