ID#2457 made on
EQc2 - Increased ventilation
LEED BD+C: New Construction, LEED O+M: Existing Buildings, LEED ID+C: Commercial Interiors, LEED BD+C: Core and Shell
Background: The project is a multi-building complex on a military reservation that includes 256,000 square feet of buildings. Included in this total are two office buildings totaling approximately 160...
Background: The project is a multi-building complex on a military reservation that includes 256,000 square feet of buildings. Included in this total are two office buildings totaling approximately 160,000 square feet, two vehicle maintenance facilities that total approximately 61,000 square feet and four warehouses that total approximately 36,000 square feet. The protocol used in conjunction with the LEED V2.2 Rating System is the LEED-NC Application Guide for Multiple Buildings and On-Campus Building Projects. Issue: This CIR relates to the vehicle maintenance building. Employing the Ventilation Rate Procedure (as opposed to the Indoor Air Quality Procedure) for a facility classed as a "repair garage" in ASHRAE 62.1-2004 appears to result in unnecessarily large ventilation requirements. The energy use for the resulting continuous ventilation is significant, and does not appear to be justified based on the results achieved. Discussion: The ASHRAE 62.1 ventilation rate procedure for a "repair garage" requires 1.5 CFM per square foot. To achieve a 30% increase in ventilation, the airflow would be 1.95 CFM per square foot. Based on calculated occupancy, this results in between about 390 to 500 cfm/person. Additionally, each repair bay is equipped with a vehicle exhaust pickup (1,400 CFM each) and its own large individual overhead door. The space is heated to 55 degrees with radiant heaters. Each maintenance area is designed for a single-zone 100% outside air system. Operational data for four similar vehicle maintenance facilities at the same reservation was collected. Four years of operational history are available. The outside air ambient condition at these facilities is the same as the proposed installation. The existing facilities are equipped with a full energy management system that permits monitoring of fan run time and indoor air quality (CO and CO2) data. The area ventilation fans for these facilities activate when high CO or CO2 was measured. The measured conditions for the three facilities with occupancy similar to the proposed facility showed CO and CO2 levels were at or near outside air ambient conditions over 95% of the time. The CO levels never exceeded 5 PPM, the CO2 levels never exceeded 800 PPM. The data from these existing facilities indicates that continuous ventilation of 1.5 CFM per square foot or higher would not provide a significant improvement in indoor air quality over demand-controlled (intermittent) ventilation. LEED requires documentation for the increased ventilation credit to be prepared using the ventilation rate procedure in accordance with ASHRAE 62.1-2004. Because the similar building performance data is available, we propose to provide documentation for this project in accordance with the "indoor air quality procedure", also in compliance with ASHRAE 62.1-2004, documented IAW paragraph 6.3.2, "Documentation", as follows: ".If the design is based on an approach that has proved successful for similar buildings, the documentation shall include the basis for concluding that the design approach was successful." . This is addressed in the LEED V2.2 Reference Guide but not used because it is somewhat more problematic to document. Providing control to a reduced level of contaminants would produce exceptional air quality for these maintenance bays and fulfill the intent of increased ventilation, while providing reduced energy use and less embodied energy in construction materials. It is also the standard of practice for maintenance facilities. Request: Document increased ventilation in accordance with ASHRAE 62.1-2004, "Indoor Air Quality Procedure". Provide increased ventilation via demand-controlled (intermittent) ventilation systems with DDC controls similar to the existing facilities for control of CO2 to 800 PPM and CO to 12 PPM. Both of these concentrations are at least 30% less than conventional criteria, and far less than regulatory levels defined in ASHRAE 62.1.
There are two questions raised by this CIR: 1. Can ventilation rates be determined using the Indoor Air Quality Procedure instead of the Ventilation Rate Procedure in Standard 62.1? No. As stated in EQ Prerequisite 1, the Ventilation Rate Procedure must be used to size the ventilation system. Hence for "auto repair rooms," the exhaust rate must be 1.5 CFM per square foot per Table 6-4. However, demand controlled ventilation using CO concentration may be used to modulate the exhaust rate down when CO levels are low. (See Appendix B in Standard 62.1 for guidelines of maximum CO concentration.) 2. Does the exhaust rate in the auto repair room have to be increased by 30% to meet EQ Credit 2? No. This credit requires that breathing zone ventilation rates required by Standard 62.1 be increased by at least 30%. Breathing zone rates are listed in Table 6-1, so it is those rates that must be increased by 30%. The exhaust rates in Table 6-4 need not be increased to achieve this credit.
Update April 15, 2011: Please note that all 2009 projects in multiple building situations must follow the 2010 Application Guide for Multiple Buildings and On-Campus Building Projects, located here: https://www.usgbc.org/ShowFile.aspx?DocumentID=7987. 2009 project teams should check this document for up to date guidance on all multiple building issues.
Related Addenda (Corrections & Interpretations)