1. Environmental Controls
Lecture 11
Passive Heating
Photovoltaics and Active Solar Panels

2. Passive Heating
BH024

3. Passive Solar Heating Zoning: Solar Gain varies throughout the day
Configure building in accordance thermal patterns and usage needs

4. Passive Solar Heating
Three major types:

5. Thermal Mass
Creates time lag for indoor air temperature changes and reduces temperature swings
Note: Temperature swings ≥ 13ºF are not acceptable
L: p , F7.6c&d

6. Thermal Mass & Insulation
Insulation decreases temperature swings

7. Direct Gain System Heat gain occurs directly in living space
Mass moderates the “greenhouse effect”
L: p. 171 Fig. 7.6a&b

8. Direct Gain Sizing Guidelines
Glazing area
L: p.173 T7.7a

9. Direct Gain Sizing Guidelines
Thermal Mass
PC materials to
L: p.174, T7.7B

10. Direct Gain—Sizing Example
Design a direct gain system with night insulation for Salt Lake City for a 40’ x 20’ (800 sf) house. H L

11. Direct Gain—Sizing Example
Find glazing area
Salt Lake City
800sf x 26%=208sf
L: p.173 T7.7a

12. Direct Gain—Sizing Example
Find thermal mass area
208sf x 3=624sf
6” thick
Revise mass location to suit design conditions
L: p.174, T7.7B

13. Direct Gain—Sizing Example
Design a direct gain system with night insulation for Salt Lake City for a 40’ x 20’ (800 sf) house.
If glazing is 8’ tall, how long is the window?
208sf/8’=26’ long
Note: verify solar aperture and adjust dimensions accordingly 8’
26’

14. Thermal Storage Wall Commonly known as a “Trombe Wall”
Space between glazing and wall is not habitable
L: p. 176, F7.9a&b

15. Trombe Wall
Provides only a limited view to outdoors
Sante Fe, NM

16. Trombe Wall Sizing Guidelines
Glazing area
L: p.173, T7.7a

17. Trombe Wall Sizing Guidelines
Wall Thickness
L: p.179, T7.10

18. Sun Spaces
Sun spaces come in three configurations
L: p.180, F7.12a

19. Sun Spaces Sloped glazing presents shading and space problems
L: p.161, F7.14a-c

20. Sun Spaces
Sun heat gain space separated from living space by thermal mass and operable partitions
L: pp. 180, F.7.12b&c

21. Sun Space Overheating
Venting and insulation may be needed to prevent overheating
Upper and lower outside vents: each should 5% of glazing area
Upper and lower “common wall” inside vents should be ≥10% of glazing area
L: p.184, F7.14ab

22. Sun Space Sizing Guidelines
Glazing area
Note: convert sloped glazing to the vertical equivalent
L: p.173 T7.7a

23. Sun Space Mass Sizing Guidelines
Wall Thickness
L: p.184, T7.14

24. Solar Performance

25. Solar Savings Fraction
Amount of reduction of non-solar energy usage when solar design is used
SSF=(Ewo-Ew)/Ewo
=(70-25)/70
=0.64 or 64%

26. Determining the SSF — Load Collector Ratio Method
Solar aperture (Ap): projection of glazing area projected onto a vertical plane H

27. Determining the SSF — Load Collector Ratio Method
Building Load Coefficient: steady state heating load of non-solar components for one day/ºF
BLC= 24 x UAnon-solar

28. Determining the SSF — Load Collector Ratio Method
Using the earlier Direct Gain example
Mass/Glazing Ratio=3
Night Insulation
6” thick
“DG-B3”
MEEB: p.1633, T.H.1D

29. Determining the SSF — Load Collector Ratio Method
Determine Load Collector Ratio
BLC= Btu/ºF-day (calculated separately)
Ap= 208 sf
LCR =BLC/Ap
=10400/208
=50

30. Determining the SSF — Load Collector Ratio Method
Determine Solar Savings Fraction (SSF)
DG-B3 LCR =50
SSF=34%
MEEB: p. 1656, T.H.3

31. Photovoltaics and Solar Panels

32. Photovoltaics Produce high grade energy (electricity)
NREL PV Testing Facility, Golden, CO

33. Photovoltaics Can be integrated into numerous building products
Entrance canopy, Thoreau Center for the Environment,
San Francisco, CA
Roof shingles, NREL Testing Facility,
Golden, Co

34. Solar Panels Produce low grade energy (warm/hot water)
Flat Plate Solar Panel, Salt Lake City, UT