ASHRAE Standard 62.1-2010 DCV in Multiple-Zone Systems: Ventilation Reset ControlAgendaPresenter: Dennis Stanke,          ...
Standard 62.1-2010 DCV in Multiple-Zone Systems                           Ventilation R                           V til ti...
“Trane” is a Registered Provider with The American                                                         Institute of Ar...
Copyrighted Materials                             This presentation is protected by U.S. and                             i...
Abstract and Venues                                • Abstract                                     – ASHRAE Standard 62.1 “...
6.0 Procedures                              • 6.1 General. Find OA intake using VRP or IAQP, or                           ...
6.2.2 Zone Calculations                                   design                              1. Calculate breathing-zone ...
6.2.3 Single-Zone Systems                                                  One recirculating air handler                  ...
6.2.3 Single-Zone Systems                                       operation                             • That’s it for desi...
single-zone system                                                                operation                               ...
zone DCV for single-zone systems                                                  operation                               ...
6.2 Ventilation Rate Procedure                             •     6.2.1 Outdoor air treatment                             •...
6.2.4 100% OA Systems                                             design                             For 100% OA systems  ...
6.2 Ventilation Rate Procedure                             •     6.2.1 Outdoor air treatment                             •...
design                               6.2.5 Multiple-Zone Systems                              For multiple-zone recirculat...
6.2.5 Multiple-Zone Systems                                        design                             5. Find uncorrected ...
6.2.5 Multiple-Zone Systems                                    design                             7. Find outdoor air inta...
Multiple-Zone Systems                                                operation                             • That’s it for...
Ventilation Reset Control                                                            operation                            ...
VRC w/o Zone-Level DCV                                                               operation                            ...
VRC w/o Zone-Level DCV                                                 operation                                          ...
VRC with Zone-Level DCV                                        operation                             • VRC resets system-l...
VRC w/ Zone-Level DCV                                                                      design                         ...
VRC w/ Zone-Level DCV                                                                   operation                         ...
VRC w/ Zone-Level DCV                                                        operation                                    ...
Quick Summary                             Dynamic reset depends on ventilation system type                                ...
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Standard 62.1: A VAV Dynamic Reset Approach

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Standard 62.1: A VAV Dynamic Reset Approach

ASHRAE Standard 62.1 “Ventilation for Acceptable Indoor Air Quality,” provides minimum design requirements for proper ventilation in commercial, institutional and hi-rise residential buildings. It allows optional “dynamic reset” controls to help match current system ventilation capacity to current load, but leaves design details for such controls to the designer. ASHRAE Standard 90.1 and ASHRAE Standard 189.1, on the other hand, both require demand controlled ventilation (DCV) for some zones, but they too, leave out design details. While relatively simple for single-zone systems, DCV can be much more complex for multiple-zone systems.

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Standard 62.1: A VAV Dynamic Reset Approach

  1. 1. ASHRAE Standard 62.1-2010 DCV in Multiple-Zone Systems: Ventilation Reset ControlAgendaPresenter: Dennis Stanke, Trane Staff Applications Engineer, FASHRAEAbstract:ASHRAE Standard 62.1 “Ventilation for Acceptable Indoor Air Quality,” provides minimum outdoor airflowrequirements at design conditions. However, ASHRAE Standard 90.1 requires some systems to be operated sothat current ventilation capacity modulates to match current ventilation load (i.e., demand). Standard 62.1allows optional “dynamic reset” controls to help match current capacity to load, but design details for suchcontrols are left to the designer. One design approached, described in this presentation, combines ventilationreset control at the system level with various zone-level “demand controlled ventilation” strategies.Learning objectivesAfter viewing this program Participants will be able to:1. Apply ventilation system design calculations for three ventilation systems: single-zone, 100% outdoor air, and multiple-zone systems (MZS)2. Summarize how demand controlled ventilation (DCV) can be incorporated in all three ventilation systems3. Apply dynamic reset to VAV systems using ventilation reset control, which responds to changes in system ventilation efficiency4. Apply dynamic reset to VAV systems by combining zone-level DCV with system-level ventilation reset control, to respond to both changes in zone population and changes in system ventilation efficiencyAgenda6.2.2 Zone calculations (zone OA)6.2.3 Single-zone systems (OA intake)6.2.4 100% OA systems (OA intake)6.2.5 Multiple-zone recirc systems (OA intake)6.2.7 Dynamic resetWrap-up/discussion
  2. 2. Standard 62.1-2010 DCV in Multiple-Zone Systems Ventilation R V til ti Reset Control tC t l Dennis Stanke September 2012 Ingersoll Rand Standard 62.1-2010 DCV in Multiple-Zone Systems-Ventilation Reset Control: Course ID: 0090008756 Approved for 1.0 GBCI hours for LEED professionals 1.5 2 © 2009 TraneMultiple-Zone Ventilation 1© 2012 Trane a business of Ingersoll Rand. All rights reserved
  3. 3. “Trane” is a Registered Provider with The American Institute of Architects Continuing Education Systems. Credit earned on completion of this program will be reported to CES Records for AIA members. Certificates of C f Completion for non-AIA members are available on l ti f AIA b il bl request. This program is registered with the 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 p product. 3 © 2009 Trane Visit the Registered Continuing Education Programs (RCEP) Website to check state requirements for Professional Development Hours (PDH) for professional engineers. www.RCEP.net 4 © 2009 TraneMultiple-Zone Ventilation 2© 2012 Trane a business of Ingersoll Rand. All rights reserved
  4. 4. Copyrighted Materials This presentation is protected by U.S. and international copyright laws. Reproduction, distribution, display, and use of the presentation without written permission of Trane is prohibited. © 2012 Trane a business of Ingersoll-Rand All rights reserved. Trane, Ingersoll-Rand. reserved 5 © 2009 Trane Learning Objectives After today’s program you will be able to: • Apply ventilation system design calculations for three ventilation systems: single-zone, 100% outdoor air, and y g , , multiple-zone systems (MZS) • Summarize how demand controlled ventilation (DCV) can be incorporated in all three ventilation systems • Apply dynamic reset to VAV systems using ventilation reset control, which responds to changes in system ventilation efficiency • Apply dynamic reset to VAV systems by combining zone-zone level DCV with system-level ventilation reset control, to respond to both changes in zone population and changes in system ventilation efficiency 6 © 2009 TraneMultiple-Zone Ventilation 3© 2012 Trane a business of Ingersoll Rand. All rights reserved
  5. 5. Abstract and Venues • Abstract – ASHRAE Standard 62.1 “Ventilation for Acceptable Indoor Air Quality,” p provides minimum outdoor airflow requirements at design conditions. q g However, ASHRAE Standard 90.1 requires some systems to be operated so that current ventilation capacity modulates to match current ventilation load (i.e., demand). Standard 62.1 allows optional “dynamic reset” controls to help match current capacity to load, but design details for such controls are left to the designer. One design approached, described in this presentation, combines ventilation reset control at the system level with various zone-level “demand controlled ventilation” strategies. • Venues (1.5 hours) – 11SEP2012 Richland, WA – 15SEP2012 Portland, OR 7 © 2009 Trane Standard 62.1 Ventilation Why It’s Important … • For comfort – reduce odors and irritation • For health – reduce building related illness and sick building syndrome • For productivity – reduce absenteeism and increase worker satisfaction • For compliance … – Section 6.2 (VRP) req’d by IMC and UMC ( ) q y – Section 4 thru 8 req’d by Std 189.1 (one IgCC path) – Section 4 thru 7 req’d as LEED prerequisite – All of Std 62.1 required by ENERGY STAR® and bEQ 8 © 2009 TraneMultiple-Zone Ventilation 4© 2012 Trane a business of Ingersoll Rand. All rights reserved
  6. 6. 6.0 Procedures • 6.1 General. Find OA intake using VRP or IAQP, or find opening parameters using NVP sing • 6.2 Ventilation Rate Procedure – Prescribes minimum rates for “typical” zones and calculations for minimum outdoor air intake rate • 6.3 IAQ Procedure – Specifies performance based on contaminant levels and subjective evaluation • 6.4 Natural Ventilation Procedure – Prescribes opening areas and requires both MV and NV 9 © 2009 Trane 6.2 Ventilation Rate Procedure • 6.2.1 Outdoor air treatment • 6.2.2 Zone calculations (zone OA) • 6.2.3 Single-zone systems (OA intake) • 6.2.4 100% OA systems (OA intake) • 6.2.5 Multiple-zone recirc systems (OA intake) • 6.2.6 Design for varying operating conditions • 6.2.7 6 2 7 Dynamic reset 10 © 2009 TraneMultiple-Zone Ventilation 5© 2012 Trane a business of Ingersoll Rand. All rights reserved
  7. 7. 6.2.2 Zone Calculations design 1. Calculate breathing-zone outdoor airflow, using Table 6-1 6 1 rates (Rp cfm/per Ra cfm/ft2) cfm/per, Vbz = Rp × Pz + Ra × Az (Eq 6-1) where Pz = peak zone population 2. Find zone air distribution effectiveness Look up Ez (typically 1.0) (Tab 6-2) 3. 3 Calculate zone outdoor airflow Voz = Vbz/Ez (Eq 6-2) 11 © 2009 Trane 6.2 Ventilation Rate Procedure • 6.2.1 Outdoor air treatment • 6.2.2 Zone calculations (zone OA) • 6.2.3 Single-zone systems (OA intake) • 6.2.4 100% OA systems (OA intake) • 6.2.5 Multiple-zone recirc systems (OA intake) • 6.2.6 Design for varying operating conditions • 6.2.7 6 2 7 Dynamic reset 12 © 2009 TraneMultiple-Zone Ventilation 6© 2012 Trane a business of Ingersoll Rand. All rights reserved
  8. 8. 6.2.3 Single-Zone Systems One recirculating air handler serves one zone EA RA OA SA (Vot) (Vpz) zone 13 © 2009 Trane 6.2.3 Single-Zone Systems design For single-zone systems – Complete first three steps for zone – Then, find outdoor air intake flow Vot = Voz (Eq 6-3) Note: – No design credit for occupant diversity, i.e., must g p y assume peak zone population – Zone ventilation efficiency (Evz = Voz-actual/Voz- design) is probably less than 1.0 during operation 14 © 2009 TraneMultiple-Zone Ventilation 7© 2012 Trane a business of Ingersoll Rand. All rights reserved
  9. 9. 6.2.3 Single-Zone Systems operation • That’s it for design, but does 62.1-2010 allow intake i fl i t k airflow to vary during operation? t d i ti ? • Of course … – Section 6.2.7 allows optional dynamic reset of zone outdoor airflow using various approaches …  Population estimate based on scheduling, occupancy sensing, people counting  Bio effluent control using CO2-based reset Bio-effluent based – Read Journal articles for “how-to” ideas 15 © 2009 Trane operation Dynamic Reset Approaches • Section 6.2.7 allows dynamic reset of OA intake based on operating conditions, including: – Variations in population – zone-level demand controlled ventilation (DCV) – Variations in system ventilation efficiency – system- level controls required • Different systems use different approaches – For single-zone systems, use simple zone-level DCV – For 100% OA systems, use zone-level DCV, but only y , , y in some VAV systems – For multiple-zone systems, use system-level controls, which can be combined with zone-level DCV • Some examples … 16 © 2009 TraneMultiple-Zone Ventilation 8© 2012 Trane a business of Ingersoll Rand. All rights reserved
  10. 10. single-zone system operation CO2-based Zone-DCV Now CO2 varies, 4800 so DCV isn’t as easy 1200 CO2 varies 62.1 2007 62.1-2007 (Std 62.1-2007) breathing zone OA, Vbz z differential CO2, ppm 4000 1000 Vbz = 3900 cfm 3200 800 CO2 = 700 ppm 2400 (Std 62-2001) 600 Vbz = 2190 cfm 1600 400 b 800 lecture classroom 200 Az = 4000 ft2 design Pz = 260 p 0 0 0 40 80 120 160 200 240 zone population, Pz © 2005 American Standard Inc. 17 © 2009 Trane one way to implement zone-DCV … operation 62.1 User’s Manual • Find breathing zone OA (Vbz) range Vbz Vb = (R  P + R  A ) (Rp Pz Ra Az) Vbz-des = (7.5  260 + 0.06  4000)/1.0 = 2190 cfm Vbz-min = (7.5  0 + 0.06  4000)/1.0 = 240 cfm • Find target indoor CO2 (Crz) range Crz – Co = N/(Vbz/Pz) Crz-des – Co = 0.0105/(2190 cfm/260 p)  1250 ppm Crz-min – Co = 0.000350 – 0.000350  0 ppm • The Controller: Match Vbz signal range to Crz range • Adjust OA damper to deliver Vot = Vbz-des/Ez at max signal, = Vbz-min/Ez at min signal 18 © 2009 TraneMultiple-Zone Ventilation 9© 2012 Trane a business of Ingersoll Rand. All rights reserved
  11. 11. zone DCV for single-zone systems operation 62.1 User’s Manual The Controller 2190 Vbz (cfm) 240 0 1250 Crz - Co (CO2, ppm) 19 © 2009 Trane zone DCV for single-zone systems operation 62.1 User’s Manual Controller adjusts Vbz, hing zone OA, Vbz (=Ez*Vot) 4800 based on sensed CO2 1200 differential CO2, ppm 4000 1000 CO2 3200 800 2400 600 1600 Vbz 400 breath 800 lecture classroom 200 Az = 4000 ft2 design Pz = 260 p 0 0 0 40 80 120 160 220 240 zone population, Pz © 2005 American Standard Inc. 20 © 2009 TraneMultiple-Zone Ventilation 10© 2012 Trane a business of Ingersoll Rand. All rights reserved
  12. 12. 6.2 Ventilation Rate Procedure • 6.2.1 Outdoor air treatment • 6.2.2 Zone calculations (zone OA) • 6.2.3 Single-zone systems (OA intake) • 6.2.4 100% OA systems (OA intake) • 6.2.5 Multiple-zone recirc systems (OA intake) • 6.2.6 Design for varying operating conditions • 6.2.7 6 2 7 Dynamic reset 21 © 2009 Trane 6.2.4 100% OA Systems design One non-recirculating air handler serves many zones EA Voz OA zone (Vot) SA CA RA Voz zone SA RA 22 © 2009 TraneMultiple-Zone Ventilation 11© 2012 Trane a business of Ingersoll Rand. All rights reserved
  13. 13. 6.2.4 100% OA Systems design For 100% OA systems – Complete first three steps for each zone – Then, find outdoor air intake flow Vot = Voz (Eq 6-4) Note: – No design credit for occupant diversity, i.e., must g p y assume peak zone population in each zone – Zone ventilation efficiency (Evz = ΣVoz-actual/ΣVoz- design) is probably less than 1.0 during operation 23 © 2009 Trane 6.2.4 100% OA Systems operation • That’s it for design but does 62.1-2007 allow intake i fl i t k airflow to vary during operation? t d i ti ? • Well, that depends … – Section 6.2.7 allows optional dynamic reset, but …  For constant volume OA systems there’s no way to reset outdoor airflow  For VAV OA systems, intake airflow can be reduced if – All zones i l d pressure-independent d include i d d t dampers – DCV zones include DCV sensors and controls – The 100% OA unit includes VAV controls 24 © 2009 TraneMultiple-Zone Ventilation 12© 2012 Trane a business of Ingersoll Rand. All rights reserved
  14. 14. 6.2 Ventilation Rate Procedure • 6.2.1 Outdoor air treatment • 6.2.2 Zone calculations (zone OA) • 6.2.3 Single-zone systems (OA intake) • 6.2.4 100% OA systems (OA intake) • 6.2.5 Multiple-zone recirc systems (OA intake) • 6.2.6 Design for varying operating conditions • 6.2.7 6 2 7 Dynamic reset 25 © 2009 Trane 6.2.5 Multiple-Zone Systems One recirculating air handler serves many zones RA EA Vpz space OA (Vot) SA (Vps) Single-path system (dual- space path is more complex) 26 © 2009 TraneMultiple-Zone Ventilation 13© 2012 Trane a business of Ingersoll Rand. All rights reserved
  15. 15. design 6.2.5 Multiple-Zone Systems For multiple-zone recirculating systems, complete first three steps for each zone then solve MZS equations: zone, 4. Find primary outdoor air fraction, Zp Zp = Voz/Vpz-min (6-5) 5. Find uncorrected outdoor airflow, Vou Vou = D*(Rp×Pz) + (Ra×Az) (6-6) 6. Find 6 Fi d system ventilation efficiency, E t til ti ffi i Ev Calculate Ev per equations (App A) 7. Find outdoor air intake flow, Vot: Vot = Vou/Ev (6-8) 27 © 2009 Trane 6.2.5 Multiple-Zone Systems design 4. Find primary outdoor air fraction for each zone or each critical zone Zp = Voz/Vpz (Eq 6-5) Note: – Vpz = Vpz-design = minimum primary airflow expected at “ventilation design” condition (usually higher than minimum box setting) – Picking Vpz-design - probably most confusing part for MZS Vpz design  Many use minimum box setting – easy but conservative  Some use 8760 simulation to find an accurate value (Maybe Std 62.1 should use 0.5*Vpz-design as default)  NOTE: “ventilation design” ≠ “thermal design” 28 © 2009 TraneMultiple-Zone Ventilation 14© 2012 Trane a business of Ingersoll Rand. All rights reserved
  16. 16. 6.2.5 Multiple-Zone Systems design 5. Find uncorrected outdoor airflow Vou = D*(R P ) + (R A ) V (Rp×Pz) (Ra×Az) (Eq 6-6) (E 6 6) Note: – Design credit for occupant diversity (D) – D = expected population/sum-of-peak populations = 50 people/100 chairs = 0.5 – Occupant diversity reduces uncorrected outdoor airflow 29 © 2009 Trane 6.2.5 Multiple-Zone Systems design 6. Find system ventilation efficiency – Fi t find average outdoor air f ti (Xs) using First, fi d td i fraction (X ) i system primary airflow (Vps) at ventilation design Xs = Vou/Vps (Eq A-1) – Then, find zone ventilation efficiency (Evz) Evz = 1 + Xs – Zpz (Eq A-2) – Finally, lowest Evz is system ventilation efficiency (Ev) Ev = min(Evz) (Eq A-8) Note: – Lowest Evz defines the “critical zone” for ventilation 30 © 2009 TraneMultiple-Zone Ventilation 15© 2012 Trane a business of Ingersoll Rand. All rights reserved
  17. 17. 6.2.5 Multiple-Zone Systems design 7. Find outdoor air intake flow Vot Vou/Ev V t = V /E (Eq 6-8) (E 6 8) Note: – Compared to 2001, the 2010 rates and equations reduce intake airflow (Vot) for many systems 31 © 2009 Trane 6.2 Ventilation Rate Procedure • 6.2.1 Outdoor air treatment • 6.2.2 Zone calculations (zone OA) • 6.2.3 Single-zone systems (OA intake) • 6.2.4 100% OA systems (OA intake) • 6.2.5 Multiple-zone recirc systems (OA intake) • 6.2.6 Design for varying operating conditions • 6.2.7 6 2 7 Dynamic reset 32 © 2009 TraneMultiple-Zone Ventilation 16© 2012 Trane a business of Ingersoll Rand. All rights reserved
  18. 18. Multiple-Zone Systems operation • That’s it for MZS design but can intake flow vary during d i operation? ti ? • Sure – Provided Section 5.3.1 (no less than required Vot under all “operating” conditions) is met … – Section 6.2.7 allows optional dynamic reset, regardless of system type • But how do you do it in a VAV system? 33 © 2009 Trane Dynamic Reset Approaches operation • Already reviewed for single zone and 100% OA • For VAV MZS operation, you could … – Use “ventilation reset control” (VRC)  Reset intake flow based only on changes in system ventilation efficiency (Ev) due to changes in zone airflow – Combine system-level VRC with zone-level DCV  Reset intake flow based on changes in system ventilation efficiency due to changes in both zone airflow and population – Use system-level DCV of some sort  Approaches not well-known, but hopefully Dr. Lau’s research addresses this 34 © 2009 TraneMultiple-Zone Ventilation 17© 2012 Trane a business of Ingersoll Rand. All rights reserved
  19. 19. Ventilation Reset Control operation • VRC resets system-level outdoor air intake flow (Vot) t (V t) at part l d conditions by: t load diti b – Assuming design population in all zones without accounting for reduced population in any zone – Accounting for changes in system ventilation efficiency (Ev) due to zone and system airflow changes – Solving the MZS equations in real time (quasi-steady state) to find current intake flow (Vot) set point required • Here’s an example building using one possible VRC approach 35 © 2009 Trane VRC w/o Zone-Level DCV design Vot req’d @ design Single Supply Single-Supply VAV System: Ventilation Design population Pz 140 140 260 260 5 40 8, 810 prim airflow Vpz 6,500 6,700 5,500 7,900 500 1,700 min expect Vpzm 4,000 4,000 4,000 4,000 300 1,300 vent rate Vbz 1,880 1,880 2,190 2,190 85 760 vent fract Zpz 0.470 0.470 0.548 0.548 0.283 0.585 Ventilation design - For each zone use: Then, find: Pz = peak zone population Vou = D*Rp*Pz + Ra*Az (5) Vpz = peak primary airflow D = Ps/Pz = 550/845 = 0.65 Vpzm = minimum expected Vpz @ design = 0.65*7,130 + 1,860 = 6,500 Then, Then find: Ev = min(Evz) (6) Vbz = Rp*Pz + Ra*Az (1) Vps = LDF*ΣVpz Ez = design zone air dist eff (2) = 0.7*28,800 = 20,200 Voz = Vbz/Ez (3) Xs = Vou/Vps Zpz = Voz/Vpzm = Vbz/(Ez*Vpzm) (4) = 6,500/20,200 = 0.322 Evz = 1+ Xs – Zpz For the system use: = 1 + 0.322 – 0.585 = 0.738 Ps = highest system population = 550 = min(Evz) = 0.738 LDF= load diversity factor = 0.7 Vot = Vou/Ev = 6,500/0.738 = 8,810 (7) 36 © 2009 TraneMultiple-Zone Ventilation 18© 2012 Trane a business of Ingersoll Rand. All rights reserved
  20. 20. VRC w/o Zone-Level DCV operation Vot Vot req’d req’d @ design (current) Single Supply Single-Supply VAV System: 100% Thermal Load (2:00 pm Friday perhaps) Friday, population Pz 140 140 260 260 5 40 8, 810 8, 390 prim airflow Vpz 4,960 5,000 4,000 4,000 500 1,700 vent rate Vbz 1,880 1,880 2,190 2,190 85 760 vent fraction Zdz 0.379 0.376 0.548 0.548 0.170 0.447 Operation w/o DCV: For each zone use: Now, controls calculate: Pz = peak zone population (entry) Vou = D*Rp*Pz + Ra*Az (5) Then, controls determine or calculate: D = Ps/Pz = 550/845 = 0.65 Vpz = current primary airflow (sensed) = 0.65*7,130 + 1,860 = 6,500 Vbz = Rp*Pz + Ra*Az (calc or entry) (1) Rp Pz Ra Az Ev = min(Evz) (6) Ez = current value (2) Vps = Vpz Voz = Vbz/Ez (3) = 20,200 Zpz = Voz/Vpz (4) Xs = Vou/Vps = 6,500/20,200 = 0.322 Evz = 1+ Xs – Zpz For the system use: = 1 + 0.322 – 0.548 = 0.775 Ps = highest system population = 550 = min(Evz) = 0.775 LDF= load diversity factor = 0.7 Vot = Vou/Ev = 6,500/0.775 = 8,390 (7) 37 © 2009 Trane VRC w/o Zone-Level DCV operation Vot Vot req’d req’d @ design (current) Single Supply Single-Supply VAV System: 100% Thermal Load (2:00 pm Friday perhaps) Friday, population Pz 140 140 260 260 5 40 8, 810 8, 390 prim airflow Vpz 4,960 5,000 4,000 4,000 500 1,700 vent rate Vbz 1,880 1,880 2,190 2,190 85 760 vent fraction Zdz 0.379 0.376 0.548 0.548 0.170 0.447 Vot-actual is less Operation w/o DCV: For each zone use: Now, controls calculate: than Vot-design Pz = peak zone population (entry) Vou = D*Rp*Pz + Ra*Az (5) Then, controls determine or calculate: D = Ps/Pz = 550/845 = 0.65 Vpz = current primary airflow (sensed) = 0.65*7,130 + 1,860 = 6,500 Vbz = Rp*Pz + Ra*Az (calc or entry)w/o DCV Ev = min(Evz) Rp Pz Ra Az VRC (1) reduces (6) Ez = current value required Vot, even at Vpz (2) Vps = Voz = Vbz/Ez (3) = 20,200 Zpz = Voz/Vpz 100%(4)thermal load:= Vou/Vps Xs Ev-actual ≥ Ev-design = 6,500/20,200 = 0.322 Evz = 1+ Xs – Zpz For the system use: = 1 + 0.322 – 0.548 = 0.775 Ps = highest system population = 550 = min(Evz) = 0.775 LDF= load diversity factor = 0.7 Vot = Vou/Ev = 6,500/0.775 = 8,390 (7) 38 © 2009 TraneMultiple-Zone Ventilation 19© 2012 Trane a business of Ingersoll Rand. All rights reserved
  21. 21. VRC w/o Zone-Level DCV operation Vot Vot req’d req’d @ design (current) Single Supply Single-Supply VAV System: 100% Thermal Load (2:00 pm Friday perhaps) Friday, population Pz 140 140 260 260 5 40 8, 810 8, 390 prim airflow Vpz 4,960 5,000 4,000 4,000 500 1,700 vent rate Vbz 1,880 1,880 2,190 2,190 85 760 vent fraction Zpz 0.379 0.376 0.548 0.548 0.170 0.447 Single-Supply VAV System: 90% Thermal Load (1:00 pm Monday, perhaps) population Pz 140 140 260 260 5 40 8,810 7,780 prim airflow Vpz 4,000 3,700 4,200 4,300 300 1,700 vent rate Vbz 1,880 1,880 2,190 2,190 85 760 vent fraction Zpz 0 470 0 508 0 521 0 509 0 283 0 447 0.470 0.508 0.521 0. 0.283 0.447 Now, controls determine or calculate: VRC w/o DCV reduces Vou = D*Rp*Pz + Ra*Az = 6,500 required Vot even more Vpz = (sensed) Vps = Vpz = 18,200 at lower thermal loads: Xs = Vou/Vps = 6,500/18,200 = 0.357 Ev-actual >> Ev-design Ev = 1 + 0.357 – 0.521 = 0.836 Vot = Vou/Ev = 6,500/0.836 = 7,780 39 © 2009 Trane Dynamic Reset Approaches operation • Already reviewed for single zone and 100% OA • For VAV MZS operation, you could … – Use “ventilation reset control” (VRC)  Reset intake flow based only on changes in system ventilation efficiency (Ev) due to changes in zone airflow – Combine system-level VRC with zone-level DCV  Reset intake flow based on changes in system ventilation efficiency due to changes in both zone airflow and population – Use system-level DCV of some sort  Approaches not well-known, but hopefully Dr. Lau’s research addresses this 40 © 2009 TraneMultiple-Zone Ventilation 20© 2012 Trane a business of Ingersoll Rand. All rights reserved
  22. 22. VRC with Zone-Level DCV operation • VRC resets system-level outdoor air intake flow (Vot) t (V t) at part l d conditions by: t load diti b – Assuming design population in non-DCV zones while accounting for reduced population in DCV zones – Accounting for changes in system ventilation efficiency (Ev) due to zone and system airflow changes – Solving the MZS equations in real time (quasi-steady state) to find current intake flow (Vot) set point required • Here’s the same example building using the same VRC approach, but with various “zone types” including both non-DCV and DCV zones 41 © 2009 Trane VRC w/Zone-Level DCV operation • Defining zone types – Z Zones without DCV ith t  Non-DCV zones (NON): Pz = peak zone population at all conditions, regardless of actual population – Population-estimating DCV zones (EST) include:  “Time-of-day” zones (TOD): Pz = predicted population  “Occupied/unoccupied” (OCC) zones: Pz = peak or zero population, depending on occupancy sensor  “Count” zones (COU): Pz = sensed number of occupants – CO2-based DCV zones (CO2) (Pz = unknown)  Breathing-zone OA flow depends on sensed difference between primary and zone CO2: Vbz = f (ΔCO2) 42 © 2009 TraneMultiple-Zone Ventilation 21© 2012 Trane a business of Ingersoll Rand. All rights reserved
  23. 23. VRC w/ Zone-Level DCV design Vot NON NON CO2 NON NON EST req’d @ design Single Supply Single-Supply VAV System: Design Ventilation population Pz 140 140 260 260 5 40 8, 810 prim airflow Vpz 6,500 6,700 5,500 7,900 500 1,700 min expect Vpzm 4,000 4,000 4,000 4,000 300 1,300 vent rate Vbz 1,880 1,880 2,190 2,190 85 760 DCV: No impact vent fract Zpz 0.470 0.470 0.548 0.548 0.283 0.585 on Vot-design Design ventilation: For each zone use: Then, find: Pz = peak zone population Vou = D*Rp*Pz + Ra*Az (5) Vpz = peak primary airflow D = Ps/Pz = 550/845 = 0.65 Vpzm = minimum expected Vpz @ design = 0.65*7,130 + 1,860 = 6,500 Then, Then find: Ev = min(Evz) (6) Vbz = Rp*Pz + Ra*Az (1) Vps = LDF*ΣVpz Ez = design zone air dist eff (2) = 0.7*28,800 = 20,200 Voz = Vbz/Ez (3) Xs = Vou/Vps Zpz = Voz/Vpzm = Vbz/(Ez*Vpzm) (4) = 6,500/20,200 = 0.322 Evz = 1+ Xs – Zpz For the system use: = 1 + 0.322 – 0.585 = 0.738 Ps = highest system population = 550 = min(Evz) = 0.738 LDF= load diversity factor = 0.7 Vot = Vou/Ev = 6,500/0.738 = 8,810 (7) 43 © 2009 Trane VRC w/ Zone-Level DCV operation Vot Vot NON NON CO2 NON NON EST req’d req’d @ design (current) Single Supply Single-Supply VAV System: 100% Thermal Load (2:00 pm Friday perhaps) Friday, population Pz 140 140 ??? 260 5 0 8, 810 8, 390 prim airflow Vpz 4,960 5,400 4,000 4,000 500 1,300 8, 030 vent rate Vbz 1,880 1,880 1,300 2,190 85 360 vent fraction Zpz 0.379 0.348 0.325 0.548 0.170 0.277 For each NON-DCV zone use: Now, for system: Pz = peak zone population (entry) Vou = D*NONRp*Pz + NONRa*Az (5) Vbz = Rp*Pz + Ra*Az (entry) + ESTRp*Pz + ESTRa*Az + CO2Vbz For each EST-DCV zone: Ps = highest system population = 550 Pz = estimated population (sensed) D = Ps/Pz-peak = 550/845 = 0.65 Vbz Rp*Pz Ra*Az Vb = R *P + R *A (calc) ( l ) = 0.65*4,780 + 1,260 + 0 + 360 + 1,300 * For each CO2-DCV zone use: = 6,030 Vbz = f (ΔCO2) (sense & calc) Ev = min(Evz) (6) For each zone, controls determine: Vps = Vpz = 20,200 (calc) Vpz = current zone primary (sensed) Xs = Vou/Vps = 6,030/20,200 = 0.299 Vbz = current reqmt (entry or calc) (1) Evz = 1 + Xs – Zpz Ez = current value (2) = 1 + 0.299 – 0.548 = 0.751 Voz = Vbz/Ez (3) Vot = small(Vou/Ev or Vot-des) (7) Zpz = Voz/Vpz (4) = 6,030/0.751 = 8,030 44 © 2009 TraneMultiple-Zone Ventilation 22© 2012 Trane a business of Ingersoll Rand. All rights reserved
  24. 24. VRC w/ Zone-Level DCV operation Vot Vot NON NON CO2 NON NON EST req’d req’d @ design (current) Single Supply Single-Supply VAV System: 100% Thermal Load (2:00 pm Friday perhaps) Friday, population Pz 140 140 ??? 260 5 0 8, 810 8, 390 prim airflow Vpz 4,960 5,400 4,000 4,000 500 1,300 8, 030 vent rate Vbz 1,880 1,880 1,300 2,190 85 360 vent fraction Zpz 0.379 0.348 0.325 0.548 0.170 0.277 For each NON-DCV zone use: Now, for system: VRC w/DCV Pz = peak zone population (entry) reduces Vot-actual Vou = D*NONRp*Pz + NONRa*Az (5) Vbz = Rp*Pz + Ra*Az (entry) + ESTRp*Pz + ESTRa*Az + CO2Vbz For each EST-DCV zone: Ps = highest system population = 550 Pz = estimated population (sensed) D = Ps/Pz-peak = 550/845 = 0.65 Vbz Rp*Pz Ra*Az Vb = R *P + R *A (calc) ( l ) = 0.65*4,780 + 1,260 + 0 + 360 + 1,300 * For each CO2-DCV zone use: = 6,030 Vbz = f (ΔCO2) (sense & calc) Ev = min(Evz) (6) For each zone, controls determine: Vps = Vpz = 20,200 (calc) Vpz = current zone primary (sensed) Xs = Vou/Vps = 6,030/20,200 = 0.299 Vbz = current reqmt (entry or calc) (1) Evz = 1 + Xs – Zpz Ez = current value (2) = 1 + 0.299 – 0.548 = 0.751 Voz = Vbz/Ez (3) Vot = small(Vou/Ev or Vot-des) (7) Zpz = Voz/Vpz (4) = 6,030/0.751 = 8,030 45 © 2009 Trane VRC w/ Zone-Level DCV operation – For design, note:  D = P /ALLP Ps/ Pz-peak, bk because occupant diversity t di it distributes total population among all zones in system  D applies to all zones for design – For operation, note:  D applies NON-DCV zones (occupant diversity credit)  D = 1.0 for EST-DCV zones (estimated Pz is independent of occupant diversity) p y)  D isn’t used for CO2-DCV zones (Vbz is determined by controller, without regard to occupant diversity  Rule: To assure adequate heat/cool capacity, Vot during operation must never be greater than Vot at design 46 © 2009 TraneMultiple-Zone Ventilation 23© 2012 Trane a business of Ingersoll Rand. All rights reserved
  25. 25. VRC w/ Zone-Level DCV operation Vot Vot NON NON CO2 NON NON EST req’d req’d @ design (current) Single Supply Single-Supply VAV System: 100%Thermal Load (2:00 pm Friday perhaps) Friday, population Pz 140 140 ??? 260 5 0 8, 810 8, 030 prim airflow Vpz 4,960 5,400 4,000 4,000 500 1,300 vent rate Vbz 1,880 1,880 1,300 2,190 85 360 vent fraction Zpz 0.379 0.348 0.325 0.548 0.170 0.277 Single-Supply VAV System: 90% Thermal Load (1:00 pm Monday, perhaps) population Pz 140 140 ??? 260 5 0 8,810 7,780 prim airflow Vpz 4,000 3,700 4,200 4,300 300 1,700 7,440 vent rate Vbz 1,880 1,880 1,300 2,190 85 360 vent fraction Zpz 0 470 0 508 0 521 0 509 0 283 0 447 0.470 0.508 0.521 0. 0.283 0.447 Now: VRC with DCV reduces Vou = 6,030 Vps = Vpz = 18,200 Vot-actual more, saves Xs = 6,030/18,200 = 0.331 more energy Ev = 1 + 0.331 – 0.521 = 0.810 Vot = Vou/Ev = 6,030/0.810 = 7,440 47 © 2009 Trane Implementation • For VRC alone or combined with zone-level DCV, design d i usually includes: ll i l d – Communicating DDC-VAV boxes – BAS with equation-solving capability – Intake-airflow sensing and control at the AHU – Building pressure control (which limits Vot reduction) • Remember: – Std 62.1 allows DCV in any system – Std 90.1 requires DCV in 40 p/1000 ft2 zones – Std 189.1 requires DCV in 25 p/1000 ft2 zones 48 © 2009 TraneMultiple-Zone Ventilation 24© 2012 Trane a business of Ingersoll Rand. All rights reserved
  26. 26. Quick Summary Dynamic reset depends on ventilation system type – Single-zone systems (no design population diversity)  Optional zone DCV allowed – 100% OA systems (no design population diversity)  CV: Zone DCV & Vot reset not useful w/constant Vot  VAV: Zone DCV & Vot reset allowed but not cheap – Multiple-zone sys (population diversity design credit):  Optional system Vot reset allowed – Based only on system ventilation efficiency (VRC) – Based on zone DCV combined with system VRC – Based only on zone DCV (not covered) 49 © 2009 Trane Thanks Any questions? Dennis Stanke dstanke@trane.com 50 © 2009 TraneMultiple-Zone Ventilation 25© 2012 Trane a business of Ingersoll Rand. All rights reserved

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