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Julian R. de Bullet ASHRAE Distinguished Lecturer debullet Consulting
SESSION OBJECTIVES At the end you should be able to: 1. Explain why a mechanical engineer should understand ASHRAE Standard 90.1-2010 2. Select the appropriate unit efficiency for a project and adjust a chiller for non-standard conditions 3. Explain when an economizer must be used 4. Describe when reheat is allowed 5. Use the fan system limitation calculation 6. State when heat recovery must be used
ASHRAE 90.1-2010 BECOMES CODE As a result of DOE s ruling, and by the authority provided through the Energy Conservation and Production Act, as amended, states are required to certify by Oct. 18, 2013 that they have reviewed the provisions of their commercial building code regarding energy efficiency and updated their code to meet or exceed Standard 90.1-2010. States may request extensions of this deadline from DOE if a state can demonstrate that it has made a good faith effort to comply with this code update.
STANDARDS AND RATING PROGRAMS Move to High Performance Buildings ASHRAE 62.1 2010 ASHRAE 90.1 2010 ASHRAE 189.1 2010 LEED 2012 ASHRAE 62.1 2007 ASHRAE 90.1 2007 LEED V3 2009 Used as baseline ASHRAE 90.1 2004 LEED V2.2 2005 ASHRAE 62.1 2004 LEED V2.1 2002 ASHRAE 90.1 1999 LEED V2.0 2000 ASHRAE 90.1 1989 ASHRAE 62.1 1989 LEED V1.0 1998 ASHRAE 90.1 1980 ASHRAE 62.1981 ASHRAE 90.1 1975 ASHRAE 62.1 1973 LEED is a registered trademark of the U.S. Green Building Council.
Codes in Effect 8
Projected Code Adoption Dates 9
ASHRAE 90.1-2007 ASHRAE 90.1-2010 109 Addenda included, 52 affect HVAC
ESTIMATED SAVINGS 2007 TO 2010 11
MAJOR CHANGES IN 90.1-2010 1. Scope expanded to cover plug and process loads (data centers) 2. Building envelope more stringent and high albedo roofs included 3. Interior Lighting Power Densities lowered, mandatory daylight controls and exterior lighting zones 4. Expanded equipment efficiencies, new energy recovery requirements, additional control requirements 5. Expanded energy modeling requirements (LEED ) LEED is a registered trademark of the U.S. Green Building Council. 12
ASHRAE 90.1 PURPOSE- CHANGES To provide minimum energy efficient requirements of buildings other than low-rise residential for: 1. Design, construction and a plan for operation & maintenance 2. Utilization of on-site renewable energy resources
ASHRAE 90.1 SCOPE Where required Applies to: 1. New Buildings and systems 2. New portions of buildings or systems 3. System & equipment additions in existing buildings 4. Covered portions of manufacturing facilities Does not apply to: 1. Single family, residential less than 3-story above grade or modular houses 2. Buildings that do not use electricity or fossil fuel
PATHS TO COMPLIANCE Mandatory These provisions must be met under all circumstances and performance can not be traded Example HVAC equipment efficiency Prescriptive These provisions are met by using the prescriptive value or using the performance method Example Air side economizer Energy Cost Budget (Performance) Allows trade-offs of prescriptive options if the total cost is equal to or less than the prescriptive option
ECB VS. PRM Energy Cost Budget Method Used to determine trade-off of performance of one feature against another feature Only part which is code intended Performance Rating Method Used to determine the improvement in performance of proposed versus baseline building
PRIMARY SECTIONS ASHRAE 90.1 2010 Regulated Sections Sect. 5.4 & 5.5 Envelope Requirements Sect. 6.4 & 6.5 HVAC Equipment Sect. 7.4 & 7.5 Service Water Heating Sect. 8.4 Power voltage drop Sect. 9.4 & 9.5 Lighting control and density Sect. 10.4 Electric Motors * See WWW.energycodes.gov/implement/determinations_com.stm
CLIMATE ZONES Marine (C) Dry Moist (A) All of Alaska in Zone 7 except for the following Boroughs in Zone 8: Bethel Dellingham Fairbanks N. Star Nome North Slope Northwest Artic Southeast Fairbanks Wade Hampton Yukon-Koyukuk Zone 1 Includes Hawaii, Guam, Puerto Rico, and the Virgin Islands Zone 1
EXERCISE 2. ASHRAE 90.1 has requirements that do not regulate the energy use of which of the following? a) Lighting power density b) Plug power from computers c) Task lighting d) Minimum insulation values for roof e) Power limit for pumps on an ornamental water garden f) Maximum amount of ventilation air that can be provided g) Data centers h) Plug loads
SECTION 6 HVAC Section 6 Heating, Ventilation and Air Conditioning 6.1 General 6.2 Definition of Compliance Paths 6.3 Simplified Approach 6.4 Mandatory Provisions 6.5 Prescriptive Path Section 11 Energy Cost Budget Method 6.7 Submittals
MAJOR CHANGES TO HVAC 1. Process applications added (data centers) 2. Updated efficiency tables and added equipment types 3. Liquid to liquid heat exchangers now covered under AHRI 400 4. Restrictions on pump head and pipe sizing 5. VAV requirement for CW and DX single zone units 6. Significant increase in insulation for ducts and pipe 7. Added radiant panel system requirements 8. Changes to airside economizer requirements 9. Changes to damper leakage requirements 10. Changes to reheat / recool minimum use and application 11. Requirement for dynamic ventilation control on VAV requirement from Std 62.1 12. Limit on use of centrifugal fan open towers 13. A climatic based requirement for energy recovery 14. New requirements for garage and kitchen ventilation 15. New requirements for laboratory exhaust
SIMPLIFIED APPROACH 1. Building is two stories or less 2. Gross floor area is 25,000 ft 2 3. HVAC system serves one zone 4. Must have single zone VAV capability 5. Cooling system is unitary packaged or split system that meet the required efficiencies 6. Economizer must be used if required by climate zone 7. Heating must be by heat pump or furnace that meets the required efficiencies 8. Energy recovery if zone and outdoor air requirement are met 9. Must use a manual changeover thermostat 10. Heat pump lockout of supplementary heater required Star indicates an important change
SIMPLIFIED APPROACH (CONTINUED) 11. Reheat and simultaneous heating and cooling is prohibited even for humidity control 12. Units with motors greater than ¾ hp must have a time clock with 2-hr override, and provide setback to 55⁰F and set-up to 90⁰F 13. Pipes must be insulated per requirements 14. Duct must be sealed and insulated per requirements 15. Air balance required 16. Multiple units to a space must be interlocked 17. Exhaust in a system over 300 CFM must be equipped with gravity or motorized damper 18. Systems over 10,000 CFM must have optimum start control
EXERCISE 3. Which of the following is not a case covered by the scope of ASHRAE 90.1 2010? Choose one answer. a) The area of a building being renovated if it is more that 50% b) Refrigerant change - out with existing equipment that does not comply c) A new building that is heated but not cooled d) A high rise apartment building where the tenant furnishes their own AC unit
EQUIPMENT EFFICIENCIES Tables 6.8.1A Air Conditioners and Condensing Units 6.8.1B Heat Pumps 6.8.1C Water Chilling Packages 6.8.1D Packaged Terminal and Room Air Conditioners 6.8.1E Furnaces, Duct Furnaces, and Unit Heaters 6.8.1F Boilers 6.8.1G Heat Rejection Equipment 6.8.1H Heat Transfer Equipment 6.8.1I VRF Air Conditioners 6.8.1J VRF Air-to-Air & Applied Heat Pumps 6.8.1K Computer Room Units
EQUIPMENT EFFICIENCIES-ALL CHANGED Air-Cooled Packaged 30% Increase 17% Increase Note: Both requirements must be met
EQUIPMENT EFFICIENCIES-CHANGES Water-Cooled Packaged
IMPACT OF ASHRAE 90.1 2010-CHANGES Air Conditioner ASHRAE 90.1 -- 2004 Air Conditioner ASHRAE 90.1 -- 2010 28
EQUIPMENT EFFICIENCIES Example Unit
CHILLER EFFICIENCIES- CHANGES 3.516 COP kw / ton Conditions: 44F LWT 85F ECWT 3 GPM/ton Path A Normal duty Path B Continuous duty
EXAMPLE CHILLER AT NON-STANDARD Assume we have a 750 ton centrifugal chiller that meets path A requirements Full load kw/ton = 0.570, IPLV = 0.539 Lvg Cond = 91.16 F Lvg Evap = 42 F Lift = 91.16 42 = 49.16 F A = 0.0000014592 x (49.16) 4 0.0000346496 x (49.16) 3 + 0.00314196 x (49.16) 2-0.147199 x (49.16) +3.9302 A = 1.0228 B = 0.0015 x 42+ 0.934 = 0.9970 Adj Full Load kw/ton = 0.570/(1.0228 x 0.9970) = 0.559 NPLV = 0.539 /(1.0228 x 0.9970) = 0.529
EXERCISE 1. When evaluating if a chiller with lower efficiency can be substituted for the mandatory requirement of ASHRAE 90.1 2010 for chiller efficiency which method should be used? Choose one answer. a) The Appendix G Performance Rating Method b) The Section 11 Energy Cost Budget Method c) The prescriptive requirement from Section 6.4 d) None, since it is a mandatory requirement
REQUIRED CALCULATIONS 6.4.2.1 Load Calculations Heating and cooling loads must be calculated per ANSI / ASHRAE / ACCA Standard 183-2007 Peak Heating and Cooling Calculations in Buildings Except Low-Rise Residential 6.4.2.2 Pump Head Pump head must be calculated by the pressure drop in the critical circuit at design
6.4 MANDATORY REQUIREMENTS Ventilation Controls 6.4.3.4.1 Stair shafts and elevators must have motorized shut-off dampers 6.4.3.4.2 1) Outdoor air and exhaust must have automatic dampers with ability to shutoff during warm-up, cool-down and unoccupied times Gravity dampers allowed For exhaust and relief if building is 3 story For Intakes in Zones 1,2,3 System is less than 300 CFM
6.4 MANDATORY REQUIREMENTS Ventilation Controls 3) Damper leak rate: Ventilation Exhaust / Relief Gravity Motorized Gravity Motorized Zone 4,5b,5c < 3 Story Not allowed 10% 20% 10% 3 Story Not allowed 10% Not Allowed 10% Zone 5a,6,7,8 < 3 Story Not allowed 4% 20% 4% 3 Story Not allowed 4% Not Allowed 4%
6.4 MANDATORY REQUIREMENTS Ventilation Controls 6.4.3.4.4 6.4.3.4.5 Ventilation fans greater than ¾ hp must have automatic shutdown capability when not required Enclosed parking garages shall be able to modulate to 50% or less of design airflow if contaminate levels are maintained
6.4 MANDATORY REQUIREMENTS 6.4.3.5:Heat Pump Auxiliary Heat Control Supplemental heater must have controls that prevent operation when the heat pump is capable of meeting the load during operation and recoveryheater operation is permitted during defrost 6.4.3.7:Humidification and Dehumidification System must be able to prevent humidification from working when dehumidification is active 6.4.3.8:Freeze Protection and Snow Melting Systems Must be deactivated above 40⁰F
6.4 MANDATORY REQUIREMENTS 6.4.3.9:Ventilation Controls for High Occupancy High occupancy is > 40 people/1000 ft 2 For spaces > than 500 ft 2 require DCV if system has: Airside economizer Automatic modulating control of outdoor air damper Airflow > 3000 CFM Unless: System exhaust energy recovery (6.5.6.1) System does not have a DDC system System outdoor airflow is 1,200 CFM
SINGLE ZONE VAV CONTROLS 6.4.3.10 1. CW AHU or fan coil with motor >5 hp must have either 2 speed motor or VFD to reduce airflow at 50% demand or less to either a) ½ of full speed b) Airflow required for ventilation per Std 62.1 2. As of 1/1/2012 DX units 110,000 Btuh or more must have either 2 speed motor or VFD to reduce airflow at 50% demand or less to 1) ⅔ of full speed 2) Airflow required for ventilation per Std 62.1
DUCT SEALING 1. All duct above 2 wg. and upstream of VAV boxes must be sealed to class A 2. Pressure testing of minimum of 25% of duct area required on duct systems over 3 wg.
EXERCISE 4 1. Select 3 mandatory requirements of ASHRAE 90.1 2010 related to HVAC units? Pick at least three answers. a) HVAC equipment part load efficiency b) 20 degree differential in WSHP loop boiler off to cooling tower on temperature c) Pumps with over 50 HP must have a VFD d) Reheat limited to less than 0.4 CFM / ft 2 e) Motorized damper leakage at no more than 10 CFM / ft 2 f) Optimum start control for systems over 10,000 CFM g) Dead band of at least 5 F between heating and cooling setpoint
6.5.1.ECONOMIZER REQUIREMENTS Comfort Cooling (air or water) All zones except 1a and 1b 54,000 Btu/h Computer Rooms Zones 1a, 1b, 2a, 3a, 4a - Not required Zones 2b, 5a, 6a, 7, 8 135,000 Btu/h Zones 3b, 3c, 4b, 5b, 5c 6b 65,000 Btu/h Exceptions: Non-particulate air treatment required by Std 62.1 Hospitals with >75% space requiring humidification above 35 F dewpoint Condenser heat recovery is used Residential spaces If internal sensible cooling at design is less that transmission at 60F System operation less that 20 hr / week Supermarkets when it will impact case If unit efficiency exceeds 42% better in 4a and 49% better in zone 5a Computer rooms in some conditions
6.5.1.1 PRESCRIPTIVE REQUIREMENTS Economizers Air Economizer Modulate outdoor air and return air to provide 100% of supply air quantity must provide relief Must be integrated with cooling and can not be controlled only by mixed air temperature Relief that prevents recirculation must be provided High limit cut-off Control Zone 4a Zone 5a Fixed Dry Bulb Not Allowed T OA > 70 Differential Dry Bulb Not Allowed T OA > T RA Fixed Enthalpy h OA > 28 Btu/lb Electronic Enthalpy Differential Enthalpy Dew-point and dry-bulb (T OA,RH OA )> A h OA > h RA DP OA >55F or T OA > 75F
6.5.1.2 PRESCRIPTIVE REQUIREMENTS Economizers Water Economizer Provide 100% of capacity by indirect evaporative cooling at 50⁰F DB and 45⁰F WB Pressure drop can not exceed 15 ft on primary or use a secondary loop Must use integrated economizer Except: Some computer room applications System where dehumidification requirements can not be met at 50⁰F DB and 40⁰F WB 6.5.1.4: All Economizer Economizer operation can not increase the need for heating energy at normal conditions
EXERCISE 5 5. A chiller using glycol solution with a freezing point less than 27⁰ F should use which efficiency rating condition? Select one answer a) Full load kw / ton b) Full load COP c) Part load IPLV d) None These are outside the range e) EER rating f) IEER rating
6.5.2 PRESCRIPTIVE REQUIREMENTS Simultaneous Heating and Cooling Limits Zone controls must prevent: Reheating Re-cooling Mixing of air that has been mechanically heated or cooled by mechanical cooling or economizer Other simultaneous operation of heating and cooling
6.5.2 PRESCRIPTIVE REQUIREMENTS Simultaneous Heating and Cooling Limits Condition 1 Exceptions where reheat is allowed if the air reheated is less than the larger of the following: 1. Air is no less than the required zone ventilation air per Standard 62.1 2. Air is < 30% of peak design airflow 3. If allowed by AHJ when shown that it reduces total energy 4. Zones requiring pressure differential or code requirement AHJ: Authority having jurisdiction
6.5 PRESCRIPTIVE REQUIREMENTS Simultaneous Heating and Cooling Limits Condition 2 Exceptions where reheat is allowed if the zone meets all the following: 1. Airflow rate in the dead band between heating and cooling is not larger than: 1. 20% of the zone peak airflow 2. Required zone ventilation air per Standard 62.1 3. If allowed by AHJ when shown that it reduces total energy 2. Reheat, recooled or mixed air is less than 50% of peak 3. Airflow between dead band and full heating and full cooling can be modulated
6.5 PRESCRIPTIVE REQUIREMENTS Simultaneous Heating and Cooling Limits Condition 3 Exceptions where reheat is allowed if: 1. Laboratory exhaust that meets Section 6.5.7.2 Condition 4 Exceptions where reheat is allowed if: 1. 75% of the reheat energy is from site recovered energy or site-solar assisted energy
EXERCISE 6. New energy for reheat is allowed in which 3 of the following situations? Select three answers. a) The airflow has been reduced to the minimum ventilation air allowed by ASHRAE 62.1 b) Minimum air volume is < than 0.4 CFM/FT 2 c) Reheat is only allowed if no new energy is used d) Reheat is never allowed except in process applications e) Air being reheated is < 30% of peak design airflow
6.5 PRESCRIPTIVE REQUIREMENTS Air System Design and Control Systems over 5 hp total system nameplate must meet the fan hp limitation based on name plate hp Fan Power limitation Supply fans, return fans, relief fans, exhaust fans and fan-powered terminal units must meet option 1 or option 2 Exceptions: Hospital and labs where pressure differential must be maintained can use VAV fan power limit Individual exhaust fans with motor name plate of 1 hp or less Motor nameplate can be no larger than the next available motor size Exceptions: If bhp is < 6 motor can be within 50% of bhp If bhp is 6 motor can be within 30% of bhp
FAN POWER EXAMPLE Option 1 VAV system supplying 25,000 CFM hp limit = CFMs x 0.0015 = 25,000 x 0.0015 = 37.5 hp Maximum is then 37.5 Nameplate hp AHU systems with 30 hp supply and 7.5 hp exhaust nameplate motors would be acceptable Option 2 Same systems full ducted and MERV 13 filters hp limit = CFM s x 0.0013 + A A = Pd x CFM / 4131 A duct = 0.5 x 22,000/4131 = 2.66 A MERV 13 = 0.9 x 25,000/4131 = 5.44 hp limit = 25,000 x 0.0013 +2.66 +5.44 = 40.6 bhp Maximum is then 40.6 bhp 52
6.5.3.2 VAV FAN POWER LIMITS (Includes series fan power boxes) All motors 10 hp and larger must: 1. Be driven by a mechanical or electrical variable speed drive 2. Or use a vane-axial or variable pitch fan 3. Or have controls that will reduce motor demand to 30% of design watts at 50% flow Static pressure sensor must be placed so that the controller setpoint is no more than 1/3 of total design static On DDC systems static setpoint must be reset by the zone with the largest demand 53
SUPPLY AIR TEMPERATURE RESET Multiple zone systems must (6.5.3.3): Provide reset control of supply air in response to load or outdoor air temperature Must be capable of resetting 25% of the difference between supply air and room setpoint Reset based on humidity is allowed Equipment rooms (data centers) must be able to fully reset Except: Zones 1a, 2a and 3a Systems that prevent reheating, re-cooling or mixing Systems with 75% reheat energy from site recovered or site solar 54
EXERCISE 7. ASHRAE 90.1 has a prescriptive requirement which limits the fan power energy. Which of these statements is true? Select one answer a) The calculation only applies to the power at part load conditions of VAV units using a variable frequency drive b) A correction factor is applied when filters with a MERV rating greater than MERV 8 are used c) The calculation of fan power applies to supply, return, and exhaust fans but not the fans in VAV fan powered terminals. d) The power calculation must be based on the nameplate rating of the motor only
6.5.4 PRESCRIPTIVE REQUIREMENTS Hydronic System Control Systems with pumps 10 hp and larger and control valves must be capable of reduction to 50% design flow Pumps over 5 hp must have the ability to reduce to 30% power at 50% flow Controls shall function to maintain minimal pressure differential and drive the valve with the greatest demand full open Differential pressure should be no more that required for 110% of heat exchanger flow Exceptions: Flow less than manufactures minimum where pump hp is 75 hp or less System has no more than 3 control valves
6.5 PRESCRIPTIVE REQUIREMENTS Hydronic System Control Pumps on systems with more than one chiller must have isolation of the used chiller (6.5.4.2) Chilled and hot water in systems > 30,000 Btu/h must reset chilled and hot water temperature based return water temperature or outdoor temperature (6.5.4.3) Except: When control reset will cause improper operation of heating, cooling, humidifying or dehumidification Hydronic systems using variable flow pumping Hydronic loops must use two-position isolation valves to stop water flow when the compressor is off applies to WSHP and unitary water cooled units
6.5.6 PRESCRIPTIVE REQUIREMENTS Energy Recovery Exhaust air energy recovery is required if: Exhaust Air Heat Recovery
EXERCISE 8. Heat recovery is required by ASHRAE 9.1 2010 under certain conditions. Which requirements are true? Select one answer. a) In zone 5a the airflow is 5500 CFM and 30% is outside air b) The energy effectiveness is less than 50% c) An economizer is not required if an ERV with a thermal effectiveness of 50% or better is used d) Energy recovery is required if 75% of the lab hood are not controlled by a demand control ventilation or schedule
6.5.9 PRESCRIPTIVE REQUIREMENTS Hot Gas Bypass Limitation Cooling systems can not use hot gas bypass or evaporator pressure control unless multiple steps of capacity are provided and maximum hot gas is limited to: 240,000 Btu/h 50% maximum > 240,000 Btu/h 25% maximum Exception: Unitary systems less than 90,000 Btu/h This includes screw and centrifugal machines and is based on the system size IE: 100 ton machine can not bypass more than 25 tons
10.4.2 Service Water Booster Systems One or more pressure sensors shall be used to vary the pump speed and/or start and stop the pumps. No device shall be installed for the purpose of reducing the pressure of all of the water supplied by any booster system pump or booster system, except for safety devices. No booster system pumps shall operate when there is no service water flow Conclusion Every booster pump system will be variable flow 61
ASHRAE 90.1 NORMATIVE APPENDIX G Performance Rating Method Demonstrate a percentage improvement above the baseline building Note: Based on energy costs Must meet 90.1 mandatory requirements Must include all project energy costs Baseline building must comply with Appendix G requirements Process energy requirements Appendix G is for modeling improved performance not tradeoff calculations
THANK YOU! 63