Utilizing Energy Recovery and Optimizing AirExchange Rates in Laboratory Buildings to Achieve Optimal Energy and Air Quality Results John Swift, Jr., PE, LEED, CEM Principal- Cannon Design Boston, MA Labs21 2011 Annual Conference Providence, RI
Labs 21 is a Registered Provider with The American Institute ofArchitects Continuing Education Systems. Credit earned on completionof this program will be reported to CES Records for AIA members.Certificates of Completion for non-AIA members are available onrequest.This program is registered with the AIA/CES for continuing professionaleducation. As such, it does not include content that may be deemed orconstrued to be an approval or endorsement by the AIA of any materialof construction or any method or manner of handling, using, distributing,or dealing in any material or product. Questions related to specificmaterials, methods, and services will be addressed at the conclusion ofthis presentation.
Learning Objectives:Learning objective 1: Understand current air exchangerecommendations in lab spaces looking at OSHA, ASHRAE andNFPA standards.Learning objective 2: Understand the benefits and challenges ofapplying desiccant energy wheels for manifolded, central air handlingsystems serving laboratory buildings.Learning objective 3: Understand the benefits of dilutionassessments, dynamic air monitoring systems and MERV 16filtration.
OverviewThe presentation will discuss thepositive energy reduction impactof reducing air changes inlaboratory spaces whilemaintaining safe and healthyindoor air quality levels for thebuilding occupants.
Design ProcessDesigning Critical Duty ProjectsRequires a Rigorous Process
Air Exchange Rates in Laboratory Buildings • Health • Safety • Protect Research • Comfort • Efficient Use of Resources
Air Exchange Rates in Laboratory Buildings Health and Safety • Safe Operating Practices • Emergency Equipment • Air Quality • Air Changes
Air Exchange Rates in Laboratory Buildings Protect Research • Air Quality • Redundancy
Air Exchange Rates in Laboratory Buildings Comfort • Optimize Indoor Environmental Quality • Indoor Air Quality • Natural and Artificial Light • Thermal Comfort
Air Exchange Rates in Laboratory Buildings Efficient Use of Resources • High Performance Design • Energy Efficient Building Systems • Ease of Maintenance and Service
Air Exchange Rates in Laboratory Buildings Source Air Changes per hour NFPA 45- 2000 8 ACH occupied, 4 ACH unoccupied NFPA 45-2011 No min/max ASHRAE- 2007 Handbook 6 – 12 ACH* and Lab Design Guide OSHA 1910 4 – 12 ACH NIH Guidelines 6 ACH
Air Exchange Rates in Laboratory Buildings • No codes- just guidelines • No standard industry practice • Higher ACH do not assure optimized Ventilation Effectiveness
Air Exchange Rates in Laboratory Buildings Factors in Determining Optimized Rate • Cooling Loads- External and Internal • Exhaust Make-up Requirements • Ventilation for Optimized Air Quality
Air Exchange Rates in Laboratory Buildings Ventilation for Optimized Air Quality • Model-based design process • Computational Fluid Dynamics (CFD) • Optimize air flow to maximize ventilation effectiveness • Measure and provide dynamic ACH control • Eliminate turbulence at fume hoods and bio- safety cabinets
Energy Wheels 2-3. Outdoor Air is Cooled, Dehumidified then How It Works: Supplied to HVAC System (Cooling) 4. Exhaust Air is Pulled from the Space1. Fresh Outdoor (Cool and Dry)Air (Hot and Humid) isPassed Through the Wheel 5-6. Exhaust Air is Heated and Humidified then Sent Outdoors
Energy Wheels TYPICAL PERFORMANCE BUFFERS SPACE FROM EXTREME OUTDOOR AIR CONDITIONSExhaust Air Return Air Exhaust Air Return Air 90 DEG 75 DEG 18 DEG 72 DEG 105 GR. 60 GR. 11 GR. 32 GR. 95 DEG 80 DEG 0 DEG 54 DEG 120 GR. 75 GR. 4 GR. 25 GR. Outdoor Air Supply Air Outdoor Air Supply Air Cooling Mode Heating Mode
Energy Wheels Function of the Purge Section • Purge dirty air trapped in wheel media as it rotates from the dirty to the clean airstream • Purge angle adjustable and driven by the pressure differential existing between the outdoor air and return air streams • Proper setting shown to limit carry-over to well below .045% in actual field commissioning tests
Energy WheelsCodes: Energy Wheels in LaboratoriesNFPA 45 requires documentation (test data and field experience) that exhaustedcontaminants are not transferred by the total energy recovery wheel. “Devices that could result in recirculation of exhaust air or exhausted contaminants shall not be used”IBC 2006 and 2009 Laboratories are not considered hazardous exhaust systems if contaminants are below 25% of flammability limit and below 1% medial lethal concentration (lab assessment analysis) Duct systems can be manifolded and wheels used if contaminants are not recirculated References 90.1 which recommends total energy (>50% total energy recovery)
ASHRAE Standard 62Purpose: To specify the minimum ventilation rates and indoor air quality that will be acceptable to human occupants and are intended to minimize the potential for adverse health effects.
Energy WheelsCodes: Energy Wheels in LaboratoriesASHRAE:In a recent interpretation of ASHRAE 62.1-2007, has indicated that mandatorysection 188.8.131.52 “does not allow for recirculation of any amount of Class 4 air nordoes it allow the use of heat recovery equipment which will result in recirculation ofClass 4 air via leakage, carryover or transfer from the exhaust side of the system.It is possible to install heat recovery equipment, such as run-around loops, heatpipes or impermeable, plate-type heat exchangers, which will allow heat recoveryfrom the Class 4 exhaust airstream while preventing cross-contaminated flow.”
Energy WheelsCodes: Energy Wheels in LaboratoriesASHRAE Fume hood exhaust air is generally classified as Class 4 air by ASHRAE 62.1- 2007. Since this section is a mandatory requirement of ASHRAE 62.1-2007, non-compliance would mean that the design does not meet the LEED prerequisite for compliance with ASHRAE 62.1-2007 which means the project could NOT be LEED certified. Project design teams will need to indicate how they will address compliance with ASHRAE 62.1-2007 while taking manifold fume hood exhaust air through proposed enthalpy wheels.
Energy WheelsCodes: Energy Wheels in LaboratoriesASHRAEAt a minimum the mechanical code identifies certain hazards that cannot beconnected to a manifold exhaust system and at minimum these should beseparated from the enthalpy wheel exhaust system. In addition, technical datareports “virtually no cross-contamination (independently certified to be less than0.04 percent)” should be provided for EHS records. This should be requested fromall potential vendors or specification should be limited to vendors meeting theagreed upon criteria and provided to EHS for review.
Design ProcessCritical Duty Project Design Process •Labs are not all the same – evaluate the purpose of the facility and establish an initial design approach •Complete a full Risk Assessment Analysis involving the Health and Safety officers •Provide independent carry-over test data for use by owner and code authorities •Complete accurate full benefit and life cycle cost analysis, highlighting both energy savings, chiller – boiler impact and carbon footprint •Provide a critical duty wheel designed specifically for laboratory environments – limit contaminant carry-over, corrosion resistance, antimicrobial surface, anti-stick, etc.
Design ProcessCritical Duty Project Design Process (continued) •Provide experienced startup to review installation, airflows, pressures, purge settings, etc. •Coordinate SF6 testing and commissioning report after final air balancing but prior to occupancy •Complete real time contaminant testing (TVOC) and commissioning report after occupancy and use of facility to document wheel performance •Monitor system performance, pressures, flows and purge performance (HSM) and alarm if problem with system •Trend energy savings over time and highlight benefits provided with owner and designer
Flexibility Fume Hood Flexibility Fume Hood Exhaust Capacity Assessment Location Fume Hood Type LF of hood Hood Max Fume exhaust length Hoods per capacity per (ft) floor floor Bldg X Standard (100 CFM/LF) 320 8 40 Bldg Y Standard (100 CFM/LF) 450 8 56 Bldg X Low Flow (60 CFM/LF) 540 8 68 Bldg Y Low Flow (60 CFM/LF) 740 8 93
Dilution AssessmentFindings:Under this worst case spill scenario, none of the chemicals listedwould be introduced to the space at more than 6% of the thresholdlimit value allowable (exposure thought to be safe to occupant - 8hours per day, 5 days per week).As it relates to recent interpretations by ASHRAE, it is important topoint out that ASHRAE allows more than 10 times this amount, or100% of the TLV to be re-entrained into the fresh air intake from theexhaust fans during a spill event (Appendix F and AIHA/ANSIStandard Z9.5).
Dilution AssessmentFindings:None of the flags shown for the 5 chemicals listed in the summaryanalysis represent a health risk.All are shown for potential odor detection under the spill scenario.The chemicals used for this analysis came from a listing of chemicalsnot detected by a monitoring system, and dont appear to bechemicals routinely used.Of those listed as commonly used chemicals, none were flagged. Inaddition, the materials with extremely low odor detection limitsshown - i.e. mercapatans - are used in very small quantities and willnot typically be available for spill in a 500 ml quantity.
Dilution AssessmentFindings:Based on the analysis there is essentially no health risk shown.During a worst case spill scenario, there will likely be a slight odordetected in the supply air for a very short period.It is also likely that there would be odor detected under this spillscenario due to the re-entrainment - even if the wheel were not to beused.
Dynamic Air MonitoringHealth and Safety Monitor Capabilities •Limit Carry-over in VAV, variable pressure environment optimizing health and safety •Real time performance monitoring and trending •Real time energy savings and accumulation •Real time airflow measurement •Alarm if purge pressure is lost •Greatly reduce fan horsepower use •Automatically determines field purge setting •Enhances Field commissioning •Enhances Cross-contamination testing •Remote monitoring
Filtration Effect on Particle Count room particles/cu ft = supply air particles/cu ft + (100,000 particles/sec / airflow in cu ft/sec) 3-10 micron 1.0-3 micron .3 - 1.0 micron MERV 14 (nominal 90-95 filter): >90% >90% 75%-85% HEPA @ 99.97%: -- -- 99.97%
Case StudyPotable water service ismuch more difficult tosupply at consistent,cost effective levels.
Energy = WaterEnergy Use per 1000 gallons of water delivered 12 10 Well Water kWh per 1000 Gallons 8 Surface Water 6 Brackish Water 4 2 Sea Water 0
Case Study4 ACH & 8 ACH Layout EXHAUST HOOD SUPPLY AIR - CHILLED BEAM (TYP.) EXHAUST REGISTER (TYP.) Supply Air provided by Chilled Beam System
Case Study12 ACH Layout EXHAUST HOOD SUPPLY AIR DIFFUSER (TYP.) EXHAUST REGISTER (TYP.) Supply Air provided by all air system (In order to achieve high air change rate, chilled beams are not used.)
Case StudyFour Models Compared: • 12 Air Changes per Hour • 8 Air Changes per Hour • 4 Air Changes per Hour (unoccupied) • 8 Air Changes per Hour, chilled beams rotated 90 degrees (perpendicular)
Case StudySummaryA state-of-the-art system that is safe, healthyand effective.Optimal thermal comfort and air quality.Controlled space pressurization based onfume hood usage and pollutant control.30+% energy savings.Flexibility for future iterations of spaceplanning and equipment concentrations.Optimized construction costs by reducing airhandling unit sizes, duct sizes, shaft sizes andpenthouse sizes throughout the building.
This concludes The American Institute of Architects Continuing Education Systems ProgramUtilizing Energy Recovery and Optimizing Air Exchange Rates in Laboratory Buildings to Achieve Optimal Energy and Air Quality Results John Swift, Jr., PE, LEED, CEM firstname.lastname@example.org Labs21 2011 Annual Conference Providence, RI