Link in with Lisa

Mixed mode ventilation – are you ready?

02:47:08 PM on 11/19/2009

While I spent most of the Greenbuild conference at the Kawneer booth and walking the expo floor, I did have the opportunity to attend a few educational sessions. One of the most interesting sessions I sat in on addressed the topic of mixed-mode ventilated buildings.

Mixed-mode design is a ventilation strategy that combines natural ventilation (operable windows) with mechanical ventilation (mechanical air conditioning), allowing the building to be ventilated either mechanically or naturally.  The goal is to reduce the environmental impact and potentially lower the energy cost of the building, while maintaining or even improving the well-being and satisfaction of the occupants.

It is probably more difficult to design a building by mixing operable windows with traditional systems, but there are several advantages to mixed-mode buildings. The first is a reduction in the amount HVAC energy that is used. Second, is the enhancement of the indoor air quality and comfort and well-being of the occupants.

There are several different approaches you can take when designing mixed-mode ventilation into your building. Some factors to consider are your location’s climate, the building’s function, the client’s expectations and any site constraints that may alter your design. Certainly buildings in mild climates with low pollution would be ideal areas to incorporate a mixed mode ventilation system.

Tied into the discussion was radiant heating and cooling strategies. Both involve a method of changing the temperature of a space by using water pipes to distribute heating or cooling throughout a building and are usually installed in the walls or floors. Since the process to change the temperature using this method can take more time than a conventional system, using operable vents can make the process more effective, especially with radiant cooling.

My biggest take away from this meeting was that integrated design approach is the key to making mixed-mode ventilation systems work effectively in your building.  Collaboration between architect, mechanical engineer, etc. is essential.

It wasn’t that long ago when HVAC systems didn’t exist and the only way to ventilate your building was by operable windows. Have we gotten so accustomed to controlled air conditioning that we aren’t willing to go back to naturally airing out buildings?

So what do you think about incorporating mixed-mode ventilation into your new building or building renovation? Have you tried any of kawneer's wide range of operable windows? Do you have any design strategies to share?

Looking forward to hearing from you,
Lisa Szematowicz


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