SECTION 297.4. Design/Construction/Renovation

(a) Building design (new construction). The following factors should be considered during the planning and design stages.

(1) New buildings. Design and construction standards that facilitate the maintenance of acceptable IAQ should be established.

(2) Site selection. During the selection of building sites, consideration should be given to minimizing or designing to avoid potential contaminant sources. Some of these considerations include the following.

(A) Environmental assessment. A Phase I (visual inspection and condition measurements) environmental assessment of property to identify on-site contamination that could affect indoor air quality should be conducted.

(B) External contaminants. Potential external contaminant sources such as combustion sources (freeways or power plants), dust generators (agricultural or cement plants), and industrial plants that may emit pollutants into the air should be identified.

(C) Climate. Climate assessment data that include factors affecting building layout and other architectural design considerations such as temperature, relative humidity, dewpoint, rain quantity and prevailing direction, elevation and prevailing winds should be developed and evaluated.

(D) Radon. A radon assessment of the site should be conducted, if applicable.

(E) Drainage. Conduct a drainage survey to assure water can be diverted from the building site and away from the building.

(3) Documentation. Facility design should include the development of owner's project requirement (the listing of facility uses, requirements and intent for the building), and basis of design (the design professional's description of the building elements and systems to accomplish the owner's project requirements) documents to guide the design and construction team in the selection of the least polluting materials and the production of a healthy building environment for the occupants. Some of the documentation and methods include:

(A) The design team should be assembled from qualified and licensed professionals that are knowledgeable in air quality issues.

(B) A building use and occupancy plan, schedule, and requirements should be assembled.

(C) An indoor pollutant source control plan should be developed to guide the materials usage, equipment selection and activities in the building.

(D) Comply with appropriate codes and standards.

(E) Assess the budget and schedule impacts of all materials and systems.

(F) A testing and commissioning plan should be developed to quantify the facility performance results required.

(G) Building operational and training documentation plans should be provided including the requirements for equipment systems manuals.

(4) Site and Facility Planning. The building design should consider the following.

(A) Building structure factors. Factors that can affect IAQ, such as the shape and size, orientation, layout, proximity to pollution-generating activities, building materials, types of windows and doors, ventilation system design, location of air intakes and exhausts, and susceptibility to pest intrusion should be considered.

(B) Internal contaminant sources. Proper venting to the outside atmosphere of pollution source areas, such as laboratories and preparation rooms, housekeeping and material storage, restrooms, workshops, cooking areas, art and hobby rooms, computer rooms, copy rooms, and other emission-producing spaces should be provided.

(C) Loading Docks. Loading docks should be designed such that vehicle exhaust shall be prevented from entering enclosed work spaces (including air intakes and building openings) by installing barriers to airflow from loading dock areas (i.e. doors, curtains, etc.) and using pressurization. Outside air intakes should not be near or above truck or other vehicle access areas.

(D) Moisture prevention. Water intrusion, condensation, water vapor intrusion, and other moisture problems in the building should be avoided through the proper design and installation of the building components. The use of vapor barriers (membrane inserted in a wall assembly to reduce moisture flow) should be based on best practices design for the local area. Care should be taken not to have two vapor barriers in one wall such as an exterior barrier with vinyl wall covering on the inside. In hot and humid climates, vinyl wall covering should not be used on exterior walls to avoid condensation and mold growth behind the covering.

(E) Space allocation.

(i) Adequate space for maintenance access and proper operation of building equipment, such as HVAC system equipment and boilers, should be provided.

(ii) Separate designated rooms used for materials and chemical storage only and that are kept under negative pressure and vented to the outside atmosphere should be provided.

(F) Building materials, interior finishes, and furnishings.

(i) The lowest chemical-emitting building materials, interior finishes, and furnishings that are practical should be used. Contaminant-emitting and retention potential of furnishings, floor and wall coverings and casework, and other interior finishes should be evaluated. Emissions data from manufacturers should be evaluated before specifying or approving construction products and building furnishings.

(ii) Materials that prevent (or at least inhibit) microbial growth without occupant exposure to potentially harmful chemicals should be used.

(iii) The use of porous or fleecy materials is discouraged where unmanaged excessive moisture or improper maintenance could occur.

(iv) Projected life cycles of materials and equipment should be considered to provide the most sustainable construction.

(v) Recycling of construction waste and materials from remodeled facilities should be provided where possible.

(vi) Maintenance requirements should be considered. Materials that can be easily cleaned with the least toxic cleaning supplies should be utilized when possible.

(vii) Building materials and products susceptible to water damage should be properly stored and protected to prevent damage before or during construction phase.

(5) HVAC system design. HVAC systems should be designed to include the following.

(A) Air intakes. Sufficient acceptable outside air to maintain a healthy environment in all occupied areas should be provided. (Reference ASHRAE Standard 62-2001). Preconditioning of outside air supplies, particularly dehumidification, is recommended where possible.

(B) Air distribution. Proper air distribution should be provided to all occupied areas.

(C) Filters. Medium to high efficiency (MERV 9 - 11) filtering systems should be used. Air handlers should be designed and selected to accommodate the pressure drops required for adequate filtration. Low capacity systems may use lower efficient filters (MERV 6 - 8) if it cannot be retrofitted for the more efficient filters. Filters should be installed to minimize air bypass around the filters and maintained per the manufacturer's recommendations.

(D) Access doors/ports. Convenient access doors/ports to facilitate inspection, maintenance and cleaning of air handling units and ducts should be provided.

(E) Coils. Coils with adequate heating and/or cooling capacity and with features to facilitate maintenance should be used.

(F) Drain pans. Insulated drain pans with proper slope and drainage to prevent standing water should be installed on all new cooling (wet) coils.

(G) Drain lines and traps. Drain lines need to be adequately sloped to provide proper drainage. Drain traps should be properly installed when drain lines from condensate pans connect to sewer systems.

(H) Ducts. Ducts with internal surfaces that are easily cleaned, not damaged by typical cleaning methods, do not harbor dust and microbials, and that will not emit materials or gases that can harm the occupants should be provided on all new HVAC systems.

(I) Return air. Ducting of return air is recommended.

(J) Positive building pressure. The rooms of the buildings should be maintained at a net positive pressure (minimum of 1 Pascal) with respect to the wall cavities and plenums, and the wall cavities should be maintained at a net positive pressure (minimum of 1 Pascal) with respect to the outside atmospheric pressure. Some areas in buildings that have isolation or process requirements, such as print shops, darkrooms, and restrooms, may require defined pressure relationships to adjacent areas.

(K) Exhaust systems. Adequate exhaust systems for restrooms, storage rooms, copy rooms, animal areas, chemistry labs, computer rooms, industrial arts rooms, kilns, home economics rooms, locker rooms/showers, swimming pools and other areas with contaminant sources should be provided. These areas should be under negative pressure with respect to adjacent areas, such as classrooms, offices and hallways.

(i) Exhausts should be vented directly to the outside.

(ii) Exhaust vents should be located to avoid contaminants being drawn back into the building and no closer than 25 feet from an air intake.

(L) Comfort. Adequate temperature and humidity control with proper air velocity should be provided to maintain comfort, process requirements, and minimize microbials and contaminants in all occupied areas.

(M) Humidity. The maximum relative humidity should be maintained below 60% throughout the year to prevent mold growth. Ideal relative humidity levels are generally between 30% and 60%, however between levels 30% and 50% will decrease the chance of mold growth. In climates where outdoor humidity levels are often less than 30% and building occupants do not complain of health effects or discomfort from the lower humidity, then lower humidity inside buildings is acceptable.

(N) Air diffusers. Air diffusers should be used to manage air flow volumes, mixing, and patterns for occupant comfort. Normal occupied spaces should have an average air velocity between 20 and 50 feet per minute in the occupied zone.

(O) Controls. Proper controls and energy management systems should be installed to maintain recommended interior conditions. Thermostats in each occupied room and conference room are preferred. Humidistats should be used in rooms where humidity control is important.

(b) Maintaining acceptable IAQ during renovation. Building occupants should be protected from airborne contaminants that may be disturbed, generated, or released during mitigation and/or renovation, including irritating or toxic substances such as asbestos, lead, pesticides, heavy metals, mold, cement dust, paint vapors, and roof tarring vapors.

(1) Asbestos Survey. Prior to any renovation or dismantling, assure that the asbestos surveys for the building in question are up-to-date. If such survey information is not available, engage a licensed asbestos consultant or other licensed professional to conduct an asbestos survey and plan for the building as per the Texas Asbestos Health Protection Act, Article 4477-3a, V.T.C.S. and Rules, §§295.31-295.73 of this title (relating to Texas Asbestos Health Protection Act), and the National Emission Standards for Hazardous Air Pollutants, 40 CFR 61 Subpart M, National Emission Standards for Asbestos.

(2) Lead-based paint concerns. Lead-based paint, used in many buildings built prior to 1978, may create an exposure risk for young children occupying or visiting the building, if the paint is deteriorating or is disturbed. Prior to any renovation or remodeling project in such a facility that is occupied or frequented by young children, a lead inspection by a state-certified person to determine the presence of lead-based paint is recommended, if the presence of such has not already been determined. If lead-based paint will be disturbed during a renovation or remodeling project, lead-safe work practices should be used to avoid unnecessary lead exposure to workers and building occupants. In a "child-occupied facility" as defined in §295.202 of this title (relating to Definitions), any "lead based paint activity", i.e. lead inspection, risk assessment or abatement, must be conducted in accordance with the Texas Environmental Lead Reduction rules, §§295.201-295.220 of this title.

(3) The IAQ Coordinator should review designs and construction activities for all proposed remodeling and renovation activities prior to their initiation.

(4) Minimize volatile organic compounds (VOCs) by purchase and use of low-emitting products, such as paints, varnishes, building materials, furnishings, etc., and processes (wet-sanding drywall). Minimize emissions from new furnishings by airing out the product before installation. Water-based solvents, when available, are preferred.

(5) Hazardous chemicals and substances. Hazardous chemicals as defined in the Health and Safety Code, §502.003 and hazardous substances as defined in the Health and Safety Code, §361.003, should be managed and disposed of in accordance with all applicable state and federal laws.

(6) Scheduling. Occupant exposure to contaminants should be minimized by scheduling renovations that may produce contaminants or uncomfortable conditions when the building is unoccupied.

(7) Isolation. Ventilation and barrier control strategies to isolate construction areas from the occupied areas should be used. Increase ventilation in occupied areas if necessary to control odors from construction area. The area of renovation should be kept under a negative pressure relative to occupied areas during renovation periods.

(8) Remediation of toxic contaminants. Procedures appropriate for toxic contaminants (lead, microbial, asbestos, hazardous chemical, etc.) should be utilized if such contaminants are expected or discovered during renovation and in some cases must be utilized under state and federal law.

(9) Filters. Filters should be changed more frequently during contaminant-generating activities, and also replaced after work is completed. The highest possible MERV rated filters should be used during renovation and for a few days after to minimize exposure to renovation related particulates and dust.

(10) HVAC equipment. Ensure that HVAC equipment is protected from damage and entry of contaminants.

(11) Water-damage. Porous building supplies that become water-damaged should be discarded to avoid the potential for mold contamination.

(12) Re-occupancy. All renovated areas should be thoroughly cleaned utilizing high-efficiency particulate air (HEPA) filtered vacuuming and adequately ventilated prior to re-occupancy.

(c) HVAC system testing. For new construction and major remodeling, the HVAC systems in those areas should be tested and balanced by an independent certified contractor at the completion of construction or remodeling.

(d) Commissioning of building. Building commissioning of new and/or renovated buildings should be provided by a trained and knowledgeable commissioning authority according to recognized national standards to assure proper operation of all building systems.

(e) Design Documentation. Design documentation including the owner's project requirements (design intent), and basis of design should be retained for the life of the facility. As-built documents should be prepared during construction and retained at the facility.

(f) Monitoring activities. Construction and renovation activities should be monitored by the owner's representative, facility IAQ coordinator, and commissioning authority.

(g) Ventilation Protocols. Ventilation protocols should be developed to include proper area exhaust rates and pressurization requirements to be used during repairing and remodeling. During initial occupancy of a new area and during re-occupancy following repairs or renovations, the fresh air rate and the total air supply rate may need to be increased until any out gassing of the new material has decreased to a level that will not cause adverse heath effects to the occupants.

Source Note: The provisions of this §297.4 adopted to be effective December 22, 2002, 27 TexReg 11759