Green building is a resource-efficient method of construction that produces healthier buildings which have less impact on the environment and cost less to maintain. This sustainable approach to construction accounts for a building’s entire life cycle: siting, design, construction, operation, maintenance, renovation and demolition (read Life Cycle Assessment for more).
Names like sustainable building, high performance building and green construction are used interchangeably to describe what is essentially the same thing, though there are variations on the theme that have slightly different meanings. Natural building, for example, is a sustainable form of building, but with an intent on using only natural building products. Sustainable design encompasses green building, yet delves into a much broader set of issues from the micro (sustainable furniture design) to macro (sustainable urban planning).
Comprehensive rating systems that certify green buildings, such as LEED, Living Building Challenge and BuildGreen, measure the sustainability of a building according to a number of criteria. Taken together, these criteria form an accurate picture of what green building is all about. The common criteria are listed below.
Sprawl is not sustainable. Green builders are encouraged to build on previously developed land rather than developing new land. It’s also important to build near existing infrastructure, such as bus routes and libraries, to reduce residents’ dependence on transportation, since the effort that goes into building a green home is wasted if the occupants have to commute great distances every day. The smaller the building site the better since there’s less environmental footprint. Sites that have been sustainably landscaped and don’t suffer from soil erosion or light pollution are also considered more sustainable.
Water reduction is built in by design, using low-flow toilets, greywater systems and xeriscaping. The focus is first on reducing the need for water (i.e. low-flow toilets) then on dealing with water once it has been used (i.e. greywater irrigation). Water collection methods such as rainwater harvesting are also central to sustainable building.
Energy and atmosphere
Green buildings are constructed using energy efficient designs (i.e. passive houses are built with super-insulation and other techniques to ensure a tight building envelope and minimal energy consumption). Processes that make use of clean energy such as geothermal and solar PV systems are also widely used in sustainable building.
Materials and resources
It’s estimated that as as much as one-third of Canada’s total waste is building related. To minimize the impact of this wasteful industry, green builders reduce material usage wherever possible. They also reuse and recycle materials by salvaging, deconstructing, remanufacturing and refurbishing. Preference is given to materials that are durable because they don’t need to be replaced as often. Care is also taken in selecting materials that are sustainably produced, come from natural, renewable sources, and require minimal transportation (read Green building materials for more).
Another aspect the relates to materials and resources is building size. Average living space per Canadian is 700 square feet, a figure that has quadrupled in a generation, according to Ecohome. As a country we have shrunk our family size, but increased our home size. This rapid growth in home size is simply not sustainable. According to 100K : “A 100 per cent increase in home size yields an increase in material usage of 40 to 90 percent… and an increase in annual energy usage of 15 to 50 per cent.”
There’s no specific home or building size that is considered sustainable, but there are guidelines. The LEED Home Size Threshold sets a neutral home building threshold that ranges from 900 to 2850 sq. ft. depending on the number of bedrooms (one to five). Going above the threshold makes it harder to achieve LEED certification, and below, easier.
Indoor environmental quality (IEQ)
Health Canada states that Canadians spend up to 90 per cent of their lives indoors, which means the quality of indoor air is much more important to our health than the quality of outdoor air. Green builders strive to construct buildings that are good not just for the environment, but for our health. Low-emitting materials are encouraged such as zero-VOC paints and formaldehyde-free furnishings. Improved ventilation and moisture-resistant products are also key IEQ attributes.
Building does not just imply the physical construction of structures. Building also means the development of a neighbourhood, the creation of a park, the redesign of infrastructure. Some consider green building to be a culture of transformation. One forward-thinking example would be the redesign of an entire suburban neighbourhood into a car-free, population dense neighbourhood with easy access to urban agriculture. Living Building Challenge captures this concept of wholistic building best with the provocative question, “What if every single act of design and construction made the world a better place?”