Passive House Window Operation is a little different, and takes a little getting use to.
As you can see in the above photo (view from the inside of the house), the window tilts to the inside, and opens inward. This has a few benefits.
1) When it is raining outside, you can still have the window open (in the tilt position).
2) Easier to clean - you don't need to hang out a 2nd story window to reach the outside
3) When the screen is placed on the outside, the elaborate triple locking mechanism - which ensures an airtight seal - isn't interfered with
4) The standard american casement window crank is a HUGE thermal bridge, since almost the entire crank mechanism is not insulated very well
The best sealed windows are the windows that have a latch the pulls the window into a seal - but I suppose there are downsides to all windows
Casement
The trouble with the Casement is screen placement when the handles are in the middle of the windows without the crank mechanism. Cleaning the outside of the glass is also troublesome.
Tilt and turn
Tilt and Turn windows tend to require special window treatments and the interference with interior furniture should be considered.
Awning
Awning windows are limited by size and amount of fresh air they let in. They also will probably not meet any kind of egress requirements. Cleaning can be difficult as well.
Some of the most common windows in North America are the double hung and sliders. Due to the tendency to be leaky, they are not recommended for use in Passive House.
Slider
Sliding Glass doors are available, but in my case they were too expensive due to an elaborate sliding mechanism to ensure an airtight seal. Sliding windows are usually not recommended due to air leaks.
Double/Single Hung
The most common North American Window, believe it or not, it not manufactured in Europe due to its leakiness. It may be the most versatile window in the USA, almost all window treatments are made for a double hung. You can have all kinds of features for it, BUT for Passive House, it is just too leaky. Another consideration is the Frame to Glass Ratio (Remember the glass is more insulating than the frame.) When you have the middle sash, you don't have glass. Where there is no glass, you don't have the much wanted solar gains.
There is also the considerations of grills (muntins) or lites. I learned that in passive house windows, to have simulated lites , expect to DOUBLE the cost of the window. You hurt your frame to glass ratio. We will not be having any divided lites in our windows - pay more for less efficiency. No Thanks!
Lites were part of the original american windows because manufacturing glass was difficult, and it was easier to transport and handle in smaller sizes. So an original window in early america was really 6 pieces of glass held together by the frame - Fun fact of the day!
Stop by next time for Window Installation Considerations!
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