How much fresh air is needed in a building?

An easy calculation is number of occupants multiplied by 30 m³ (1059 ft³) per hour. For example, if I have 3 people in a family home, I will need to have 3 x 30 m³ of fresh air, or 90m³ per hour. This means that I will also have to plan my system accordingly to mark out fresh air supply areas in the house - bedrooms, living room, family room - and exhaust areas - bathroom, kitchen, utility room.

Some things to consider for good ventilation:

• Right sizing systems for HRV and HVAC is critical for Passive House - ask your Energy Advisor about this!
• Extreme cold climates may need to preheat incoming air before the heat recovery ventilation unit.
• Plan for uniform ceiling heights throughout the building
• Consider durable and flexible ducting connected from the HRV / ERV to high quality vents to reduce noise.