What is the warmest part of the building in winter?

In winter, the warmest part of a building is typically the south side. This is primarily due to the angle of the sun's rays during the colder months. The southern exposure receives the most direct sunlight throughout the day, which helps to warm the building more effectively. In many climates, especially those in the northern hemisphere, the south-facing side is most likely to benefit from solar gain, making it warmer compared to the other orientations.

The factors influencing this warmth include the positioning of windows, roof overhangs, and even the landscaping surrounding the building. Decisions such as placing large windows or patios on the south side can enhance the thermal comfort of a space during winter months by allowing more sunlight to enter and warm the interior. Consequently, when designing or positioning a building, it's advantageous to consider maximizing southern exposure for heating efficiency in colder seasons.