Rating System

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

Rating System Version

v3 - LEED 2009, v2 - Schools 2007, v2 - LEED 2.2, v2 - LEED 2.0

Inquiry

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.)