Korvausilma

Korvausilma, translated as make-up air, is a term used in Finnish building services engineering to describe air that is intentionally supplied to a space to compensate for air that is exhausted, drawn off by ventilation systems, or lost through building leaks. The concept is essential for maintaining indoor air quality, pressure balance, and proper operation of mechanical ventilation.

Korvausilma is most relevant in spaces with significant exhaust ventilation, such as kitchens, bathrooms, industrial areas, or highly airtight buildings. If air is removed without adequate replacement, negative pressure can develop, causing backdrafts, infiltration of outdoor pollutants, and discomfort. Make-up air can be provided through dedicated ducts from outside, via infiltrations controlled by dampers, or through mixed strategies that combine mechanical supply with controlled openings. In colder climates, cor­rect tempering and filtration of korvausilma are important to avoid heat losses and to protect indoor air quality.

Design and operation considerations include appropriate sizing of the make-up air flow, placement of supply diffusers to prevent drafts, filtration to remove outdoor pollutants, and coordination with exhaust systems to achieve air balance. Automatic controls and building management systems often regulate korvausilma based on measured exhaust, room pressure, or occupancy and pollutant loads. Common challenges involve avoiding uncomfortable drafts, excessive energy use, or unintended pressure differences between spaces.

Regulatory guidance for korvausilma exists within Finnish building standards and ventilation guidelines. Practically, the term appears in architectural and engineering documentation as part of ensuring balanced and healthy indoor environments. See also ventilation, make-up air, air balance, and indoor air quality.