Estructura de Nombre Único

Objectives

• to minimize the contamination of indoor air during construction and during operation. • to reduce or eliminate the use of materials

that emit contaminants or pollutants to indoor air.

Indoor air pollutants can be introduced by various construction processes, interior activities, inadequate maintenance and by materials specified and used in buildings.

Compounds introduced during construction and renovation can contaminate the indoor environment and lead to long-term problems with indoor air quality. HVAC systems are especially vulnerable to contaminants such as dust, VOC’s, and micro-organisms. Contaminants can remain in HVAC systems for long periods of time, causing serious health problems to building occupants. Strategies to minimize contamination during construction include:

• isolating HVAC systems;

• isolating work areas to minimize overall contamination;

• cleaning frequently during construction; and • cleaning thoroughly after construction but

before system startup.

During construction or renovation, it is important to schedule the installation of pollutant-absorbing materials as late as possible in the construction process. Some materials, such as fabric-coated partitions, carpets, insulation, ceiling tiles and gypsum products will absorb VOC’s from paints and sealants used during construction. By installing these products at the end of the process, VOC’s have nowhere to be absorbed, thus resulting in a better IAQ. Finally, the allocation of sufficient time (at least two weeks) for systems operations prior to occupancy, permits a complete flushing of building air, thus improving indoor air quality. However, the release of contaminants from the building reduces the quality of outside air and contributes to smog. After occupancy, common office equipment (such as photocopiers and fax machines) produce volatile organic compounds that contaminate the rest of the building. Design teams should provide adequate measures to prevent the transmission of these VOC’s to the entire building by providing HVAC solutions that isolate this equipment, by locating exhaust air vents to serve them or by providing separate ventilation systems.

Many manufactured materials emit VOC’s; including adhesives, sealants, composite wood products and carpets. PVC and vinyl products also emit a range of atmospheric pollutants. The best design strategy to reduce the amount of VOC and other contaminants in the indoor environment is to specify low emission materials. (Refer to the Materials and Resources section).

Certification or labeling programs are in place to provide minimum performance standards. For example, Environment Canada’s EcoLogo Certification Criteria for paints and surface coatings stipulate that a product must not be formulated or manufactured with formaldehyde, halogenated aromatic solvents or heavy metals such as mercury, lead, cadmium or chromium. Paints and stains must not contain VOC’s in excess of 200 grams per litre and varnishes in excess of 300 grams per litre.

2

SDCB 101 – Sustainable Design Fundamentals for Buildings

Indoor air contaminants are particularly harmful to allergy sufferers. The design of environments for hypersensitive occupants is a specialty of some Canadian architects. A housing project in the Ottawa region demonstrated that a low toxicity indoor environment can be achieved with no premium on construction costs.

Buildings usually have cleaning and maintenance routines associated with them. The selection of low maintenance natural building products may reduce the use of chemical cleaning products or maintenance materials such as paints. The Liu Centre at the University of British Columbia illustrates the use of low toxicity finishes requiring minimal maintenance.

The maintenance and cleaning of indoor air supply and distribution ducts is important. Therefore, easy access to ducts and shafts for periodic cleaning must be provided. Concealed ducts should be avoided whenever possible. An under floor air system with access floors provides for easy and economical cleaning. The interior of an air supply duct that has not been cleaned for 25 years is a frightening sight, as evidenced by this duct with a 10mm layer of organic and bacterial “growth” contaminating all the air that flows through it.

Summary of Strategies for Use

across Canada

• Minimize HVAC system contamination during construction.

• Provide for an adequate period to flush the building before occupancy.

• Isolate areas and activities that generate VOC’s such as photocopiers, and storage areas for cleaning and maintenance supplies. • Specify low emission materials that minimize

or eliminate off gassing.

• Specify low maintenance materials to reduce the use of chemical cleaning products. • Prior to selecting a product, determine

the level of emissions of VOC’s from the manufacturer.

• Specify certified products that meet a minimum standard.

• Provide maintenance access to all air supply and distribution systems.

Indoor Air Quality Chapter 7.1

A housing project in the Ottawa region demonstrated that low toxicity indoor environments can be achieved with no premium on capital cost.

Interior of duct that has not been cleaned.

The Liu Centre at the University of British Columbia illustrates a minimal use of overall finishes. Low toxicity and low maintenance were primary considerations for the selection of finishes.

Case Studies

Low Cost Dwelling for the Environmentally Hypersensitive

Phillip Sharp Architect Ltd, Ottawa, ON

Liu Centre for the Study of Global Issues

Architectura, in collaboration with Arthur Erickson, Vancouver, BC

Resources

Canada’s EcoLogo

www.environmentalchoice.com

OIKOS Green Building Source

www.oikos.com/products

Building Materials for the

Environmentally Hypersensitive, CMHC

www.cmhc.ca

Public Works and Government Services Canada, IAQ

www.pwgsc.gc.ca/rps/iaq

In document Manual de Declaración de Prácticas de la Infraestructura de Firma Electrónica de la Comisión Nacional de Bancos y Seguros (página 38-0)