1. Implementing DCV with ASHRAE 62.1 John Murphy, LEED ® AP BD+C, ASHRAE Fellow Applications Engineer Trane Ingersoll Rand La Crosse, Wisconsin 9 March 2016 Lexington, Kentucky

2. Implementing DCV with ASHRAE 62.1 2 ASHRAE Standard 62.1-2013 Section 6.2.7 6.2.7 Dynamic Reset. The system may be designed to reset the outdoor air intake flow (V ot ) and/or space or ventilation zone airflow (V oz ) as operating conditions change. 6.2.7.1 Demand Control Ventilation (DCV)… 6.2.7.2 Ventilation Efficiency… 6.2.7.3 Outdoor Air Fraction… 6.2.7 Dynamic Reset. The system may be designed to reset the outdoor air intake flow (V ot ) and/or space or ventilation zone airflow (V oz ) as operating conditions change. 6.2.7.1 Demand Control Ventilation (DCV)… 6.2.7.2 Ventilation Efficiency… 6.2.7.3 Outdoor Air Fraction… Examples mentioned include: Variations in zone population (“demand-controlled ventilation” or DCV) Variations in ventilation efficiency due to changes in airflow (“ventilation reset” or “ventilation optimization”) Variations in OA fraction due to airside economizer operation (“VAV box minimum reset”)

3. Implementing DCV with ASHRAE 62.1 3 Demand-Controlled Ventilation (DCV) An energy-saving control strategy that responds to the actual “demand” (need) for ventilation in a zone by varying the rate at which outdoor air is delivered to that zone. cfm required = cfm/person  number of people local code, ASHRAE 62.1

4. Implementing DCV with ASHRAE 62.1 4 DCV with ASHRAE Standard 62.1 Agenda Requirements of ASHRAE Standard 90.1 Common DCV technologies Implementing DCV is various types of systems – Single-zone systems – Dedicated (100%) outdoor-air systems – Multiple-zone recirculating systems

5. Implementing DCV with ASHRAE 62.1 5 ASHRAE Standard 90.1-2010 (mandatory requirement) Demand-Controlled Ventilation 6.4.3.9 Ventilation Controls for High-Occupancy Areas. Demand control ventilation (DCV) is required for spaces larger than 500 ft 2 and with a design occupancy for ventilation of > 40 people per 1000 ft 2 of floor area and served by systems with one or more of the following: a. an air-side economizer, b. automatic modulating control of the outdoor air damper, or c. a design outdoor airflow > 3000 cfm. Exceptions: a. Systems with exhaust air energy recovery complying with Section 6.5.6.1. b. Multiple-zone systems without DDC of individual zones communicating with a central control panel. c. Systems with a design outdoor airflow < 1200 cfm. d. Spaces where the supply airflow rate minus any makeup or outgoing transfer air requirement is less than 1200 cfm. 6.4.3.9 Ventilation Controls for High-Occupancy Areas. Demand control ventilation (DCV) is required for spaces larger than 500 ft 2 and with a design occupancy for ventilation of > 40 people per 1000 ft 2 of floor area and served by systems with one or more of the following: a. an air-side economizer, b. automatic modulating control of the outdoor air damper, or c. a design outdoor airflow > 3000 cfm. Exceptions: a. Systems with exhaust air energy recovery complying with Section 6.5.6.1. b. Multiple-zone systems without DDC of individual zones communicating with a central control panel. c. Systems with a design outdoor airflow < 1200 cfm. d. Spaces where the supply airflow rate minus any makeup or outgoing transfer air requirement is less than 1200 cfm.

6. Implementing DCV with ASHRAE 62.1 6 > 40 people / 1000 ft 2

7. Implementing DCV with ASHRAE 62.1 7 ASHRAE Standard 90.1-2013 (mandatory requirement) Demand-Controlled Ventilation 6.4.3.8 Ventilation Controls for High-Occupancy Areas. Demand control ventilation (DCV) is required for spaces larger than 500 ft 2 and with a design occupancy for ventilation of ≥ 25 people per 1000 ft 2 of floor area and served by systems with one or more of the following: a. an air-side economizer, b. automatic modulating control of the outdoor air damper, or c. a design outdoor airflow > 3000 cfm. Exceptions: 1. Systems with exhaust air energy recovery complying with Section 6.5.6.1. 2. Multiple-zone systems without DDC of individual zones communicating with a central control panel. 3. Systems with a design outdoor airflow < 750 cfm. 4. Spaces where > 75% of the space design outdoor airflow is required for makeup air that is exhausted from the space or transfer air that is required for makeup air that is exhausted from other space(s). 5. Correctional cells, daycare sickrooms, science labs, beauty and nail salons, and bowling alley seating. 6.4.3.8 Ventilation Controls for High-Occupancy Areas. Demand control ventilation (DCV) is required for spaces larger than 500 ft 2 and with a design occupancy for ventilation of ≥ 25 people per 1000 ft 2 of floor area and served by systems with one or more of the following: a. an air-side economizer, b. automatic modulating control of the outdoor air damper, or c. a design outdoor airflow > 3000 cfm. Exceptions: 1. Systems with exhaust air energy recovery complying with Section 6.5.6.1. 2. Multiple-zone systems without DDC of individual zones communicating with a central control panel. 3. Systems with a design outdoor airflow < 750 cfm. 4. Spaces where > 75% of the space design outdoor airflow is required for makeup air that is exhausted from the space or transfer air that is required for makeup air that is exhausted from other space(s). 5. Correctional cells, daycare sickrooms, science labs, beauty and nail salons, and bowling alley seating.

8. Implementing DCV with ASHRAE 62.1 8 impact of 90.1-2013 Correctional waiting room Lecture classroom Lecture hall Multi-use assembly Restaurant dining room Cafeteria / fast food dining Bars, cocktail lounge Conference / meeting Break room Telephone / data entry Transportation waiting Auditorium seating area Place of religious worship Courtroom Legislative chambers Lobby Spectator area Disco / dance floor Gambling casino Stage / studio Correctional waiting room Daycare Classroom (ages 5-8) Classroom (age 9+) Lecture classroom Lecture hall Computer lab Media center Music / theater / dance Multi-use assembly Restaurant dining room Cafeteria / fast food dining Bars, cocktail lounge Conference / meeting Lobby / pre-function Break room Reception area Telephone / data entry Transportation waiting Auditorium seating area Place of religious worship Courtroom Legislative chambers Lobby Museum / gallery Spectator area Disco / dance floor Health club / aerobics room Gambling casino Stage / studio ≥ 25 people / 1000 ft 2 > 40 people / 1000 ft 2

9. Implementing DCV with ASHRAE 62.1 9 DCV with ASHRAE Standard 62.1 Agenda Requirements of ASHRAE Standard 90.1 Common DCV technologies Implementing DCV is various types of systems – Single-zone systems – Dedicated (100%) outdoor-air systems – Multiple-zone recirculating systems

10. Implementing DCV with ASHRAE 62.1 10 ASHRAE Standard 62.1-2013, Section 6.2.7.1 Demand-Controlled Ventilation 6.2.7.1 DCV shall be permitted as an optional means of dynamic reset. Exception: CO 2 -based DCV shall not be applied in zones with indoor sources of CO 2 other than occupants or with CO 2 removal mechanisms, such as gaseous air cleaners. 6.2.7.1.1 The breathing zone outdoor airflow (V bz ) shall be reset in response to current occupancy and shall be no less than the building component (R a × A z ) of the DCV zone. Note: Examples of reset methods or devices include population counters, carbon dioxide (CO 2 ) sensors, timers, occupancy schedules, or occupancy sensors. 6.2.7.1.2 The ventilation system shall be controlled such that at steady-state it provides each zone with no less than the breathing zone outdoor airflow (V bz ) for the current zone population. 6.2.7.1.3 The current total outdoor air intake flow with respect to the coincident total exhaust airflow for the building shall comply with Section 5.9.2. 6.2.7.1 DCV shall be permitted as an optional means of dynamic reset. Exception: CO 2 -based DCV shall not be applied in zones with indoor sources of CO 2 other than occupants or with CO 2 removal mechanisms, such as gaseous air cleaners. 6.2.7.1.1 The breathing zone outdoor airflow (V bz ) shall be reset in response to current occupancy and shall be no less than the building component (R a × A z ) of the DCV zone. Note: Examples of reset methods or devices include population counters, carbon dioxide (CO 2 ) sensors, timers, occupancy schedules, or occupancy sensors. 6.2.7.1.2 The ventilation system shall be controlled such that at steady-state it provides each zone with no less than the breathing zone outdoor airflow (V bz ) for the current zone population. 6.2.7.1.3 The current total outdoor air intake flow with respect to the coincident total exhaust airflow for the building shall comply with Section 5.9.2.

11. Implementing DCV with ASHRAE 62.1 11 Time-of-Day (TOD) Schedule Scheduling function of the BAS is used to define the amount of outdoor air required in a zone for each hour … based on estimated population

12. Implementing DCV with ASHRAE 62.1 12 0 50 100 150 zone population, P z midnight6 a.m.noon6 p.m.midnight example: high school cafeteria Occupancy/Ventilation TOD Schedule 200 estimated P z each hour

13. Implementing DCV with ASHRAE 62.1 13 People Counters

14. Implementing DCV with ASHRAE 62.1 14 Occupancy Sensor / Motion Detector Sensor is used to determine if people are present – Simple, binary input When a zone is occupied: – Zone ventilation setpoint is set to design outdoor airflow When a zone is unoccupied: – Zone ventilation setpoint is reduced to “building” ventilation airflow (R a × A z )

15. Implementing DCV with ASHRAE 62.1 15 example: conference room Occupancy Sensor Floor area (A z ) = 300 ft 2 Design population (P z ) = 10 people Required outdoor airflow at design population V bz-design = R p  P z + R a  A z = 5 cfm/p  10 people + 0.06 cfm/ft 2  300 ft 2 = 68 cfm Required outdoor airflow at zero population V bz-standby = 5 cfm/p  0 people + 0.06 cfm/ft 2  300 ft 2 = 18 cfm 6.2.7.1.1 The breathing zone outdoor airflow (V bz ) shall be reset in response to current occupancy and shall be no less than the building component (R a × A z ) of the DCV zone. 8.3 Systems shall be operated such that spaces are ventilated in accordance with Section 6 when they are expected to be occupied. ASHRAE Standard 62.1-2013 (see also official interpretation 62.1-2010-4) 6.2.7.1.1 The breathing zone outdoor airflow (V bz ) shall be reset in response to current occupancy and shall be no less than the building component (R a × A z ) of the DCV zone. 8.3 Systems shall be operated such that spaces are ventilated in accordance with Section 6 when they are expected to be occupied. ASHRAE Standard 62.1-2013 (see also official interpretation 62.1-2010-4)

16. Implementing DCV with ASHRAE 62.1 16 Official Interpretation 62.1-2010-4 Interpretation #3: When a local occupancy sensor indicates that a zone served by a multiple-zone recirculating system is unoccupied, that zone’s VAV box may have the minimum airflow setpoint set to zero and any zone fan required for ventilation turned off. There is no requirement under the Ventilation Rate Procedure to provide the area portion (R a  A z ) of the V bz determined with Equation 6-1 to the zone when the zone is unoccupied. Question #3: Is this interpretation correct? Answer #3: No. Section 6.2.7.1.2 requires that V bz shall be no less than the building component in the DCV zone. official interpretation 62.1-2010-4 Interpretation #3: When a local occupancy sensor indicates that a zone served by a multiple-zone recirculating system is unoccupied, that zone’s VAV box may have the minimum airflow setpoint set to zero and any zone fan required for ventilation turned off. There is no requirement under the Ventilation Rate Procedure to provide the area portion (R a  A z ) of the V bz determined with Equation 6-1 to the zone when the zone is unoccupied. Question #3: Is this interpretation correct? Answer #3: No. Section 6.2.7.1.2 requires that V bz shall be no less than the building component in the DCV zone. official interpretation 62.1-2010-4

17. Implementing DCV with ASHRAE 62.1 17 “occupied-standby” mode Addendum P to ASHRAE 62.1-2013 6.2.7.1.1 For DCV zones in the occupied mode, breathing zone outdoor airflow (Vbz) shall be reset in response to current population. 6.2.7.1.2 For DCV zones in the occupied mode, breathing zone outdoor airflow (Vbz) shall not be less than the building component (Ra x Az) for the zone. Exception: Breathing zone outdoor airflow shall be permitted to be reduced to zero for zones in occupied-standby mode for the occupancy categories indicated in Table 6.2.2.1 provided that airflow is restored to Vbz whenever occupancy is detected. Section 3 Definitions occupied mode: when a zone is scheduled to be occupied occupied-standby mode: when a zone is scheduled to be occupied and an occupancy sensor indicates zero population within the zone addendum P to ASHRAE Standard 62.1-2013 6.2.7.1.1 For DCV zones in the occupied mode, breathing zone outdoor airflow (Vbz) shall be reset in response to current population. 6.2.7.1.2 For DCV zones in the occupied mode, breathing zone outdoor airflow (Vbz) shall not be less than the building component (Ra x Az) for the zone. Exception: Breathing zone outdoor airflow shall be permitted to be reduced to zero for zones in occupied-standby mode for the occupancy categories indicated in Table 6.2.2.1 provided that airflow is restored to Vbz whenever occupancy is detected. Section 3 Definitions occupied mode: when a zone is scheduled to be occupied occupied-standby mode: when a zone is scheduled to be occupied and an occupancy sensor indicates zero population within the zone addendum P to ASHRAE Standard 62.1-2013

18. Implementing DCV with ASHRAE 62.1 18 physical activity level, MET 012345 0.5 0 1.0 1.5 2.0 CO 2 production, L/min CO 2 production (RQ=0.83) office work sleeping walking light machine work very lightmoderatelight Source: ASHRAE Standard 62.1-2013, Figure C-2 CO 2 Sensor Production of CO 2 is related to the person’s level of activity (MET). Therefore, CO 2 can be used as a "tracer gas" for occupancy.

19. Implementing DCV with ASHRAE 62.1 19 CO 2 -Based DCV 0 200 400 600 800 1000 1200 1400 1600 CO 2 concentration, ppm steady state conditions time CO 2 outdoors 15 cfm/p 20 cfm/p 10 cfm/p CO 2 indoors

20. Implementing DCV with ASHRAE 62.1 20 CO 2 -Based DCV CO 2 concentration, ppm time CO 2 indoors C OA = 350 ppm C space = 1050 ppm C space – C OA = N / V OA N= CO 2 generation rate, cfm/person V OA = ventilation rate, cfm/person 0 200 400 600 800 1000 1200 1400 1600

21. Implementing DCV with ASHRAE 62.1 21 CO 2 -based DCV Setpoints Vary by Application CO 2 generation rate (N) varies with activity level – Refer to Appendix C of ASHRAE 62.1 Ventilation rate (V OA ) differs by space type and cfm/person varies as zone population changes Outdoor CO 2 concentration (C OA ) varies by location – Most designers use a one-time reading from the site or a conservative value from historical local data "Unless combustion fumes are present, the outdoor CO 2 concentration in most locations seldom varies more than 100 ppm from the nominal value." ASHRAE Transactions, 1998 "Unless combustion fumes are present, the outdoor CO 2 concentration in most locations seldom varies more than 100 ppm from the nominal value." ASHRAE Transactions, 1998

22. Implementing DCV with ASHRAE 62.1 22 DCV with ASHRAE Standard 62.1 Agenda Requirements of ASHRAE Standard 90.1 Common DCV technologies Implementing DCV is various types of systems – Single-zone systems – Dedicated (100%) outdoor-air systems – Multiple-zone recirculating systems

23. Implementing DCV with ASHRAE 62.1 23 DCV in a Single-Zone System SA OA RA EA space CO 2

24. Implementing DCV with ASHRAE 62.1 24 implementing DCV in a single-zone system ASHRAE 62.1 User’s Manual (Appendix A) Example: University lecture classroom Floor area (A z ) = 1000 ft 2 Peak population (P z ) = 65 people CO 2 generation rate (N*) = 0.0105 cfm/person (light desk work) Outdoor CO 2 concentration (C OA ) = 350 ppm For this occupancy classification, Table 6.2.1.1 of ASHRAE Standard 62.1-2013 requires: R p = 7.5 cfm/person R a = 0.06 cfm/ft 2 * N, cfm/person = MET  0.0084 for average adult population (Standard 62.1-2010 User’s Manual, p. 158)

25. Implementing DCV with ASHRAE 62.1 25 implementing DCV in a single-zone system Example: University Lecture Classroom 1) Calculate breathing-zone outdoor airflow (V bz ) for both design population and with zero people V bz = R p × P z + R a × A z V bz-design = 7.5 × 65 + 0.06 × 1000 = 550 cfm (8.5 cfm/p) V bz-DCVmin = 7.5 × 0 + 0.06 × 1000 = 60 cfm (>75 cfm/p)

26. Implementing DCV with ASHRAE 62.1 26 implementing DCV in a single-zone system Example: University Lecture Classroom 1020 200 400 600 800 1000 zone population, P z 30405060 0 0 1200 7.5 cfm/p + 0.06 cfm/ft² V bz-design = 550 cfm V bz-DCVmin = 60 cfm 6.2.7.1.1 The breathing zone outdoor airflow (V bz ) shall be reset in response to current occupancy and shall be no less than the building component (R a × A z ) of the DCV zone. 6.2.7.1.2 The ventilation system shall be controlled such that at steady- state it provides each zone with no less than the breathing zone outdoor airflow (V bz ) for the current zone population. ASHRAE Standard 62.1-2013 6.2.7.1.1 The breathing zone outdoor airflow (V bz ) shall be reset in response to current occupancy and shall be no less than the building component (R a × A z ) of the DCV zone. 6.2.7.1.2 The ventilation system shall be controlled such that at steady- state it provides each zone with no less than the breathing zone outdoor airflow (V bz ) for the current zone population. ASHRAE Standard 62.1-2013 breathing-zone outdoor airflow (V bz ), cfm 1400

27. Implementing DCV with ASHRAE 62.1 27 implementing DCV in a single-zone system Example: University Lecture Classroom 2) Calculate steady-state indoor CO 2 concentration (C s ) for both design population and with zero people C s = C OA + N / ( V bz / P z ) C s-design = 350 + 0.0105 / (550 cfm / 65 people) = 1600 ppm C s-DCVmin = 350 + 0.0105 / (60 cfm / 0 people) = 350 ppm

28. Implementing DCV with ASHRAE 62.1 28 implementing DCV in a single-zone system Example: University Lecture Classroom 1020 200 400 600 800 1000 zone population, P z 30405060 600 800 1000 1200 1400 1600 400 0 0 1200 7.5 cfm/p + 0.06 cfm/ft² desired space CO 2 concentration (C s ), ppm breathing-zone outdoor airflow (V bz ), cfm C s-DCVmin = 350 ppm C s-design = 1600 ppm 1400 200

29. Implementing DCV with ASHRAE 62.1 29 implementing DCV in a single-zone system Example: University Lecture Classroom V bz-design = 550 cfm indoor CO 2 concentration, ppm V bz-DCVmin = 60 cfm outdoor airflow, cfm when indoor CO 2 is between 350 and 1600 ppm, adjust damper proportionally between 60 and 550 cfm set position of OA damper to bring in 60 cfm when indoor CO 2 equals 350 ppm set position of OA damper to bring in 550 cfm when indoor CO 2 equals 1600 ppm For single-zone systems, V ot = V oz = V bz /E z (assumes E z = 1.0) C s-design = 1600 ppmC s-DCVmin = 350 ppm

30. Implementing DCV with ASHRAE 62.1 30 implementing DCV in a single-zone system Control Coordination Issues SA OA EA RA 1.Economizer operation should override DCV 2.Don’t forget about building pressure control 1.Economizer operation should override DCV 2.Don’t forget about building pressure control space CO 2 P

31. Implementing DCV with ASHRAE 62.1 31 DCV and Building Pressure Control 6.2.7.1.3 The current total outdoor air intake flow with respect to the coincident total exhaust airflow for the building shall comply with Section 5.9.2. 5.9.2 Exfiltration. For a building, the ventilation system(s) shall be designed to ensure that the minimum outdoor air intake equals or exceeds the maximum exhaust airflow. Exceptions: 1.Where excess exhaust is required by process considerations and approved by the authority having jurisdiction, such as in certain industrial facilities. 2.When outdoor air dry-bulb temperature is below the indoor space dew-point design temperature. Note: Although individual zones within a building may be neutral or negative with respect to outdoors or to other zones, net positive mechanical intake airflow for the building as a whole reduces infiltration of untreated outdoor air. ASHRAE Standard 62.1-2013 6.2.7.1.3 The current total outdoor air intake flow with respect to the coincident total exhaust airflow for the building shall comply with Section 5.9.2. 5.9.2 Exfiltration. For a building, the ventilation system(s) shall be designed to ensure that the minimum outdoor air intake equals or exceeds the maximum exhaust airflow. Exceptions: 1.Where excess exhaust is required by process considerations and approved by the authority having jurisdiction, such as in certain industrial facilities. 2.When outdoor air dry-bulb temperature is below the indoor space dew-point design temperature. Note: Although individual zones within a building may be neutral or negative with respect to outdoors or to other zones, net positive mechanical intake airflow for the building as a whole reduces infiltration of untreated outdoor air. ASHRAE Standard 62.1-2013

32. Implementing DCV with ASHRAE 62.1 32 DCV with ASHRAE Standard 62.1 Agenda Requirements of ASHRAE Standard 90.1 Common DCV technologies Implementing DCV is various types of systems – Single-zone systems – Dedicated (100%) outdoor-air systems – Multiple-zone recirculating systems

33. Implementing DCV with ASHRAE 62.1 33 implementing DCV in a dedicated OA system OA Delivered Directly to Each Zone SA local HVAC unit CA EA VAV box dedicated OA unit OA VFD CO 2 RA CA SA CO 2 RA V ot = Σ V oz

34. Implementing DCV with ASHRAE 62.1 34 implementing DCV in a dedicated OA system OA Delivered to Single-Zone Units RA CA SA RA CA EA dedicated OA unit OA VFD RA CO 2 SA VAV box SA local HVAC unit V ot = Σ V oz

35. Implementing DCV with ASHRAE 62.1 35 implementing DCV in a dedicated OA system Control Coordination Issues Requires pressure-independent OA dampers for any non-DCV zones Requires variable airflow at the dedicated OA unit Don’t forget about building pressure control!

36. Implementing DCV with ASHRAE 62.1 36 DCV with ASHRAE Standard 62.1 Agenda Requirements of ASHRAE Standard 90.1 Common DCV technologies Implementing DCV is various types of systems – Single-zone systems – Dedicated (100%) outdoor-air systems – Multiple-zone recirculating systems

37. Implementing DCV with ASHRAE 62.1 37 implementing DCV in a multiple-zone recirculating system 1) CO 2 Sensor in Every Zone? SA OA RA EA space CO 2

38. Implementing DCV with ASHRAE 62.1 38 implementing DCV in a multiple-zone recirculating system 1) CO 2 Sensor in Every Zone? Requires a CO 2 sensor in every zone – CO 2 level doesn’t change much in many of the zones – Non-critical zones will always be over-ventilated – Increases installed cost, maintenance, and risk of energy waste Requires BAS to poll all sensors and then determine required OA damper position Requires method to ensure minimum outdoor airflow 6.2.7.1.1 The breathing zone outdoor airflow (V bz ) shall be reset in response to current occupancy and shall be no less than the building component (R a × A z ) of the DCV zone. ASHRAE Standard 62.1-2013 6.2.7.1.1 The breathing zone outdoor airflow (V bz ) shall be reset in response to current occupancy and shall be no less than the building component (R a × A z ) of the DCV zone. ASHRAE Standard 62.1-2013

39. Implementing DCV with ASHRAE 62.1 39 implementing DCV in a multiple-zone recirculating system 2) CO 2 Sensor in Common Return Duct? SA OA RA EA space Under-ventilates some zones while over-ventilating others CO 2

40. Implementing DCV with ASHRAE 62.1 40 implementing DCV in a multiple-zone recirculating system 2) CO 2 Sensor in Common Return Duct? 6.2.7.1.2 The ventilation system shall be controlled such that at steady-state it provides each zone with no less than the breathing zone outdoor airflow (V bz ) for the current zone population. ASHRAE Standard 62.1-2013 6.2.7.1.2 The ventilation system shall be controlled such that at steady-state it provides each zone with no less than the breathing zone outdoor airflow (V bz ) for the current zone population. ASHRAE Standard 62.1-2013

41. Implementing DCV with ASHRAE 62.1 41 implementing DCV in a multiple-zone recirculating system 3) DCV at Zone Level + Ventilation Reset loungerest room storageoffice conference rmcomputer roomreception area elevators vestibulecorridor CO 2 OCC TOD

42. Implementing DCV with ASHRAE 62.1 42 implementing DCV in a multiple-zone recirculating system 3) DCV at Zone Level + Ventilation Reset Use all zone-level DCV approaches, each where it best fits – CO 2 sensors: densely-occupied zones with highly- variable population – Occupancy sensors: low-density offices or densely- occupied zones where population varies only minimally – Time-of-day schedules: zones with predictable patterns

43. Implementing DCV with ASHRAE 62.1 43 implementing DCV in a multiple-zone recirculating system 3) DCV at Zone Level + Ventilation Reset OA CO 2 OCC SARA CO 2 TOD OCC Current required outdoor airflow (V oz ) Current primary airflow (V pz ) Current OA fraction (Z pz ) communicating VAV controllers AHU or rooftop unit with flow-measuring OA damper Reset intake airflow (V ot ) Building Automation System Find highest OA fraction (Z pz ) Calculate current system ventilation efficiency (E v ) Calculate current system intake airflow (V ot )

44. Implementing DCV with ASHRAE 62.1 44 implementing DCV in a multiple-zone recirculating system 3) DCV at Zone Level + Ventilation Reset Saves energy during partial occupancy Lower installed cost, less maintenance, and more reliable than installing a CO 2 sensor in every zone – Use zone-level DCV approaches where they best fit (CO 2 sensor, occupancy sensor, time-of-day schedule) – Combine with ventilation reset at the system level Earn LEED EQc1: Outdoor Air Delivery Monitoring Monitor CO 2 concentrations within all densely occupied spaces... Provide a direct outdoor airflow measurement device capable of measuring the minimum outdoor air intake flow... IEQ credit 1, LEED-NC (v2009) Monitor CO 2 concentrations within all densely occupied spaces... Provide a direct outdoor airflow measurement device capable of measuring the minimum outdoor air intake flow... IEQ credit 1, LEED-NC (v2009)

45. Implementing DCV with ASHRAE 62.1 45 ASHRAE Standard 90.1-2010 (prescriptive requirement) Ventilation Reset 6.5.3.3 Multiple-Zone VAV System Ventilation Optimization Control. Multiple-zone VAV systems with DDC of individual zone boxes reporting to a central control panel shall include means to automatically reduce outdoor air intake flow (V ot ) below design rates in response to changes in system ventilation efficiency (E v ) as defined by ASHRAE Standard 62.1, Appendix A. Exceptions: a. VAV systems with zonal transfer fans that recirculate air from other zones without directly mixing it with outdoor air, dual-duct dual-fan VAV systems, and VAV systems with fan-powered terminal units. b. Systems required to have the exhaust air energy recovery complying with Section 6.5.6.1. c. Systems where total design exhaust airflow is more than 70% of total design outdoor air intake flow requirements. 6.5.3.3 Multiple-Zone VAV System Ventilation Optimization Control. Multiple-zone VAV systems with DDC of individual zone boxes reporting to a central control panel shall include means to automatically reduce outdoor air intake flow (V ot ) below design rates in response to changes in system ventilation efficiency (E v ) as defined by ASHRAE Standard 62.1, Appendix A. Exceptions: a. VAV systems with zonal transfer fans that recirculate air from other zones without directly mixing it with outdoor air, dual-duct dual-fan VAV systems, and VAV systems with fan-powered terminal units. b. Systems required to have the exhaust air energy recovery complying with Section 6.5.6.1. c. Systems where total design exhaust airflow is more than 70% of total design outdoor air intake flow requirements.

46. Implementing DCV with ASHRAE 62.1 46 CO 2 -Based DCV for Multiple-Zone HVAC Systems ASHRAE Research Project 1547 Compares various control sequences Further enhances control sequences and setpoints for multiple-zone recirculating ventilation systems

47. Implementing DCV with ASHRAE 62.1 47 Implementation of RP-1547 CO 2 -Based DCV Control Sequences ASHRAE Research Project 1747 “Valid logic was developed in RP-1547, but it is not readily implemented in real control systems.” “This project will develop practical control sequences, then test them in a real-world building environment with a commercial-grade DDC system.” RFP for ASHRAE Research Project 1747 “Valid logic was developed in RP-1547, but it is not readily implemented in real control systems.” “This project will develop practical control sequences, then test them in a real-world building environment with a commercial-grade DDC system.” RFP for ASHRAE Research Project 1747 Project began in September 2015 … with expected completion by February 2017

48. Implementing DCV with ASHRAE 62.1 48 DCV with ASHRAE Standard 62.1 Summary ASHRAE Standard 62.1 allows dynamic reset of ventilation air as operating conditions change ASHRAE Standard 90.1 is requiring DCV in more types of spaces Consider CO 2 -based DCV in densely-occupied zones with widely-varying population Use other DCV technologies (occupancy sensors, time-of-day schedules) where they make sense Combine DCV with ventilation reset in a VAV system to avoid the need to sense CO 2 in every zone

49. Implementing DCV with ASHRAE 62.1 49 DCV with ASHRAE Standard 62.1 Further Reading American Society of Heating, Refrigeration and Air-Conditioning Engineers, Inc. 2011. 62.1 User’s Manual. Atlanta, GA: ASHRAE. – Appendix A: CO 2 -Based Demand-Controlled Ventilation – Appendix B: Ventilation Reset Control Murphy, J. 2008. “CO 2 -Based Demand-Controlled Ventilation with ASHRAE Standard 62.1,” HPAC Engineering (Sep): pp. 36-47. Stanke, D. 2006. “Standard 62.1 System Operation: Dynamic Reset Options”, ASHRAE Journal (December): pp. 18-32. Stanke, D. 2010. “Dynamic Reset for Multiple-Zone Systems,” ASHRAE Journal (March): pp. 22-35. ASHRAE Research Project 1547. CO 2 -Based Demand-Controlled Ventilation for Multiple-Zone Systems. January 2014. ASHRAE Research Project 1747 (in progress). Implementation of RP-1547 CO 2 -based DCV for Multiple-Zone Systems in DDC Systems.