As a general rule we don’t recommend the use of turbine roof vents (also called “whirlybirds”). These vents are designed to draw air out of the attic when the wind catches their fins.
Unfortunately, in homes that are not “air-tight” it may draw conditioned air (heated or cooled air) up and out through the ATTIC space. In “air-tight” homes, turbine roof vents may cause back drafting to occur with fossil fuel burning appliances (e.g. gas furnace) allowing dangerous by-products of combustion such as Carbon Monoxide (CO) to enter the home. They can also be noisy when in operation and let rain / snow in. Further, if this type of vent is truly needed to vent the attic they will only work as intended in the presence of a breeze.
Ventilation of attic spaces is important and can maximize comfort levels, energy efficiencies and life spans of roof coverings (e.g. shingles), roof decking / underlay material (e.g. plywood sheathing) and the structure itself (e.g. rafters, trusses) when accompanied with proper, and sufficient, insulation and vapour barriers. Attic ventilation when accompanied with proper insulation can assist with “ice damming” issues too. A general rule of thumb is to have about 40% of the venting at the roof ridge area and about 60% from the soffit areas.