ASHRAE STD 160
Criteria for Moisture-Control Design Analysis in Buildings
|Publication Date:||30 November 2016|
This addendum revises Sections 6.1 and 7.5 as indicated below. Since the publication of Standard 160-2009, it has become apparent that the performance evaluation criteria for mold growth are too stringent. Section 6.1 currently prescribes a simplified criterion that is easy to calculate but difficult to meet: a flat 80% 30-day running average surface relative humidity criterion, bounded by temperatures between 5°C (41°F) and 40°C (104°F). A number of researchers and practitioners have reported to the committee that assemblies that are known to have satisfactory performance in reality are failing the criterion in simulation. Furthermore, the scientific literature indicates that mold growth requires a much more complex description. Mathematical models have been developed that predict mold growth risk as a function of time, surface temperature, and surface relative humidity. Such models can readily use as inputs the hourly outputs of a hygrothermal simulation. The mold growth model selected for implementation in Section 6.1 of Standard 160 by this addendum is empirical and has been validated with experimental data for different materials with varying sensitivities to mold growth. This addendum will bring the standard more in line with the current state of knowledge about mold growth while providing a less stringent criterion. Changes to Section 7.5 bring the reporting requirements in line with the changes to Section 6.1.
Note: In this addendum, changes to the current standard are indicated in the text by underlining (for additions) and (for deletions) unless the instructions specifically mention some other means of indicating the changes.