SPLAYED WINDOWS: A LIGHT IDEA

 

     The renovation of our green church is moving along nicely and we are now at the stage where some of the details that will improve the in-door occupancy quality is ready to take shape. The windows fall into that category.

     Increasing exposure to daylight and capturing passive solar heat is always high on any green home project and this one is no different, in that regard. 

The existing windows are tall and narrow, 

with stained glass panes that we wanted to retain for the external visual view and the beautiful hues that grace the interior. The plan is to install new energy efficient windows on the inside of the present openings and leave the originals in place.  Given the height of the interior at over seventeen feet, our higher windows actually deepen the daylight time period.

    A feature that you don’t see often is the use of angled or splayed windows in the “buck” of the window opening and I have added these to the design. The term splayed is used to describe a window opening that has an angle built into the side of the opening; the opening is wider on the inside than it is on the outside. This idea started centuries ago when defense of a castle was necessary. These “slits” in the walls allowed archers to change position and cover a wider area of defence while making it difficult for the attackers to eliminate the archer. In peaceful times our forefathers found that these angled sides to a window allowed in a lot more natural light than the actual opening size would suggest. The cost and availability of glass was a factor in those days, as well. More natural light meant reducing the need for lanterns until later in the day.

    The popularity of “splayed” window openings remained in vogue until the turn of the 20th century when cost and availability of manufactured windows with assembled frames gained in popularity. It was a lot quicker to assemble a square buck than a splayed one and speed of assembly took over. Today, the method of choice remains a square opening and conventional frames made of various materials. The green building industry long ago picked up on the advantage of these angled window openings and their popularity is slowly increasing.

    We are very fortunate to have a building with a near perfect north-south exposure so that we could take advantage of the light and not have a large number of north windows to consider. As noted previously, once we are done, Krumpers Solar Blinds will be installed to assist in this passive solar heating and cooling.

    An angle of close to 60 degrees and a depth of around nine inches are considered optimum for the bucks. I knew when we began the “green church” renovation that we were going to build a complete interior wall assembly, thereby significantly deepening the original window sills. However, once the wall panelling and trim was installed and the new, energy efficient windows set into the original frame, we ended up with about 7.5 inches. The 60 degree wall angle, however, was easier to attain and we are close to that angle in the opening.

     Because I was concerned about the envelope of the new walls and getting a tight seal, it was decided to frame and fit the walls short of the actual original openings and then insulate and seal effectively. This left a space to be filled that allowed us some flexibility as the original window openings, while a good size are not all square. This meant custom fitting each opening. Working with our crew, we experimented with a couple of ideas and settled on creating  two support strips made of pine, each piece ripped at a different angle to fit inside the splayed opening. We then tried to pack cellulose in behind a plywood backer that was attached to the strips. This failed; it was too difficult to fill the cavity with consistency. Back to the drawing board, we went, making up new plywood backers, this time with small holes strategically located to allow the installation of low pressure window spray foam in the cavities. We went to great effort to foam carefully so as to put no pressure on the plywood backer. This backer will support the finish pine dress piece, which will be glued onto the plywood, thus allowing a fastener free surface for a neat, clean finish trim piece.

    While this may seem to be going to extremes, in fact, the extra cost will be far outweighed by the benefits of extra natural light and the elimination of a possible cold zone. While everyone enjoys the aesthetic beauty of natural light, it’s well documented that sunlight contains vitamin D and some small amount is thought to penetrate glass benefiting those who suffer health issues from depression to obesity. The passive solar benefit, with respect to a decrease in heating bills, is also well documented. More light translates into more heat, provided there is some method of capturing this heat in the winter. Our windows and solar blinds are designed to do exactly that and we expect to retain up to 80% of the winter passive solar heat in the church.

    A number of readers who are following the project have asked for pictures of the interior progress, so this week I have included a few. The walls are 90% done and the new natural cedar loft rose up from a pile of sawn posts this week. If you wish to follow our progress, please go to www.alltechgreenchurch.ca