SESSION 10811:00am – 12:30pm
Energy Efficiency in Existing Buildings and Tenant Improvements
Presenter: Rod Yeoh
PrincipalOmicron Architecture
Engineering Construction
Session Co-sponsored by
Omicron AEC+ Architecture, Engineering, & Construction+ Established in 1998+ Now almost 200 office and field staff+ Head office in Vancouver+ Office in Calgary, Satellite offices in Victoria,
BC & Toronto, ON+ Integrated Project Delivery focus + Market Sectors – Institutional/Commercial,
Retail, Renewals, Office Interiors, Residential/Oilsands
Outline
+ Existing Systems+ Evaluate Equipment+ Reduce Loads+ “Right-size” Equipment+ Energy Efficiency
Trends+ Re-commissioning
Existing Systems+ Most large office buildings in
downtown areas 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+ Smaller office buildings (usually
outside of downtown core)– Water Source Heat Pumps
Existing Systems+ Smaller office buildings
– Rooftop VAV• Typically with
electric/hydronic re-heat coils
– Fan powered mixing boxes
• Maintains constant volume to space by mixing return air
Existing Systems+ Smaller office buildings
– Multi-zone• Hot Deck• Cold Deck• Dampers mix zone
supply temperatures as required
• Good thermal comfort
• Not so good efficiency
Existing Systems+ Smaller office buildings
– 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
+ 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
+ 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 EquipmentAnalysis of existing
equipment+ Infrared
Thermography– Detects “hot
spots” in electrical components and equipment
– Can help identify electrical issues in HVAC equipment
Reduce LoadsEnvelope Upgrades+ IF the Building is already having envelope issues,
or needs to be re-roofed, increasing insulation or replacing glazing may make sense
Reduce LoadsEnvelope Upgrades+ Study for CoV – Green Retrofits
– Glazing upgrades can save over 20% of total energy costs per year for a typical downtown office tower
– Balance with incremental cost of higher performance glazing if already planning a glazing replacement
Reduce LoadsEnvelope Upgrades+ Heating and Cooling Calculations and Energy
Simulations should be performed+ In some instances, increasing insulation could
actually increase energy use
Reduce LoadsLighting+ Lighting Loads in
the past– Up to 4 watts per
square foot+ New Lighting
– Can be under 1 watt per square foot
Reduce LoadsLighting+ Replace T12 lights
with T8 or T5+ Magnetic ballasts to
electronic+ Occupancy sensors+ Daylight sensors &
controls+ Most likely strategy
in Tenant Improvements
Reduce LoadsOther Cooling Loads+ Computers
– CRT Monitors – 110 Watts operating– LCD Monitors – 30-40 Watts operating
Reduce Loads
Heating Loads+ Ventilation Air
– Check existing ventilation levels
• May be over/under ventilating
– ASHRAE 62-2007 Requirements
• 17 cfm per person required for office space
• 7 cfm per person required for reception areas
Reduce LoadsHeating Loads+ Ventilation Air
– Heat Recovery on Ventilation systems
• Enthalpy Wheels• Air to Air Heat
Exchangers• Glycol loops• Heat pipes
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– Replaced Glazing– Reduced lighting
loads– Reduced Chiller Size
by 15%– Reduced Boiler size
by 10%
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+ VSD or small jockey motors on Cooling
Tower fans+ Water Side Economizers
– CoV Study – if no air side economizing, simple payback in as little as 4 years – different for other locations
New Equipment Efficiencies+ Old boilers were rated
at 70% to 80% efficiency
+ New near condensing boilers are rated at up to 86% efficiency
+ CoV Study– New mid-efficiency
boilers – 7 year simple payback – could be quicker in Alberta
New Equipment Efficiencies+ New condensing boilers
are rated at up to 98% efficiency– At more practical return
water temperatures, more like 90%
+ Review type of heating system and boiler return temperatures for condensing
New Equipment Efficiencies
+ Motor efficiency
Horsepower Standard (%) High Efficiency (%)
1 78.0 82.5
5 84.0 89.6
10 84.0 91.1
15 87.5 91.7
25 90.2 93.0
50 91.7 94.1
250 94.1 95.8
New Equipment Efficiencies+ VAV Systems
– Older systems use variable inlet vanes or other mechanical means to vary airflow
– New systems (or retrofits) use VFDs– Full floor Tenant Improvement
System Efficiencies in TI’s+ Duct & Pipe insulation
– Can pay back in as little as 3-5 years+ Energy efficient (Energuide)
equipment and appliances
System Efficiencies in TI’s+ Controls
– Re-commissioning– Calibration– Adding DDC or setback control– Morning warm-up or pre-cooling
+ Sub-metering
New Equipment Efficiencies+ Financial Incentives and Rebates
– Province of Alberta• “Light it Right” Program
(www.lightitright.ca)– Restaurant– Retail– Multi-unit Residential– Office/Hotels– Warehouse/Recreational Facilities– Rebates for lighting & controls
Energy Efficiency Trends+ Dedicated Outdoor Air Systems
– Separating space conditioning and ventilation loads+ Displacement Ventilation and Underfloor Air
Distribution 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 large or district plants
Energy Efficiency Trends+ Renewable Energy
– Solar• Photovoltaics• Solar Hot Water• Direct solar heating/Solar Wall
– Wind– Green Power certificates
Re-Commissioning+ Re-commissioning of Building
Systems (RCx)– 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 2 years.
Re-Commissioning+ New DDC Control
systems– Can Increase
Efficiency • Ensuring systems are
operating as intended• Resetting setpoints to
optimize energy use• Optimal start up
routines • Track changes in
energy usage and report exceptions
Re-Commissioning+ Check trends on DDC system
– entering and leaving chilled/heating water temperature versus setpoint/setback/schedule
– equipment schedule — on/off — versus time of day– zone temperature & setpoints versus time of day.
Re-Commissioning+ BC Hydro Continuous Optimization Program
– Will pay for re-commissioning in addition to installation of pulse meter and energy management software
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 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%
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 Equipment
10 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 Equipment
10 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