Natural ventilation - as built

From Green Garage Detroit
Jump to: navigation, search

return to As Built


Open windows.jpg
Months natural ventilation is likely in RED BOX

Many of the windows at the Green Garage open. We utilize natural ventilation as much as possible at the Green Garage. Natural ventilation is an ancient technique of cooling and ventilating buildings. It relies on a combination of buoyancy (hot air rising or the stack effect), and wind (cross ventilation) to allow fresh air to flow in the building. Natural ventilation assists in about 50 - 90 days per year during the spring, summer and fall months. Clearly in the months of extreme weather, natural ventilation makes no contribution. Natural ventilation is provided by opening the building's windows. More information is available on our Natural Ventilation pattern page.


Flickr Error ( Photo not found ): PhotoID 3576085691

We use 2 forms of natural ventilation: cross and stack ventilation.

Cross Ventilation

  • The cooler air enters the building through operable windows on the windward walls.
  • The warmer indoor air escapes through the leeward wall.
  • Casement windows are used as fins to guide the wind into the building when it is coming in at an angle to the window.

Stack Ventilation

  • The cooler air enters the building through low operable windows or vents.
  • The warmer indoor air escapes through windows or vents high in the wall or in the roof.

Hybrid Cross-Stack Ventilation

  • We combine cross and stack ventilation into a hybrid system to take advantage of both strategies.
  • Cool air enters through low windward openings and warm air exits through high leeward openings or stacks.
  • Placement of the inlets and outlets determines the distribution path.

Determination of Natural Ventilation Days

Natural ventilation days are decided based on a number of decisions regarding temperatures and dew points. We use a color-coded system based on 3 simple decisions:

  • Is the outside dewpoint temperature 55 degrees or less?
  • Is the outside dewpoint less than the inside dewpoint?
  • Is it cooler outside than inside by 3 degrees?

If all 3 answers are yes, we can open the windows. If we were to open the windows in less favorable conditions, it would bring too much moisture and heat into the building, causing our HVAC equipment to have to work harder. Here is the Daily Worksheet we use to make the determination.

Natural ventilation day decision-making process.

See Also

Ventilation system