planning natural ventilation at the design stage avoids the need for costly ventilation systems
Ventilation
Why is ventilation so important?
- Ventilation removes unwanted heat from internal spaces on warm days. The movement of air over skin also helps to keep people cool.
- Ventilation helps to provide fresh air to a space and remove stale air.
- Building and furniture materials emit chemicals into the air which can be harmful to human health. Ventilation helps to remove these chemicals from the house.
- Ventilation helps to remove moisture from the house (e.g. from cooking and showers, but also from people).
Our design decisions on ventilation of the house are covered in the Project Blog called Passivation. We have decided to keep the ventilation simple but effective and use natural ventilation throughout with mechanical ventilation in high moisture areas such as bathrooms (extractor fan) and kitchen (rangehood). 
Windows to on the north and south elevations allow cross ventilation through the main spaces (image shows ground floor)
We are including the following features to provide good natural ventilation:
- Windows that can be left securely open throughout the day, even when the house is unoccupied.
- Opening windows in every room.
- Opening windows on opposite sides of the room where possible to allow cross-ventilation.
secure opened windows allow ventilation through day, avoiding overheating and a stuff house in the evening
For natural ventilation to be effective we will have to think about how we use the house. This will be easy for most of the year, but may need a little more careful consideration in the winter to maintain reasonable internal temperatures. For example, opening the windows when there are high internal gains (like when you have all your mates round or are cooking a big dinner) or opening the windows on the morning of a sunny winters day when there will be sufficient solar gain to reheat the house.
In order to remove moisture in the house the following practises will need to be considered:
- Turning on the mechanical ventilation system as soon as moisture is produced, for example turning on the kitchen ranghood when cooking or the bathroom extractor fan when having a shower.
- Keeping steaming cooking pots near the kitchen exhaust.
- Opening windows in the kitchen when steam is being produced away from the kitchen exhaust, for example when pouring hot cooking water into the sink or washing up.