Ventilation. We see the word increasingly bandied about in the form of ‘natural ventilation’, ‘green ventilation’ and ‘mechanical ventilation’, but what do these really mean? And are they really that important?
Well, yes. Our interior spaces need to be ventilated in order to expel excess carbon dioxide that we ourselves emit, as well as to remove smoke, moisture, dust, bacteria and other ‘dirty’ elements from the air inside. Air needs to be continually circulating in order for it not to become stagnant, and ventilation is the key behind these circulation processes.
While there is a differentiation between green and non-green ventilation, the more correct terminology is natural and mechanical ventilation. In understanding the difference between the two features it is possible to explore all of the different ventilation types that fall into these two categories.
Natural ventilation is the process whereby interior air is replaced by exterior air without the support of mechanical means. This in its simplest form, is achieved through opening windows, and the inclusion of vents in buildings. Natural ventilation can also be maximised through correct window orientation, which enables cross ventilation and encourages a natural airflow and exchange.
Mechanical ventilation is the process of cooling and circulating interior air by a non-natural or ‘forced’ means. These include fans, air filters, air conditioners, which are ventilation technologies that enable interior/exterior air exchange. While these technologies may seem more efficient than natural ventilation, oftentimes they can in fact be overkill, with associated carbon emissions and energy costs making them an incredibly unattractive ventilation choice in this current green building era.
As the title would suggest, hybrid ventilation means are a mix of both mechanical and natural ventilation means. In some cases natural ventilation is in fact not the most successful way to promote airflow (for example in basements the use of operable windows can create moisture issues in the rest of the building) and the use of coexisting, linked ventilation processes is necessary.
However, the hoopla surrounding natural ventilation in the green building sector is often misleading. When a building is cited as using ‘natural ventilation’ and even in some cases ‘green ventilation’, this could be as simple as the inclusion of a window that opens.
It is important to remember that while a building’s green or even sustainability status strongly relies on efficient and eco-friendly ventilation, these ventilation types alone do not simply make a building green or sustainable.
In truly understanding these processes and building features it is possible to discriminate between truly eco-friendly and energy efficient buildings and those that simply sound as though they may be.