Saving Energy Requires Smaller Windows But Architects Like Them Big

Modern architecture was easier when windows were big. But when you are trying to design to save energy, big windows are a problem. High-quality units are expensive, and they are still generally not as energy efficient as a lousy wall. That's why I have written before that windows are hard.

This addition to a residential building in Aubervilliers, France, shows an interesting approach that we have seen before: Put the window in a big frame. PietriArchitectes renovated the older existing building, added a floor on top, and built the extension on the site of an old garage.

The extension is built out of prefabricated cross-laminated timber (CLT) panels. The architects explained: "Wood prefabrication allows the setting up of a low-nuisance construction site for the neighborhood, as well as speed of execution thanks to final assembly being carried out on site." The architects describe the design of the façade of the addition:

"The street facade of the extension was designed as a tableau, a graphic element that contrasts with the weft and sobriety of the existing building and its original brick facade. In this way, a game of material, of contrast between hollow and full, is played between the anthracite zinc and the slatted wood, drawing skewed frames around the bay windows."

The architects do not discuss in any detail in their statement or on their site if they did this for any other reason than the aesthetic, but we have seen this before.

In 2013, the first certified Passivhaus residence was designed by NK Architects in Seattle, with Rob Harrison acting as the Passive House Consultant. Harrison noted on his website that the design originally had a 4-foot wide and 20-foot high window on the north side, but even with the highest-performing glass available at the time, the numbers didn't pencil out with a window that big.

Harrison wrote:

"The only avenue to optimizing the performance left was to add south glazing and reduce north glazing. I proposed, and as you can see, NK Architects executed my idea of chamfering a set of deep-set punched windows instead of the tall fixed window on the bay, using CFC-free polyiso to maintain a decent average R-value in the assembly."

A version of this was used in the Stirling Prize-winning Goldsmith Street project by Mikhail Riches with Cathy Hawley. The Royal Institute of British Architects noted: "To be certified Passivhaus, the windows had to be smaller than the proportion in a Georgian or Victorian terrace, so the architects have used a set-back panel around the windows to give an enlarged feel, and panels of textured brick have been introduced into the main elevations, again to balance the feel of the fenestration along the terrace."

We have shown Passivhaus-inspired projects that didn't hit the numbers because the architects wanted bigger windows or bumpier facades, but this project has become the poster child for the benefits of Passivhaus and why you should work the windows. The Guardian recently described the project as "lifechanging" because "at a time of health fears for more than 3 million households struggling to pay for heating," it provides "a glimpse of how much better it would be if the UK’s homes were properly insulated and ventilated."

I have often tried to make the case that architects should design from the inside out: "Keep the windows as small as you can get away with and still let in the light and views that you want, with an eye for proportion and scale. And keep it simple."

I have suggested that "instead of treating a window as a wall, as so many modernists do, think of it as a picture frame around a carefully chosen view."

But sometimes, that picture needs a substantial frame to set off the picture properly. According to Marissa Lupkas, quoting picture frame historian Suzanne Smeaton, "While not the focal point, frames are an annex of the viewing experience. Smeaton explained that “design elements echo and reinforce composition.” That seems to be what PietriArchitectes are doing in Aubervilliers.