Innie/outie window operation
I am familiar with much of the conversation regarding thermal performance as it relates to innie/outie windows (https://www.greenbuildingadvisor.com/blogs/dept/musings/innie-windows-or-outie-windows). My concern here relates more specifically to operation of innie/outie windows as well as “middies”.
My concern is as follows:
It seems that “conventional” windows on regular houses are either double-hungs, sliders, single hungs, casements, or awnings, all of which swing outward or slide in one plane.
This works well in conventional, ie code-minimum style, construction in that the window is on the outside of the frame and then swings outward (in awning or casement) or slides up (or to the side) in hung windows and sliders.
Conversely, thick European windows maybe are often installed as innies… or close to innies… so the tilt turn operation which brings the window in like a hopper or swinging in like a door seems ideal.
But in a “middie” window, which to some extent is the conclusive ideal in the discussion following the article linked above, I am confused about window operation.
It seems like the surrounding window frame on a “middie” window in a thick wall will greatly reduce airflow in either outswing or inswing operatoin. In fact, a slider or single hung seems like the best way to get a maximum opening for airflow in this condition, but I am well aware that this is basically a no-go from a thermal performance / air sealing standpoint.
In the detail attached, even if the exterior trim were to be reduced in width, there is ~5″ of surround on both the inside and the outside of the window. It seems to me this will inhibit airflow regardless of whether the window swings or tilts inward or outward, and I know I don’t want a double hung or slider. Am I overthinking this? Will people just open the windows more? This seems a particular problem for tilt/turns because they only open a certain amount in the “tilt” mode.
I’m certainly leaning away from tilt/turns for this reason, and back to casements and awnings.
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Replies
To Ethan,
I went through much the same series of thoughts three years ago while deciding on windows. I am sure you will have plenty of air no matter which window you ultimately choose.
Our environment is climate zone 6A or worse depending on the year, with a windy season in the spring. The general level of wind is about 5-7 mph according to some weather statistics I obtained locally. For what it is worth, my home has walls over 12" thick due to similar out-sulation choices. I went with semi-outie set Alpen windows for energy reasons and sealing quality. Also for being made of fiberglas pultrusion material.
We chose mostly fixed windows, the rest are awning style except where fire egress demands casement. ( I am ignoring the double hung and sliders for the same energy reasons you noted. ) There is no problem getting air into the house. In fact we reduced the number of operable windows based on local comments about the winds. I also looked at the Euro style tilt and swing windows, but ultimately rejected them for a variety of reasons, air flow not being a major one. One reason was the inconvenience of a large window swinging into the room. Awkward for furniture and window treatments as well as the plants and cats residing on the 7" deep interior sills.
I have never found out if the tilt and swing types would flap in the winds we have, but I can say the opening mechanisms on both the awning and casements are sturdy and unlike door hinges, swing the window in a way that air is admitted top and bottom for the awning. The same effect on the casements allows one to reach out the "hinge" side for easier washing. Skinny arms help. We experience rain bursts with no particular warning so the awning windows are "set and forget" if we are away from the house. The casements will admit water so we only crack them a bit if we leave.
All the windows were set in bucks that move the window position past the general sheathing which has 6" of foam over that. The finish detail leaves the window frames set back about 3" from the nominal house wall which is stucco. Lots of detailing to make sure the window bucks were sealed and the drainage planes unimpeded. Will not be doing this method again. I would comment on your wall section but I am already way long on this.
I think airflow into the house will depend a lot more on room layout than window type. Mr. Holladay has often mentioned the magic air arrows in ventilation diagrams which don't really behave as shown. It is best to review closely the overall layout of operable windows and how room might be closed off at various times. We created a major pathway for circulation that draws air in at the first floor and up the main stairs to windows at the top to pull cool night air in. The living room, family room and kitchen and master bedroom all have two windows for cross flow even when the top most windows are closed during the day. We do have very low humidity which might make our choices different from your own.
Choosing a window that is durable, energy efficient and tight sealing was my primary goal. I am very happy with the Alpens so far, especially the seal. The awning and casement which are essentially the same thing seal very well. I was surprised to find my neighbor on his tractor in my yard one winter day having not heard the diesel engine at all. I could only reflect on the crappy double hungs at our previous house that let all the road noise and cold air through.
Be sure to check the bedroom windows for egress minimums and just where you are potentially dropping out to. The sill height is also important if you have less mobility than a six year old. I skipped interior trim by making the wall wrap into the opening. Check with trim carpenters about just how expensive is can get creating the very deep sills and sides. We also have skipped window treatments as we are fortunate enough to not have neighbors in sight, but plan now if you intend to use them. Blocking for screws is heaven when you have them in place. Hope this helps some.
For the casements, do they open all the way? I was planning on doing full innie windows, all awnings except the egress, which has to be a casement. but if it wont open all the way it won't count as the egress, correct?
The Wagonista,
Yes, they open all the way to 90 degrees to the frame. The "hinge" side actually slides away from the closed position such that you can reach out and wash the face of the window from inside. At least as long as your arm will go. There should be a diagram on the Alpen site. Do check your egress width requirements and keep the somewhat reduced exit width in mind so as to not get surprised by a picky inspector. It is a bit cold out here, so forgive my not measuring exactly. I would say four inches comes to mind.
A 30" width window would open to 25"-26+" depending on how wide you open it. At approx a 50 degree open position the available width might be 2+ inches greater than at the 90 degree position. It has not been clear to me if the code defines "open" to mean widest possible width available or widest cranked position available. Either way, I certainly would rather go through a casement over a double hung at my age.
The position re: middie, innie, outie has no effect on the opening since it stops at 90. I have a mix of awning, casement and fixed set middie. The awning and casement both perform very well and seal well. I had to use the casement for egress points, but like the awning because we can leave them open slightly and not worry about the random sudden rains we get during warm weather.
You don't say where you are building, but if it is a particularly windy area like my own, you will find many of your windows will likely stay closed. I received good advice from someone locally that had put in many awning windows that now stay shut lest they get blown out of the house. That said, both the casement and awning hardware on my windows to well in the winds. Not much back and forth play in the mechanism.
However you set them, pay very close attention to the flashing and materials used for sills and surrounds. I have a "faux-dobe" look for the house and one detail that is critical is the drip lips I incorporated above each window. Without them the water sliding down the wall would travel back to the window. If you are using more traditional trim elements, be sure to arrange the top trim to drop the drips forward.
Thank you Roger!
I built a model of the Inline Tilt Turn (301) and tried it at 10 degrees and 15 degrees open. I don't actually know the angle of the tilt configuration. I'm still worried that it doesn't seem very "open" but maybe I'm not understanding airflow or what the big deal about tilt/turn is. Everyone seems to really like them around here...
Ethan,
European tilt/turn windows are an acquired taste. If you grew up in Germany, you're used to them. If you're a typical American who likes ordinary curtains, and who likes to put knick-knacks on your window stools, they are a pain.
We have curtain in Europe as well. Along with tilt/turn windows. So you gotta move the curtains every time you want to open the window completely :D
That said, in modern houses with no curtains, uninterrupted view through a single pane window is worth it. It's a whole other thing. Depending on the view outside, obviously :)
Martin, I wasn't asking whether tilt/turns are culturally appropriate in North America, Roger & Davor I appreciate your insight.
I'm really wondering about the effective opening of Tilt/Turn (and come to think of it any swinging window... casements and awnings would have the same issue) in deeply insulated window openings.
I guess wind finds its way around.
Ethan,
I would say that common sense governs. You open your window wide enough to get the result you want.
If you aren't getting enough fresh air, you just open it a little wider. If the breeze is too much, you shut the window partially until you find the sweet spot.
Thanks, Martin. I guess I just don't know how wide the tilt part of the tilt/turn opens, or if it can be opened by degrees or just is open or shut. My sketch above shows that in my wall assembly, there is a large difference between a 10 and 15 degree tilt opening. That's a question for the window manufacturer, I know. But my experience getting answers from window manufacturers makes a visit to the DMV seem efficient. I have gotten more window info here at GBA than from any window manufacturers, even the ones that seem at first to have a lot of info. I think they get tired of answering so many questions.
Tilt-turn windows in "tilt" mode, open only a couple inches along the top, and a triangle along the sides (hinged at bottom), and have two positions only (tilted in and closed tight). You can leave them "tilted" open with minimal fear of rain, winds, burglars, or toddlers falling out. Although not a big area is open, they can be left open, so should get plenty of ventilation. Whether innie, outie or middie, there's enough window frame area for clearance between the tilted-in window and the wall (window buck inner surface).
In "turn" mode, tilt/turn open up like a casement except toward the interior instead of exterior movement, so can open up very wide for maximum ventilation. Note that sliders, double hungs and single hungs open less than 50% of sash/glazing area. The sash covers half the glazing area when open wide. Casements and tilt/turn (in turn mode) open up almost all the glazing/sash area for ventilation, so allow more ventilation when fully open than sliders, double hungs or single hungs.
I've learned that inline fiberglass tilt turns open 8", which is a variable angle depending upon the size of the window.