Natural ventilation, or lack of.

The modernist triumph of bare-arse glass for fully airconditioned office buildings has become the ubiquitous answer for high rise residential.

Brisbane is now plagued by them. Pretty much the same for other Australian capitals with different climates.

The first dilemma on observation is: is it office or residential. A slightly open sash is espied.

Maybe residential – since when has an office building had an openable window?

Through a gap in the onslaught of glass a recess in the façade is seen; maybe a veranda camouflaged by the glass balustrade merging into the amorphous sheen.  Fair chance it’s residential. (I detest modern glass balustrades.) Then the open slit of a window leads one to wonder: is that all the natural ventilation needed to comply with the National Construction Code [NCC] for habitable rooms. It is minuscule.

The NCC 2019 Vol. 2 Part 3.8.5 says: Ventilation requirements

Ventilation must be provided to a habitable room, sanitary compartment, bathroom, shower room, laundry and any other room occupied by a person for any purpose by any of the following means:

[a] Openings, windows, doors, or other devices which can be opened—

With a ventilating area not less than 5% of the floor area of the room required to be ventilated …

Explanatory information:

The ventilating area of the window is measured as the size of the openable sash of the window. This is the case regardless of the type of window, i.e. whether it is an awning, casement or sliding window and irrespective of the restrictions on the openable sash.

“irrespective of the restrictions on the sash” I interpret as it can open 1mm and comply. This clause flabbergasts me, and I want my understanding to be wrong.

Should readers of the codes –  as I did –  imagine the 5  per cent ventilation area would be free of obstruction, you are wrong. What is the actual open area? An awning window, as the now only seen answer in these high-rise unit blocks is the example.

Allow a room of 12 square metre – average for a bedroom. At 5 per cent of the habitable floor area 0. 6 sq m results giving a sash 1 metre high by 0.6m. Child safety requirements result in an opening of 125 mm maximum.

To always comply, and avoid litigation, few to none would not lessen the 125 mm. At 125 mm the true open air area is 0.15 sq m. Four windows are now needed to achieve 5  per cent – not one!

If the window is insect wired more ventilation is blocked.

Some councils demand “don’t perve-on-your-neighbour screens”. The maximum open area of such screens in Brisbane is 25 per cent up to 1700 mm above floor level. So, 75 per cent more air is blocked.

If the NCC believes in 5 per cent of the floor area –-nothing else –  the clause should become:

With a ventilating area not less than 5 per cent of the floor area of the room to be ventilated.

Explanatory Information

The ventilating area is measured as the unobstructed area at 90 degrees horizontally to the wall. For any obstructions the opening size is to be increased to ensure the minimum. Common obstructions are: sashes in their most open position, fixed insect screens and any other fixture.

The NCC has eight climate zones in the energy efficiency section and none in ventilation. Ventilation minimums must also vary for the zones.

I lived in Port Moresby in a Commonwealth government designed house built after WW2 like those in Darwin. The ventilated wall area of all rooms was close to the floor area: 100 per cent – and the NCC says 5 per cent for Darwin is enough!

While I lead an almost fully unairconditioned life, many readers possibly went from an AC birth, home in an AC car, to an AC house, to an AC school, to an AC workplace and view an openable window as unnecessary.

Recent events with Covid 19 must cause them and the NCC to be concerned. It is well to remember a report years ago that concluded the healthiest housing was the most air leaky.

Professor Lidia Morawska director of QUT’s International Laboratory for Air Quality and Health  said on ABC News:      

“We don’t have any quantitative data about this and, of course, every environment is different, but what I do if I go to any place, I look around. How many people are there? How, according to my judgement, is the place ventilated?

“If I see that potentially in not ventilated places, the risk is high, I don’t go in there.”

On Coronavirus and AC she adds,” [Recirculation] can bring back the virus into the supplied air. So, ventilation as high as possible and no air recirculation.”

Why does the NCC have such a small minimum at 5 per cent and then allow the area to potentially be zero per cent and comply?

Maybe: [a] developer lobbying to cut costs as openable windows cost more than fixed glass, and now AC units are foolishly considered as essential as underpants for modern life.

The flogging real estate agent would say,” If it’s not there, it won’t sell.” [b] child safety is viewed as primal and all other requirements are sacrificed.

Neither cuts the mustard.

Developers waste money on multiple toilets based on the same “won’t sell” argument. If such indulgences   must go for openable windows to be built at the same cost—great! Money spent where it should be.

I find it incomprehensible that the Australian Building Codes Board (ABCB) — drafters of the NCC– would allow a non-true ventilatable area to be reduced for safety reasons when it is dead easy to solve the child danger problem and have the ventilation.

Maybe they should ask their parents how they stopped them falling out of cots with more than 100 per cent ventilation area.

If there are any doubts about fresh air, recent images of 14-day quarantines exiting to the street from rooms –  most likely with fixed glass and only AC in expensive hotels –  exclaiming with euphoric glee: “Fresh air! Fresh air!” And the high-rise Victorian Housing Commission flats with windows opening to a slit at the sill, successfully fulfilling can’t-fall-out-of-window demands while looking like a prison, should prove the health benefits of access to fresh air.

After all, external air is ultra-violently sterilised [sunlight] as opposed to toxicogenic recirculated air.

ABCB must redress what they have allowed to happen and what healthy building design needs to be, as revealed by Covid19.

If they applied the same logic to a fire escape door as the ventilation area of a window sash it would be: “the fire door has to be of a size to allow two humans to pass through simultaneously. The escape area is measured as the area of the door irrespective of the restrictions placed on the door.”

Finally, to avoid discrimination against fresh air, I wish to suggest to the ABCB: an openable window can be closed, fixed glass cannot be opened.

Russell Hall is a Brisbane-based architect with experience in residential, retail, commercial and industrial design. He is interested in designing whatever comes along.

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  1. All these ventilation problems presuppose that the air outside is fresh and breathable. Once upon a time I was in that mode too … if there were no openable windows in the apartment, I was not interested. Give me an old place any day, where the drafts take care of winter aeration.

    There’s a lot in the news about sick building syndrome, mold, as mentioned above, and disease recirculated in aircon. Yes. I agree things must be done to improve these.

    But along came the bush-fires and smoke hanging around for days. Something else to take into consideration. Even cities copped it. A lot of people developed allergies to smoke. Heating a house in regional areas can still be done by burning firewood. Some days the allergic can’t go outside, must run the air-con all day or expect to cough all day. There’s no cure other than fixing all the issues at the same time.

  2. Hi Guys,
    Everything Russell and contributors said is this article contributes to exposing the ventilation issues, there are various solutions, I see the increase in safe modern louvre window use, with many informative YouTube presentations.

    For ventilation and cooling, louvres have been used for years, decades, centuries, even double hung- windows allowing the top window to be opened can provide security giving the same benefits.

    One major problem with louvers PRIVACY, yes you can have these” frosted,” however, no view, everyone wants privacy, therefore windows irrespective of their functioning types for opening are covered in some way.

    To this end the window coverings become a barrier and impede any air movement inwards forcing any window covering to move and rattle at times, so people close their windows. I have viewed a very slick louvre window site, basically there is no mention of window coverings.
    Wonder why?

    Providing natural ventilation was “sort of “addressed by the old-fashioned provision of building gaps and wall vents which addressed air changes, mould and condensation reduction.

    However, airtightness complimented by residential conditioning of internal stale air have stifled these provisions, compliments of the ABCB and associates with their own commercial agendas.

    Covid19 has exposed the issue of lack of natural ventilation, and the louvre widow industry are offing a solution which is compromised by NO PRIVACY.

    A better solution is required, but vested interests will stifle innovation, and regulatory bodies will sit on their hands while people are dying.

    Even when Covid19 is addressed fresh air is still required for healthy humans that then reduces jurisdictions health budgets.

  3. Thank you Russell very much for your powerful story. And the additional comments made on risks from mould compound this extremely serious situation.

    Finally we have a courageous architect to speak out about the blindingly obvious benefits and suitability of natural ventilation in residential buildings across Australia’s varied climates. Climates which have no bearing to Europe and most of North America.

    Add in COVID-19’s emergency health measures (6 July report) for increased natural ventilation to disperse viral load, by opening doors and windows, and the regulatory house energy ratings are going to be busted apart.

    Vast areas of Australia have low or non-existent winter heating requirements. Additionally, 99% of mainland Australia experiences hot or hot-humid climates.

    Russell’s missile-like attack against the ABCB is warranted.
    Ventilation is so poorly defined in the BCA-NCC.

    I contend that this was deliberately engineered by the ABCB around 2000 so as to assist the introduction of and secure the longevity of the foundational structure of NatHERS (owned by CSIRO), which is anchored and cemented on the base house assumption that all houses are artificially heated and whole house refrigeratively cooled. A ridiculous base assumption for all of Australia.

    NatHERS never provided a secondary logical option of the ‘unconditioned’ free-running mode, which was heavily advocated by a professor in tropical architecture at James Cook University.

    In 2000, a Univ Adelaide PhD academic alerted the ABCB that proceeding with NatHERS would be perilous and throw up grave errors. One of many case stories were provided. A fully ventilated Katherine home was totally energy efficient experiencing no heating or cooling costs, but achieved a zero star rating under NatHERS.

    A few weeks ago NT cattlemen won a dramatic legal case with a massive payout required to be paid to the cattlemen from the Commonwealth, as a consequence of the Four Corners program against animal abuse in overseas abattoirs.

    The international crisis of COVID-19 is contributing to the further collison and intersection of indoor air quality and residential building energy efficiency regulations.

    If the NCC 2022 allows 7 Star NatHERS to be adopted, there is a distinct chance that the federal and state governments will be exposed to legal challenge. NatHERS is incompatible with dramatically increased natural ventilation of residential buildings. I don’t pretend to have all the answers for high rise living. Such buildings are likely to face HVAC system alterations to require increases of outdoor air mixing, and UV irradiation procedures fitted to each appliance.

    It is also worth noting that the ABCB ploughed ahead in 2009-10 to adopt 6 Star NatHERS in the BCA, in defiance of the official RIS Regulatory Impact Statement expressly stating that there was no justification for 6 Star.

    Don’t hold your breath waiting for an ABCB or Standards Australia response to this important FIFTH ESTATE discussion. Neither are interested hearing or taking advice from the public, be that ordinary individuals or those with PhDs. Nearly every mandated regulation is heavily influenced by powerful commercial stakeholder interests. It’s called “Committee Capture”.

    Extensive reading on this and more, see – REPORTS

  4. This is hiding a massive issue. We are now regularly seeing brand-new buildings no longer fit-for-occupancy because apartments have overtaken by mould. This occurs because our building envelope is ‘air-tight’ (to be energy efficient), but now there isn’t sufficient ventilation to prevent a build-up of moisture from people breathing.

    Sad thing, is the Builder built to NCC, and the mechanical contractor ventilated to AS1668.2. So, it is upto the proud new owner to solve

  5. All very valid points – the ventilation openings of windows is definitely not accurately defined by the NCC with the result being apartments that often have very limited ability to be naturally comfortable. In the event of a power failure in warm weather, those apartments would quickly become uninhabitable.

    Russell, you might be interested in the 2 reports referenced in this article.