Rating System

LEED BD+C: New Construction, LEED BD+C: Schools, LEED ID+C: Commercial Interiors, LEED BD+C: Core and Shell, LEED O+M: Existing Buildings

Rating System Version

v2 - LEED 2.2, v2 - Schools 2007, v2 - LEED 2.0, v2 - LEED 2.0, v3 - LEED 2008

Inquiry

Our project includes a large open industrial/distribution facility type space and will not have an HVAC system. Given the nature of the facility, we cannot provide 4% of the project\'s floor area as net operable area for natural ventilation. Therefore an engineered passive ventilation system is required to meet local code requirements. The project is located in an area with low scale development in a broad valley with no nearby hills or other obstructions. Under the current design, ventilation to the facility will be provided by roof mounted turbine ventilators to draw air out of the space coupled with low wall intakes for supply. The turbine ventilator is tested to draw a given CFM of air at a wind speed of 4 MPH. NOAA data indicates a minimum mean wind speed of 7 MPH in the area. We will calculate the ASHRAE 62.1 ventilation rate for the space based on the number of turbine ventilators installed and the CFM provided by each in a 4 MPH wind, knowing that the actual ventilation rate will be higher based on typical wind speeds. For example, one portion of the project is 45,000 SF. Based on ASHRAE 62.1, the required ventilation rate for a facility of this size will be 2,700 CFM ( 45,000 SF x 0.06 cfm/SF). The current design is based on a 24-inch throat size for the ventilation turbine. Based on the manufacturer\'s data this model will yield 2,350 CFM of exhaust at 4 MPH wind speeds. Due to local code requirements, this portion of the project will require 6 of these 24-inch turbines. The total volume of exhaust provided is 14,100 CFM. The design team would like clarification if this approach of using an engineered passive system to meet local code requirements also meets the requirements of IEQ prerequisite 1.