The energy efficiency of a log home is a very good question.The first thing to understand about a log home is that no matter how thick the logs are or what species the home is made from, logs cannot do their job of insulating unless they are stacked tightly and the homeowner checks for leakage. Logs are a natural product and it is part of the nature of the log to compress, shrink, and also acclimate itself to its new surrounding. Log homes perform very well in the energy efficiency world. There is no doubt about it.
Now on with our log home energy efficiency evaluation. Log homes possess a thermal mass. Thermal mass is the tendency of a natural product to absorb and then slowly really release heat or cold. If you think of a rock. If the sun shines on it the rock will remain warm to the touch even after the sun goes down. This is thermal mass. Many natural products including cement and logs possess this quality. So with a log home, the home absorbs and then releases, thus recycling some of the energy produced by the environment around it.
Stick frame homes, though possessing a good R-value when insulated properly, have no toe hold in thermal mass. This is a attribute only innate to natural products such as wood.
After reading several studies, these two stood out the most to me. A few years ago an independent study group conducted the following case study. Located in Michigan, a cooler place in the United States, they built two homes side by side. The first home was a standard construction home with good insulation. The second home was a milled log home of a comparable size. Over the test period it was shown that the log home had an energy savings of 25% over the 24 hour test period.
How could this be? Let’s look at the study a little deeper. When the temperature outside was 25 degrees Fahrenheit, the standard construction home required 8.1 kilowatts hours to maintain 72 degrees on the inside. In contrast, the log home required only 6 kilowatt hours to maintain 72 degrees. Simple subtraction shows a difference of 2.1 kilowatt hours– a savings of 25 % in favor of the log home.
The other home study I would like to mention was preformed by The Log Home Council. Their study reflected a 15 % energy savings of a log home over a stick frame home of the same size.
Some European countries require a very high R value. The standard 8 inch milled log is not thick enough to satisfy the R-value equivalents that are required. So only the thick 12 to 16 inch diameter handcrafted log homes are suitable to send to some foreign countries.
Most of the shrinkage, compression, and acclimation of the logs occur during the first year. After that the logs tend to move very little. It is a wise idea to have your builder revisit the log home when it is a year old and check for any areas that might need some more attention to seal the weather. Log home assembly materials such as: soft rod insulating gasket, double rows of foam tape between the rows, and a lot of log home screws per row which are employed during the construction of the log home make the seams between the row of logs more air tight. I do not feel it is a fair assumption that all log home have to be chinked. In fact I feel that is a very uninformed option. Instead I think each log home should be taken as an individual.
In the 1990’s the technology improved and foam gaskets came into use. This greatly helped to improve the sealing between the rows of logs. Years ago no sealant or caulking of any kind was used between the rows. So again, each log home should be taken as an individual. Chinking can help to seal a drafty log home but if you are beginning with new construction, using premium grade logs, have an overlap of log to log over a curved surface between the rows, and things like double rows of foam tape or soft rod gaskets in place between the logs, then chinking becomes much more of a personal preference than an a necessity to seal the drafts out of the log home.