Status (updated 6/21/2012): Ongoing
Funding sources: CBE Industry Consortium
Project Objective
Develop a web-based graphical user interface for thermal comfort prediction according to ASHRAE Standard-55. Include models for conventional building systems (predicted mean vote) and also for comfort using the adaptive comfort model, and with increased air speeds (for example, when using fans for cooling). Provide ongoing upgrades and new features, such as visualization of comfort boundaries within the psychrometric chart.
Significance to Industry
In the design and operation of buildings and mechanical systems, an advanced understanding of human comfort presents opportunities to save energy while still keeping occupants comfortable. The standard convention of attempting to maintain a narrow temperature band can be an energy-intensive practice. Instead, using CBE’s comfort prediction tools with ASHRAE Standard-55 as a guide, building designers may find that a wider temperature band will provide adequate comfort, saving a significant amount of energy. In other cases, the tool can be used to assess the comfort of low-energy designs.
If a building has provisions for air-movement such as ceiling fans or desk fans, the predicted mean vote (PMV) model with elevated airspeed can be used. In a naturally ventilated building, the adaptive comfort model can be used. This tool provides options for all three of these system choices, verifying compliance with ASHRAE Standard 55-2010. The compliance verification can also be used for LEED credits.
Research Approach
We have identified a number of features that will be important for practitioners, and will phase them in as we develop and improve the tool. We will include the ability to plot how the predicted percentage dissatisfied (PPD) and adaptive comfort ranges change in the psychrometric chart when clothing and metabolic activity are varied within a given range. We will also allow users to feed the results of a thermal comfort calculation into a document that is ready to support LEED documents for the thermal comfort points. This will include thermal comfort model outputs as well as a short questionnaire relating to local thermal discomfort.
Future enhancements to the tool include the ability to visually compare two or more thermal comfort scenarios, and to predict comfort for specific parts of the body (hands, feet, torso, etc.). We plan to allow users to upload a weather file in EnergyPlus format (.epw) or comma-separated values (CSV) format to calculate the running average temperature for the adaptive comfort model.
Finally, we will enable the CSV import/export of the results. In addition, the tool will be continuously updated based on any approved changes to ASHRAE 55-2012.
Video Tutorials
Overview of the tool's main features
Using the adaptive method features
Using the tool for LEED documentation
Local (indivdual body part) discomfort assessment
Publications
Hoyt, T., K.H. Lee, H. Zhang, E. Arens, and T. Webster. Energy savings from extended air temperature setpoints and reductions in room air mixing. Proceedings, International Conference on Environmental Ergonomics, 2009.
Schiavon, S., and A.K. Melikov. Energy saving and improved comfort by increased air movement. Energy Build, 2008.
The tool may be used to predict comfort in naturally ventilated spaces.
Comfort with enhanced ventilation, such as a fans, may also be predicted with this tool.