fixed, single-hung, double-hung, awning windows

The Why and Wherefore of Windows


Windows serve many purposes.  They connect us to nature, offering views and natural light; they can provide fresh air to warm or cool us.    We’ve rhapsodized about their illuminant qualities before – today we’ll dig into a little more history and technical information about these essential elements of building design.  

A (very) short history of Windows

At one point, a window was the only source of amenities like light and interior air movement. Winifred Gallagher’s excellent book, House Thinking: a room-by-room look at how we live, describes windows as “cost free utilities.”  She points out that we take less advantage of those features now that we have such easy access to artificial light and heating and cooling.  

The earliest windows were just holes in a wall which let in a little bit of light and out smoke and noxious smells.  They had to be small so as not to disturb the structure of the wall … and also so that they didn’t let out more air (warm) than people wanted.  Over time, people added hanging curtains, security screens and even translucent membranes that kept out the cold but let in the light.  

Glass for windows was used by the Romans (but only in the most luxurious of homes).  But only as recently as the 1600s were glass windows common to average residential construction (in Europe).

Common Window Types

These are the basic types of windows found in residential and small commercial projects.   Different windows are common to different eras, building types and uses.  Single and double-hung windows are generally found in older construction.  Sliders are (in these designers’ opinion) an abomination of cheap, developer construction and to-be-avoided.  Casement windows offer the maximum amount of vent – open air space – when open and can provide some of the best seal when closed.  Awning and hopper windows can be left open during (limited) precipitation without risking a lot of water inside the building.

common window types

 Since operable windows are always more expensive than similar constructions of fixed windows, its common to design a system that mixes and matches – tall fixed windows with an operable awning above or hopper below, for example.

Size and Scale

In The Perfect House: a journey with the renaissance master Andrea Palladio, Witold Rybczynski describes his astonishment at the difference between the modern residential windows that he was used to, and the design of the windows designed by Palladio, at Villa Saraceno.   

“Perhaps its because I’m used to modern houses, where everything is ‘just large enough,’ that Palladio’s amplitude is so striking.  […] The windows, for example, which are all the same, are 4 1/2 feet wide and no less than 8 1/2 feet tall.  When I open the shutters in the morning, its not like raising the blinds at home.  Through the tall windows I can see more sky than land, which both brings the exterior into the house and heightens the sense of protective shelter when I close the shutters at night.”

His point is the wonder of such generously sized views out as compared to a code-minimum.  A different take-away is that simply the difference in scale is exciting to an American used to operating in a world of prefabrication and standard materials.  

The shape of a window also affects our experience of it.  Looking through a tall narrow double hung window gives more of a person sized shape than the full-landscape view offered by more horizontal slider windows.  Looking through a sheet of plate glass in a standard picture window gives a much different feeling than peering through the interlocking muntins in a leaded glass one.  Variation, and particularity, lend strength to design with windows.  

Glazing – the Glass Inside the Frame

The construction of a window has a lot to do with how much temperature change it lets into your building (along with all that lovely natural light). has a really excellent page breaking down the energy performance of windows and doors, and explaining some of the technical terms you’ll encounter if you find yourself purchasing new windows.

Three factors regulate the thermal effectiveness of a window:

  • Air leaking in around unsealed edges or through the frame construction
  • Heat radiating in or out of the window in the form of sunshine or cooling at night
  • Heat being conducted through the materials of the glass or frame

They also have one of the best and simplest descriptions of U-factor and SHCG ratings that we’ve found.  Check it out.

The next time you glance out a window to check the weather, consider its shape and construction, and the weight of historical development, which created it.  Shout out in the comments if you have a favorite window in your life and why.