At the end of its life, a brick is effectively just a manufactured clay stone with a special shape. It breaks down into earth since it comes from earth. Clay mining is comparatively benign, compared to ore mining for metals, which requires far more material to be extracted and processed to produce the finished product. Clay is not a resource that is in short supply, which makes it a more attractive material to use, as well.
The main reason brick isn’t an even greener building material is that it takes a lot of energy to make a brick. However, the extra energy is relative. An Australian government website comparing wood siding to brick veneer shows that exterior walls with the same backing construction with brick have about three times as much embodied energy per unit of wall area. (A timber board clad wall takes 188 MJ per square meter; brick veneer requires 561 MJ per square meter.) The trade off is in durability and maintenance. Brick is much lower maintenance than other materials. Most brick will last for generations with only some minor tuck pointing to repair joints.
A 100-year old building is considered old by North American standards. While a wood sided building will have been repainted many times and have had repairs and replacement of parts that have broken down over that period, the brick on a brick building of the same vintage will be little changed from the day it was first laid in place. Durability is another hallmark of green building, and a brick building that is properly designed and constructed and maintained can last for centuries.
A list of the benefits of brick comes from the Sustainability Resources website
of the Denver Chapter of the AIA:
Brick is resistant to damage from wind and water, and does not need additional finishes.
• Compressive Strength:
Brick can carry heavy loads, but it is often used as a veneer over a separate structural system
because of cost. Many brick manufacturers provide larger brick sizes to be used in a single Wythe (layer)
for load bearing.
• Acoustical Performance:
Brick’s mass makes it good for reducing sound transmission; however, its hard surface reflects sound.
• Chemical Makeup:
Brick’s raw materials are chemically inert; consequently, they will not contribute to indoor air pollution.
Brick is non-flammable and makes an excellent fire barrier.
Brick and other masonry products are heavy and dense. While this makes them durable building materials,
it also makes transporting them an energy-intensive process. The best way to deal with this is to use locally produced brick. In regions where brick is widely used, sources within a couple hundred miles should be easy to find. If brick is not widely used in your area, it is probably less appropriate to use, and the transportation energy required to obtain it should be considered.
Brick is also a recyclable material. Old brick walls can be carefully demolished and a high percentage of the individual bricks can be salvaged and re-used. The character and quality of good recycled brick can be very appealing, and good recycled brick sometimes even commands a higher price than some kinds of new brick. Depending on the market and the region you are in, recycled brick may or may not be readily available. But the energy from deconstruction and cleaning old brick is almost certainly less than that needed for making new brick, so extending the material life in this way is a great way to save the embodied energy and extend the life of this material.