SoCalGas - Indoor Air Quality
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Indoor Air Quality

Establishing a Healthy Environment

Goals

Using a consulting firm, Healthy Buildings International, Inc. (HBI), the ERC was designed and established as a living model of Southern California Gas Company's environmental awareness. It was therefore essential that the ERC begin operations and remain as a healthy building - a productive and efficient place reflecting a strong commitment in this arena.

HBI helped in the realization of this goal -- first, by reviewing and evaluating the building design, including the construction materials and the mechanical systems. Second, it developed an indoor air quality plan which included indoor air quality commissioning guidelines to allow the establishment of baselines for the indoor environment shortly after the building was occupied. Finally, HBI established an indoor air quality monitoring program to evaluate the building construction practices. This established the baselines and has included periodic inspections to ensure that indoor air quality goals continue to be achieved in the months and years to come.

Air Quality by Design

The design outdoor air quality requirement for the ERC is 20 cubic feet/minute/person, which is in line with ASHRAE Standard 62, and equates to 800 ppm carbon dioxide assuming an occupancy level of 142 square feet/person. Consideration had been given to the different activity levels expected in the various parts of the new complex; the three air-handling units (AHUs) serving the building are to be equipped with carbon dioxide sensors for control of the outside air dampers, depending on the occupancy loads in the areas served. These sensors will be placed in the return-air ducts of these units to modulate the outside air dampers and maintain carbon dioxide levels below 700 ppm. Airborne particulate levels in the supply-air to the building will be controlled by the use of 12-inch-deep box filters and 2-inch-deep pleated panel filters in the main AHUs, with respective efficiencies of 65 and 35%, as determined by the ASHRAE Atmospheric Dust Spot test. Energy-efficient technologies used included directed evaporative cooling systems for two AHUs.

Desiccant cooling systems are installed in kitchen areas, where higher-than-normal latent heat loads are expected. These are an efficient type, incorporating a desiccant heat recovery wheel, allowing for the economic intake of outside air for proper ventilation.

Prior to occupancy, ventilation procedures were carried out to coincide with the application of interior finishes, etc., in order to minimize the build-up of construction pollutants.

The Results

The results of IAQ measurements over a six-week period (January through February, 1995) confirmed that the ventilation rates were preventing any build-up of indoor pollutants. From accompanying tables, summarizing these results, it can be seen that RSP levels never exceeded 70 ug/m3. Carbon dioxide levels ranged between 550 and 875 ppm before the AHUs were in operation; after they were started, the levels were consistently between 400 and 600 ppm.

graph1

After start-up of the AHUs, the temperature levels in the occupied space ranged from 68 to 79F and relative humidity from 25 to 51%. The levels of total VOCs showed a marked reduction after construction was finished and the AHUs were operating. (A minor increase was noted during February, but the levels then settled below 500 ug/m3.) Formaldehyde gas levels were never higher than 0.044 ppm during the sampling period.

graph2

Further air quality measurements of these same indoor pollutants were made during a consultant's inspection in July, 1995. Results showed that under normal occupancy and operating conditions, all levels were well below any suggested standards. Temperature and relative humidity readings were within the ASHRAE-suggested comfort ranges.

Pressure differential checks showed that the ERC was operating under a positive air pressure to the outside and that the exhaust systems were effectively ensuring air flow into toilets from the adjacent areas. Microbial sampling from AHU internal surfaces and airborne samples from the occupied space gave satisfactory results.

Other Factors That Influence ERC Indoor Air Quality

Interior Paint

Nontoxic paint was used in the ERC. The paint contains no petroleum derivatives, volatile organic compounds (VOCs) or other organic solvents.

Flooring Sealers

Nontoxic alternatives to urethanes, lacquers and varnishes were used on hardwood floors, thus reducing VOC emissions which react with nitrogen oxides and sunlight to form smog.

Sheet Flooring

A nontoxic, durable linoleum flooring made from linseed oil is installed in various ERC spaces, including the multi-media control room and various storage areas. This product is made from flax, pine tree resins, wood flour, jute and cork and does not emit dangerous gases when exposed to extreme heat. It is also antibacterial; under laboratory conditions, linseed oil inhibits the growth of staph and/or bacillus. Linoleum also requires less maintenance, cleaning and buffing compared to vinyl flooring because linoleum promotes a matte finish, while vinyl flooring promotes a gloss finish, which requires more product and labor. Manufacturing is environmentally friendly and requires very little energy use. Production waste within the factory is also reused.

Carpet and Padding Adhesives

A nontoxic acrylic, pressure-sensitive adhesive is used in the ERC's carpet and carpet padding installation. Off-gassing from traditional carpet and construction adhesives is a major contributor to poor indoor air quality. This product forms a tough, permanently tacky, resilient glue line that withstands heavy traffic.

Tile Adhesive (3-in-1 Adhesive).

The tile adhesive used in the ERC is a nontoxic, nonflammable product containing no petroleum-based solvents. It is used to bond ceramic, vinyl, parquet and Formica tiles.

Carpet Padding

Filler material on the back of the Interface carpet tiles installed in the ERC is treated with a broad-spectrum, anti-microbial product called "Intersept." Intersept inhibits the growth of bacteria and fungi, which are major contributors to unhealthy indoor air.

Office Partition Panels

The fabric covering the ERC office partition panels is also treated with the Intersept anti-microbial agent to improve indoor air quality.

HVAC System

In the main hall, sensors monitor carbon dioxide levels and adjust fresh air intake to optimize indoor air quality. In addition, periodic inspection and maintenance of the air conditioning systems help to ensure optimal indoor air quality. Maintenance includes adjusting outside air intake volumes, cleaning cooling coils and drain pans, and changing air filters.

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