The Gemini Residences, Copenhagen, are a series of flats built around the outside of two converted grain silos on the waterfront. This photo shows one of the striking naturally lit and ventilated atria.

The Gemini Residences, Copenhagen, are a series of flats built around the outside of two converted grain silos on the waterfront. This photo shows one of the striking naturally lit and ventilated atria.

natural ventilation

We now spend up to 90% of our time indoors in buildings that account for 40% of our total energy consumption. Getting building design right is essential, not only to reduce our environmental impacts, but also to keep us healthy and comfortable.

Natural ventilation is one of a number of green building technologies that has the potential to make a big difference. Supplying fresh air using the freely available forces of wind and buoyancy (stack effect) can cut energy consumption in half and reduce incidences of 'sick building syndrome' by a factor of three. There is particular scope to use natural ventilation in tall buildings with atria, where stack effect can be utilised to its fullest potential.

 The CH2 Building is a 6 Green Star building housing the council offices in downtown Melbourne. The building uses a mixed mode ventilation strategy, employing both natural and mechanical ventilation at different times of day. The natural ventilation scheme (pictured) uses a combination of top-down inlet chimneys and exhaust stacks, heated by solar gains and topped with wind cowls, to drive night-time cooling. The building uses less than half of the energy of the building it replaced, and is in the top 20% of buildings in Australia for occupant comfort and satisfaction.

The CH2 Building is a 6 Green Star building housing the council offices in downtown Melbourne. The building uses a mixed mode ventilation strategy, employing both natural and mechanical ventilation at different times of day. The natural ventilation scheme (pictured) uses a combination of top-down inlet chimneys and exhaust stacks, heated by solar gains and topped with wind cowls, to drive night-time cooling. The building uses less than half of the energy of the building it replaced, and is in the top 20% of buildings in Australia for occupant comfort and satisfaction.

The use of natural ventilation in large buildings has seen success around the world with a number of benchmark buildings (such as the CH2 Building, Melbourne, pictured on left) setting the standard for energy efficiency and comfort. However, the resurgence of natural ventilation is still relatively recent and, as such, the prevailing attitude within industry is still one of caution.

Andy believes that the key to promoting natural ventilation is to provide simple and intuitive guidance to everyone involved in the design and operation of buildings - from engineers and architects to clients and end-users. His research focusses on the use of simple mathematical models - with their foundation in the core physics of heat and air flows - to determine rules of thumb for design, in the form of easy-to-understand charts and back-of-envelope calculations. By providing a common ground for all parties early on in the design of a building, Andy hopes that his research will help to inform the green building designs of the future.

Andy is a member of the CIBSE Natural Ventilation Group committee.