Passive Hybrid Downdraught Cooling

Transcription

1 Passive Hybrid Downdraught Cooling

2 Copyright The content of this course is the copyrighted property of Green Building Education Services, LLC. Reproduction or distribution of this presentation - including print and electronic distribution - without the permission of Green Building Education Services is prohibited.

3 Continuing Education 1.5 hours with GBCI 1.5 hours with AIA/CES (LU) GBES will report you hours to GBCI and AIA automatically after you finish the course and pass the assessment quiz.

4 GBES is a Registered Provider with the American Institute of Architects Continuing Education Systems. Credit earned on completion of this course will be reported to AIA/CES for AIA members automatically. Certifications of Completion for non-aia members are available upon request. This course is registered with AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product.

5 Learning Objectives Explain the differences between passive downdraught cooling, active downdraught cooling and hybrid downdraught cooling Name three technologies that can form effective hybrid systems with passive downdraught cooling Discuss how passive cooling might affect a building s form Explain the LEED credits associated with passive hybrid downdraught cooling

6 PDEC PHDC Uses evaporative cooling and natural ventilation exclusively. Uses both evaporative downdraught cooling and a mechanical backup system.

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8 Air Conditioning 12% U.S. electricity supply 40% of Peak Load 50% Efficiency of fossil fuel electric plant

9 Evaporative Cooling

10 Air Circulation

11 What is Passive Downdraught Cooling?

12 Passive Appropriate for hot, dry conditions Depends on evaporating water in the airstream Uses natural ventilation Active Appropriate for hot, humid conditions Depends on fans, chilled water coils or a/c Uses mechanical equipment for cooling and/or to speed ventilation Hybrid Combines techniques

13 Applying Passive Cooling

14 Active vs. Passive Cooling Chart

15 Established Related Technologies

16 Evaporative (Swamp) Coolers

17 Adding a Heat Exchanger

18 Qanat

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22 Two Systems Working Together Cooling systems located at the top of the building or in a tower Vertical air circulation space or spaces Provision for horizontal air circulation Properly sized warm air vents Complementary strategies

23 Passive Cooling Methods Sprayed mist or water droplets Shower (shower towers) Misting apparatus (misting towers) Drip pipe or board Wet pads, filters or porous surfaces Porous ceramics Wetted cellulous pads An air stream flowing past a stream of water Qanat Waterfall or water feature

24 Central atrium Central shaft Perimeter tower Detached tower

25 Air Intake Geometry: Central Atriums and Shafts

26 Air Intake Geometry: Perimeter Towers

27 Air Exhaust Geometry

28 Ask Yourself Where will the cool air be used? Just in the central atrium? In the spaces around the cooling area? In the entire building? How can this best be accomplished? By a central open area? By a closed tower with vents? By shafts or light wells with vents? Where will the air intakes be located? Wind direction? Height? Architectural form? Where will the intake and/or exhaust vents be located, and how will the air reach them?

29 Cool Towers

30 A Cellulous Pad Distribution pad Cooling pad Water drains to recirculation system

31 Porous Ceramic Evaporators (EvapCool)

32 Porous Ceramic Design Concepts

33 Shower and Misting Towers

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35 Misting Towers

36 Designing a Passive Cooling Tower Calculate internal heat gain Develop thermal comfort model Calculate flow rate required to remove heat gains Relate to air flow rate and cooling efficiency Calculate air intake opening sizes and exhaust vent size

37 Designing a Cool Tower

38 Thermal Modeling

39 Sample Design Process

40 Active Cooling Systems for Hybrid Use Fans Chilled water cooling coils Conventional air conditioning Ice storage air conditioning

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42 Chilled Water Cooling Coils

43 Ice Storage Air Conditioning Photo: Trane

44 Conventional Air Conditioning vs. Chilled Water Cooling Coils

45 Measuring Efficiency Air Conditioning Systems EER Energy Efficiency Ratio BTU/watt At 95 F, outdoor dry bulb temperature Reflects summer peak loads Best for peak load reduction SEER Seasonal Energy Efficiency Ratio BTU/watt On average for the whole cooling season across the U.S. Used to compare systems

46 Complementary Strategies Green Roofs and Landscaping White and Blue Roofs Wind Catchers Night Ventilation Night Sky Radiation Ground Source Cooling Controlling Solar Gain

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49 Wind Catchers

50 Night Ventilation

51 Night Sky Radiation

52 Ground-Source Cooling

53 Controlling Solar Gain Building orientation Window and door design Overhangs Shading devices Thermal mass Insulation

54 Scottsdale Fire Station No. 2 LEED Platinum 14,000 SF 40% Less power $1,000 energy savings / year

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57 Communications antenna Fan Misting ring 84 19% RH 64 85% RH

58 Zion National Park Visitor Center 7,600 SF Cool tower, cellulous pads Natural ventilation Nighttime ventilation Overhangs

59 Comfort Center

60 Source: NREL and NPS

61 Zion Visitor Center Complex Actual Energy Use,

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63 Torrent Research Centre Gujarat, India Misting system in atriums, chimney stacks Complimentary strategies: Thermal mass Nightime ventilation Shading and recessed windows Vegetation and landscaping

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65 Torrent Centre User Perceptions Too Hot or Too Cold

66 Torrent Centre User Perceptions Too Dry or Too Humid

67 Sandra Day O Conner Courthouse Phoenix, Arizona Misting tower Double facade

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69 Project Specific Considerations Local Climate Cost and suitability Level of control Heating coordination

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71 NO PASSIVE HYBRID Check microclimate PASSIVE Or PHDC Check microclimate (maybe no)

72 Cost / Benefits 2-15 years 4-12% ROI for retrofits depending on climate of new build cost for PHDC 19-23% of new build costs for A/C

73 LEED Credit Synergies EA Prerequisite/ Credit Energy Performance IEQ Credit Outdoor Air Delivery Monitoring IEQ Credit Increased Ventilation SS Credit Stormwater Design

74 Resources PHDC (design software available) The Architecture and Engineering of Downdraught Cooling, a Design Sourcebook, by Brian Ford, et.al. Whole Building Design Guide: Natural Ventilation Sustainable Federal Buildings Database femp.buildinggreen.com LEED Projects Directory

75 Follow us on twitter Hashtag #GBES Like us on facebook facebook.com/greenbuildingeducationservices

76 Poor Fair Average Good Excellent

77 Passive Hybrid Downdraught Cooling Thank you for listening!