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Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
Natural Ventilation and Hydronic Cooling in Humid Climates
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Natural Ventilation and Hydronic Cooling in Humid Climates

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  • 1. NATURALVENTILATION AND HYDRONIC COOLING IN HUMID CLIMATES GULF COAST GREEN 2013 Matthew Brugman, MSCE, LEED AP BD+C
  • 2. AIA/CES “Affiliated Engineers, Inc.” is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES). Credit(s) earned on completion of this program will be reported to AIA/CES for AIA members. Certificates of Completion for both AIA members and non-AIA members are available upon request. This program 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. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.
  • 3. COURSE DESCRIPTION This session is intended to review the benefits and design realities of using natural ventilation and hydronic (water-based) cooling systems in humid climates, with a special emphasis upon the Gulf Coast. Issues related to occupant comfort, system control, design implications, and potential failure mechanisms will be discussed.
  • 4. LEARNING OBJECTIVES At the end of this presentation, participants will be able to: 1. Identify the applicability of hydronic cooling and/or natural ventilation systems in humid climates 2. Understand the basic thermal comfort and mechanical design challenges of these systems 3. Have a basic understanding of the control implications for these systems in humid climates 4. Have a basic understanding of the of architectural design implications of hydronic cooling and natural ventilation
  • 5. OUTLINE HUMID CLIMATES THERMAL COMFORT NATURALVENTILATION BENEFITS APPLICABILITY & APPROACHES HYDRONIC SYSTEMS CONDENSATION CHILLED BEAMS RADIANT SYSTEMS
  • 6. HUMANTHERMAL COMFORT PHYSICAL FACTORS INTHERMAL COMFORT METABOLIC RATE CLOTHING LEVELS AIRTEMPERATURE RADIANT SURFACETEMPERATURES AIR SPEED RELATIVE HUMIDITY
  • 7. HUMANTHERMAL COMFORT
  • 8. HUMANTHERMAL COMFORT THERMAL COMFORT MODELS STATIC Static comfort models are based entirely upon physiological criteria and assume that human perceptions of comfort do not adapt to changes in environment. Local discomfort issues typically ignored. (Also called the PMV Method) ADAPTIVE Adaptive comfort models assume that human notions of thermal comfort change based upon the prevailing outdoor conditions. Comfort criteria are built from field observation, surveys, and statistical analysis of occupant responses as well as physiological calculations.
  • 9. HUMANTHERMAL COMFORT ASHRAE 55 The typical comfort standard adopted throughout the US, ASHRAE 55-2010 provides for both STATIC andADAPTIVE comfort criteria in system design. STATIC comfort criteria ranges in ASRHAE 55 are expressed as a range of allowable air temperatures and relative humidity values for given conditions. ADAPTIVE comfort ranges are expressed in terms of prevailing mean outdoor air temperature and the OPERATIVETEMPERATURE.
  • 10. HUMANTHERMAL COMFORT ASRHAE 55 – STATIC COMFORT MODEL (PMV) Air Speed = 30 fpm Metabolic Rate = 1.2 met (standing) Clothing = .5 clo (summer indoor clothing) Air Speed = 30 fpm Metabolic Rate = 1.7 met (slow walk) Clothing = .36 clo (shorts & t-shirt)
  • 11. HUMANTHERMAL COMFORT ASRHAE 55 – ADAPTIVE COMFORT MODEL The ASHRAE 55 ADAPTIVE comfort ranges are generally used when determining the comfort of a natural ventilation scenario as it assumes that occupants are free to adapt their clothing and other conditions. OPERATIVETEMPERATURE is the combined temperature that humans actually experience when the mean radiant temperature and dry bulb air temperature are accounted for together. At its simplest, it’s the average of radiant and dry bulb temperatures in space.
  • 12. HUMANTHERMAL COMFORT ASRHAE 55 – ADAPTIVE COMFORT MODEL Air Speed = 60 fpm Air Speed = 180 fpm 90% acceptability 80% acceptability
  • 13. HUMANTHERMAL COMFORT LOCAL DISCOMFORT There are specific instances when discomfort local to a small area must be addressed: RADIANT ASYMMETRY – Large differences between radiant surface temperatures create asymmetrical heat loss/gain, a condition which distracts occupants and can lead to discomfort. DRAFTS – High air speeds at low temperatures can create localized excessive cooling.
  • 14. HUMANTHERMAL COMFORT LOCAL DISCOMFORT VERTICALTEMPERATURE DIFFERENCE – A change of more than 5 to 7 degrees from head to toe is often uncomfortable. Especially important for stratified systems such as displacement ventilation and under floor systems. FLOOR SURFACETEMPERATURE – Low floor temperatures can create too much conduction of heat out of the feet, creating excessive cooling the extremities. Floor temperatures below 62F should be avoided, with 65F or higher being preferable.
  • 15. HUMANTHERMAL COMFORT WHAT DOES IT ALL MEAN? If building occupants are allowed to adapt their clothing to ambient conditions, comfort boils down to controlling three aspects: RADIANT SURFACETEMPERATURES AIRTEMPERATURE AIR SPEED
  • 16. VERNACULAR SOLUTIONS WHAT DIDWE EVER DOWITHOUT A/C?? DEEP SHADESTO CONTROL SURFACETEMPERATURE
  • 17. VERNACULAR SOLUTIONS WHAT DIDWE EVER DOWITHOUT A/C?? CROSS FLOW AND STACKVENTILATION TO INCREASE AIR SPEED
  • 18. NATURALVENTILATION BENEFITS OCCUPANT CONTROL – Providing individual control over natural ventilation reduces occupant comfort complaint ENERGY SAVINGS –When outside air conditions allow for natural ventilation, cooling and heating energy use can be reduced or eliminated ROBUSTNESS – Buildings with natural ventilation can continue to function even during mechanical failures HEALTH – Natural ventilation provides direct access to outside air and has been shown to reduce the spread of infection in healthcare settings
  • 19. NATURALVENTILATION APPROACHES – NATURALVENTILATION STACKVENTILATION – Moving air primarily via natural convection currents and thermal buoyancy WIND DRIVEN – Positioning openings to take advantage of pressure differentials and wind to move air through a space CROSS FLOW vs SINGLE SIDED
  • 20. UNIVERSITY OF WASHINGTON – HUSKY UNION BUILDING
  • 21. PLAIN,WI – GREENTTEC
  • 22. UC RIVERSIDE – SCHOOL OF MEDICINE
  • 23. KAUST
  • 24. NATURALVENTILATION DRAWBACKS – NATURALVENTILATION MOISTURE – Full natural ventilation systems offer no means to control moisture and humidity NOISE & POLLUTION – Negative exterior conditions are difficult to address with natural ventilation systems FINE CONTROL – Natural ventilation provides only coarse control over pressure and temperature relationships
  • 25. NATURALVENTILATION APPROACHES – MIXED MODEVENTILATION MIXED MODE – A combination of traditional mechanical solutions and natural ventilation. Mechanical systems supplement natural ventilation processes when thermal comfort cannot be maintained. CONCURRENT – Same space, same time CHANGE-OVER – Same space, different time ZONED – Different spaces
  • 26. UNIVERSITY OF WASHINGTON – MOLECULAR ENGINEERING
  • 27. NATURALVENTILATION CONTROLS - MIXED MODEVENTILATION FULLY MANUAL – Occupant control over opening and mechanical system interactions. FULLY AUTOMATIC – Building automation system runs actuators to control natural ventilation openings along with mechanical system controls. (Best option for hot and humid climates) MIXED CONTROLS –Typically achieved by contact sensors to detect when occupants use openings, HVAC systems adjusts automatically
  • 28. NATURALVENTILATION DRAWBACKS – MIXED MODEVENTILATION CONTROLS – Integration of control systems can be difficult, and training staff in proper system control is critical FIRE & SMOKE – Concerns over smoke migration ENERGY CODES – Many energy codes and authorities deter the use of operable windows and mechanical HVAC in the same space
  • 29. NATURALVENTILATION APPLICABILITY INTHE GULF COAST HOUSTON NEW ORLEANS MIAMI FRANKFURT 80% ADAPTIVE COMFORT 40% OF HOURS 9AM-6PM 46% OF HOURS 9AM-6PM 61% OF HOURS 9AM-6PM 17% OF HOURS 9AM-6PM 90% ADAPTIVE COMFORT 29% OF HOURS 9AM-6PM 33% OF HOURS 9AM-6PM 44% OF HOURS 9AM-6PM 12% OF HOURS 9AM-6PM If we can manage humidity, the Gulf Coast has a very large potential for natural ventilation systems to be effective
  • 30. NATURALVENTILATION CONTROLLING HUMIDITY MIXED MODE SYSTEMS – Allow the use of mechanical system when needed SCHEDULING – Night flush and pre-cooling can allow a space to ride through hot periods AIR SPEED – Increased air speeds counteract the discomfort of increased humidity levels CONCURRENT DEHUMIDIFICATION – Dehumidification through Dedicated Outside Air Systems (DOAS), in situ dehumidifiers, etc
  • 31. PHASE CHANGE MATERIAL CEILING INSTALLATION
  • 32. AIR SPEED IS CRITICAL!
  • 33. HYDRONIC COOLING WATERVS AIR HEATTRANSFER Water is a much more effective heat transfer medium than air VOLUME The volume of water needed to carry a certain amount of heat is much smaller than the same volume of air (1” pipe can carry as much energy as 18” rectangular duct) PUMPING Water pumps are mechanically more efficient than fans, reduced noise
  • 34. HYDRONIC COOLING TYPICAL SYSTEMTYPES RADIANT Water is used to heat/cool surfaces for radiant heat transfer (includes chilled sails) FAN UNITS Small fan/coil combinations that blow warm/cold air into a space (includes wall induction units) CHILLED BEAMS A special diffuser/coil combination that induces space air to flow over a coil filled with chilled water. Can be active or passive.
  • 35. HYDRONIC COOLING CHILLED BEAMS - PASSIVE ~ 6 watts of cooling capacity per linear foot
  • 36. HYDRONIC COOLING CHILLED BEAMS - ACTIVE ~ 12+ watts of cooling capacity per linear foot
  • 37. FROM EXPERIMENTALTO MUNDANE
  • 38. HYDRONIC COOLING CHILLED BEAM MOISTURE CONTROL MOISTURE SENSORS Moisture sensors on the chilled beam coil can reset the water temperature in the beam DEW POINT CONTROL By properly dehumidifying the air supplied to a chilled beam or space, the dew point can be suppressed to avoid condensation *Active chilled beams create a microclimate around the coil surface and can operate with water several degrees below the dew point without forming condensation
  • 39. HYDRONIC COOLING DEDICATED OUTSIDE AIR SYSTEMS (DOAS) DOAS DOAS systems are intended to condition only outside ventilation air supplied to a space, and are typically design to filter and dehumidify air with or without energy recovery. DOAS systems are often constant volume, but at very low supply volumes. Because DOAS systems are not the primary cooling system, ductwork tends to be much smaller than in a traditionalVAV system.
  • 40. HYDRONIC COOLING TYPICAL RADIANT SYSTEMS RADIANT SLAB –Tubing is embedded in a floor or ceiling slab to heat and cool the surface PANELS – Metal panels are heated or cooled to create the radiant surface, typically ceiling mounted CHILLED SAILS – A radiant cooling panel with multiple openings meant to provide more convective cooling
  • 41. PLAIN,WI – GREENTTEC
  • 42. STANFORD – CESI ADMIN
  • 43. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan 75 70 65 60 55 50 45 40 35 30 25 20 15 10 Temperature(°F) Date:Fri01/JantoFri31/Dec Surfacetemperature: (proposed.aps) External dew-pointtemp.:USA_CA_San.Jose.Intl.AP.724945_TMY3.epw(USA_CA_San.Jose.Intl.AP.724945_TMY3.epw) DEWPOINTVS SLABTEMP – 66F SLAB
  • 44. DEWPOINTVS SLABTEMP – 62F SLAB Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan 80 70 60 50 40 30 20 10 Temperature(°F) Date:Fri01/JantoFri31/Dec External dew-pointtemp.:USA_CA_San.Jose.Intl.AP.724945_TMY3.epw(USA_CA_San.Jose.Intl.AP.724945_TMY3.epw) Surfacetemperature: (proposedat62wosails.aps)
  • 45. HYDRONIC COOLING RESPONSETIME Radiant systems (especially slabs) respond slowly to changes in thermal load, so good application of radiant technology will include strategies to reduce thermal gains: Orientation Shading Sufficient Insulation Proper Glazing Selection Pick the low-hanging fruit first!
  • 46. HYDRONIC COOLING RESPONSETIME 01 02 03 04 05 06 07 08 09 10 11 88 86 84 82 80 78 76 74 72 70 Temperature(°F) Date: Thu 01/Jul to Sat 10/Jul Air temperature: Flex Space (sesi radiant floor.aps)
  • 47. HYDRONIC COOLING CAPACITY
  • 48. MAKINGTHE CASE FOR NATVENT & HYDRONIC WHAT DOES IT COST? FIRST COST – First costs can be higher than traditional HVAC systems, especially mixed mode natural ventilation BUILDING REUSE – Because nat vent and hydronic systems take up less space, older facilities can be successfully reused LIFE CYCLE COSTS –Typical NV and radiant systems have very beneficial life cycle costs, but not short term (less than 10 year) paybacks
  • 49. QUESTIONS? Matthew Brugman mbrugman@aeieng.com This concludesThe American Institute of Architects Continuing Education Systems Course

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