ID#5318 made on
EQc3 - Moisture control
LEED BD+C: Homes, LEED BD+C: Multifamily Midrise
EQ credit 3 requires the project to "install dehumidification equipment with sufficient latent capacity to maintain relative humidity at or below 60%". Under what conditions should this RH r...
EQ credit 3 requires the project to "install dehumidification equipment with sufficient latent capacity to maintain relative humidity at or below 60%". Under what conditions should this RH requirement be met - at design conditions? 100% of the year? 95%? Requiring hourly calculations might be overly burdensome.
What latent loads are assumed in the house? It's always possible to have 10 people living there and running the shower continuously. I think it would be helpful to have LEED spell out the latent loads they'd like to have considered. I'd suggest relying on ASHRAE Fundamentals or something similar.
The TASC does not want to create performance standards for this measure, so it will be largely left to the discretion of the Provider and Green Rater. The dehumidification equipment should not be expected to maintain RH < 60% for every hour of the year, as that is unreasonable. However, maintaining RH < 60% at design conditions is insufficient. If the system is designed to accommodate 90-95% of the hours in the year, that is acceptable.
When determining the latent loads to include, it's reasonable to follow ASHRAE Fundamentals or a comparable standard. The latent loads from the ventilation system should be included, as well as reasonable indoor loads associated with occupant behavior.
Updated 10/1/13 for rating system applicability.
Related Addenda (Corrections & Interpretations)