Designing for 100% OA In Hospitals. Southland Industries

Transcription

1 Designing for 100% OA In Hospitals Southland Industries

2 Designing for 100% OA In Hospitals Chris Skoug, PE March 31,

3 Why Choose 100% OA for Hospitals?

4 Designing for 100% OA In Hospitals Key Objectives 1. DOAS vs. 100% OA 2. Heathcare ventilation requirements 3. Energy Standards pertaining to Healthcare 4. Hospital Energy Model Simulation 5. Practical Application of 100% OA system Layout 6. Benefits of a 100% OA system 7. Summary / Questions March 31,

5 Difference Between DOAS and 100% OA DOAS System Coupled with Terminal Devices Ventilation Air is Smaller Percentage (primary air) Recirculation Air Present 100% OA Delivered to Spaces 100% Fresh/Ventilation Air Energy Recovery Two Duct System March 31,

6 100% OA with Energy Recovery March 31,

7 Recirculating HVAC System Healthcare facilities typically have high ventilation requirements (25-40% OA to meet code required ventilation) March 31,

8 Journey & Potential Benefits Background Journey of designing 100% OA for healthcare - (2008) Walter Reed (Bethesda, MD), 540,000 sf outpatient/treatment + 150,000 sf inpatient expansion - (2010) Ft Hood, TX hospital replacement, 950,000 sf replacement hospital - (present) current applications (Climate Zone 4A) Why consider 100% OA? - Improved indoor air quality (IAQ) due to zero recirculated air is benefit to all occupants - Energy reduction and sustainability are valued project goals - Flexibility and Adaptability of the HVAC system is valued benefit - Reduction in Peak Cooling load (central plant equipment size reduction) - Improved Constructability will also result in Improved Construction Schedule March 31,

9 Design Challenges Overcoming Energy Consumption: Roadblocks to 100% OA - Operational Energy Penalty (main focus) - First Cost (project specific) How do we address/neutralize increased energy consumption between recirculating systems and 100% Outside Air? - Review ventilation standards (ASHRAE Std ) - Review energy standards (ASHRAE Std ) March 31,

10 Code Review Overcoming Energy Consumption: Ventilation for Healthcare - AIA 2006/ASHRAE AIA 2010/ASHRAE ASHRAE (Ventilation of Healthcare Facilities) - Guidelines for the Design & Construction of Healthcare Facilities (AIA 2010) merged with ASHRAE some differences, but vetted by committee - Military healthcare criteria (UFC ) varies, but is close enough to consider the same for this presentation. Evolution of Energy Codes (pertaining to Healthcare) - ASHRAE Standard Ventilation Rates (baseline vs proposed) - Exhaust Air Energy Recovery - Fan Power Limitation calculation March 31,

11 Healthcare Ventilation Requirements: ASHRAE excerpt Air Classification per ASHRAE 62 Class 1 Unobjectionable air Class 2 Toilets; mildly objectionable Class 3 Janitors closets; objectionable Class 4 Laboratory exhaust, harmful Air Reclassification per ASHRAE 62 when passing through and energy recovery wheel. Class 1 can mix with Class 1 Class 2 10%can mix with Class 1 Class 3 5%can mix with Class 1 Class 4 cannotmix with Class 1 March 31,

12 Healthcare Ventilation Requirements: ASHRAE excerpt Upstream of Filter Bank No. 2 and Leakage allowance (Enthalpy wheel) Airborne Infectious Isolation (AII) rooms not allowed 5% leakage allowance Not allowed with Enthalpy Wheel: (ER waiting, Lab hood exhaust, autopsy, nuclear medicine, etc.) March 31,

13 Healthcare Ventilation Requirements: Is 5% leakage allowance achievable? 5% leakage allowance March 31,

14 Energy Standards (Ventilation Rates): ASHRAE /2010 excerpts ASHRAE Proposed = Baseline ASHRAE /2013 If Proposed has excess OA, then Baseline = code minimum And less than Proposed March 31,

15 Energy Standards (Energy Recovery): ASHRAE excerpt 5000 cfm or greater; 70% OA or greater March 31,

16 Energy Standards (Energy Recovery): ASHRAE excerpt As system volume increases, %OA mandating energy recovery decreases March 31,

17 Energy Standards (Energy Recovery): ASHRAE excerpt March 31,

18 Energy Standards (Fan Power Limitation): ASHRAE excerpt Proposed = Baseline No fan power credit for improved effectiveness March 31,

19 Energy Standards (Fan Power Limitation): ASHRAE excerpt Energy Recovery Device, other than Coil Runaround Loop (2.2 x Energy Recovery Effectiveness) 0.5 in w.c. for each airstream Ex: (2.2 x 0.5) 0.5 = 0.6 in w.c. whereas (2.2 x 0.9) 0.5 = 1.48 in w.c. March 31,

20 Energy Standards (Economizer): ASHRAE excerpt Prescriptive Path > 54,000 Btu/h Appendix G (PRM) Not Required March 31,

21 Energy Model Exercise Bldg Description Consider a 500,000sq.ft Bedtower in Climate Zone 4A - Airside Differences Between Proposed and Baseline Proposed= 100% Outside Air Baseline = 30% Outside Air, 70% Recirculated Air - Controlling Variables to Focus Airside Design: Heating and Cooling Plants Building Envelope Lighting & Misc Loads March 31,

22 Energy Model Exercise Patient Bedtower (half floor layout) March 31,

23 Energy Model Exercise Patient Bedtower (half floor layout) March 31,

24 EnergyModel Exercise: Inputs *608 total patient bedrooms; 567,270 sf total area March 31,

25 EnergyModel Exercise: Room Inputs March 31,

26 EnergyModel Exercise: System Inputs March 31,

27 EnergyModel Exercise: Plant Inputs March 31,

28 EnergyModel Exercise: Utility Rates March 31,

29 EnergyModel Exercise: EW Performance March 31,

30 EnergyModel Exercise: EW Performance March 31,

31 EnergyModel Exercise: EW Performance March 31,

32 EnergyModel Exercise: System Summary March 31,

33 EnergyModel Exercise: Results 1 March 31,

34 EnergyModel Exercise: Results 2 March 31,

35 EnergyModel Exercise: Results 3 March 31,

36 Application of 100% Outside Air March 31,

37 System Concept Layout March 31,

38 System Applied Layout: Ft Hood, TX March 31,

39 System Applied Layout: Ft Hood, TX March 31,

40 System Applied Layout: Ft Hood, TX March 31,

41 System Applied Layout: Ft Hood, TX March 31,

42 System Applied Layout: Ft Hood, TX March 31,

43 Simple Control Sequence Energy Wheel control SOO - Vary Wheel Speed to Meet Setpoints - Bypass Damper at 100% economizer conditions Climate Zone 4A bin analysis 100%OA - Eliminates Need for DCV Sequencing 500 sf, and greater than 40 people per 1000 ft2 March 31,

44 Benefits of a 100% OA Approach Flexibility/Adaptability Converting Spaces to Meet Increased Rates - OA Infrastructure In Place Lab Exhaust (needs dedicated exhaust) Nuclear Medicine Waiting Areas (needs dedicated exhaust) Conference Rooms No retabfor min OA, No coil replacement Use of 100% OA as DOAS for non-clinical spaces - Storage rooms, elec/mech rooms, facility offices, etc March 31,

45 Benefits of a 100% OA Approach Improved Maintainability Energy Wheel control SOO - Vary Wheel Speed to Meet Setpoints - Bypass Damper at 100% economizer conditions - Eliminates Need for DCV Sequencing - Calibration of DP sensor not req, if DB control Airside Economizer Inherent - No relief/return damper control No Waterside Economizer March 31,

46 Benefits of a 100% OA Approach Energy Reduction Energy Wheel Effectiveness vs. Fan Energy Reduced Total AC Rates for 100% OA Systems? - Patient Room Air Changes - Operating Room Air Changes March 31,

47 Benefits of a 100% OA Approach Improved IAQ LEED for Healthcare (v4) - Credit for Enhanced IAQ strategies (30% increase) - Credit for Indoor Air Quality Assessment (Flush Out) - Innovation Credit ( zero recirculation) Mitigating HAIs - 1 out of every 20 patients - 99,000 annual deaths - 100% OA reduces potential exposure to airborne infectious disease and other pathogens Microbiology for the Built Environment - Dr. Jessica Green, Director of the Biology and Built Environment (Biology and the Built Environment Center // University of Oregon) March 31,

48 Benefits of a 100% OA Approach Improved Constructability One less system to coordinate and install (combined Return Air and General Exhaust Air) Affects shop labor, field labor, supervision, coordination effort, and material cost Less space (2 duct vs. 3 duct) - Horizontal distribution more of a coordination effort - Vertical pathways can be reduced in size March 31,

49 Designing for 100% OA In Hospitals Summary 1. Not all projects, but shows that 100% OA can be applied in a humid climate zone (4a) 2. Code changes pertaining to ventilation and energy recovery 3. Sizing enthalpy wheel for high effectiveness 4. Ongoing IAQ research and conferences IAQ 2016 Defining Indoor Air Quality: Policy, Standards and Best Practices Co-Organized by ASHRAE and AIVC Sept , 2016 Alexandria, VA March 31,

50 Questions? March 31,

51 ContactInformation Address Chris Skoug, PE Dresden Street Suite 177 Dulles, VA On the web Southlandindenergy.com Twitter.com/southlandind Facebook.com/southlandind LinkedIn.com/southlandind

52 The American Revolution Museum at Yorktown Omar Hawit Westlake Reed Leskosky

53 The American Revolution Museum at Yorktown Context of the Project on Site Sustainability Project Space Programming Design Criteria System Overview - Central Plant System Overview - Airside Psychometric Analysis Commissioning

54 The American Revolution Museum at Yorktown Site

55 The American Revolution Museum at Yorktown Site

56 The American Revolution Museum at Yorktown Site

57 The American Revolution Museum at Yorktown Sustainability Targeting LEED-NC Silver certification 28% Energy Reduction from ASHRAE High-Perfenvelope: thermal insulation, infiltration control Lighting: daylight and occupancy sensors, timer switches, LED Water use reduction, landscaping irrigation and plumbing use

58 The American Revolution Museum at Yorktown Space Program Critical Spaces

59 The American Revolution Museum at Yorktown Space Program Approx. Square footage: Gross: 80,000sf Museum Exhibit: 20,000sf (Critical Env. Ctrl) Museum -Pre-function: 11,250sf (Theater, Lobby, Ticketing, Grand Corridor) Office: 3,500sf Curatorial: 4,400sf Retail: 3,400sf Education: 4,500sf Café: 825sf

60 The American Revolution Museum at Yorktown Design Criteria Indoor Exhibit Design Criteria Similar to ASHRAE Climate Class A Temperature 70 o F +/-2 o F Humidity 50% +/- 5% Control of outside air is paramount Climate Zone 4A Winter lows below 14 F Summer highs above 90 Fdb / 79 Fwb Pressurization to Control Infiltration Slightly Positive in the Summer Neutral in the Winter

61 The American Revolution Museum at Yorktown Artifacts and Collection Recent Acquisition of Earliest Known Portrait of African-American Slave Ayuba Suleiman Diallo By William Hoare of Bath c. 1733

62 Chilled Water Plant 212 tons The American Revolution Museum at Yorktown System Overview Central Plant Variable Speed, Hi-Efficiency, Air-Cooled Chiller Variable Primary Configuration Consider Minimum flows and bypass Sized to Meet Aggressive Dehumidificaiton Temperatures

63 The American Revolution Museum at Yorktown System Overview Central Plant Heating Hot Water Plant (2) 2000MBH Boilers High-Efficiency, Condensing Boilers, +94% Multiple HX per boiler for Turndown (20:1) Reheat is Greater than Typical for Museum Low Temperature Heating Hot Water, 135 o F Consider VAV Terminal Unit Reheat Coils High Reheat Airflow due to Critical Control Spaces Variable Primary Configuration Consider Minimum flows and bypass Facilities Staff on Condensing Boiler Systems

64 The American Revolution Museum at Yorktown System Overview Airside Schematic Central DOAS Distributed to Multiple AHUs Reduced Maintenance Cost One Central Enthalpy Wheel and Humidification System, Instead of six or more Limit the Number of Enthalpy Wheels Facility Maintenance not familiar with Enthalpy Wheels Reduced First Cost Squeeze on the Budget Desire for Redundancy AHUs at Permanent Gallery, Humidifiers, Emergency OSA

65 The American Revolution Museum at Yorktown System Overview Airside Schematic Central DOAS Distributed to Multiple AHUs DOAS AHU AHU AHU VAV Gallery Gallery Gallery

66 The American Revolution Museum at Yorktown System Overview Roof Plan

67 The American Revolution Museum at Yorktown System Overview Roof Plan

68 The American Revolution Museum at Yorktown DOAS Shop Drawing

69 The American Revolution Museum at Yorktown DOAS Control Diagram Heating Coil Cooling Coil Enthalpy Wheel Humidifier Exhaust Air Terminal Unit Supply Air Terminal Unit

70 The American Revolution Museum at Yorktown AHU Control Diagram Pre-Treated Outside Air Heating Coil Cooling Coil VAV Terminal Units with Reheat

71 The American Revolution Museum at Yorktown Partial Permanent Gallery Exhibit Design

72 The American Revolution Museum at Yorktown Partial Permanent Gallery Exhibit Design

73 Psychrometric DOAS Winter db/wb Humidification Energy Recovery

74 Energy Recovery Psychrometric DOAS Summer db/wb

75 Refined Control with Gallery Air Handling Units Psychrometric DOAS Feeding Circulating AHU

76 Psychrometric Constant Dew Point Control DOAS Leaving Air Dew Point Initial Set Point of 50 o Fdp Reset based on Critical Zone This first winter allowed reset up to 58 o Fdp This summer expect reset down to 48 o Fdp

77 The American Revolution Museum at Yorktown AHU Control Diagram Pre-Treated Outside Air Heating Coil Cooling Coil VAV Terminal Units with Reheat

78 Psychrometric DOAS - Lower Temperature Chilled Water Chilled Water Cooling Coil selected to allow for ~48 o Fdp Lower Coil Face Velocities Deeper Coil

79 Commissioning: A must for any project, twice as critical for Museums Commissioning, M&V Ongoing Expect at Least One Year of Detailed Data Monitoring Weekly Reviews of System Performance to Start Monthly Reviews to Watch Affect of Seasonal Changes Exhibit loans and Insurance Require Trended Data to Show Compliance

80 Commissioning, M&V DOAS Monitoring Temperature (F) Relative Humidity (RH%)

81 Outside Airflow (CFM) Commissioning, M&V Outside Air Monitoring

82 Commissioning, M&V Space Temperature and Humidity Temperature (F) Relative Humidity (RH%)

83 Questions? Omar Hawit - ohawit@wrldesign.com

84 Applying DOAS to VRF James Brackett Mechanical Engineer Mitsubishi Electric US Cooling & Heating 2013 Mitsubishi Electric& Electronics USA, Inc.

85 Objectives Ventilation Understand key considerations for incorporating ventilation into a VRF System

86 Typical Ventilation Concerns How do you normally incorporate outside air in WSHPs or Four Pipe Fan Coil design? What are your major concerns with ventilation air design with these systems? How do you typically address those concerns?

87 Ventilation Methods of incorporating OA into VRF systems Ventilation Accessories ERV Unit DOAS System 100% OA RTU

88 Select the Method of OA Delivery Ventilation Air Indoor Units Independent DOAS

89 OA Delivery via Indoor Units 1. Utilizing indoor units for OA delivery 2. Calculate air temperatures 3. Understand considerations for humidity

90 Duct Knockout Options

91 Duct Knockouts Filter Fan Outside Air Supply Air Supply Air Return Air

92 Duct Knockouts Auxiliary fan is required to bring in outside air Static Pressure Charts available in Engineering Manuals Consider effect on sound levels with increased airflow

93 Return Air Options

94 Return Air Fan (Optional) Filter Outside Air Supply Air Return Air

95 Ventilation Accessories Filtration Filter racks come standard in all indoor units Accessories are available to accommodate filters up to MERV 13 For field-supplied filters, always check filter pressure drop against available static pressure

96 Air Calculations Entering Air Temperature (EAT) Supply Air Temperature (SAT) Calculate Mixed Air Temps Calculate loads with OA included Check against EAT range Calculate and verify SAT

97 Example Summer Conditions What is the mixed air temperature? OA 95 F DB / 77 F WB 124 cfm RA 80 F DB 67 F WB 370 cfm

98 Indoor Units EAT Range Air Temperature 55 F 60 F 65 F 70 F 75 F 80 F 85 F Cooling EAT Range 59 F WB 75 F WB Heating EAT Range 59 F DB 81 F DB

99 Capacity Tables Qsensible CFM EAT SAT 11,200 BTU/h 494 CFM 83.7 F 62.7 F

100 Example Winter Conditions What is the mixed air temperature? OA: 10 F DB 124 cfm RA: 70 F DB 370 cfm

101 Indoor Units EAT Range Air Temperature 55 F 60 F 65 F 70 F 75 F 80 F 85 F Cooling EAT Range 59 F WB 75 F WB Heating EAT Range 59 F DB 81 F DB

102 Capacity Tables Qsensible CFM EAT SAT 11,300 Btu/h 494 CFM 53.4 F 74.6 F

103 Humidity VRF indoor units control based on dry-bulb temperature only In climates that experience humidity, consider using pre-treating air to remove humidity

104 Humidity Example MA OA (50%) RA (50%) Dry Bulb ( F) Wet Bulb ( F) Relative Humidity Outside Air (OA) % Return Air (RA) % Mixed Air (MA) %

105 Humidity Example MA COA (50%) DOAS OA RA (50%) Dry Bulb ( F) Wet Bulb ( F) Relative Humidity Outside Air (OA) % Conditioned OA (COA) % Return Air (RA) % Mixed Air (MA) %

106 Dry Mode Recommend scheduling dry mode for humid climates LEV opens to full capacity, fan runs on lowest speed for highest moisture removal Entering Air LEV

107 Review of Considerations Booster fans may be required to bring in outside air Air may need to be pre-treated to meet EAT requirements Consider humid conditions when selecting OA ratios

108 Pre-Treating Equipment Energy Recovery Ventilator (ERV) Dedicated Outdoor Air System (DOAS) 100% OA RTU

109 ERV

110 ERV Applications Centralized Ventilation

111 ERV Applications Centralized Ventilation Zoned Ventilation

112 ERV Applications Centralized Ventilation Zoned Ventilation Entering air conditions Temperature: 14 F F Relative Humidity: 80% or less

113 ERV Modes Three Modes of Operation: Recommended Mode 1. Energy Recovery Heat Exchange 2. By-pass No Exchange 3. Automatic Automatically switches between Energy Recovery and By-pass modes based on temperature only

114 Energy Recovery Mode Bypass damper EA RA OA SA

115 ERV Technology Total Energy Recovery: Sensible and Latent Sensible heat travels from higher temp. to lower temp. through the partition plate via conduction. Water-vapour-permeable, treated cellulose membrane Latent heat travels from higher humidity to lower humidity driven by vapor pressure difference.

116 Energy Recovery Efficiencies 300 CFM Model 470 CFM Model 600 CFM Model 1200 CFM Model Temperature recovery efficiency 65.5% 69% 67% 67% Enthalpyrecovery efficiency (Heating) 63% 64% 64% 64% Enthalpyrecovery efficiency (Cooling) 50% 51% 50% 50% Efficiencies stated are for Extra High Fan Speed

117 Dedicated OA System (DOAS)

118 DOAS Application DOAS OA IDU IDU EA Restrooms Corridor Room Transfer Air

119 DOAS System Components DOAS with no reheat DOAS Outdoor Unit DOAS with reheat DOAS Outdoor Unit BC Controller

120 DOAS System 1 DOAS with no reheat Monitor OA Temperature in DB DOAS with reheat 1 Monitor OA Temperature in DB 2 Monitor OA Humidity 2 Monitor OA Humidity 3 Monitor Coil LAT Dry Bulb Control setpoint via Dip Switch (50F/55F/60F) or Remote Controller (50F-70F) 3 4 Monitor Cooling Coil LAT Dry Bulb Control setpoint via Dip Switch or Remote Controller (50F/55F/60F or 45%RH at Point 4) Monitor Reheat Coil LAT Dry Bulb Control setpoint via Remote Controller (63F-83F) 1 2 COIL COOLING COIL REHEAT COIL 3 4

121 Packaged DOAS

122 Packaged DOAS Packaged DX without ERV Packaged DX with ERV

123 Split System DOAS Split DX with ERV

124 Example Schematic Integrated with VRF Indoor Units Outside Air Supply Air Return Air

125 Example Schematic Complete DOAS Outside Air Supply Air Return Air OA

126 Summary Methods of incorporating OA into VRF systems ERV Unit DOAS System 100% OA RTU

127 Experience Ventilation Understand key considerations for incorporating ventilation into a VRF System