ASHRAE Research: Planning Tool Improves Occupant Comfort
With the assistance of a thermal comfort strategy developed and enhanced at Kansas State University (KSU), these may soon be not-so-familiar complaints.
The strategy provides engineers and architects with tools to specify the physical characteristics of a room - including a detailed description of windows - and then determine if the occupants will be thermally comfortable.
It was developed through research funded by ASHRAE. More information on the research will be presented as part of the technical program poster session held at ASHRAE's 2005 Winter Meeting, February 5-9, in Orlando, FL. The session will take place 11 a.m.-1 p.m., February 8.
Over the last decade, KSU researchers Byron Jones, Ph.D., and Kirby Chapman, Ph.D., have developed the building comfort analysis program (BCAP). This suite of programs uses a number of parameters to determine occupant thermal comfort, including operative temperature, the percentage of the occupants that will be dissatisfied with the thermal conditions, and a psychological profile referred to as the predicted mean vote. Thermal comfort is defined as the perceived level of satisfaction one has of the thermal environment.
KSU researchers incorporated the impact of windows and frames on occupant thermal comfort at various locations within the room.
Windows tend to be one of the most important components affecting thermal comfort. Window systems - also known as fenestration systems - include all construction components of the window, such as the frame, glazing and spaces between the glazing panels.
"Window manufacturers offer numerous options such as low-emissivity coatings, plastic films, insulated spacers and new frame materials," Chapman, who served as principal investigator, said. "All of these options create distinctly different thermal and optical properties when compared to walls. Because of the complexity of a fenestration system, the need existed to incorporate these components into thermal comfort calculations."
Using over 100 simulations, the research team created a graphical tool that can be used by designers to select the proper window system to create an acceptable level of thermal comfort. This graphical tool will be incorporated into a future edition of the ASHRAE Handbook.
One of the outcomes from the research was software that allows designers to actually design for thermal comfort. This particular software tool is substantially different from other software tools, such as EnergyPlus and DOE-2, according to Chapman.
Instead of a single thermal comfort measure for a particular space, the new software creates a "Thermal Comfort Signature" of the occupied space. This signature separates the space into areas that are too hot, too cold, or just right. With that information, the architects and designers can then adjust the design accordingly to maximize the floor space that is thermally comfortable. The results obtained help to quantify the
impact by correlating the comfort index to the floor space area that is thermally comfortable.
"This may be one small step for engineers, but a giant leap for the thermal comfort of mankind," Chapman said.
The project, RP-1162, Window Performance for Human Thermal Comfort, was overseen by ASHRAE Technical Committee 4.5, Fenestration.