Important actions to protect and improve Indoor Air Quality during each phase of the design and construction process are presented in this module. Establish IAQ design goals. For example, demonstrate that: Adequate budget to meet the IAQ design goals and specifications should be planned considering: As documentation accumulates, it should be organized and assembled in durable, moisture-resistant binders. Supplemented by operating and maintenance recommendations, project documentation creates a complete owner’s manual for the building, and is good insurance against liability claims. Identify IAQ codes and standards to be met. IAQ-related documentation during project planning would include: Evaluate and document site conditions that can impact IAQ. Plan the building location, orientation and major site activities on the site to minimize contamination of the indoor environment. Relevant features should be documented and noted on design drawings. Locate onsite pollutant sources away from and downwind of air intakes.

Roadways, parking, loading areas, trash and chemical storage areas are typical sources. The building envelope will affect thermal comfort, HVAC capacity requirements, lighting quality (daylight) and view, potential infiltration of outdoor (or underground) contaminants and moisture. Plan space uses to maximize the potential for isolating occupants from sources of contaminant through physical distance, physical barriers, exhaust systems and pressure control. General Design Provisions: The HVAC system is critical to the building’s ability to provide thermal comfort and ventilation of building contaminants. Outdoor air ventilation rate and indoor climate conditions should meet the design requirements (e.g., ASHRAE 62-1999 and ASHRAE 55-1992) under all operating conditions, including peak and minimum load. Plan HVAC zones (with single thermostat) so that the thermal demands of all spaces within each zone are similar during all seasons. When different spaces having different thermal requirements are in the same zone, occupant discomfort is inevitable and solutions to complaints will be difficult (or impossible).

Avoid placing thermostats in direct sunlight, near equipment or other heat sources, or on exterior walls. Plan heating and cooling capacity to satisfy the peak (design) conditions that occur under extreme or worst-case conditions. Capacity requirements should be calculated considering both the sensible (heat) and latent (humidity) loads. og air purifierPeak latent load may occur at subpeak sensible load. filtrete ultra quiet air purifier reviewCapacity requirements should be calculated based on the outdoor airflow and thermal comfort requirements adopted in the design goals (e.g. ASHRAE 62-1999 and ASHRAE 55-1992).oreck air purifier and humidifier Consider separate dehumidification prior to cooling, or energy recovery systems to improve performance and energy efficiency and reduce capacity requirements and therefore first costs.

If humidification is needed, steam is preferred as a moisture source. The source of steam should be from potable water to avoid contamination from additives to boiler or steam water supplies. Energy efficient building design, lighting and HVAC design can reduce capacity requirements and lower first costs. Selected Design Provisions of ASHRAE 62-1999: ASHRAE Standard 62-1999 also identifies specific measures that should be taken to IAQ problems as they relate to the ventilation system. These measures are included elsewhere in I-BEAM, but it is useful to know that they are part of the ASHRAE Standard See ASHRAE Guideline 1-1996, The HVAC Commissioning Process for detailed recommendations. Exhaust of Indoor Sources and Pressure Control of Sources (Also see Section in HVAC Chapter) Where major indoor sources are expected, exhaust ventilation and proper pressure control should be planned. Systems with direct exhaust from sources that also generate heat (e.g. copy machines) may also reduce HVAC energy requirements.

The patterns of air circulation and flow, between outdoors and indoors, from basements and crawl spaces, between floors, and between spaces on each floor may be more important to IAQ than the HVAC system or system components. Air circulation patterns showing areas of positive and negative pressure should be drawn for the building as a whole, and for all occupied spaces and major source areas. The flow of outdoor air into the building must be planned to slightly exceed the total airflow out of the building from all exhausts, combustion flues and stack effect exfiltration to insure that the building is positively pressurized, to avoid infiltration of outdoor pollutants. (In cold climates the risk of condensation in the building envelope increases if the building is pressurized so that moisture control may be the dominant concern in planning pressure relationships.) Consider air flow and pressure relationships under worst case scenarios (e.g. kitchen exhaust fans running full in cafeteria.

Consider the effect on a neighboring print room, or a boiler room where backdrafting of the flue is a possibility. Avoid underground ducts or a duct through crawl spaces where possible.Non-ducted returns complicate system balancing resulting in the potential for areas of stagnant air, undesirable pressure relationships and contamination of the return airflow. Develop a program statement that defines the range of possible occupant densities, activities and layouts to allow the designer to plan flexibility or sufficient capacities for future changes. Specify alterations to the system that can be accommodated under the HVAC design used, and what changes to the system would be required. Carefully analyze location of supply and return air grills for all occupied spaces, as well as the throw capacity of diffusers, and airflow pathways. Map the anticipated airflow patterns to insure proper air mixing (or plug flow airflow if that is planned). Avoid short-circuiting of supply air to return air.

Also avoid dead spaces (e.g. provide for a 2-3 inch air space between the floor and workstation partitions to facilitate air circulation). Particle pollutants cause mucus membrane irritation and other effects, and can foul ventilation system components and reduce efficiencies. Fine particles comprise only a small portion of the total particle mass, but constitute the overwhelming majority of the number of particles. Filtering larger particles is most important for protecting equipment, while filtration of finer particles is most important for human health and comfort. Filtration efficiency for a given filter will vary with particle size. Thus, a filter rated as 40% efficient by the ASHRAE dust spot method will have about that efficiency for large (above 2.5 microns) and very small (0.01 microns and less) but have close to zero efficiency at 0.1 to 0.5 microns. Air cleaning may be considered as a means of control for specific contaminants experienced from a nearby outdoor source, or an unusual indoor source.

Air cleaning mediums (e.g. treated charcoal, potassium permanganate) should be chosen carefully to insure effective target contaminant removal. Work with manufacturers to select products with the desired emission profile, and develop a strategy to minimize building contamination during installation. Require information about emissions from manufacturers. Manufacturers have both a marketing and liability motivation to test their products. Testing laboratories and emission testing protocols are rapidly developing. In selecting materials, investigate the materials potential to pollute the indoor environment in four key areas: Select and/or negotiate for materials with low emissions and quick decay rates where possible. Use this information to determine strategies for the sequence of installation and the ventilation strategies during installation. Negotiate pre-shipment storage techniques that accelerate emissions of partitions, carpets and similar materials prior to installation.

Sometimes perforated containers can serve to facilitate off gassing during shipment. Many IAQ problems occur as a result of poor construction practices, change orders, or field orders. Monitoring all work is critical to good IAQ. Monitor field orders, shop drawings and change orders impacting IAQ specifications and designs. Check deviations from construction documents. Monitor IAQ specifications during progress by inspections, and check that products and materials specified are being used. Protect current and future occupants during construction. An isolation strategy is usually a necessary condition for effective IAQ control, but it is made more feasible to achieve when pollutant emissions are also controlled through material selection and installation strategies. Check the integrity of the entire building envelope by performing the following: Commissioning of HVAC System (Construction Phase) Proper commissioning in the construction phase insures that the building is built correctly and that it works right before occupancy.