Window Performance for Human Thermal Comfort Progress Report Quebec City July 2005

1. Window Performance for Human Thermal ComfortProgress Report� Quebec CityJuly 2005 Charlie HuizengaHui ZhangPieter Mattelaer Tiefeng YuEdward Arens University of California, Berkeley Peter LyonsArup Fa�ade EngineeringMelbourne, Australia

2. Objective Develop a technical basis for a method to rate the thermal comfort performance of windows. 12-month project, completion for Santa Fe meeting

3. Literature review progress 20 page overview of the literature ~175 relevant papers identified ~40 papers summarized Draft available on NFRC website

4. How windows influence comfort

5. Primary factors influencing window comfort Window geometry Room geometry Occupant location Glazing system Frame type Exterior conditions (Tdb, wind, solar) Interior conditions (Tair, surface temperatures, RH, air velocity) Human factors (clothing, metabolic rate, location)

6. View factor

7. Predicted Mean Vote (PMV) Comfort Model The two-node model consider the whole-body as two compartments, core and skin. The PMV model calculates heat transfer for the entire body. Both models are limited in use in asymmetrical environment which only has impact on parts of the body.The two-node model consider the whole-body as two compartments, core and skin. The PMV model calculates heat transfer for the entire body. Both models are limited in use in asymmetrical environment which only has impact on parts of the body.

8. Predicted Mean Vote (PMV) Comfort Model PMV model assumptions Whole-body energy balance Clothing covers entire body uniformly One skin temperature across the entire body The two-node model consider the whole-body as two compartments, core and skin. The PMV model calculates heat transfer for the entire body. Both models are limited in use in asymmetrical environment which only has impact on parts of the body.The two-node model consider the whole-body as two compartments, core and skin. The PMV model calculates heat transfer for the entire body. Both models are limited in use in asymmetrical environment which only has impact on parts of the body.

9. Local discomfort Most thermal comfort complaints are a result of local discomfort rather than overall comfort Windows often cause local discomfort because the longwave radiation is stronger on one side of the body PMV predicts overall comfort but is not able to assess local discomfort UC Berkeley has a developed a sophisticated model that is able to predict local discomfort

10. UC Berkeley Comfort Model 16 body segments, 4 layers (core, muscle, fat, and skin) Transient Blood flow model Heat loss by evaporation(sweat), convection, radiation, and conduction Clothing model (including heat and moisture transfer) UCB Comfort model divides a human body into 16 parts, adding detailed physiology considerations.-physiology modelUCB Comfort model divides a human body into 16 parts, adding detailed physiology considerations.-physiology model

11. UCB Comfort Model output

12. UCB Comfort Model interface

13. Window temperature distribution

14. Window to wall ratio (WWR)

15. Example Simulation Geometry

16. Comparison of PMV and UC Berkeley Comfort Model

17. Spatial distribution of comfort

18. Example comfort ranges for generic glazing types

19. Window Size, Temperature and Discomfort Zone Depth

20. Comfort vs. interior air temperature and window surface temperature Remove the ppd. Same colorRemove the ppd. Same color

21. Effect of considering frame and edge of glass temperature Analyze the two-directional vs. one-directional. NFRC: what is the glass temperature that you can feel comfortable. For double glass, what outside air can go. List issues. No direct solar, explain it.Analyze the two-directional vs. one-directional. NFRC: what is the glass temperature that you can feel comfortable. For double glass, what outside air can go. List issues. No direct solar, explain it.

22. Window geometry impacts Analyze the two-directional vs. one-directional. NFRC: what is the glass temperature that you can feel comfortable. For double glass, what outside air can go. List issues. No direct solar, explain it.Analyze the two-directional vs. one-directional. NFRC: what is the glass temperature that you can feel comfortable. For double glass, what outside air can go. List issues. No direct solar, explain it.

23. Possible indices of window thermal comfort Point-in-time indices (for both NFRC winter and summer conditions) Thermal comfort index at NFRC summer and winter conditions for a specified geometry (window size and occupant location) Required indoor air temperature for NRFC summer and winter conditions to achieve comfort Minimum distance from the window that a person can be and still be comfortable Maximum and minimum outside temperature that remains comfortable Annual indices Annual average comfort index Number of hours outside outside the comfort zone Annual energy required to modify room air temperature to maintain comfort Percent of floor area in a specified room that remains comfortable to a certain level over the year (100% would be the best performance)

24. Summary of issues to address Geometry of room and window Location of occupant relative to the window Different glass/frame combinations and maybe in the future: Downdraft off cold, tall window Interaction with HVAC systems Air temperature distribution effects Radiative coupling with interior surfaces (e.g., impact of window on other interior surface temperatures)

25. Conclusions Near windows, thermal comfort heavily affected by glass surface temperature Good interface between Window, Therm and UC Berkeley model software Public domain tools Frame effects small (area-wise) but will be included Several promising contenders exist for simple comfort index Diffuse solar warming of glass to be added Global (direct + diffuse) solar can be considered for extended design tool but probably not in simple NFRC index Merci beaucoup!