Rating System

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

Rating System Version

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

Inquiry

Our project is a 571,400 square foot automated distribution center in central Ohio. The space breaks down into: - 160,800 square feet of racked material storage with limited transient access by users - 375,800 square feet of automated order fulfillment space - 200,000 square feet of elevated equipment platforms in the order fulfillment space - 35,000 square feet of office (10,000 SF in a central core and the remainder on the outside edge of the building) Operator characteristics for these areas will result in clothing insulation values below 0.5 clo and timeweighted metabolic rates above 2.0 for the equipment operators and order fulfillment staff. In ASHRAE 55, Section 5.1 clarifies the use of the standard as: "The vast majority of the available thermal comfort data pertains to sedentary or near sedentary physical activity levels typical of office work. This standard is intended primarily for these conditions. However, it may also be used to determine appropriate environmental conditions for moderately elevated activity." This is further noted in the two options for determining thermal comfort: - The Graphical Method only applies to occupants with 0.5 to 1.0 clo of clothing and a metabolic rate between 1.0 and 1.3 met. - The PMV-PPD Method only applies to occupants with clothing values less than 1.5 clo and metabolic rates between 1.0 and 2.0 met. Normative Appendix A to the standard (a fully incorporated part of ASHRAE 55) also states: "As metabolic rates increase above 1.0 met, the evaporation of sweat becomes an increasingly important factor for thermal comfort. The PMV method does not fully account for this factor, and this standard should not be applied to situations where the time-averaged metabolic rate is above 2.0 met. Typically, rest breaks (scheduled or hidden) or other operational factors (get parts, move products, etc.) combine to limit timeweighted metabolic rates to about 2.0 met in most applications." We are proposing to exclude the warehouse and order fulfillment areas from the Thermal Comfort: Design Credit Calculations due to process requirements that do not permit the use of ASHRAE 55. In addition, the normal industrial practice of spot-cooling for operators cannot be measured in ASHRAE 55 as the PMV-PPD model does not allow for airspeeds over 0.2 m/s (40fpm) and the adjustment factors provided in section 5.2.3 of the standard do not apply to situations where either the clothing is outside of the 0.5 to 0.7 clo range or the metabolic rate is outside of the 1.0 to 1.3 met range. Will it be acceptable to exclude the warehouse and order fulfillment areas from this credit due to process considerations while still complying with the standard for all other building areas?