Texas Administrative Code › Title 25 - HEALTH SERVICES › Part 1 - DEPARTMENT OF STATE HEALTH SERVICES › Chapter 297 - INDOOR AIR QUALITY › Subchapter A - GOVERNMENT BUILDINGS › Section 297.4 - Design/Construction/Renovation

Current through Reg. 49, No. 28; July 12, 2024
(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.