A good snow roof has good ventilation and insulation.

When it comes to ventilation the International Residential Building Code otherwise know as IRC is the most recommended standards.

IRC Standards (click here), there are several sections on roofs, but, ventilation and/or exhaust systems is what one would be looking for.

The best source of measuring the quality of the insulation for a home is through the DOE of the USA.

Department of Energy (click here)