Building For The Environment.
The basic function of a building is shelter – essentially to keep us safe, from the elements and also from predators. Our ancestors devised ways to use the environment and its natural offerings to provide them with shelter and meet their ‘needs.’ eg. caves, stone, earth, ice, animal hide, and plants such as; timber, leaf, straw and thatch.
Many historic structures had excellent qualities – some performed better in certain respects compared with those of today.  For example, using raw materials:
  • A cave has a great thermal mass for maintaining even temperature throughout the seasons, and ideally only one opening so that air is not able to blow through it.
  • Mud, wood and thatch facilitate the construction of well insulated structures.
  • Using only ice, an igloo can be constructed enabling occupants to survive a fierce arctic storm.
Such structures often had a means of heating and of controlling ventilation (eg. fireplace, flaps over openings, doors).

Modern buildings are still required to meet those basic needs of safety and shelter. Additionally, due to our exploitation of cheap energy sources (eg. coal, oil, gas,..), we’ve been able to add many luxuries such as air conditioning – hence the term “Conditioned Space” referring to the area of a building that is ‘lived in’ and which typically is conditioned by heating and cooling systems, as opposed to “un-conditioned” spaces within a building (eg. garage, plant room).

Instead of working with nature we have come to use technology and cheap energy to conquer nature and create our desired environment “on demand.”  Whenever our indoor environment is uncomfortable, we often take the easy way out and ‘hit the switch’ to satisfy our wants.
           Too hot? – Switch ON the Air Con.
           Too cold? – Switch ON the Heating.
           Too cold here and too hot over there? – Switch ON both, Heating AND Cooling!

This has contributed to increasing overuse of fossil fuels which has had serious effects on our environment, and on our future. The need to reduce our energy requirements was identified decades ago, and whilst we have made progress (via better; building design, insulation of buildings, HVAC and appliances, renewable energy sources), our energy consumption continues to grow.

How do you reduce your energy usage without compromising on comfort?
All buildings lose energy – the critical issue is how quickly they lose it. The quicker our buildings lose the energy we put into them, the more energy we must continue to add to maintain the conditions that we want. If we slow down the rate of energy loss, we’ll need less energy input to maintain our desired conditions.
Concepts such as those of “Passive House” promote the approach of intelligently designed structures in which the Conditioned Space has excellent energy retention properties, and so requires less energy input to meet our needs (safe shelter) and our wants (comfort and luxury).
If the energy put into a building cannot escape, or at least not easily escape, the building will:
  • require less energy input in the first place to become comfortable,
  • retain maximum effect of the energy that is put into it,
  • need less ongoing energy input to maintain the status.

Energy gain and loss (ie. transfer) occurs in three ways :
  • Conduction - energy passing through a material. eg. wall, ceiling, glass, floor, window frame,..
  • Radiation    - the waves of energy emitted by an object. eg. the sun’s energy warming an external wall.
  • Convection - the energy carried via a fluid or air/gas. eg. hydronic heating, gas ducted heating, a breeze through an open window or door, drafts through holes or gaps.

To reduce the incidence of Conduction (including Thermal Bridging) and Radiation we can use materials with insulating properties or components (eg. masonry, timber, polystyrene, insulwool insulation in walls and ceilings, double glazing, thermal break window frames, lagging on heated/chilled water or refrigerant piping,...)

To reduce the incidence of Convection requires the structure to have, low air leakage (ie. ideally no uncontrolled air flow through gaps/cracks/cavities/poor appliances or fixtures,...)

You can ‘see’ the; insulation, plaster, brickwork, woodwork, double glazing and so on.
You cannot readily ‘see’ whether a building has low air leakage (ie. good airtightness).
However, without a good level of building airtightness, significant energy can simply, quickly and continuously be lost to the atmosphere. ie. Uncontrolled air leakage or air infiltration to/from the outdoors.

     Just as, "Many hands make light work..,"  many gaps will make light work of losing your building's energy.

Airtightness is a “passive” means of saving energy – once you have it, it does not generally incur further cost, though you do have to maintain it. (eg. repair and seal any gaps that appear over time, and be vigilant that any work on the building is carried out carefully and with a view to maintaining its airtightness.)

Poor airtightness will effectively drag down the performance or potential benefits of everything else as energy simply ‘pours out’ through the gaps.

Achieving good Airtightness.
Airtightness will not happen by accident. Many materials (elements) may be involved in the formation of an Air Barrier (ie. Building Envelope) which will separate the ‘conditioned space’ from the ‘non-conditioned space.’
eg. Plasterboard, membranes, masonry walls and floors, window glass, window frames, external doors, timber, structural steel, sealing tapes, caulking, glazing, …etc.
Achieving a good level of airtightness requires a well-planned approach including:
  • Airtightness Design: Intelligent building design incorporating:
    • a thoroughly defined air barrier with details on all transitions (eg. element to element, element to structure,…) and appropriate bonding methods (eg. tape, glue, caulk, primer paint,… that are specifically suitable for achieving long lasting airtightness)
    • an air leakage target,
    • a suitable HVAC providing and maintaining adequate fresh air intake,
  • Airtightness Elements: Selection of appropriate materials and products that can form an effective air barrier.
  • Airtightness Build: Correct construction, installation and transitioning of the elements is essential. The air barrier must be secure and strong enough to cope with air pressure differences created across it by; wind, stack pressure, HVAC systems and so on, and to ensure a lasting and uninterrupted barrier to uncontrolled air flow (ie. air leakage).

It is not enough to have the right ingredients – you also need the right recipe and techniques to put it together effectively.

If the above "Airtightness" points are properly executed the result will be an ‘Air Barrier System (*1)’ (or simply ‘Air Barrier’) which effectively restricts the air leakage of the enclosure.
* Note 1 – the Air Barrier is not necessarily in the right place to also be a Vapour Barrier, which sometimes needs to be located differently and thus be a separate system.

Once built, performing a quantative Air Leakage Test (*2) will confirm whether an effective Air Barrier System has been established - this is the only way to determine the actual leakage rate of the Air Barrier system. Once the actual air leakage rate is known you can decide if it is right for your requirements, or whether the Air Barrier System needs further attention.
* Note 2 – an Air Leakage Test is also known as; Airtightness Test, Building Envelope Test, Air Barrier Test, Fan Door Test, Blower Door Test.


Effectively, insulation (including eliminating thermal bridges) and airtightness are two sides of the same coin.
One addresses energy loss 'through materials' to the outside.
The other addresses energy loss 'through gaps' to the outside.

Without good airtightness a building will indefinitely and excessively lose energy.
You can choose to accept this excessive energy loss and compensate for it by having your heating or cooling running more intensely, or more frequently, to keep you comfortable. This will incur higher energy needs typically leading to more costs and greenhouse gas emissions.
Alternatively, you can compromise and put up with less comfortable conditions to limit your energy usage.

Having a building that is well insulated is a passive way to reduce energy loss.
Having a building that is ‘airtight’ is a passive way to reduce energy loss.

Both are required to achieve the best performance.

A reduction in energy losses typically enables:
  • Smaller HVAC requirements. (eg. reduced - size, load, running time, maintenance costs, ..)
  • Fewer resources used in the manufacture, transport and installation of smaller HVAC.
  • Lower energy usage and lower associated costs.
  • Lower greenhouse gas emissions by industry and by you.
You can of course save energy costs by generating and even storing your own. eg. Solar PV and batteries. But with a well insulated and well sealed building, you'll typically need LESS PV and LESS batteries because your HVAC will require less energy.

The ideal way to ‘save’ energy is by not needing to use it in the first place.

As good as they may be, all high efficiency “active” devices still consume energy.
             eg. Regardless of how good your high efficiency Air Con is, it still needs some electricity from somewhere.

The more “Passive” our buildings are, the better.

If your building is very well sealed and very well insulated, you might not need heaters or air cons at all. Your electricity or gas needs might then be very low and you might require:
- Less PV panels to buy, install, maintain,..
- a smaller inverter,
- less battery capacity,
- less heating gas or electricity to buy,

You might even start to approach "Passivhaus" type efficiencies. Imagine that - all buildings needing only a fraction of the energy that they consume today.
That's one achievable way that Australia might meet its Climate Action commitments.


Heard about Passivhaus?

Is it for eccentric people?

Passiv / Passive - in terms of building materials it means something that does not require power to do what it does. eg. once made things such as; double glazed windows, insulation, airtight construction, thermal mass, appropriate shading over windows,... do not need a power supply to do what they do.
Examples of "Active" items (ie. requiring power input to function) are; reverse cycle air/con, HRV, gas heater, electric pumps,..
Get your Passive components right and you'll need less Active components.

HAUS - A German word for house or building.
eg. house, schoolhouse, opera house, parliament house, warehouse, council chamber, hospital, high rise, officeblock, theatre,...virtually any building.

PASSIVHAUS - The German name of a particular standard that specifies strict criteria for building design and energy efficiency. it started with houses but can, and is, being applied to many building types.

Passive House - Anglo Saxon phrase relating to PASSIVHAUS, but often taken literally (erroneously) as only applying to houses. Passive House principles can be applied to any building.


Most 'Passive House' buildings in the world to date are actually houses, but that is changing with many commercial buildings now certified PH. If you want to seriously reduce your heating/cooling energy needs, take a good look at Passive House. You will see that PH ideas are starting to appear in regular buildings, and even applying just some of the principles can make a big impact.

A little bit more...
Embodied energy - from Wikipedia "Embodied energy is the sum of all the energy required to produce any goods or services, considered as if that energy was incorporated or 'embodied' in the product itself. The concept can be useful in determining the effectiveness of energy-producing or energy-saving devices, or the "real" replacement cost of a building, and, because energy-inputs usually entail greenhouse gas emissions, in deciding whether a product contributes to or mitigates global warming. "

image-972784-pergola.jpg
All the best equipment, but for some reason it's still

impossible to keep cool in summer, or warm in winter!



Resources on Airtightness
Government sites
Sustainability Victoria  -     Services and advice - Draft Proofing

International Specialised Skills Institute - Report


Zero Carbon Hub   Builder's Guide          A British guide on building more efficient homes.  (note - There's a lot to learn from European efficient building ideas. They've been at it for a long while.)


Passive House is not just about 'houses' - the principles are being applied to commercial buildings, hi rise apartments and more.

University of Woollongong