Log Cabins And Energy Efficiency: Why Thermal Mass Matters

Log homes are an excellent example of green construction — they're made out of renewable resources and the durability of their thick logs gives them an incredibly long lifespan. However, there's some controversy about whether or not log homes are energy efficient. Energy efficiency is a major concern if you're looking for a green home. Are log homes truly energy-efficient? Let's examine some of the issues surrounding energy efficiency in log homes.

The Problem: Wood Is a Worse Insulator Than Fiberglass

While wood is better insulator than other building materials such as concrete, it's not as good as fiberglass. It's impossible to use fiberglass insulation on the walls of a log home — if you did, you'd obscure the beautiful view of your home's natural logs.

The fiberglass insulation used in the construction of modern homes means their walls are better insulated from the weather outside, even though their walls are thinner than the walls of log homes. Fiberglass became the most popular form of insulation for a reason — it's very effective.

Wood's poor insulating capabilities compared to fiberglass have led some people to say that log homes are not energy-efficient homes. However, that neglects a very important factor in overall energy efficiency.

High Thermal Mass in Log Homes Keeps Temperatures Steady

You may have heard that you should store gallon jugs of water in the freezer in order to prepare for severe weather. If you lose power during the storm, the frozen water will help your freezer stay colder longer, keeping your food from spoiling. Why does it work? It's the concept of thermal mass — adding mass to your freezer increases its resistance to temperature change.

The concept of thermal mass applies just as easily to log homes. The natural logs used in the construction of these homes are usually six to eight inches thick and extremely heavy. Log homes simply have a much greater mass than comparable wood frame homes of the same square footage?

How does this apply to energy efficiency? A high thermal mass keeps temperatures stable throughout the day. The sunlight and warm weather of the daytime hours warm the natural logs, which can hold a substantial amount of heat energy due to their high mass. When temperatures fall outside in the evening, the high thermal mass of the logs helps to prevent the cold outside air from lowering the temperature inside.

Thermal mass is the reason that log homes are energy-efficient despite wood having worse insulating capability than fiberglass. Maintaining a comfortable temperature inside your home is more complex than how well your insulation works — it also has to take into account the ability of your home to easily resist temperature change. Log homes are much better at outside temperature fluctuations than wood frame homes, which keeps you comfortable all day long without needing to turn on the heater or the air conditioner.

On a final note regarding energy efficiency, it's important to avoid drafts caused by settling logs. As the logs used to construct the home dry out over time, gaps can open up between them that let the outside air in. A drafty log cabin isn't energy efficient at all! Drafts can easily be prevented by either drying the logs beforehand in a kiln or by applying foam gasket tape between the logs. Log home kits that have energy efficiency in mind will include these measures in their plan, giving you a truly green, energy-efficient home.