The house will be completely mechanically ventilated and none of the windows will be open-able. The system will change the air in the house at least 10 timesĀ each day so keeping the air very fresh. The system will formed from the following parts (from input to output):-

  1. Earth Tubes
  2. Inlet Filters
  3. Counterflow Heat exchanger
  4. Fan
  5. Distribution to all rooms
  6. Extraction from all rooms
  7. Extract Filters
  8. Fan
  9. Counterflow Heat exchanger
  10. exhaust to outside

Earth Tubes

Air will be collected from under the garage roof eaves on the side of the building and routed to a set of 12 tubes (150mm Twinwall plastic pipes) buried 2.5m underground. These tubes will then run to the house over an average distance of 17m. While passing through the tubes the air will be conditioned to a relatively stable state, approximately 15 degrees C and any excess humidity removed. The earth at this depth has little seasonal variation in temperature and will only vary slightly with the seasons and air passing through.

Inlet Filters

On entering the house the air will pass through a set of filters. These will a number of filters in sequence progressively getting finer until the final electrostatic filter.


Both incoming and outgoing air will be moved by centrifugal fans.

Counterflow Heat exchanger

This is a device made of multiple layers of air separated by thin films. All even layers the air flows from inside to out and odd layers from outside to in. The air flows are inĀ opposite directions. When the fresh air exits the exchanger it will be nearly the same temperature as the outgoing air, thus most of the energy in the air stays inside the house (90%+).

Distribution to all rooms

The air will then be piped to all rooms with adjustable air flows into each room. The air will be distributed by continuous vents along the skirting boards. The feed to each room will have a adjustable heater to give complete control of the temperature of each room.

Extraction from all rooms

Air will be collected from each room from a central point in the ceiling and ducted back to the utility room. Again the extract rate will be controllable for each room.

Extract filters

A fairly coarse filter to remove most of the dust from the air so as not to clog up the heat exchanger.

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