The Case for Energy Recovery in addressing Commercial Building Indoor Air Quality

Transcription

1 The Case for Energy Recovery in addressing Commercial Building Indoor Air Quality Fundamentals Common Misconceptions Performance Certification Applications

2 Learning Objectives Improve and broaden dialog concerning the role and importance of Energy Recovery Ventilation Define Energy Recovery Ventilation Review fundamental terms involved in description and operation of Energy Recovery Ventilation Review the fundamentals to apply effective and reliable Energy Recovery Ventilation Compare and Contrast common Energy Recovery Ventilation Media Applications

3 Why Energy Recovery? Address issues related to Indoor Air Quality Improve heath and productivity of occupants Elevated CO2 levels Moisture control Off gassing of Volatile Organic Chemicals Comply with energy codes Save energy / reduce energy consumption Building Functionality and Economics Reduce HVAC system costs

4 Indoor Air Quality Basis of Discussion Rate of ventilation air required, most often by mechanically induced (forced) outside (ventilation) air ASHRAE 62.1 for CII Buildings ASHRAE 62.2 for low-rise residential buildings LEED Increases ventilation rates over ASHRAE standard

5 What is Ventilation Air? The Air used to provide acceptable indoor air quality per prescribed ventilation rates outlined in ASHRAE Standard 62

6 Why Ventilate? PPM CO2 (THOUSANDS) PRESCHOOL FACILITY- CO2 levels obseved Before Ventilation Strategy M N M HOURS ASHRAE-1000 PPM CO 2 LIMIT OSHA 800 PPM CO 2 LIMIT OUTDOOR PPM CO 2

7 Why Ventilate? PRESCHOOL FACILITY- After ERV Installation PPM CO2 (THOUSANDS) TIME CLOCK TURNED OFF - ERV TIME CLOCK TURNED OFF - ERV ASHRAE-1000 PPM CO 2 LIMIT OSHA 800 PPM CO 2 LIMIT OUTDOOR PPM CO M N M HOURS

8 Fundamental Terms Differences in performance and cost is significant ERV aka: Energy Recovery Ventilator Heat Exchanger Sensible and Latent Recovery Energy Wheel Static Plate Core Enthalpy Enthalpic Plate HRV aka: Heat Recovery Ventilator Sensible Recovery Heat Exchanger

9 Energy Recovery Ventilation Opportunities Every commercial building needs ventilation Cost Benefits Downsize HVAC equipment Reduced ductwork complication Favorable payback Quantifiable energy savings Rebates (where applicable) Performance Benefits Decouple ventilation from space conditioning Demand control ventilation Humidity control Capture exhaust energy

10 Fundamentals of Energy Recovery Ventilation Summer: Pre-cooling /drying of hot & humid incoming air Winter: Pre-heating/humidifying of cold & dry incoming air Transfers upwards of 55-75% of the energy in the exhaust air stream to fresh air stream Wheels or Plates are most common

11 Elements of Properly Performance Applied ERV Media independently certified - AHRI Ratio between highest energy recovered vs. lowest device operation energy consumed in the recovery process (vs. cost / footprint) Recovery Efficiency Ratio (Guideline V)

12 Value Elements of Properly Applied ERV Easy to drop into HVAC systems Minimal complexity Minimal maintenance Minimal commissioning effort

13 Elements of Properly Reliability Applied ERV Performance and operation is consistent and reliable as HVAC equipment applied on project Confident in downsizing the HVAC equipment

14 The Potential for Energy Efficiency - State of Iowa S. W. Hadley, OAK RIDGE NATIONAL LABORATORY

15 One-Year Example of Adding a Commercial 1850 cfm ERV 3.8 tons cooling equipment downsize (Conventional AC system avoided installed cost $5,700) Annual energy savings $2, Annual demand savings $ Total energy savings $2, Simple payback: 0.5 years Software selection tools

16 General ERV Selection ERV Selection Core/Wheel CFM Per air stream (leaving EA/ entering OA) Static Pressure Drop Summer/winter weather data (ASHRAE standard) Electrical voltage, phase and horsepower required to operate ERV ERV Selection Wheel Specific Purge air - Project schedules will show an imbalance of up to 50% between EA/OA Common for Wheel ERV to clean media surface Cross leakage/contamination consideration Condensate/defrost strategy consideration

17 Common Energy Recovery Media / Packages HRV: Heat Recovery Ventilator Core material: Aluminum or Plastic Sensible only recovery 20-30% total effectiveness Manufacturers: Fantech, Lifebreath, Venmar ERV: Enthalpy Wheel Wheel material: Aluminum Synthetic Fiber Polymer Sensible and Latent recovery 70-80% total effectiveness Manufacturers: Greenheck, SEMCO ERV: Enthalpy Core Core material: Hydroscopic Resin Sensible and Latent recovery 60-65% total effectiveness Manufacturer: RenewAire, S&P, Mitsubishi

18 HRV: Sensible Core Numerous Media Manufacturers Packaged HRV Equipment Common Transfer material Aluminum Polypropylene Performance The return and supply airstreams pass within air passages perpendicular to each though the plate material Liquid water is a common byproduct Critical Media Components End pans and frame Defrost Drain pan Associated plumbing

19 ERV: Enthalpy Wheel Transfer Performance Media rotates between the airstreams transferring the energy from exhaust airstream to the supply airstream Critical Media Components Cassette Bearings Wheel Segments Wheel Drive Belt & tensioner Pulley Wheel Motor Frost control

20 ERV: Enthalpy Wheel Packaged Options 300 to 20,000 cfm Indoor and Rooftop Stand Alone Energy Recovery Ventilator Energy Recovery w/heating Energy Recovery w/heating and Cooling Energy Recovery w/evaporative Cooling Dedicated Outdoor Air Systems

21 ERV: Enthalpy Core Transfer Performance Air passages perpendicular to each airstream though the plate material Sensible via conduction Latent via diffusion Straight Air Passages Laminar Flow Typical Velocity ft./ min. Static pressure loss inch

22 ERV: Enthalpy Core Packaged Options 70 to Unlimited cfm Indoor and Rooftop Stand Alone Energy Recovery Dedicated Outdoor Air Systems Energy Recovery Bypass Tight Humidity Control

23 Attributes of a Superior Enthalpy Core Performance AHRI Certification UL 1812 flammability rated Design and Construction Symmetrical/well proportioned Fully adhered construction Unobstructed airflow Similar transfer materials Critical Media Components End pans and frame

24 Addressing Common Misconceptions Media performance, correct equipment sizing and application, warranty and maintenance influence actual performance Static plate core: Is made of a high engineered polypropylene Core will not burn Core will transfer sensible and latent energy Energy Star does not have a U.S. standard for HRV and ERV AHRI-1060 certified versus performance in accordance with AHRI standards or some other standard

25 ERV Design Ideas: Downsize Heating and Cooling Equipment Retrofit: Preconditioning OA with ERV can allow conventional Heating and Cooling systems to remain unchanged Increases in outdoor air load w/o increasing the size of the equipment

26 ERV Design Ideas: Downsize Heating and Cooling Equipment New: Preconditioning OA with ERV allows for downsized HVAC equipment New ERV technology is more reliable making downsizing more viable Oversized H&C equipment is expensive and inefficient Increase H&C system efficiency Reduce H&C equipment cost Payback on ERV cost <5 yrs Annual energy savings

27 ERV Design Ideas: Peak Load Reduction Oversized AC is inefficient, ineffective and expensive Can lead to short cycling ERV can be a strategy to manage peak load Largest contributor to peak load is ventilation Tie ERV in to BMS or apply zone approach

28 ERV Design Ideas: Recirculation of Toilet Exhaust ASHRAE Standard , Section Class 2 air shall not be transferred in to Class 1 spaces Exception When using an energy recovery device, recirculation from leakage (EATR), carryover or transfer (Purge air) from the exhaust side of the energy recovery device is permitted Not to exceed 10% Another Option: An AHRI 1060 rated static plate core with no recirculation through the core for defrost 0% EATR 0% purge air

29 ERV Design Ideas: Must Use Ventilation Wheel to Control Humidity When outdoor air conditions are dryer than 70wb, RenewAire total effectiveness is comparable to most Wheels At most locations around the US there are very few ventilation hours where the wet bulb temperature exceeds 70 degrees National Weather Service 40-year weather data bin hours / 8760 hours p/yr / ASHRAE Design Test Conditions 95/78 City 75 F WB 73 F WB 70 F WB Detroit New York Washington DC Columbus Pittsburgh Columbus Boston

30 ARI-1060 Winter Sensible 90% 80% 70% 60% Effectiveness 50% 40% 30% Wheel Median 20% Heat Pipe Plate 10% RenewAire 0% Unit Number

31 ARI-1060 Summer Total Effectiveness RenewAire 78 WB Wheel Heat Pipe Plate RenewAire 75 WB RenewAire 73 WB RenewAire 70 WB Median Unit Number

32 ERV Design Ideas: Zoning ERV Supports space sensitive, architectural and historically sensitive building requirements Mechanical room not required Smaller equipment and smaller duct diameter Duct space only required above ceiling Eliminate large rooftop footprint Source point controls are low cost and simple Operation is based on ASHRAE ventilation rates Simple, lower cost, less complex maintenance Maintenance affects the zone, not entire building

33 ERV Design Ideas: Replace non process exhaust fans with ERV CFM/watt consumed per airstream (OA/EA) Energy Star standard for bathroom and utility room fans is 2.8 watt p/cfm (EA only) ERV cfm/watt can be competitive depending on the manufacturer Compare and contrast Fan exhausting 100% of heating and cooling ERV recapturing up to 75% of heating and cooling ERV Advantages Payback of ERV: <5 yrs Advantages of ERV remain for 10+ years IAQ advantages

34 ERV Design Ideas: Simple ERV CO2 control with RTU Economizer Separate static-plate ERV from RTU RTU economizer runs standard based on enthalpy control ERV runs based on CO2 control from the space Simple, self-correcting system control!

35 ERV Design Ideas: Simple ERV CO2 control with RTU Economizer ERV turns off RTU opens economizer panel for free cooling CO2 levels drop quickly in the space Economizer conditions: 55F DB OA, cooling mode

36 ERV Design Ideas: Using ERV with a VRF system VRF fan coil units have strict EAT ranges Typical Cooling EAT Range 59 F WB 75 F WB Typical Heating EAT Range 59 F DB 81 F DB Bringing in too much untreated outside air may cause the mixed EAT to be outside the acceptable range Using a zoned or central ERV can bring EAT to an acceptable temperature without needing a full DOAS system!

37 ERV Design Ideas: Using ERV with a VRF system Without ERV: Unacceptable EAT Typical Heating EAT Range 59 F DB 81 F DB OA 300CFM 5F DB RA 706 CFM 70F DB Mixed Air 1006 CFM 50.8F DB With ERV: Acceptable EAT OA 300CFM 51.2F DB RA 706 CFM 70F DB Mixed Air 1006 CFM 64.4F DB

38 Media Performance Comparisons HRV, ERV Enthalpy Wheel, ERV Enthalpy Core

39 AHRI Exchange Media Certification Required by ASHRAE 90.1 Addendum E. and where rebates are available to be submitted with application Pressure drop in 100% cfm 100 & 75% rated cfm for heating and cooling conditions Sensible Latent Total Exhaust Air Transfer Ratio, Outdoor Air Correction Factor, and Purge Angle or Setting (if applicable) at 0.00 in H 2 O [0.0 Pa] and two or more pressure differentials Tested at Balanced Airflow Performance at Standard Conditions Winter - OA= 35 Fdb, 33 Fwb RA=70 Fdb, 58 Fwb Summer - OA= 95 Fdb, 78 Fwb RA= 75 Fdb, 63 Fwb

40 comparison of energy-recovery technologies Typical Performance ERV wheel ERV Enthalpy Plate Exchanger HRV wheel HRV plate heat exchanger coil loop heat pipe airside pressure drop (per side), in. H 2 O

41 comparison of energy-recovery technologies Typical Performance ERV wheel ERV Enthalpy Plate Exchanger HRV wheel HRV plate heat exchanger latent sensible latent sensible sensible sensible coil loop heat pipe sensible sensible effectiveness, %

42 comparison of energy-recovery technologies Typical Performance ERV Wheel ERV Enthalpy Plate Exchanger HRV Sensible Plate Exchanger Heat Pipe Outdoor Air Correction Factor

43 comparison of energy-recovery technologies Typical Performance ERV Wheel ERV Enthalpy Plate Exchanger HRV Sensible Plate Exchanger Heat Pipe Exhaust Air Transfer Ratio

44 Comparison of energy-recovery technologies Typical Frosting Conditions ERV wheel Chicago, IL 6 AM 6 PM, weekdays (all hours, all days) 12 hrs (79 hrs) 7 hrs (25 hrs) 557 hrs (1788 hrs) ERV core HRV wheel HRV plate heat exchanger coil loop heat pipe -50 F -30 F -10 F 10 F 30 F 50 F outdoor temperatures at which frosting typically occurs, F

45 Exchange Media Flammability Rating All components pass UL-723 test for burning characteristics of building materials Less than 25/50 flame spread/smoke developed rating The basic standard: UL 1812 Ducted Heat Recovery Ventilators. National Fire Protection Association (NFPA) 90A and 90B 90A: Standard for air conditioning and ventilating systems 90B: Standard for warm air heating and air conditioning systems

46 ERV Maintenance Comparison Wheel Routine Inspection / Replacement Components Wheel cassette Drive belt Belt motor Air seals Defrost Cleaning Procedure Short soak Overnight soak Media Remove and Reinstallation Segments Entire wheel Replace Filters Core Routine Inspection Core face Filters Cleaning Procedure Vacuum core face of any accumulated particulate Media Removal and Reinstallation Not required Replace filters

47 ERV Media Warranty Comparison Enthalpy Wheel: Five year warranty against manufactures defects and workmanship * Source: Airexchange Enthalpy Core Ten year performance warranty against performance degradation * Source: RenewAire

48 ERV Application Examples And Common Attributes Non process exhaust AHRI 1060 Certified Media Recovery effectiveness 0% Cross Contamination Zero Purge Air No active defrost deployed 10-year performance warranty

49 Zone or Central ERV Approach Zone Ventilation Codify all Building Exhaust Points into a Ventilation List Satisfy the intake air of Suitable Exhausts with ERV Satisfy the Replacement of Non-Recoverable Exhausts with Makeup Air Equipment Satisfy any Remaining Balance of intake air with Fans, Makeup Air Equipment or the equivalent Central Ventilation Feed building ventilation in to one centralized system Distribute out to individual VAV boxes or fan coils

50 Applying Energy Recovery Zoning HVAC Systems Integrated ERV/Fan Coil in School Classroom

51 Zone ERV with DX Air Handler

52

53 Zone Energy Recovery 1 indoor Horizontal ERV Two restroom exhaust points Exchanging 450 CFM fresh air into building

54 Applying Energy Recovery Central HVAC Systems

55 Roof Top Connect in to Air Handling Unit 14 rooftop ERVs Exchanging 21,000 CFM fresh air into building

56 100% OA Rooftop Application

57 Fractional Source Point- Toilet Exhaust

58 Fractional Rooftop Ventilation 17 rooftop ERVs Exchanging 60,000 CFM fresh air into building

59 ERV Media Installed in Air Handling System ERV Cabinets Manifold Stack -(3)- CA4X Units Exhaust Air Blower Service Area Fresh Air Blower Packaged Air Conditioning Unit

60 ERV Media Integrated in to HVAC System 1 indoor ERV cabinet Integrated in to HVAC system Exchanging 3,000 CFM fresh air into building

61 ERV Core Custom Application: Hospital Installation 4 indoor ERV cabinets Integrated in to custom enclosure and third party fans and blowers Exchanging 8,000 CFM fresh air into building

62 ERV Core: Custom Modular Air Handling Unit Exchanging 6,000 CFM fresh air into building

63 Discussion Resources renewaire.com ERV Calc Define ventilation needs Equipment sizing Develop project schedule Payback analysis ASHRAE Weather data RenewAire ERV Product data Submittals Guide specs Drawings (Revit, PDF, 3D, DWG) About RenewAire Downloads Commercial Residential Other Sources ahridirectory.org ashrae.org/ epa.gov/ hvi.org/ ul.com/global usgbc.org/ energystar.gov/ nfpa.org/index.asp

64 Thank you for your time