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TROX USA

HVAC for Educational Facilities. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •. TROX USA. Past practices Mixed air systems with local fans and/or compressors

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TROX USA

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  1. HVAC for Educational Facilities • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • TROXUSA

  2. Past practices Mixed air systems with local fans and/or compressors First costs and system familiarity were the driving factors Increased interest in displacement ventilation Proven IAQ benefits due to enhanced contaminant removal Potential energy savings Acoustics Recent Developments • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •

  3. Normal teacher voice level is 50 to 60 dBA • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Classroom Acoustics Signal at receiver should be 15 dBA above background Background Noise

  4. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Classroom Acoustics • Demographics • 13 to 15% of students slightly impaired • 10 to 15% of students learning in a language not spoken at home • Cost of Poor Classroom Acoustics • 3% of children need out of class support services ($2,500 annually) • 1% of children need outside placement ($15,000 annually) due to acoustics Annual cost of $6,300 ($7/FT2) per classroom Based on a 900 ft2 classroom with 28 students

  5. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Classroom Acoustics Basis of ANSI Standard S12.60 • Objectives of Standard: • Establish SNR that will enable all students to hear teacher speaking at normal voice level • Academic improvement • Reduction of teacher vocal stress • Provisions of Standard • Reverberation times of 0.6 seconds • Background noise levels ≤ 35dBA in all core learning areas!

  6. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Classroom Acoustical Study • Minnesota school district • 48 classrooms tested • 45% over 50 dBA • 15% below 40 dBA • None below 35 dBA Source: Classroom Acoustical Study (ATS&R, 2005) >55 dBA 10% 35-40 dBA 15% 40-45 dBA 21% 50-55 dBA 35% 45-50 dBA 19%

  7. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Classroom Acoustics • Current: In new construction, plans submitted under WAC 246-366-040 shall specify ventilation equipment and other mechanical noise sources in classrooms are designed to provide background sound which conforms to a noise criterion curve or equivalent not to exceed NC-35. The owner shall certify equipment and features are installed according to the approved plans. • Proposed: Noise control — Construction requirements (1) School officials shall design ventilation equipment and other mechanical noise sources in classrooms to provide background sound which conforms to a noise criterion curve or equivalent not to exceed NC-35. School officials shall certify, or hire the appropriate person to certify, that ventilation equipment and other mechanical noise sources are installed according to the approved design.

  8. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Adoption • LEED™ for Schools (2007) • ASHRAE Handbook (Applications, 2007) • Various school districts • State of Connecticut • New Hampshire Department of Education • New Jersey School Construction Board • Ohio School Facility Commission • New York City Public Schools • Arlington County (VA) Public Schools

  9. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Displacement Ventilation

  10. Displacement Conditioning of Classrooms • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Heat Source

  11. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Adjacent Zone • Adjacent Zone • Area where velocities greater than 40 fpm may exist • Occupants should not be located within this area • Defined by manufacturers’ literature V ≤ 40 FPM L0.2

  12. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Adjacent Zone TE V ≤ 40 FPM Adjacent Zone Percentage of Room Height (X) Occupied Zone Maximum 5°F ASHRAE Standard 55 L0.2 TS 0.50 (TX – TS) / (TE – TS)

  13. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Adjacent Zone Effect Adjacent Zone = 9 feet Adjacent Zone Area = ~190 ft2

  14. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Adjacent Zone Effect Trox Adjacent Zone = 9 feet Adjacent Zone Area = ~120 ft2 VS. Brand “X” Adjacent Zone = 21 feet Adjacent Zone Area = 600 ft2 Aprox. Cost For School Construction ~$200/Ft2 Cost of lost space due to larger adjacent zone: $81,000 per Class room

  15. Adjacent Zone Effect So why is there such a difference between manufactures? Nozzles VS Perforated

  16. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Displacement Conditioning Advantages • Low space acoustical levels

  17. Low space acoustical levels Enhanced contaminant removal efficiencies Independent studies Minnesota elementary school • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Displacement Conditioning Advantages

  18. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Displacement Conditioning Advantages Minnesota Elementary School • Identical classrooms • Tests conducted over two week period • CO2 concentration at six foot level monitored • Mixed system: 1200 PPM • DV System: 400 PPM 1600 1400 1200 Mixed Air System (UV) 1000 CO2 Concentration (PPM) 800 600 Displacement System 400 Time

  19. Low space acoustical levels Enhanced contaminant removal efficiencies Reduced operational costs More periods of free cooling • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Displacement Conditioning Advantages in the Northwest

  20. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Air-side Economizer Opportunities in the Northwest 49% Increase in Free Cooling (ASHRAE BIN DATA FOR SEATTLE)

  21. Enhanced contaminant removal Excellent space acoustics Reduced operational costs Slightly higher supply airflow rates Lower ΔT with conventional ceiling heights Larger terminal units Larger fans and ductwork Separate heating system required Use with DOAS is not feasible Airflow requirement for sensible cooling is 2.2 to 2.5 times ventilation airflow rate. 65 to 70% of return is recirculated to room • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Displacement Conditioning Issues in Northwest

  22. Energy and IAQ Related Advantages Free air-side cooling during a large portion of the year Guarantees delivery of appropriate ventilation air to classrooms Operational Advantages Simplifies use of CO2 demand control ventilation Minimizes likelihood of system modification • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Advantages of DOAS Systems

  23. Air-water Cooling System Passive Chilled Beams • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Passive Chilled Beam

  24. Reduce space airflow requirement to space ventilation rate Reduced air handling units and ductwork Enables use of DOAS Compliant Acoustics Reduced transport costs Separate heating system still required Possible thermal comfort issues Potential drafts below beams doing large amounts of cooling Condensation potential Chilled water must be supplied above space dew point No condensate trays • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Passive Beam Advantages and Disadvantages

  25. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Displacement Chilled Beams • Induction Nozzles • Primary air delivered at 50 to 55ºF • Mixing within terminal elevates supply air to appropriate temperature • Integral Heat Transfer Coil • Room air induced through coil • Supplements space cooling • Eliminates separate heating system

  26. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Displacement Chilled Beams Cooling mode operation 100% Exhausted Return Air 420 CFM (82 to 85ºF) Primary Airflow 420 CFM (52 to 55ºF) Room Air 840 CFM (75 to 78ºF) Chilled Water (57 to 60°F) Supply Air 1260 CFM (62 to 68ºF)

  27. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Displacement Chilled Beams Heating mode operation Primary Airflow 420 CFM (55 to 60ºF) Room Air 840 CFM (70 to 72ºF) Hot Water (120 to 130°F) Supply Airflow 1260 CFM (82 to 85ºF)

  28. Acoustic levels compliant with ANSI S12.60-2009 Heating and cooling supplied through same terminals No concern regarding condensation Simple system with minimal maintenance requirements Reduce ducted airflow requirement to space ventilation rate Reduced air handling units and ductwork sizes Enables use of DOAS • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Displacement Chilled Beam Advantages

  29. Heating Coil • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Displacement Chilled Beams with DOAS Airflow quantities based on 6 classrooms per AHU Exhaust Air 2700 CFM @ 84F Return Air (82°F) Heat Recovery (Optional) Outside Air 2700 CFM @ 90F Supply Air (51 to 54°F) 51°F Dew Point OA Damper Filters Cooling Coil Blower

  30. 12 to 15 Points • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • LEED Credits LEED for Schools Version 2007 • Energy and Atmosphere • Credit 1 Energy reduction 4 to 6 points • Credit 4 Enhanced refrigerant management 1 point • Indoor Environmental Quality • Credit 1 OA monitoring and maintenance 1 point • Credit 2 Increased ventilation (30%) 1 point • Credit 7 Compliance with ASHRAE 55-2004 1 point • Credit 9 Enhanced acoustical performance 2 points • Credit 10 Mold prevention (RH < 60%) 1 point • Innovation & Design Process • Dedicated outdoor air system (no recirculation) 1 to 2 points

  31. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Installation Examples

  32. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Installation Examples INSERT ADDITIONAL SLIDES WITH PHOTOS FROM MINNEAPOLIS SCHOOLS HERE

  33. HVAC for Educational Facilities • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • TROXUSA

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