What type of heating system is required to maintain a suitable indoor temperature?

Active or passive space heating systems are both necessary to maintain a suitable indoor temperature, making this the correct choice. Active heating systems, such as furnaces and heat pumps, use fuel or electricity to generate and distribute warmth effectively in a building. They can respond quickly to changes in temperature and can be automated for efficiency.

Passive heating systems, on the other hand, utilize building design, materials, and orientation to maximize solar heat gain and minimize heat loss without mechanical means. This can include features like large south-facing windows, thermal mass materials, and appropriate insulation.

The combination of both systems is essential in creating a comfortable indoor climate. Depending on various factors such as geographic location and building characteristics, one type may be more prominent than the other in different scenarios. However, relying solely on passive systems would not guarantee adequate heating in all conditions, particularly in colder climates or during extreme weather events. Thus, integrating both active and passive systems offers a comprehensive approach to heating that meets varying demands efficiently.