When a Tree Falls
Over the past couple years I have become a regular reader of the Green Building Advisor blogs. Although we are two years away from breaking ground on the 780 sq ft home we have planned, I feel as if there just isn’t enough time to absorb even a fraction of the body of knowledge known as “building science.” As with most things, the more I dig into it, the more I find that I don’t know (and the more I wonder how much I really do need to know). It’s too late, however, for a retreat into the bliss of unknowing.
I’ve spent quite a bit of time scratching my head as I pour through journals in search of current analysis, opinions, and experience with low-tech methods for home insulation and ventilation. Unfortunately, much of the contemporary debate and construction practices focus on the highly engineered, high-tech products and methods. There is very little in most of today’s so-called green buildings that is delivered to the job site without complex and energy intensive input from engineers, chemists, factory workers, and raw materials that have been extracted from who knows where.
Recently I read of a Passivhaus home built atop a 16” layer of extruded polystyrene, enclosed with similarly thick layers of chemically manufactured insulation and structural components in the walls and roof. The materials list is filled with acronyms (EPS, OSB, SIP, TJI, etc.) and cryptic techy names (DensGlass, Intello Plus, Solitex Mento Plus, Agepan, etc). Forget about locally sourced. This stuff relies on input from around the globe that is then globally transported and comes with global consequences. The amount of energy tied up in the finished products that make up a “green” home – embodied energy – can easily exceed the amount of energy saved in heating/cooling the home over its lifespan.
Embodied energy (as defined in a Green Building Advisor article titled, “All About Embodied Energy”) includes:
- The energy required to extract the raw materials used to make the building.
- The energy required to transport the raw materials to the factory where the building components are manufactured.
- The energy required to manufacture the building materials.
- The energy required to transport the building materials to the building site.
- The energy required to put the materials together at the building site, including the energy needed to transport the workers to the site.
- The energy needed to maintain a building component throughout its life; this type of embodied energy is sometimes referred to as “recurring embodied energy.”
- The energy required to dispose of a building component or recycle it at the end of its life.
While looking at the complete impact of so-called low energy buildings, a recent study by Catarina Thormark found that, “For a service life of 50 years, production and transportation of materials accounted for 60-75 % of the [buildings’] total impact.”
While it may require less fuel to heat today’s green homes once they’re built, the energy that goes into them before the occupants can move in often outweighs the savings in monthly fuel bills.
So, what’s all this got to do with the picture (above) of Marion sitting on a downed tree? Those trees represent a contribution, albeit modest, of both locally sourced energy and locally sourced building materials that were grown on site and will not travel more than a few hundred feet on their journey from the forest to a finished product in the home.
The trees came down during a 2012 springtime “wind event” (increasingly common in this day and age). When they fell, Marion and I were a half-mile away getting the mail. We heard what sounded like a cannon fire. While we were curious, we dismissed the booming noise as something a neighbor up the mountainside was up to. We didn’t think about it again until we were sitting beside the garden some days later. We glanced through the trees toward the upper meadow. Startled by the sight (and wondering how we’d missed seeing it earlier), we got up to investigate.
The main culprit had been a 93-foot poplar (we took out the tape and measured it) that the wind had uprooted near the stream bank. On its way to the ground, that poplar took down a straight and tall cherry tree, a large white birch, a smaller white ash and a section of an adjacent sugar maple. Raw materials were delivered to our doorstep.
We cut the lower sections of the trees into 8 to 16-foot lengths and stacked them next to our firewood pile with the intention of taking them to the local sawyer we’d used in previous years. The rest of the wood was sorted into piles of either “sugar wood” or “house wood.” (It actually takes more wood to make our maple syrup in the spring than it takes to heat our tiny house for a year.)
Through the rest of that summer I eyed those saw logs and mulled over my options for getting them to the sawyer. I really didn’t want to cut them up into the short lengths that could be loaded into the pickup truck (then taken to the sawyer in multiple trips). Borrowing a trailer was an option, but had complications, too. We considered buying our own trailer (something we certainly could make lots of use of) but, as winter approached, I had yet to make up my mind. The logs were off the ground and protected from moisture. The ends were sealed. There was no rush to sort it out.
By spring I’d made up my mind. The answer was none of the above. I decided to bring the mill to the logs. We could either hire a portable sawmill operator to bring a mill onsite and saw the logs into boards, or invest in a tool of our own. We decided to purchase our own mill. The cost was justified in the savings we’d realize by using our own white ash trees to produce flooring for the new barn. The milling of the blow-downs was a bonus. (Ah, the powers of rationalization!)
In previous years I’d stopped to watch the Wood Mizer product demonstrations at the annual Tunbridge Fair. Knowing that they’d be trailering mills to the fairgrounds again this year I took advantage of the savings on shipping (free) by ordering a mill in early September. Once the foundation work for the barn was complete and other priority fall chores were out of the way it was finally time to assemble the mill and start cutting.
A seasoned sawyer I am not. I was very nervous as I moved the blade into a length of birch for my first cut. Marion stood ready with the camera. The blade moved through the wood with ease – until it came to a log support that I’d set too high, nicking it just below its top. Dang! Why do we have to learn things the hard way?
I shut the saw down, repositioned the log supports, then started to drive the blade again. Success followed, along with lots of fun work. I found it incredibly exciting when sliding each cut board off the log. There was great anticipation for what I’d find inside, and great satisfaction in knowing that I’d see this wood along every step of its journey to the finished product, right here on this land.
By the time I’d packed up the mill to be stored in the barn, I had about 700 board feet of sawn wood, stickered and stacked where it will remain for the year or more of air drying required before it can be used for furniture. The birch and cherry is destined for cabinet doors and drawer faces. The poplar may find its way into drawer boxes. The maple had some amazing grain and richly figured heartwood that will be used for something requiring an artistic touch. Finally, there are the nice wide planks from three white pines that had blown down near the base of our road last spring. We’ll find a use for them, I’m sure.
Once our house is finished, the materials will have been sourced from places near and far. That’s the reality I’ve come to accept. Some will have origins close by, such as the timbers that will become the frame and the stone we’ll use in the foundation. The cedar siding shingles will likely come from trees grown in the Pacific Northwest. Other products will come via origins more difficult to trace, like the metal roofing and plywood sheathing and moisture barriers, etc.
The contributions from this piece of land will not be insignificant, however. I dream of one day standing in our kitchen, preparing a meal from food raised on the land just outside the door while surrounded by the beauty of the wooden cabinets, tables, and chairs I’ll make from the trees that grew by the stream within view of my window.