Ventilation is an important component of good design, leading to healthy, naturally comfortable and thermally efficient homes and buildings.

Two reports, one by the Victorian Government, and the other by the University of Melbourne, discuss the importance of natural ventilation in apartment living, and ways to achieve it through good design.

Report 1: Better Apartments – Public Engagement Report

This report by the Victorian Government is, in fact, a discussion paper released as part of the development of their Better Apartments Design Standards to gather feedback from the design industry and the community about the relative importance of various aspects of apartment living.

Public interest in the design standards was strong with over 1700 people responding to the survey, 145 submissions being received and 235 people participating in workshops, forums and interviews.

Natural ventilation more important than views, sunlight or noise

Natural ventilation was ranked by survey and written respondents as the third most important issue affecting apartment living, with only ‘daylight’ and ‘space’ placed higher. The respondents ranked ‘natural ventilation’ as being more important than ‘sunlight’, ‘outdoor space’, ‘noise’ and ‘outlook’.

Apartments with good ventilation command a price premium

About 80% of the survey respondents agreed or strongly agreed with the statement that “an ‘airy’ apartment that has good natural daylight, direct sunlight and good ventilation is essential and is worth paying more for”.

Report 2: Living Well – Apartments, Comfort and Resilience in Climate Change

Produced by the University of Melbourne for the Australian Communities Foundation Green Cities Innovation Fund, this report primarily considers the performance of typical Melbourne apartments with west facing windows (a worst case scenario) during heat waves without mechanical cooling, and the retrofit opportunities to improve their performance.

How the test was conducted

The report authors modelled a 4-week period in 2009 that included a heatwave period of 3 days with day-time temperatures over 40°C and night-time temperatures above 25°C. Therefore, apartments with western orientations, no mechanical cooling and windows that do not open would be uncomfortably hot.

Key findings from the report:

1. Without natural ventilation or mechanical cooling, apartments will be uncomfortably hot: With the windows always closed, on average, the indoor temperatures in the apartments would be above 25°C for 77% of the 4-week period. One of the apartments was predicted to only drop below 25°C for 2% of the 4-week period despite the outside temperatures dropping below 15°C for 7 nights.

2. Opening the windows reduced indoor temperatures: Running the modelling with the windows able to be opened to naturally cool the apartments resulted in a 71% reduction in the amount of time that the indoor temperatures were above 28°C – the temperature above which overheating is more likely to result in negative health impacts.

3. Restricting window openings for fall prevention could result in uncomfortably hot indoor temperatures: Such windows would only be able to be opened to a maximum of 120mm. If a sliding window 1800mm wide has its opening restricted to only open to 120mm, then ventilation possible through 45% of the window’s area will only be possible through 6% of the window’s area – nowhere near the 50% assumed in the modelling. This will, therefore, significantly reduce the effectiveness of natural ventilation resulting in indoor temperatures closer to those modelled with the windows permanently closed.

4. People will rely more on air conditioners to maintain indoor comfort: When natural ventilation is non-existent or ineffective, residents will simply run their air conditioners to reduce indoor temperatures. This will drastically increase their electricity consumption, pushing up their power bills and greenhouse gas emissions, not to mention the corresponding strain on the power grid increasing the likelihood of power outages during heat waves.

Pay attention to ventilation openings when specifying apartment windows

Architects and building designers should ensure the right windows are specified for apartments. People value being able to open their windows to allow natural ventilation and the modelling shows the potential for apartments with restricted window openings to be power-hungry at best and dangerously hot and stuffy at worst.

With ventilation openings on both sides of each blade, Altair louvre windows from Breezway featuring the Stronghold System are perfect for maximising natural ventilation in apartments even when openings are restricted to comply with BCA’s fall prevention requirements.

Read the two reports:

Report 1: Better Apartments – Public Engagement Report

Report 2: Living Well – Apartments, Comfort and Resilience in Climate Change

To read Breezway's whitepaper on the topic, click here.