indoor

Indoor refers to spaces or activities located inside a building or other enclosed structure. It is the opposite of outdoor, which describes spaces exposed to the open air. Indoor environments are designed to provide shelter, safety, and comfort through controlled temperature, humidity, lighting, and air quality, as well as built features such as walls, floors, and ceilings.

Indoor spaces are diverse and purpose-built. Residential interiors include homes and apartments for living and personal care, while commercial interiors cover offices, shops, and service venues. Institutional spaces include schools, hospitals, and government buildings. Industrial interiors accommodate manufacturing, warehousing, and logistics. Design considerations address layout, accessibility, safety codes, acoustics, and energy efficiency.

Indoor environmental quality (IEQ) refers to the overall health and comfort of indoor spaces, incorporating ventilation and air filtration, moisture control, thermal comfort, lighting quality, and sound. Poor IEQ can contribute to health issues, reduced concentration, and fatigue. Standards and guidelines from organizations such as building codes and environmental agencies encourage adequate ventilation, clean air, moisture management, and low-emission materials.

The concept of indoor life expanded with modern architecture and climate control, enabling year-round occupancy and new work and living patterns. In recent decades, emphasis has grown on sustainable design, energy efficiency, and healthy indoor environments, leading to innovations in airtight building envelopes, radiant heating, LED lighting, and air purification technologies.