Airtightness Assessment of Residential buildings
What we do for your home

We help clients achieve greater energy efficiency and occupant comfort levels by identifying air leakage issues in their premises enabling informed remedial action to ‘make the building tight and ventilate it right’. We do this in 4 key ways:
  • Advisory prior/during design & construction to advise or offer direction in achieving an airtight building.
  • Inspection during the build to air sealing is being performed through the construction stages
  • Airtightness testing during construction phase of your new building or during a refurbishment – to verify the airtightness target of the design is being met/exceeded. 
  • Diagnostics - should the airtightness target not be met we can perform detailed diagnostics utilising physical inspection, tracer smoke and thermal imaging technology, to produce a report, highlighting remedial actions for your builder.
What Do You Do?

What do you do when the weather is getting cooler and your home is getting cold and uncomfortable? 
Typically the actions would be:
  • Close all external doors.
  • Close all windows.
  • Turn 'ON' the Heater.
 Most people would see that it would be wasteful to turn ON the Heating whilst leaving any external door or window 'open.'

What do you do when the weather is getting hotter, and your home is getting hot and uncomfortable?
Typically the actions would be:
  • Close all external doors.
  • Close all windows.
  • Turn 'ON' the Air Conditioner.
Most people would see that it would be wasteful to turn ON the Air Conditioner* whilst leaving any external door or window 'open.'
(* note: this does not apply to Evaporative Cooling systems which require some open windows or external doors for air flow.)
What is not thought about is that there are almost always many unnecessary gaps and cracks in the building envelope which, when added together, are often the equivalent of a permanently open window.
A 'window' that is OPEN all of the time, night and day, continually draining away your heating and cooling energy, and the dollars you've paid for that energy. Your comfort and your dollars needlessly drifting out into the atmosphere.
Sometimes the fixing of air leaks is called "draft proofing" - though that is usually just scratching the surface and dealing with the obvious air leaks - door and window seals, bathroom exhaust fans,... what we're talking about here are the 'holes' that you do not know about and might never find otherwise.

blower door test, fan door, air permeability, air pressure testing, thermal imaging, thermography, condition monitoring
Flame producing appliances :
You must seek a out appropriate advice and make sure that flame producing appliances are installed by appropriately skilled and qualified people.
If you have a flame producing device - fireplace, combustion heater, gas stove/oven, kerosene heater,..etc or even just lots of candles - then you must for example have a sufficiently leaky building (not ideal!), additional openable vents, a good 'Controlled Ventilation' system (ideally Heat Recovery Ventilation) or other means of keeping the internal air quality good. For "flame" devices to work they must have available air to draw in and burn to produce heat, and for the gases from the flame to be able to be expelled effectively from the building.
Traditionally adequate (excessive) fresh air flow was achieved with the fitment of extra (and energy sapping) external vents throughout buildings.

Fireplaces :
You must seek out appropriate advice and make sure that fireplaces are built by skilled and qualified people. Even with a fireplace you can still achieve good airtightness when the fireplace is not in use via the fitment of modern high quality dampers to control the chimney and fresh air to the room.
                                    From Sustainability Victoria - Chimney Damping   

For very airtight buildings :
Buildings with very low air leakages rates - and thus usually great energy savings potential - will likely require installation of full time fresh air mechanical ventilation to ensure adequate fresh air supply to every room. (eg. Heat Recovery Ventilation systems in cool and temperate climates, and Enthalpy Recovery Ventilation systems in Humid climates.)

Your level of airtightness will determine the need to fit Carbon Monoxide, Carbon Dioxide or Oxygen detectors to warn you if those gas levels get out of range. eg. You need some monitoring and warning system in case the mechanical ventilation system fails to bring in enough fresh air due to; power outage, equipment malfunction, filters getting clogged, vents being obstructed, ...etc. you need some warning system.

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Sealing of penetrations

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Fan Door set up (aka Blower door)

Thermal Image showing air leakage at a window surround.
Air leakage is shown here as darker coloured streaks indicate that there are gaps where external air is entering the room.
Airtightness - Benefits of improving the building:
  • Identify contributors of heating, cooling and comfort issues which can be remedied to improve occupant comfort, typically decreasing unwanted draughts and hence allergens, dust and dirt.
  • Increase the value and attractiveness of the property/development to future investors.
  • Obtain verification of the actual building envelope performance. i.e. quantify how “leaky” your building is for comparison to benchmarks.
  • Better building airtightness leads to a reduction in loss of conditioned air and hence lower energy bills, better rejection of outdoor noise, and helps make the building "feel" better to be in.
  • An added benefit of having an airtight building is a reduction in your carbon footprint as you lose less energy through the building envelope. i.e. reduced environmental impact.


  • Prior/during design to advise or offer direction in your approach to achieving an airtight building.
  • Conduct an on-site briefing on how to build airtight with Builder and Site Manager who in turn can brief the trades people used.
  • Inspection to check air sealing is being performed through the construction stages.

Airtightness/ Blower Door Test

  • Gaps are often obscured by internal building finishes or external cladding. The only satisfactory way to verify that the building fabric is reasonably airtight is to measure the leakiness of the building fabric as a whole.

  • We do this by performing a blower door/air pressure test of the building. The fan creates a pressure differential to outside and measures air leakage over a range of pressures to return an air leakage result, measure in ACH (air changes/hour).


  • If the test result does not meet target, we can locate where air leakage is occurring.

  • With the blower door running we use diagnostic tools such as an infrared camera and tracer smoke to locate leakage areas. The images and recorded data is compiled in an audit report which provides the customer/builder with specific areas for sealing/remediation.


3ARK Brochure of Airtightness services.

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3ARK House Airtightness Services

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Life cycle for delivering an Airtight Home

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3ARK, helping people to reduce energy costs.

Fan door

Two fans set up for air leakage testing.

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Retrotec Trained lead testers.
Certified to Level 1, 2 and 3 (large/complex buildings) in the use of Fan Door for Air Leakage Testing in Large Buildings..
IR image of a floor heating vent and window.
The darker areas show the outside cool air that is leaking into a room - at the skirting boards, window sills and surrounds, around the floor vent,..
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Thermograph of a House Identifying escaping heat..
Water Ingress onto plaster ceiling.
New roof sheeting (and membrane) had leakage issues evident after a severe storm.
See regular photo at RIGHT --->
Door leaks

Heated air getting out at the top right of the door. Cold air getting drawn in at the bottom of the door.

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Wall mounted Air Conditioner.
Air leakage behind the unit at the lower left where its refrigeration piping passes through the wall.

Normal appearance of plaster ceiling.
No evidence at all of the water that has pooled on top of the plaster ceiling. Eventually the water damage will become apparent and generally cost a lot more to repair.
Missing ceiling insulation