BOMA QBT STEPS FOR INCREASING

BUILDING ENERGY EFFICIENCY

Rod Yeoh, P.Eng., P.E., LEED® APPrincipal, Omicron

February 2009

Outline

+ Existing Systems+ Evaluate Equipment+ Reduce Loads+ “Right-size” Equipment+ Energy Efficiency

Trends+ Re-commissioning

Existing Systems

+ Most Buildings in the downtown core have Central Plants– Central Chiller plant– Central Boiler plant (or steam from Central

Heat)

Existing Systems+ Air Handling Systems

– Central or Floor by Floor• Free cooling available with outside air

Existing Systems

+ Terminal Systems– VAV Terminal Units

• with or without re-heat– Fan Coil Systems

• 4 Pipe and 2 Pipe

Existing Systems+ Buildings Outside Downtown Core

– Water Source Heat Pumps

Existing Systems

+ Buildings Outside Downtown Core– Rooftop VAV

• Typically with electric re-heat coils

– Fan powered mixing boxes

• Maintains constant volume to space by mixing return air

Existing Systems

+ Buildings Outside Downtown Core– Multi-zone

• Hot Deck• Cold Deck• Dampers mix zone

supply temperatures as required

Existing Systems+ Buildings Outside Downtown Core

– Rooftop VVT• Variable Volume,

Variable Temperature

• “Polls” zones and supplies heating or cooling as required

• Correct zoning is very important

Evaluating Equipment+ ASHRAE Tables

– Data based on Surveys done in the US in 1978 by ASHRAE. Updated in 1986

– Estimates based on time to replacement, not failure

– Various reasons for replacement• Failure• General Obsolescence• Reduced reliability• Maintenance costs• Energy use• Environmental conditions

Evaluating Equipment+ ASHRAE Tables

– Equipment life is extended with good maintenance

Evaluating Equipment+ Lawrence Livermore National Laboratory

(LLNL) & Whitestone Research have done studies of equipment service life to failure of various types of equipment

+ Contributing Factors towards longer LLNL service lives– Complete and consistent maintenance schedule– Regular condition assessments– Replace equipment on down slope of failure

distribution

Evaluating Equipment

Evaluating Equipment

Evaluating Equipment

Evaluating Equipment

Evaluating Equipment

+ Vibration testing– Can identify issues

with bearings, wear, unbalance

– Can identify problems earlier than other methods

– Can prevent catastrophic failure in equipment

Analysis of existing equipment

Evaluating Equipment

+ Infrared Thermography– Detects “hot spots” in

electrical components and equipment

– Can help identify electrical issues in HVAC equipment

Analysis of existing equipment

Reduce Loads

+ IF the Building is already having envelope issues, or needs to be re-roofed, increasing insulation or replacing glazing may make sense

Envelope upgrades

Reduce Loads

+ Heating and Cooling Calculations and Energy Simulations should be performed

+ In some instances, high performance glazing could actually increase energy use

Envelope upgrades

Reduce Loads

+ Lighting Loads in the past

– Up to 4 watts per square foot

+ New Lighting– Can be under 1

watt per square foot

Lighting

Reduce Loads

+ Replace T12 lights with T8 or T5

+ Magnetic ballasts to electronic

+ Occupancy sensors+ Daylight sensors

Lighting

Reduce Loads

+ Computers– CRT Monitors – 110 Watts operating– LCD Monitors – 30-40 Watts operating

Other cooling loads

Reduce Loads

+ Ventilation Air– Check existing

ventilation levels• May be over ventilating

– ASHRAE 62-2004 Requirements

• 17 cfm per person required for office space

• 7 cfm per person required for reception areas

Heating loads

Reduce Loads

+ Ventilation Air– Heat Recovery on

Ventilation systems• Enthalpy Wheels• Air to Air Heat

Exchangers• Glycol loops• Heat pipes

Heating loads

Reduce LoadsMotor Loads+ Demand Controlled Ventilation+ Variable Speed Drives on VAV systems &

Pump systems

“Right” Size Equipment

+ Once Loads are Reduced– Look at replacing

main plants: chillers, boilers, rooftop units

– Don’t just replace with same size

– Size to suit new loads

– Add Redundancy

“Right” Size Equipment

+ Evergreen Building– Reduced Chiller

Size by 15%– Reduced Boiler size

by 10%– At $1,000 per ton,

saved about $30,000

New Equipment Efficiencies+ Average efficiency of a

chiller installed in 1980-1990 – 0.85-0.90 kW/ton– Could be as high as 1.2

kW/ton+ Old chillers can also get

oil logged – keep adding refrigerant with oil in it, reduces efficiency by up to 10%

New Equipment Efficiencies+ New Centrifugal Chillers have an efficiency of

0.40-0.50 kW per ton+ Efficiency can go down to as low as 0.25 kW

per ton with VFD chillers

New Equipment Efficiencies+ Old boilers were rated

at 70% to 80% efficiency

+ New near condensing boilers are rated at up to 86% efficiency

+ New condensing boilers are rated at up to 98% efficiency– At more practical return

water temperatures, more like 90%

New Equipment Efficiencies+ Motor efficiency

95.8 94.1 250

93.0 90.2 25

91.1 84.0 10

82.578.01

94.1 91.7 50

91.7 87.5 15

89.6 84.05

High Efficiency (%)Standard (%)Horsepower

New Equipment Efficiencies+ VAV Systems

– Older systems use variable inlet vanes or other mechanical means to vary airflow

– New systems (or retrofits) use VFDs

New Equipment Efficiencies

+ VAV Systems– Power varies

as cube of fan speed

New Equipment Efficiencies+ New DDC Control

systems– Can Increase

Efficiency • Ensuring systems are

operating as intended• Resetting setpoints to

optimize energy use• Optimal start up

routines

New Equipment Efficiencies+ BC Hydro Product Rebates

– VFDs for Fans and pumps– HVAC Occupancy sensors for PTAC and PTHPs– CO sensors for Parking exhaust– Lighting products & controls

Energy Efficiency Trends+ Dedicated Outdoor Air Systems

– Separating space conditioning and ventilation loads+ Displacement Ventilation and Underfloor Air Distribution

systems

Energy Efficiency Trends+ Radiant Heating and Cooling Systems

Energy Efficiency Trends+ Co-generation

– Generate Heat and Power at the same time

– By-product heat can be used for cooling through absorption chillers

– Generally more efficient for district plants

Re-Commissioning+ Re-commissioning of Building

Systems– The Office of Energy Efficiency

(NRCan) has cited studies that show that re-commissioning can improve energy efficiency by 5-15%, with a payback under two years.

Re-Commissioning+ Monitor your building

efficiency– Utility Bills

• Compare recent bills with historical data & vacancy rates, energy efficiency upgrades, etc.

• Compare peak demand on utility bills with energy usage

• Compare energy usage patterns with weather & occupancy patterns

Re-Commissioning+ Check trends on DDC system

– entering and leaving chilled-water temperature versus time of day– equipment schedule — on/off — versus time of day– zone temperature & setpoints versus time of day

Prioritizing Capital Projects+ Life Cycle Cost

Assessment– Analysis should include

all Costs in life of component

– Life Cycle Cost (LCC) as “the total discounted dollar cost of owning, operating, maintaining, and disposing of a building or a building system” over a period of time

Prioritizing Capital Projects+ Life Cycle Cost Assessment

– For one-time costs:

Prioritizing Capital Projects+ Life Cycle Cost Assessment

– For recurring costs:

Prioritizing Capital Projects+ Life Cycle Cost Assessment

– Summarize alternatives:

Prioritizing Capital Projects+ Life Cycle Cost Intangibles

+ Issues such as IAQ and thermal comfort affect productivity

+ Productivity cost is very hard to quantify

+ Original Construction 2%+ Maintenance Costs 6%+ Personnel Costs 92%

Prioritizing Capital Projects+ Life Cycle Cost Example

Prioritizing Capital Projects+ Life Cycle Cost Example

Thanks! Any Questions?

Evaluating Old Equipment10 Tips for increasing chiller efficiency

1. Keep a daily log– A log builds a history of operating conditions, including

temperature, pressure, fluid level and flow rate. 2. Keep tubes clean

– Chiller efficiency declines rapidly when tubes become fouled. The compressor's approach temperature, the difference between the temperature of the fluid leaving the heat exchanger and the saturation temperature of the refrigerant being cooled or heated, is a good indicator of heat transfer efficiency.

Evaluating Old Equipment

10 Tips for increasing chiller efficiency

3. Treat condenser water– Condenser water loops using open cooling sources,

such as atmospheric cooling towers, require water treatment to prevent fouling. Erosive conditions, for example, sand flowing through the tubes at high velocity, may pit tubes.

4. Reduce entering water temperature– Lowering the temperature of the water entering the

condenser can improve the chiller's efficiency.

Evaluating Old Equipment

10 Tips for increasing chiller efficiency

5. Control water velocity– Too low a flow rate leads to laminar flow, reducing heat

transfer. Too high a flow rate leads to vibration, noise and erosion. Flow rates should be kept between 3 – 12 feet per second velocity in tubes. Confirm with Manufacturer.

6. Maintain refrigerant charge – Low refrigerant charge, usually resulting from leaks,

causes the compressor to work harder and achieve less cooling effect.

Evaluating Old Equipment10 Tips for increasing chiller efficiency

7. Purge non-condensables – Air and moisture are two non-condensables that can

leak into low-pressure chillers. Non-condensables can reduce chiller efficiency by as much as 4% at 60% load and 7% at 100% loads.

8. Analyze compressor oil – High moisture levels can indicate a purge unit

problem, which has a significant effect on efficiency.

Evaluating Old Equipment10 Tips for increasing chiller efficiency

9. Check wiring – check chiller electrical connections, wiring and

switchgear for hot spots and worn contacts.

10. Modulate speed – Under the right operating conditions, variable speed

drives offer significant energy savings. Variable speed drives also act as "soft starters" to reduce the motor's inrush current.