
I hate to be this sort of guy. But if you had read the article it mentions a study that found exactly the opposite of what you claim.
Researchers have also found that even in most cold North American climates, the energy savings from cool roofs during warmer months outweigh any added heating costs in the winter.
That’s not disproving what the article said. Heating can dominate while the impacts of white roofs are still beneficial.
For one, the sun is far more active in summer than winter, especially further up north.