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Natural Ventilation

Natural ventilation is a key component of the passive design principles embodied in our work, reflecting our commitment to provide thermal comfort and healthy indoor environments.

1 Blight Street Sydney

Natural ventilation uses differential pressure to deliver fresh air into buildings. This differential can be caused by wind or the stack effect (buoyancy effect) of warm air rising.

Wind creates positive pressure on the windward side of buildings and negative pressure on the leeward side. Pressure equalisation between the two sides causes horizontal cross ventilation of floor plates. Wind driven natural ventilation requires a relatively direct and unobstructed route between the windward side and leeward side of a building. Extreme wind conditions need to be moderated.

1 Bligh Street
The naturally ventilated full-height atrium opens out into the public space, where conditions are tempered by relief air from the office levels, and heated in-slab using waste heat from the trigeneration plant.

The stack effect is achieved through vertical separation of supply and exhaust openings. As air heats its buoyancy increases. By purging hot air at high-level, cooler fresh air is drawn into the building at low-level. Buoyancy induced natural ventilation can be achieved through high- and low-level openings within individual spaces, or through linking a series of spaces to a vertical air path such as stair shafts, thermal chimneys or open atria, thus drawing fresh air into the building.

Qantas Headquarters
Naturally ventilated atrium space is the social heart of the campus.

Natural ventilation systems consider:

  • Climate – external air temperature and humidity range
  • Prevailing wind direction
  • Surrounding form of landscape and built environment
  • Adverse impact of noise and other forms of pollution
  • Building use and occupancy
  • Thermal comfort temperature range

These considerations inform:

  • Orientation and relationship to the site
  • Floor plate depths
  • Organisational layout
  • Envelope design – location of supply and exhaust openings

1 Bligh Street
General guidelines recommend single-sided natural ventilation for spaces of up to 6m in depth or with a ratio of no more than 2.5 times depth to height. Double-sided natural ventilation is typically recommended for spaces of up to 12m in depth.

The challenge is often realising project-specific functional, organisational and contextual requirements, along with climatic and geographical considerations. For example, large-scale, multifunctional projects that encompass varying ‘heat loads’ and ventilation requirements, often require a combination of ventilation modes including mechanical, mixed-mode and natural ventilation.

Natural ventilation must also coordinate with thermal comfort throughout a space (including in areas around the building’s perimeter), and glare control such as curtains or blinds that may affect air flow.Benefits of natural ventilation include:

  • Healthy indoor environment
  • Reduced capital and operating costs
  • Low-maintenance

 

Queen Elizabeth II Courts of Law
Double glass cavity facade system is an integral component of the air climate control system.

At Architectus, natural ventilation is a key part of the integrated and holistic design methodology we use to create innovative, resilient and engaging environments for future generations.

The Macquarie University Incubator wins Green Good Design 2018 award

Macquarie University Incubator
The mechanical solution for the Incubator is designed to benefit from external conditions, providing assisted natural ventilation to the spaces for more than 60% of the year as required, and tempering incoming air in peak seasons to maintain a comfortable environment. This is aided by the building’s form with the overhanging roof and solid façade elements minimising external solar and heat gains.