Indoor Air Quality
Good indoor air quality enhances resident health and comfort and is an essential goal for any building. A high quality indoor environment requires careful design, construction, and choice of materials. Indoor air quality requires design that incorporates adequate air exchanges, well designed ventilation and avoidance of mold through moisture control, all of which complement a strategy that achieves energy efficiency and building durability.
The most effective way to reduce exposure to indoor air pollutants is to keep residents away from sources of pollution. Ventilation design provides for adequate exchanges of fresh air. A well-designed building envelope keeps moisture and mold at bay. Clean construction practices and smart materials specifications reduce dust and volatile organic compounds (VOCs). Attentive maintenance emphasizes non-toxic solutions.
As you begin planning for your building, develop an indoor air quality management plan and specify each building team member's responsibilities in contract documents. Consider the following best practices:
Exclude pollutant sources
- Let in fresh, clean air by keeping intake vents away from exhausts and moisture sources.
- Keep residents safe by checking for radon, tightly sealing between the garage and the home, and specifying carbon monoxide sensors.
- Directly vent heating equipment, ovens, bathrooms, and cleaning supply closets.
- Implement a non smoking policy and use entry mats that remove dirt from shoes.
- HVAC installation. Cover ductwork during construction, then vacuum it and install new filters before turning on the central heating/cooling system.
- Drying time. Use a schedule to allow concrete, spray insulation, sealants, and adhesives to dry or cure so that they do not absorb water or VOCs.
- Clean up. Keep the construction site clean, and clean thoroughly at completion. Install insulation with care.
- Air it out.
- Flush the building with outside air for at least 30 days as furniture, fittings, and equipment are installed.
- Paint, finish, clean, and perform preventative pest control well before residents move in.
- Don't "bake out" the building, as it might cause more IAQ problems.
Choose non-polluting materials
- Paint, sealants, and wallpaper. Choose low- or no-VOC options.
- Avoid products that contain formaldehyde when you purchase particleboard, fiberboard, plywood, and joint compound.
- Flooring. Minimize carpeted areas and use "Green Label" or other third party certified carpet, pad, and adhesives. Avoid vinyl flooring.
- Choose non-toxic cleaning products and keep Materials Safety Data Sheets (MSDS) onsite.
Manage moisture and humidity
- Waterproof the slab-on-grade and direct water away with eaves, proper drainage planes, and flashing. Have a waterproofing consultant review the work.
- Install bathroom exhaust controls that use a timer or humidistat. EnergyStar labeled fans are quiet; the quieter they are, the more they will be used. Given Washington D.C.'s humid climate, consider a humidistat to control whole-house humidification/dehumidification system.
- Protect moisture-sensitive construction materials with just-in-time delivery and dry storage. Check moisture content in wood and subfloor/substrate before covering.
- Insulate cold water pipes and HVAC ductwork in unconditioned spaces to avoid condensation. Keep plumbing supply lines out of exterior walls.
- Fresh air is essential. Ventilate continuously (with manual override), preferably with balanced exhaust and supply fans or with a heat-recovery or energy-recovery ventilator.
- Opt for operable windows to ventilate and boost energy efficiency.
- Seal, seal, seal. Caulk is cheap, but energy isn't. Seal all penetrations to attics, to the outside, and between floors and stud cavities. Establish continuous air barriers between each unit and ventilate them separately.
- Verify, commission, and maintain HVAC equipment to ensure air delivery to and quality in each room under full and partial loads.
- Ductwork. Install high performance filters and ensure access to clean/change them regularly. Insulate with non-porous duct liners, external thermal insulation, or acoustical baffles.
- Keep water out with rainproof louvers and lower air intake velocities.
- Economizer cycles are a smart choice for fresh air and effective cooling.
- Consider transfer grilles or heat exchangers to improve system efficiency.
- Consider radiant heating.
Maintenance is key
- Regular maintenance and calibration of HVAC systems.
- Designated health and safety manager responds to all indoor air quality complaints.
- Educate maintenance staff and residents regarding healthy pest control, cleaning methods, and low-VOC household options. Show residents how to operate the ventilation systems and how to incorporate natural ventilation.
- Avoid water damage. Establish procedures for inspection and, in the case of leakage or other problems, mitigation.
- Care in repair and renovation. When material removal, painting, sanding, and other disruptive activities are anticipated, consult the Sheet Metal and Air Conditioning Contractors' National Association (SMACNA) IAQ Guidelines for Occupied Buildings Under Construction.