Tight, energy-efficient envelopes change how fresh air enters a building. In new construction, ventilation is not an add-on—it is part of the thermal, moisture, and health strategy from the first line on the drawing.

1. Design to real occupancy

Air-change rates should reflect how many people will live or work in the space, moisture loads from cooking and showers, and any hobby rooms with extra ventilation needs. Undersizing leads to stale air and mould risk; oversizing wastes energy and can create noise or draft complaints.

2. Mechanical vs. “natural only”

High-performance homes increasingly use balanced mechanical ventilation with heat recovery (MVHR). It keeps filtration and humidity control predictable year-round. If you rely only on trickle vents and bathroom fans, verify that the architect’s air permeability targets still allow reliable background ventilation after blower-door testing.

3. Ductwork that actually performs

Smooth routing, minimal bends, sealed joints, and correct insulation on cold-side duct runs prevent condensation and pressure loss. Poor duct installs are a leading cause of “the unit is fine but the rooms are stuffy.” Commissioning should include measured flow at terminals, not only “it runs.”

4. Kitchens and wet rooms

Extract hoods that recirculate carbon filters do not remove moisture. Plan dedicated extract to outside where codes allow, and coordinate make-up air so you do not depressurise a tightly sealed house in a way that pulls flue gases or radon inward.

5. Filters, maintenance, and handover

Specify filter classes, change intervals, and who owns maintenance after handover. Leave labelled drawings, balancing reports, and access panels so future owners can keep the system effective for decades.

Closing. Indoor air quality in new builds is a systems outcome: envelope tightness, ventilation design, installation quality, and commissioning together. Treat ventilation with the same rigour as structure or waterproofing, and occupants notice the difference immediately.