It is called the tiny window problem, and it is a pane in the glass.
The spread of sash windows in high-rise apartment blocks across Sydney and other capital cities is limiting ventilation and threatening health and wellbeing, says Estelle Grech, an urban planner and director of planning, fairness and equity with the Committee for Sydney.
Under the building code, a room must have ventilation – via windows or doors – equivalent to 5 per cent of the floor space.
The problem? The size of the opening is determined by the size of the sash, the inner frame supporting a window’s glass, and not the area that can be opened.
But in most high rise, fall protection rules mean sash windows can open only to the size of a child’s head, 125mm.
Grech said the “restrictors” reduced the effective opening to 10 to 15 per cent of the sash.
“A window counted as delivering 5 per cent of floor area in ventilation therefore delivers closer to half a per cent,” she said. “The apartment complies. But it barely breathes. Just like we need to breathe to live, apartments need to breathe to be liveable.”
The committee’s chief executive, Eamon Waterford, has written to the Australian Building Codes Board (ABCB) asking it to amend the National Construction Code to measure natural ventilation by the effective opening area and not the sash area.
“We increasingly see apartments with no genuinely openable window at all, or only a balcony door that a household with young children or a pet cannot safely leave open.”
Waterford said the goal of providing fresh air was not reaching the homes where it was needed most. It has also created two classes of home owners – those who live in well-ventilated detached homes, and apartment dwellers.
To increase the flow of air, and meet the code, Bates Smart architects has mixed vertical and horizontal louvres with sash windows at two projects, including the 23-storey Banksia apartment block at Norwest Quarter. At another project, Riviere at Kangaroo Point in Brisbane, they used fixed perforated screens with full sliding windows.
A director with Bates Smart, Matthew Allen, said the louvres provide the same level of child safety as sash windows while increasing the amount of fresh air flowing by five to six times.
Balcony doors “can open as much as you like. But any room that doesn’t have a balcony, you’ve got to deal with these windows with fall protection.”
In a case study in the Committee for Sydney report on “breathable density”, Allen wrote that the louvres were delivered without compromising safety, and via a routine approval process.
He said the problem was that sash windows had become the default from the outset: “Proof that habit, not regulation, is the barrier to breathable apartments.”
But architect and commentator Tone Wheeler said the science around fresh air in apartments and houses was inexact, and needed more investigation. “Wind pressure is variable, air pressure is variable,” he said. Depending on that, in some circumstances the 125mm opening was enough. In other cases, it could be too much.
Louvres are slightly more expensive than traditional sash windows.
Andy Nichols, director of development in NSW with developer Mulpha, which built Banksia, said he was a huge believer in natural ventilation wherever possible.
On social media, home owners often share tips and tricks on how to adjust or remove “restrictors” that can turn a hot Sydney day into a nightmare.
A spokesperson for Australian Building Codes Board (ABCB) said that anyone can suggest changes to the National Construction Code, and provide evidence to support their proposed changes and demonstrate the benefits, costs and technical merits. The board would assess them on merit.
Start the day with a summary of the day’s most important and interesting stories, analysis and insights. Sign up for our Morning Edition newsletter.
From our partners
Read the full article here
