Building Control Strategies That Work to Improve Your Energy Bottom Line

Transcription

1 Building Control Strategies That Work to Improve Your Energy Bottom Line William D. (Skip) Milton MBA, CEM, CEA Assistant Director of Facilities Operations Texas Children s Hospital

2 Objective: Learn how to implement no cost/low cost measures to reduce your facilities energy cost.

3 Definitions: Baseline: Facility energy cost prior to implementation of any ECM s. Balance Point: Theoretical OAT that building does not require heating or cooling. Benchmark: Comparison of performance to an industry standard. Delta (Δ): Change in a measured or controlled process variable. Energy Conservation Measure (ECM): Measures that reduce energy usage or cost. Energy Use Index (EUI): BTU s per Square Foot of Gross Space (Benchmark Value) Dollars per Square Foot of Gross Area (Baseline Value) Measurement and Verification (M&V): Process of validating the performance of implemented ECM s Reset Ratio: The slope of a variable medium set-point based upon a measured vairable.

4 Before You Start! 1. Gather your facilities most update design documents (MEP) drawings and schedules. 2. Check, and record, current settings and sequences against the design documents. 3. Use this information as your reference base for future changes.

5 Establishing a Baseline This is simple. Just total a years cost of energy for a facility and device by the facility's gross square footage. You may desire to baseline individual months cost.

6 Example of yearly energy cost compared to gross area 7.00 TCH Energy Cost vs. Campus Square Footage FY07 FY08 FY09 FY10 FY11 FY12 $/SF SF 1,000,000 Note that the baseline was established in 2007

7 Benchmarking Use the Portfolio Manager located at: IT IS FREE!

8 ECM #1 Audit Monthly Utility Bills. Electric bills are clear as mud!

9 ECM #1 Audit Monthly Utility Bills. 1. Check invoice to determine if meter was read or if the charges are for an estimated reading. If estimated ask utility why the meter was not read and how the estimate was determined. 2. Compare pervious month s ending meter reading with this month s beginning meter reading. They should be the same. 3. Apply the current rate schedule to the measured commodity. The results should match the billed amounts. 4. Verify that the proper taxes are charged. 5. Compare month s usage to usage for the same month last year. 6. Document errors and notify the utility, in writing, of the errors.

10 ECM #2 Yearly Inspect Calibrate and/or Replace Equipment Sensors: Temperature, Relative Humidity, Pressure, Flow, (Air and Liquid) Kwh, KW, BTU,

11 ECM #2 Yearly Inspect Calibrate and/or Replace Equipment Sensors: 1. Establish a sensor replacement parameter. i.e. specified % offset requires replacement instead of calibration. 2. Insure sensor is correct for the application and is located in the correct position to measure the sensed variable. 3. Verify current sensed value against a separate calibrated instrument value. 4. If values are different calibrate or replace faulty sensor. 5. Flow sensors require annual cleaning.

12 ECM #3 Establish and Implement Room Temperature Set Points.

13 ECM #3 Establish and Implement Room Temperature Set Points. 1. Start out with public areas and commercial spaces. 2. Establish reasonable cooling and heating limits for your facility. 3. For electro mechanical thermostats use set-point limits and T-stat guards. 4. For electronic thermostats use programmable settings. 5. For BAS space sensors with or without set-point adjustment install limits in controllers. AHU, Terminal units, VAV boxes 6. Regularly inspect values to insure continued compliance.

14 ECM #4 Schedule occupied/unoccupied operation of equipment: Space temperature set points, Lighting, AHU s, Chiller/s, Boilers, and

15 ECM #4 Schedule occupied/unoccupied operation of equipment: 1. Meet with staff to develop agreed upon occupied/unoccupied schedules. 2. Consider EVS after hours cleaning schedules. 3. HVAC and lighting schedules for the same space may be different. 4. Consider installing timed override capabilities for some area/s. 5. Consider using daylight harvesting where possible. 6. Insure and communicate measures to alter schedules for special use requirements. 7. Communicate schedules to entire O&M staff. 8. Get ready to address questions.

16 ECM #5 Control Chilled Water Δ-T

17 ECM #5 Control Chilled Water Δ-T Calculating Savings: ΔT = (CHWR Temp CHWS Temp) Deg. F BtuH = (GPM x 8.34) X ΔT TonH = BtuH/12,000

18 ECM #5 Control Chilled Water Δ-T 1. Research CHW Low Delta-T Syndrome on Internet. 2. Consider controlling ΔT from 13F to 18F. 3. Determine sweet spot for your facility. 4. Control ΔT values manually or automatically. 5. Outside air temperature drives ΔT values. 6. Monitor AHU SA temperatures for positive cold deck temperature droop. 7. Check final filters for any condensation. 8. Check ΔT values at least daily.

19 ECM #6 Control Heating Medium Temperatures. Consider Outdoor Air Temperature Reset for Hot Water

20 ECM #6 Control Heating and Cooling Medium Temperatures. Consider Outdoor Air Temperature Reset for Hot Water. 1. Base HVAC heating water temperature on OAT. 2. Colder OAT requires warmer water and warmer OAT requires cooler water. 3. Set lower water temperature value at, or near, building balance point. 4. Set upper temperature limit at OAT value requiring significant cooling. 5. Heating water example: HW-T= 110F when OAT = 55F HW-T= 60F when OAT = 85F (The values are dependent on the building and HVAC system capabilities)

21 ECM #7 Control Heating and Cooling AHU Deck Temperatures. Consider Outdoor Air Temperature Reset

22 ECM #7 Control Heating and Cooling AHU Deck Temperatures. Consider Outdoor Air Temperature Reset This is the same concept as the previous reset tactic Cooling example: AHU Cooling SA-T = 55F when OAT = 85F AHU Cooling SA-T = 58F when OAT = 55F (The values are dependent on the building and HVAC system capabilities)

23 ECM #8 Adjust Air Flows to Meet Code Minimums. Reference ASHRAE 62.2 Ventilation Standards

24 ECM #8 Adjust Air Flows to Meet Code Minimums. Reference ASHRAE 62.2 Ventilation Standards (Most AHJ use ASHRAE 62 as their standard) 1. Physically measure space volume to determine required supply CFM requirements. 2. Adjust air flow settings to comply with your AHJ s minimum requirements. Most AHJ s follow ASHRAE standards. 3. Monitor performance monthly to insure compliance.

25 ECM #9 Reduce Simultaneous Heating and Cooling for Dual Duct VAV Boxes.

26 ECM #9 Reduce Simultaneous Heating and Cooling for Dual Duct VAV Boxes. 1. Program a dead band, range of temperature that requires no mechanical HVAC, into space controller set points. 2. Establish and set heating, cooling, and standby airflows. 3. Observe the performance of the box including the cooling and heating valves. Verify that the box reaches and maintains set points. 4. Make sure the control valves fully close.

27 ECM #10 Establish Occupied/Unoccupied set points for VAV Boxes.

28 ECM #10 Establish Occupied/Unoccupied set points for VAV Boxes. In unoccupied control the VAV Box will modulate to maintain the temperature set point of 78 degrees except that the minimum airflow set point is zero (0) CFM so there will never be the need for reheat in unoccupied mode to maintain the cooling set point.

29 ECM #11 Measure Flow Differential Pressures at the Correct Place.

30 ECM #11 Measure Flow Differential Pressures at the Correct Location. Locate the differential pressure sensor at the hydraulically most remote point in the piping system.

31 ECM #12 Utilize Measurement and Verification Activities to Insure Continuous Compliance. Monthly, Daily

32 ECM #12 Utilize Measurement and Verification Activities to Insure Continuous Compliance. Use at least one year s baseline energy usage data and weather data (HHD/CDD) to develop a simple predictive regression for reference. Microsoft Excel has an easy to use regression tool.

33 KtonH ECM #12 Utilize Measurement and Verification Activities to Insure Continuous Compliance WT CW Degree Day Correlation y = x Cooling Degree Days

34 TonH ECM #12 Utilize Measurement and Verification Activities to Insure Continuous Compliance WT TonH Degree Day Regression TonH = 1.31(CDD) Regression Actual 0 Month

35 Questions William D. (Skip) Milton