Ben and Kay Adam-Smith have a difference in opinion over which windows to specify for their new build Passivhaus home. While Ben is keen to minimise mullions, transoms and window frames, Kay believes this takes away from the aesthetics.
A visualisation of Ben and Kay's house
Today's episode is really a short story about aesthetics. Life would be very boring if we all liked the same thing. However, what happens when you're working with your other half on a self build and you strongly disagree about something? How do you move on? Well we haven't answered that one yet, but we can share the disagreement and let you know what happens over the course of time!
I (Ben) also feel like I might have said what my wife is saying a few years ago. I believe I've grown in my understanding since then and so now my opinion has changed.
Mullions, transoms and window frames
Firstly what are mullions and transoms? Well, they are the structural elements that divide up sections of a window. Mullions are vertical while transoms are horizontal.
There's no denying that the use of mullions and transoms can make some beautiful windows (and in the photo above there's stained glass as well).
In the past, it was just not possible to manufacture large single pieces of glass and so to achieve a big window, a number of small ones needed to be ‘stitched' together.
Large glazing is now possible
Probably a window's most important function is to provide that visibility from one side to the other.
Windows without mullions and transoms therefore do a better job of connecting the inside to the outside.
As we spend 90% of our time indoors, you could argue that the view out is more important than the aesthetic appearance of the window from the outside.
Big open windows are not the norm
In a country where our period properties make up a large proportion of the housing we live in today, it is hardly surprising that we gravitate towards their features.
That's perhaps why Kay would like two of three ‘lights' (subdivisions) in each window.
She also thinks that a lot of houses that use large panes of glass just don't look right; they look like they need to be sub-divided.
Reducing the amount of glazing in a window impacts on its performance
The frame is generally the weak point of the window.
Chris Parsons of Parsons + Whittley says: “We want more glass and less frame in the way, because the more glass we have the better the performance of the window. When you start dividing them up with mullions and transoms, you now can't insulate that part of the frame by wrapping anything around it.”
How much glass is actually in a window?
Windows for our Passivhaus don't have to be certified products
Part of the problem when building a Passivhaus is that you just can't use any window. You have to use one that has a good thermal performance. Reliable data is always needed in order to model the house accurately in the Passive House Planning Package (PHPP).
However, Chris Parsons says: “You don't need to use a certified Passivhaus window in a Passivhaus but we do need to have independent testing of the performance of the window so that we can model it properly.”
Keep an open mind
This can be a great attitude to anything in life and it's just the same with architecture.
Ben made this video in 2013, when he Our past has a strong grip over us.