Wood – The Better Builder
Wood is one of Earth’s most valuable resources – it’s renewable, it’s sustainable, and it’s energy efficient. However, until recently, wood has been overlooked as a major building material in urban settings.
Today, based on technological advancement and scientific analysis, it’s become clear that building with wood – even high-rise buildings – is becoming a reality. With exponentially increasing populations and a growing demand for more sustainable approaches to construction, it’s very likely that urban environments will increasingly rely upon our oldest building material – wood!
1. Wood requires less energy than other common building materials
Embodied energy is the total energy required for the extraction, processing, manufacture, transportation, installation, use, maintenance, and disposal of building materials to the building site. The lower the embodied energy, the lower the environmental impact, monetary costs, and time investment associated with a material.
Wood has very low embodied energy levels compared to other common building materials. For example, a wood house can have anywhere between 40-60 per cent less embodied energy than a house made of concrete or steel. For production alone, a ton of softwood requires four times less energy than a ton of brick, five times less energy than a ton of concrete, 24 times less energy than a ton of steel, and 126 times less energy than a ton of aluminum.
Wood’s comparably low embodied energy levels is largely due to the intense heating and cooling processes steel and concrete must go through prior to construction. While wood harvesting is energy intensive, processing and manufacturing is somewhat simple, reducing overall time and energy costs.
2. Building with wood is more efficient
When you picture a typical construction site, you often think of a noisy eye-sore and inconvenient traffic backup. However, wood building construction sites are a far cry from this conventional scene.
First, wood construction is incredibly fast. With 15,000 km2 of cross-laminated timber able to be installed per day, mass timber projects can be completed 25 per cent faster than similar projects using other common building materials. For example, the timber portion of the nine-story residential Stadthaus building in London took a crew of four men only 27 days to erect – 30 per cent faster than it would take a comparable structure in an alternate building material to go up. Here in Canada, UBC’s 18-storey Brock Commons was completed in only 70 days – that’s two floors completed per week! This speed in combination with the predictability of mass timber and ability to build year-round makes wood an extremely cost-effective and efficient building material.
Wood building construction sites are also far less noisy, which is better for workers and nearby residents. Construction speed and ease can lead to 90 per cent less construction traffic – all at a lower cost that other materials.
Finally, building with wood creates less on-site waste. Due to the high volume of prefabrication involved in mass timber construction, there is little to no waste on the job site; further, manufacturers can often re-use residuals/scraps for other uses. For instance, the construction of UBC’s Brock Commons reduced on-site waste by about two-thirds.
In some cases, cross-laminated timber can even be made from trees that have been killed by pests, like the Mountain Pine Beetle!
3. Wood is a natural insulator
Some of the most substantial building costs and environmental impacts are related to operation, with heating and cooling costs at the top of the list.
Enter wood: the natural insulator. The cell structure of wood is made up of air pockets, allowing it to be five times more insulative than concrete, 400 times more insulative than steel, and 1,770 times more insulative than aluminum. As a result, wood buildings require less energy to heat and cool, leading to reduced energy bills. For instance, it’s estimated that a small house made of wood in Montreal would use 2,900 kW-h less per year than the same sized house made of steel.
Further, wood is hygroscopic, meaning it has the ability to absorb or release moisture to act as a buffer against external changes in humidity and temperature.
4. Exposed wood improves occupant well being
Biophilic design places heavy emphasis on incorporating aspects of the natural world into construction. It aims to foster health and productivity, and has been connected to reduced blood pressure, improved short-term memory, and overall more positive emotions. Building with wood is the perfect example of biophilic design!
Many studies have established a link between wood and human health. Common benefits experienced by occupants of wood buildings include lower stress levels, improved attention and focus, greater creativity, quicker recovery from illness, and reduced pain perception. A literature review of over 40 studies supported this finding, concluding that interior wood can induce physiological relaxation.
Wood buildings can also benefit the physical health of occupants. Wood, considered to be hypo-allergenic, prevents the accumulation of particles, like dust or pollen, which can occur on other surfaces or finishes. It can also regulate humidity levels, further contributing to air quality.
5. Building with wood is GREEN!
One of the most attractive elements of building with wood is its ability to lock up sequestered carbon far beyond the natural life span of a tree. While the manufacturing and production of other building materials emit a significant amount of carbon, wood buildings represent carbon sinks.
For example, a study done in New Zealand found that a 17 per cent increase in wood usage in the building industry would lead to a 20 per cent reduction in carbon emissions from building material manufacturing. This figure becomes quite significant when you consider that CO2 emissions from the building industry account for about 40 per cent or more of global CO2 emissions. To put this into perspective, a five-storey wood building could reduce the same amount of CO2 as taking 600 cars off the road for a year.
Here in Canada, a life cycle assessment study drawing on data from the region of Toronto concluded that wood buildings can emit up to 29 per cent less greenhouse gases than other conventional building materials, contributing to savings equivalent to anywhere between 3.6 to 8.6 years of global warming gas emissions.
Further, this study found that wood design resulted in three times less water pollution and 12 per cent less air pollution than other design materials, solidifying wood as one of the most environmentally responsible building products.
Find out what an architect has to say about wood.
To find out more about how wood is used in buildings visit Wood Works.