I’ve often written that one concept central to eco-thrifty design thinking is that of ‘multiple functions.’ You can save resources (eco) and money (thrifty) when one element in your design can do a number of different things. A recent example I used in this column was our Shacklock 501, which can heat our home and cook our dinner using wood as a fuel, but also ‘stores’ solar energy in the form of heat on sunny winter days.
Passive solar Shacklock 501 and passive solar cat.
The specific placement of the 700-kilogram Shacklock within our home was an important design decision for optimal passive solar performance. Unfortunately, when I am asked to audit other people’s homes I see many cases of what appear to be thoughtlessdesign decisions. One common example is the placement of glazing (windows and doors) without any regard to the sun, which can lead to unnecessary heat gain and/or unnecessary heat loss.
In Whanganui, a southwest facing, single-glazed window is likely to be a net energy loser in winter and a net energy gainer in summer. In my opinion, this is exactly opposite to the way glazing should serve a home and its occupants. During our renovation, we removed one southwest-facing window that made our home hot in summer and cold in winter, and replaced it with an insulated wall that keeps us cool in summer and warm in winter.
Before and after, southwest window (in yellow area) removed.
If you have one or more such troublesome windows but are not in a position to remove them, there are a couple of easy things you can do to remedy the situation. The obvious one is to draw your curtains during summer afternoons to exclude the sun, and to keep them drawn as much as desirable in winter to reduce heat loss. A less well-known design strategy is to plant one or more deciduous trees on the southwest side of your home to shade it from the summer afternoon sun. An even better idea is to plant deciduous fruit trees such as apples, peaches, pears or apricots to provide shade and snacks.
An even less well-known strategy is one I came up with while working with a homeowner in St. John’s Hill. This approach is most definitely a niche strategy involving south facing glass doors. In my opinion, any southerly-oriented glass door is likely to be more liability than asset.
One of two south-facing glass doors.
The aforementioned home in St’ John’s Hill provides two perfect examples to illustrate my point. One old four-panel rimu glass door with dimpled glass leads directly into the garage on the south side of the home, and another identical door leads to a small, covered south-facing landing at the back door.
Neither door receives any direct sunlight during the coldest months of the year, making both net energy losers. Furthermore, the homeowner saw no benefit of a glass door leading to the dark, cold garage or to the seldom used back door, which was located in the kitchen that had plenty of large, north-facing windows.
Our solution: Extreme Door Makeover – Eco-Thrifty Edition!
Pink Batts fitted into glass panes.
As you can see from the photographs, I took each door off its hinges, cut and placed fiberglass insulation over each pane of glass (both sides), and then screwed into place precisely cut sheets of thin plywood (both sides). The homeowner later primed and painted the ply to match.
Door after, waiting to be primed.
From my perspective, this strategy transformed both doors from extremely low thermal performance to very good thermal performance, all at a fraction of the cost of replacing them with new, well-insulated doors. Once again, eco-thrifty design thinking rides to the rescue with a win-win-win solution. Yahoo!