ID#5614 made on
EQc7.1 - Thermal comfort - compliance with ASHRAE 55-1992
LEED BD+C: New Construction
In the mid-Atlantic states, the primary concern with humidity control is keeping humidity out of our buildings. The need to add active humidification in this borderline climate is generally limited t...
In the mid-Atlantic states, the primary concern with humidity control is keeping humidity out of our buildings. The need to add active humidification in this borderline climate is generally limited to only 2-3 months out of the year, and even within those months the need to add humidification is not always necessary, especially if energy wheels capture building humidity and return it to the space, and if human contributions to indoor humidity can be factored into the calculations. In an effort to balance equipment cost and increased energy consumption with the benefits of active humidification, is it acceptable to the US Green Building Council to consider human contributions to indoor humidity as part of a project's compliance with EQc7.1 and EQc7.2, acknowledging that humidity levels might start below ASHRAE-acceptable levels when the building opens in the morning? Is there a certain time threshold by which humidity levels would have to be modeled to reach ASHRAE 55-1992, Addenda 1995 standards in order to prove credit compliance?
The intent of EQ Credits 7.1 and 7.2 is to encourage monitoring and control of building temperature and humidity levels. EQ Credit 7.1 requires the provision of a comfortable environment per ASHRAE Standard 55 for the building occupants. EQ Credit 7.2 requires the implementation of a permanent monitoring and supervisory control system to ensure the continued delivery of that environment. EQ Credit 7.1 specifically requires control, but the project has some leeway in determining how the control would be accomplished. In general, the project needs to demonstrate that humidity is controlled, or demonstrate through modeling/analysis that humidity control will not be necessary to maintain comfort. To achieve the point, the project could demonstrate that the building sequence of operations addresses humidity control, whether automatically or manually. However, the point would not be achieved simply because the mechanical system has an effect on humidity. (For example, the presence of an air conditioning system alone does not imply that humidity is controlled, merely that the system affects humidity.) As for the need to install humidification and dehumidification equipment, this would be dependent on climatic conditions, as related to attempts to meet the requirements of ASHRAE Standard 55 in EQ credit 7.1. ASHRAE Standard 55 shows that occupants contribute to humidity levels therefore human contributions to indoor humidity should be calculated as part of a project's compliance with EQc7.1 and EQc7.2. If the design team can provide calculations and a narrative that the building will be within the temperature, humidity and air flow requirements of ASHRAE Standard 55 for 98% of the time that the building is occupied, EQ Credit 7.1 can be achieved. Calculations could include psychrometric analysis and/or output from a building energy model. Applicable internationally.
Related Addenda (Corrections & Interpretations)