Toxic emissions
The sources of pollution in a building are more numerous than we realize. In addition to the construction materials themselves, including glues and finishes that may emit volatile organic compounds (VOCs) such as benzene and formaldehyde, poor building management may result in the proliferation and spread of mould, dust or contaminants from cleaning products. It is important to remember that human activity also produces many pollutants, including perfumes, electronic devices or cigarette smoke.
The Centre for Sustainable Development has replaced materials that are suspected of being toxic with materials that are recognized as being less toxic, such as no-VOC paints and urea-formaldehyde resin-based adhesives. The following strategies will aim to address several other common sources of contaminants:
- Use of non-toxic cleaning products
- Improved ventilation
- Maintaining optimal humidity
- Ventilation of bathrooms and hoods to outside
- Purging of the building before occupation
- Regular cleaning of the ventilation system
Plant wall
Even when using the best treatment systems, interior air in buildings is almost always lower quality than exterior air. This is due to human activity, which generates contaminants that are literally imprisoned inside due to the tightness of the building’s envelope. Over an extended period, the absorption of these contaminants could have a negative impact on health.
By supplementing air exchange with the outside, bio filtration cleans the building’s air by removing chemical compounds that cannot be processed by even the best filters.
Characteristics of the CSD’s plant wall
- Approximately one plant/ft2 for a total of 40m2 arranged on 5 floors.
- A duct built behind the plant wall "inhales" the atrium air through the network of plant roots.
- Micro-organisms living in symbiosis with plant roots feed on polluting molecules. The growing medium, polyester wool, is woven in a way that maximizes the contact surface of roots and the movement of air.
- Nutrient-rich water flows into the root system, nourishing plants and intercepting dust suspended in the air.
- The wall will be made of 75-80 plant species.
Raised floor
Displacement ventilation is a technique consisting of tempering a space by injecting air into it through floor diffusers (the exhaust outlet is in the ceiling). Such a system can make use of an area located between the structural slab and the floor finishing. This space, called a plenum, acts like a pipe whose large volume reduces the feed rate.
The plenum consists of a metal grill supported by poles. The empty spaces in the grill are filled with square cement-core slabs that are placed on seal cushions. Some slabs are equipped with a mechanical valve to regulate air flow from the plenum. The slabs can be easily moved, which makes it simple to reposition air outlets, electrical outlets and data.
Displacement ventilation
- Using mechanical valves that are easily accessible, displacement ventilation increases comfort by allowing users to control the ambient temperature.
- The warm and cool air supply comes from below, which allows for better air mixing and improves user comfort.
- In addition to maximizing free cooling potential, this approach requires lower velocity and lower volume of outside air – factors that result in energy savings.
- According to Natural Resources Canada, there may be fewer pollutants (CO2) in spaces that use displacement ventilation compared with those that use mixed flow ventilation. This reduction results in lower risks for asthma and sick building syndrome.
