It is much warmer inside buildings in Canada so it's easier to be inside, compared with in Japan.
「室内は日本よりもカナダの方が暖かく過ごしやすいです。」は英語に訳すならこのようです。
It is much warmer inside buildings in Canada so it's easier to be inside, compared with in Japan.
室内が暖かくて過ごしやすい。→ It is warmer inside buildings so it is easier to be inside.
The insides of buildings in Canada such as houses, shopping malls, supermarkets tend to be warmer than in Japan.
カナダの室内、つまり言え、ショッピングモール、スーパーが日本より暖かいです。
Canada has central heating.
カナダがセントラルヒーティングがあります。
ご参考までに。