Trees consist of innumerable long, thin, bundled together tube-like cells called tracheids. These contain a lot of air and moisture, which make the wood insulating, able to adjust to humidity, and effective for soundproofing. Thanks to these cells, the walls are able to recover from outside pressure. Furthermore, the walls of the tracheid cells are made of thin stick-like crystal structures (microfibrils) consisting of cellulose molecules.
- Insulating Properties: A thick wall is formed by the large amount of air in cellulose, acting as a barrier to outside heat. Imagine an excellent insulating material tightly surrounded by a hard outer shell. Wood is twelve times more insulating than concrete. It transfers heat 1/500th as easily as iron and 1/1700th as easily as aluminum, and it is much less heat conductive than many other materials as well. In the olden days, people lined the inside of safes with wood. If there were a fire, the wood would stop the heat conducted by the iron, and save the bank notes inside from burning!
- Natural Air Conditioning Effect: Wood reacts constantly to its surrounding environment. If the humidity is high, wood absorbs moisture. If the humidity is low, it emits moisture. Wood acts as a “natural air conditioner,” keeping room temperature constant. Inside a log house, the air is neither too humid nor too dry. If one were to measure the humidity in a room with an air conditioner, one would find the area in front of the air conditioner to be cool, but the area near the door would be warm. Rooms made of wood don©t have the same unevenness, due to the wood’s humidity-adjusting properties.
- Durability of Wood in Relation to the Age of the Tree: It is said that the older the tree, the stronger the wood it produces. From the time the tree is harvested, the cellulose molecule structure which gives the wood its strength loses the water in its cells. This causes crystallization, and makes the wood strong. When wood is as old as the tree was at harvest time, it is at its strongest. In other words, the wood of a 100-year-old tree will be at its strongest 100 years after the tree is harvested and the wood of a 1,000-year-old tree will be at its strongest 1,000 years after harvest. Wood is indeed a very durable material.
- Light Yet Strong: Reinforced concrete is a manmade material which combines iron bars to resist tensile force and concrete to resist compressive force. However, weight by weight, coniferous wood is four times stronger. If one were to build two houses of the same strength out of reinforced concrete and wood, the wooden house would be much lighter. The energy of an earthquake is proportionate to the weight of a building. The heavier the building, the more it is affected by the earthquake. Therefore, a wooden house is more earthquake resistant.
- Relaxing Environment: It has been scientifically proven that a kind of terpene substance emitted by wood, which is used for protection against invaders, is effective in relaxing the mind and body. This is the so-called “forest bath” effect. This effect does not change once the tree has been harvested. It continues to provide us with a deeply relaxing environment.
- Log houses do not burn easily: It is common knowledge that wood burns easily. However, this does not apply to thick logs. It has been proven in experiments that big trees in their natural state do not burn easily. A layer of charcoal forms on the outside part of the tree. It is difficult for the fire to reach the inside, as there is a lack of oxygen. Experiments have been conducted which compare wood, iron and aluminum. Results have shown that as temperature rises, iron softens, and in less than five minutes it loses more than half its strength. Aluminum goes limp in only three minutes. In comparison, it takes ten minutes for the strength of wood to decrease by 20%, and twenty minutes for it to lose half its strength. Wood is weakened by heat, but it takes time for heat to penetrate logs.
- What about the fact that wood rots? Nobody wants their house to rot, but rotting itself is not a bad thing. The reason industrial waste has become a problem is that it doesn’t rot! It’s important to know what causes the natural phenomenon of rotting, and be able to deal with it. For wood-rotting bacteria to grow, three conditions must occur simultaneously: moisture, the right amount of humidity, and plenty of oxygen. In other words, if just one of these conditions isn’t present, the wood will not rot. These days, there are very effective anti-rot protective wood coatings on the market, and if one makes sure the home is aired sufficiently, rot can be easily avoided.
- Wood is environmentally friendly: Wood is formed by photosynthesis, for which solar energy is necessary. The chlorophyll in leaves reacts to light by synthesizing dextrose and starch with carbon dioxide from the atmosphere and moisture from the roots, causing the tree to grow. Animals and humans grow by eating plants and other animals. It can therefore be said that we have photosynthesis to thank for our existence. These days, global environmental problems are a major issue all over the world. One of the biggest problems is that of global warming, caused by burning fossil fuels which release too much carbon dioxide into the atmosphere. It is the forests of the world that counteract this problem. If wood is burned or left to rot, it decomposes into carbon dioxide and water. However, if it is used for as long as possible in a log home, the carbon dioxide is not released, and if a new tree is planted to replace it, more carbon dioxide stays fixed than before construction of the house. A 100-year-old tree should be used to make a house that lasts more than 100 years, and it should be replaced with a new tree. Using wood efficiently in this way is the key to protecting the environment.
- Wood is spiritually soothing: If infants are given a choice between a plastic toy and a wooden toy, they will more often choose the wooden one. This is probably because wood was once a living thing, and touches people’s hearts in some way. Studies have shown that teachers and students in schools with wooden interiors find they tire less easily, and in such schools there is less violence than elsewhere.