HVAC Technology Enhancements and Design Solutions

Transcription

1 HVAC Technology Enhancements and Design Solutions Energy Conservation Focus Ryan R. Hoger, LEED AP Environmental Impact of Buildings* 40% of total U.S. energy consumption 39% of total U.S. CO 2 emissions 72% of total U.S. electricity consumption *Commercial and Residential 1

2 Environmental Impact of Buildings* 100% USA Energy Consumption (BTU) 38.2% 28% 33.4% 32% Transportation Industry 40% 28.3% Buildings* Residential & Commercial Buildings 2010 DOE Buildings Energy Data Book Quadrillion BTU Site > dropped to in Quadrillion BTU Primary IECC 2012 effective 7/1/14 in Massachusetts 2

3 DOE A/C & Heat Pump Standards Effective Jan. 1, 2015 Note: Southern states now have higher requirements for SEER and sometimes EER. DOE Water Heater Standards Effective April 16,

4 Proposed Standards Furnaces increase from 78 to 80% AFUE 2015 Commercial Electric Motors May 2016 Furnace Fans essentially making ECM the min Pumps around Gas Boilers 90% minimum around Fans & Blowers, WSHP, PTACs, Room A/C, Icemakers, Commercial Refrigeration, Pool Heaters, Clothes Washers & Dryers, Dishwashers, Transformers, TV Set-top Boxes, Battery Chargers, Lighting, Stoves/Ovens, Fridges/Freezers, etc. Commercial Federal Tax CREDIT 30% for Solar Thermal 4

5 Utility Programs Funded by residential and commercial customers Line item on gas and electric bills that note monthly contribution to program In deregulated states, generally 3rd party suppliers also must collect fee Common Types of Utility Incentives Equipment Installation by Contractor Any contractor can facilitate Residential Prescriptive, Commercial Prescriptive, and Commercial/Industrial Custom Typical incentives include HVAC equipment and tune-ups, control systems, commercial lighting, etc. Multi-family and Small Business Direct Installs Generally the utility or pre-approved subcontractors do the work Typically include low flow shower heads, CFL bulbs, thermostats, etc. Energy Audits Generally the utility or pre-approved subcontractors do the work No or low cost audits are performed and incentives are available to take action on the identified solutions in the audit On-bill Financing (OBF) Generally for residential and small business 5

6 Commercial Consumption DOE Buildings Energy Data Book 8.88 Quadrillion BTU Site Quadrillion BTU Primary Commercial HVAC Energy Consumption 27% of all commercial HVAC energy is used by fans!!! 6

7 Existing Buildings 5 Million Commercial/Institutional Bldgs in US 300 Billion ft2 existing in 2000 Includes 82 billion estimated to be renovated before 2030 Over 70% of the estimated 427 billion ft2 buildings that will be standing in 2030 were already standing in 2000 Great opportunities for energy efficiency improvements in existing buildings Steps to Saving Energy Identify the areas of energy improvement potential Consider HVAC interaction with other building systems as related to energy use Act quickly on low/no cost improvements Consider capital investments in energy saving HVAC technologies 7

8 Identify Improvement Areas Investigation survey Find original documentation Plans and Specs Sequences of Operation As-built drawings Perform energy audit Benchmarking and utility analysis Energy Star Portfolio Manager Re-commission or retro-commission Use monitoring tools HVAC Interaction w/ Building Systems First reduce the cooling / heating load Lighting Upgrading to more efficient fixtures saves energy twice: Once for the lighting electricity itself And again for the reduced cooling required 8

9 HVAC Interaction w/ Building Systems First reduce the cooling / heating load Building Envelope Increase insulation and install it correctly The higher the R-value, the better then insulation HVAC Interaction w/ Building Systems First reduce the cooling / heating load Building Envelope Upgrade windows The lower the U-Factor, the greater resistance to heat flow, the better the window s insulation value The lower SHGC, the less solar heat it transmits 9

10 Existing Control System Issues Operator not effectively trained Systems have been locked out by operator Scheduling is not optimized (sometime running 24/7) Economizer control not optimal (too high of limit) Static pressure setting on variable speed pumps and AHU s too high. No auto reset on (variable speed) pumps and AHU s VFD locked out on (too high) of a minimum speed due to perceived requirement Supply air temp not reset to limit use of reheat Exhaust fans running continuously Retro-commissioning Most Common* Improvements *DOE / Lawrence Berkley National Lab Study

11 Retro-commissioning Savings for Key Improvements** **DOE / Lawrence Berkley National Lab Study 2009 RTU Study Results* *2004 Study by New Buildings Institute 503 RTUs at 181 Sites 11

12 HVAC Low/No Cost Opportunities Systems have never been commissioned at all Perform functional performance tests Economizer dampers and controls inoperative or in poor condition Test bi-annually - repair or replace Sensors not recalibrated on regular basis (especially enthalpy and CO2 sensors) Recalibrate sensors bi-annually Coils not properly cleaned HVAC Low Cost Opportunities High efficiency motors not utilized or oversized Do economic analysis and remove/replace with high efficiency motors where economically Upon burnout, upgrade to high efficiency Do a motor load test and right-size the motor Equipment in generally poor overall condition Initiate recommended O&M procedures - savings of 5-10% Inlet vane dampers utilized Replace with VFDs Pumps oversized and throttled back Trim pump impellers, right-size motors as appropriate Add VFDs 12

13 Capital Improvements to Strongly Consider Older than yrs RTU s Electric boilers Control systems Older than years Chillers and cooling towers Condensers Fans, pumps, and motors Boilers Any age Systems w/ constant volume pumping Pneumatic controls systems Programmable Thermostats & Occupancy Controls 13

14 Programmable Thermostats Stop running heating/cooling 24/7!!! Relaxes heat/cool setpoints when space not occupied Only setback about 5º (use 65º for heat and 80º for cooling) Need to setback minimum of 6 hours to be effective On average saves 25-30% on heat/cool energy* If installed in every home would save about 5% of total US energy consumption* *John Hopkins Univ. AICGS Policy Report Programmable Thermostat Study Results* Residential stats responsible for 11% of total US energy What kinds of stats do people have? 14% have no stat at all 56% non-programmable 30% programmable Of those with programmable stats 89% have rarely or never programmed a stat Only 30% of programmable stats are actually programmed In winter, 60% use for night setback, only 45% setback during day In summer, 55% use for night, same for day time 2003 Carrier study also revealed that 53% of prog stats were in hold * DOE, EPA, and Lawrence Berkley National Labs Study 14

15 Programmable Thermostats Easy to retro-fit Adaptive Intelligent Recovery 2-stage stat for integrated economizer as 1 st stage Shut off ventilation during unoccupied hours Internet accessible Payback less than 6 months *John Hopkins Univ. AICGS Policy Report Internet Thermostats Low cost alternative to BAS Ethernet or Wi-Fi No PC software uses standard web browser No access fees Text/ alerts 15

16 Internet Thermostats Internet Thermostats 16

17 Phone Apps for Thermostats Occupancy Sensors Motion detectors Control lights and HVAC in transient spaces Light activated thermostats Control HVAC when lights on Payback less than 3 months CO2-based Demand Controlled Ventilation (DCV) Legally reduce code vent air Payback less than 18 months Operable window interlock Disables zone heat/cool Unmanned spaces - parking garages, loading docs, etc. Up to 80% fan energy reduction 17

18 Economizers Outdoor Air Economizers Use outside air for free cooling instead of compressors 3 main types of control Dry-bulb Temperature (enable when OA < 60º) Enthalpy (enable when OA < 70º and humidity low) Differential Enthalpy (is OA better than RA?) 18

19 IECC 2012: Commercial Economizers IECC 2012 already required 13 states Also additional requirements for relief/exhaust, integrated economizer, types of economizer control, water-side economizers, etc. Helena MT Duluth, MN Boise, ID Chicago, IL Burlington, VT Salem, OR Baltimore MD San Francisco CA Phoenix, AZ El Paso, TX Memphis TN Miami FL Albuquerque, NM Houston, TX 19

20 Outdoor Air Economizers Integrated economizer Economizer assists compressors on certain days Building pressure relief needed Occupancy control Open to ventilation position only when building occupied (interlock to time clock of stat) instead of whenever fan on Payback less than 6 months Outdoor Air Economizers 20

21 Variable Speed Drives and Zoning Systems Variable Frequency Drives (VFDs) Retro-fit to fans and pumps Varies the power input to motor On average building fan systems in the US are oversized by 60%* If a motor running at 100% speed costs $1,000/month, what about: Running at 75% speed = $420 Running at 50% speed = $125 Soft start means less wear & tear on couplings, belts, and motors Payback less than 18 months *John Hopkins Univ. AICGS Policy Report 21

22 FAN LAW BASICS Energy saved... Let s quickly re-visit the third fan law: 9 8 Third Fan Law Brake horsepower (BHP) varies as the cube of the fan speed: For simplicity, if we assume RPM 1 = 1000, BHP 1 = 2.0, and then decrease fan speed to 677 RPM (or 67%) Flow and Power Relative Wheel Velocity CFM BHP VAV Zoning Systems Diversity credit Fan energy reduction Supply air reset Static reset 15-50% energy savings* Improved comfort ROOFTOP HEATING AND COOLING UNIT ROOF CEILING PLENUM RETURN SUPPLEMENTAL REHEAT RETURN THROUGH CEILING PLENUM ZONE 1 ZONE 2 ZONE 3 ZONE 4 *2011 DOE Report Energy Savings Potential and RD&D Opportunities for Commercial Building HVAC Systems 22

23 Single Zone VAV or Staged Air Volume (SAV) Improves humidity control and saves energy Saves about 25-30% electrical energy in Midwest climate Minimum OA needs means of automatic adjustment when fan slows Similar logic could potentially be applied to heating mode if RTU has multiple stage heat, but pay attention to heat exchanger airflow needs Variable Speed Pumping Retro-fit Add VFDs to pumps Hot or chilled water systems Usually required by code on new systems Control to differential pressure at farthest coil Requires 2-way valves at each zone Need bypass pipe at end of line or one far zone with 3-way valve Be sure to maintain minimum flow thru chillers Use flow meter 23

24 Capital Improvements Building Automation Systems Centralized controls Change scheduling for multiple HVAC units at same time Monitor health of equipment Internet accessible Alarming via text msg or Collect/trend data Integrate to lighting control or security system 24

25 Chiller Plants Series counterflow About 15% energy reduction Waterside economizer Free cooling option Paybacks less than 3 years Evaporative condensing 35-50% energy reduction vs. air-cooled CH CH Boiler Plants New standard cast iron boilers are typically 80% efficient Even the best are only 82-88% Older boilers from the 1960, 70, & 80 s are only 50-70% Condensing boilers are typically 93-96% Best are 98%, lowest are 90% Choosing a 95% boiler vs. 80% will save about 16% energy Going from 60 to 98% will save 38% Outside air reset saves another 10-15% 25

26 Outside Air Reset Adjusts the boiler water setpoint based on outside air temp When 0 F outside, you need design water temp (usually 180 F) When 60 F out, may only need 120 F (or 150 F for non-cond. boilers) Don t use a mixing valve for OA reset on a condensing boiler Built-in control feature of most condensing boilers 26

27 Outside Air Reset for Radiant Floor Instead of 120 to 180 F, the reset will probably be 85 to 110 F, as the outdoor temp drops from 60 to 0 F. OA reset will be temporarily overridden for domestic water or snow melt run cycles Outside Air Reset for Old Non- Condensing Boilers Can also be added to old-style cast iron boilers, but requires mixing valve and separate controller, can t let boiler condense so must maintain 155 F minimum supply temp (and 135 F return), energy savings will not be as good 27

28 Geothermal Systems Water Source Heat Pumps (WSHP) Reject heat to ground instead of air or cooling tower Pull heat from earth in winter Heat/Cool Geo Chiller Uses standard fan coils in zones, not heat pumps AC chiller = 3 COP, WC chiller = 5 COP, Geo chiller = 6 COP Elec. Heat = 100%, Gas boiler = 90%, Geo heat chiller = 350% 28

29 Potential HVAC Energy Conservation Analyzed 40 technologies Summary report shows top 15 technologies Power station provides about 1.1 quad per year 1 quad = BTU/H U.S. Department of Energy July DOE Study U.S. Department of Energy July

30 Dedicated Outdoor Air Systems (DOAS) Decouples outdoor air loads from space heat/cool loads Improvements to IAQ Combines well with ERV, radiant, chilled beams, VRF, displacement ventilation, geothermal, fan coils, etc. Energy Recovery Ventilators (ERV) (detailed module this afternoon) Uses exhaust air to pre-heat or pre-cool ventilation air Can be adapted to existing systems HRV or ERV? Wheel or fixed plate? Improvements to IAQ Required by code in some cases Paybacks less than 24 months 30

31 Variable Refrigerant Flow (VRF) (detailed module this afternoon) Up to 40 indoor units on single/dual condensing unit Diversity credit Very high heating COP - 3 to 4 times as efficient as electric resistance or gas heat Ease of retro-fit Simultaneous heating and cooling in different zones Individual zone control Improved humidity control Radiant Cooling (detailed module this afternoon) Used with DOAS to de-couple outdoor air loads from space heat/cool loads Reduction in the required air handler CFM Higher temperature chilled water utilized, providing more efficient chiller performance, potential to double the COP if dedicated chiller loop is used PEX tube in floors, ceilings, and/or walls Radiant ceiling panels 31

32 Chilled Beams (detailed module this afternoon) Developed in 1980s and very popular in Europe Used with DOAS Active or passive beams OA + induction = supply airflow Up to a 60% reduction in the required air handler CFM Higher temperature chilled water is utilized (57-62 F), thus providing more efficient chiller performance More Thoughts 32

33 Right Sizing Equipment On average building fan systems in the US are oversized by 60%* Most chillers are oversized by 50 to 200%** Spend < 1% of operation at full load Don t add safety factors when sizing or selecting Better dehumidification Smaller equipment will dehum better allowing higher cooling setpoints Less temperature swings Equipment runs even cycles instead of rapid on off on Lower first cost Smaller is better *John Hopkins Univ. AICGS Policy Report **US EPA Report Good Energy Management is Good Business Worker Productivity Costs MORE than Energy Pie charts: ASHRAE Journal July 2013 Table: U.S. Department of Energy July

34 Resources ASHRAE 90.1 Updated every 3 years Specifies minimum energy performance for new buildings International Energy Conservation Code (IEEC) ASHRAE: Energy Efficiency Guide for Existing Commercial Buildings The Business Case for Building Owners and Managers Dr. Stanley Mumma s DOAS Website Resources ASHRAE Advanced Energy Design Guides Prescriptive approach by climate zone 30% Guides Save 30% more energy than ASHRAE versions published: Office, Retail, School, Warehouse, Hotel, Healthcare 50% Guides Save 50% more energy than ASHRAE versions published: Office, Retail, School, Hospital Free download at 34

35 Resources Financing Utility Rebates Federal Tax Incentives HVAC Equipment Leasing ESCO 35

36 Ryan R. Hoger, LEED AP Special Thanks to those who allowed me to use their slides or graphics today Ryan R. Hoger, LEED AP