ID#1740 made on
EQc3.2 - Construction IAQ management plan: before occupancy
LEED BD+C: New Construction, LEED ID+C: Commercial Interiors, LEED BD+C: Schools, LEED BD+C: Retail, LEED ID+C: Retail, LEED BD+C: Healthcare
We have a ~100,000 square foot 3-pointed T-shaped building with five floors. On the first floor there is an additional 7,800 sq. ft single story extension that will be used for a cafeteria and kitchen...
We have a ~100,000 square foot 3-pointed T-shaped building with five floors. On the first floor there is an additional 7,800 sq. ft single story extension that will be used for a cafeteria and kitchen. The other sections are approximately 5,500 sq. ft. on each of floors 1 - 5 for a total of approximately 16,500 sq. ft. per floor. Each section is attached to a core and has similar furnishings and usage including both open and private offices and conference/training rooms with the following exceptions: the first floor includes an entrance lobby and the second floor includes a movable filing area and a server room. The HVAC system utilizes variable air volume boxes with induction fans. Separate air handling units (AHUs) in each section on each floor serve the three main vertical sections. There is one outdoor air fan on the roof above each section (3 total) which supply outside air down to the respective sections' five AHUs. There are an additional nine ceiling-mounted AHUs for the cafeteria and one unit for the kitchen. These ten units are supplied with outside air through one rooftop intake fan that is ducted to each unit. In summary, there are fifteen main AHUs, nine cafeteria AHUs, and one kitchen AHU (25 total). If one were to interpret a "separate ventilation system" as each individual AHU, this would infer 25 sampling locations, which is pointlessly excessive and costly for a 100,000 square foot building. It risks returning to the days when no IAQ testing was done because there was no cost effective protocol in the LEED credit system. We see no technical reason why the criterion should be based on individual AHUs. Identical AHUs used to serve multiple zones all deliver the same volume of outside air per person per ASHRAE requirements for the respective space use. The volume of outside air in supply air varies with time, not by zone i.e. with variations in outside air temperature. The point sources of indoor air pollutants in and around the building and its mechanical system, and their treatment, will be independent of the number of air handling units used to serve the building. If a building designer uses one four-ton AHU vs. four identical one-ton AHUs, what will sampling in four locations achieve? Due to the unique T-shaped design, the building core breaks what would have been contiguous floors into separate areas. While these areas are not physically contiguous, they have similar furnishings and space usages, which present similar indoor pollutants. In order to re-establish an economically and logistically sound method for wide use across multiple building formats, we have selected this project to seek clarification on the following terms: 1) "separate ventilation system" in a building with numerous AHUs and 2) "contiguous floor area" in unusually shaped buildings. We propose that for each portion of the building served by a separate ventilation system, the number of sampling points must not be less than one per 25,000 square feet, or for each contiguous floor area, whichever is larger, with the following clarifications: 1) Allow contiguous floor area to be defined as areas with similar furnishings and space usage, even if the space crosses a building core (but not up or down a floor). 2) Require at least one sample in each building use location, i.e.. cafeteria vs. office vs. warehouse (server rooms are not included since they are not regularly occupied). 3) Allow "separate ventilation system" to be defined as fundamentally different HVAC designs, i.e.. heat pumps vs. built-up units vs. TDV (underfloor) vs. overhead mixing. Following the above protocol, we propose to sample six locations in this building: 1st Floor Cafeteria 1st Floor Lobby 2nd Floor Filing Area 3rd Floor Private Office 4th Floor Training Room 5th Floor Open Office (A "separate ventilation system" could be interpreted as AHUs served by a common outside air source. This would require excessive sampling in buildings equipped with small rooftop package units and thus is not practical.)
Per the LEED-NCv2.2 requirements, the number of sampling sites would be one per each of the separate ventilation systems. The NCv2.2. requirement for one sampling location in "each portion of a building served by a separate ventilation system" is based upon the fact that the ventilation systems define a distinct mixed volume of indoor air as tested under the required minimum outside air percentage mode. Since there may be expected to be variations in the indoor air concentrations in this mixed zone, there is a further requirement that the area in the zone with the least ventilation and greatest presumed contaminant source strength be tested. The contaminants in this mixed volume of air are determined by the emissions from the materials in the air space and the amount of outside air being delivered to the air space. As both the materials and the outside air delivery rates in different ventilation system zones can vary, separate air contaminant measurements are required for each ventilation system zone. If the delivery of outside air on an air change per hour basis and the materials in a ventilation zone are identical (e.g. a specific type of hotel room, or apartment/condominium with separate ventilation systems) a HERS random sampling plan may be employed (i.e. random 1 in 7 selection from each model of room). In addition, for buildings with large numbers of identical rooms each with separate ventilation systems, a minimum of 3 rooms for a particular model of room shall be deemed sufficient. If one or more of the three measurements made per model room fail than an additional three of that type guest room be tested. All failed rooms will be re-tested following flushing with outside air. In this specific case, if the cafeteria space is one undivided open space with identical (not just similar) materials throughout the space and the delivery of outside air on an air change per hour basis is identical for each system, then a HERS random air sampling of 1 in 7 of the 9 ventilation system zones is acceptable. Thus, 2 test locations are required for the cafeteria space (i.e. randomly select 2 of the 9 ventilation system zones) and these locations shall include the area with the least ventilation and greatest presumed contaminant source strength in each zone. The kitchen, which is both a separate space with a separate ventilation system and different materials requires a second test location. Again, to include the area with the least ventilation and greatest presumed contaminant source strength is acceptable. The five floors of the main building with three separate ventilation systems that serve separate spaces with different materials requires one sampling location per ventilation system, again to include the area with the least ventilation and greatest presumed contaminant source strength is acceptable. Thus, a total of 18 test locations are required, two in the cafeteria, one in the kitchen and 15 in the main building.
Related Addenda (Corrections & Interpretations)