Enclosure
Design for a tight building envelope to maximize the performance of the HVAC system. Meet or exceed Energy Star leakage area (less than 1.25 s.i./100 sf. (Reference 1)
- Building should be able to be sealed off from exterior events that would raise outdoor pollutant levels such as, toxic spills, pesticide spraying, fires, traffic accidents, and rush hour traffic.
- Operable windows are preferred. Being able to open windows is an important access issue for chemically sensitive individuals and can be beneficial for other occupants in certain situations. Operable windows should be detailed to minimize air infiltration.
Design to prevent pest problems. (Appendix 3)
- Use inert pest resistant materials. When treatment of wood is required, treating with disodium octaborate tetrahydrate may be among the safer options.
- Incorporate pest barriers such as termite shields, window screens, and bird screens in construction details. Bird and bat droppings pose great IAQ risks.
- Some pesticides such as boric acid are considered environmentally safe. If used, granular or gel forms are preferred. Care should be taken to ensure that particles do not infiltrate interior habitable space.
Shield occupants from external sources of EMF. Windows with low e glazing, metal roof, and siding components may reduce certain interior EMF. (Reference 2)
Roof Design
- Pitched roofs are preferred, because they shed water quickly, clean the roof of pollutants and potential toxins, and are less prone to leakage.
- Inert roofing materials, such as coated metal or clay tile, are ideal. Note that galvanized metal presents a rust hazard and should be avoided.
- Flat roofs are not preferred. If used, membrane and high albedo (highly reflective to heat) type are recommended. Asphalt or modified bitumen built-up roofs are less preferable. (Reference 3)
Wall Design
- Use best design practices to prevent moisture and condensation within walls. Calculate dew points for each exterior wall (and roof) type to verify performance at each condition. Provide detail for all flashing and counter-flashing locations.
Foundation Design
- Provide under-slab vapor barriers, insulation, and damp-proofing to prevent moisture infiltration and condensation.
Protect stored building materials from water damage and mold growth.
Avoid use of water-damaged or mold-affected materials.
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