1. Design vs. Delivery:
What goes right is also wrong!
Toronto Regional Green Building Festival 2007
Stephen Pope, OAA, MRAIC
CETC Sustainable Buildings and Communities
24 October, 2007

2. Big energy simulation benefits…BUT
• Can’t build and monitor
commercial buildings like we do
test houses!
• Simulation shows the cross
system impacts of building
services in a whole building
environment – identifies revenge
effects of performance changes;
• BUT…real utility bills often vary
from simulated performance;
• Simulation process needs to be
understood to correctly interpret
the results;
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3. Variations from real performance
“It’s tough to make predictions, especially about the future.”
Yogi Berra
• Why?
• Real conditions change from design conditions;
• Different tools give different solutions;
• Tools are taken up without adequate training – Canadian simulation industry
is very small;
• Simulations are often improperly prepared.
• What can be done?
• Recognize the assumptions used in energy simulation software;
• Use the right tool for the job;
• Understand the limitations of the tools;
• Establish quality assurance processes for design with simulation inputs;
• Use simulation in supportive design environments like the Integrated
Design Process.
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4. Variations are to be expected
• Weather patterns are changing;
• Building performance monitoring is not common;
• Currently we monitor based on complaints;
• How does one know how many people are in the building, at what times of
day and for how long?
• Documenting all possible variables is exceptionally difficult,
expensive, and often unnecessary;
• Only sensitive variables need documentation… but different building types
have different sensitivities;
• Tools take short-cuts;
• Trade-offs are made between ease of use and accuracy of representation.
• Measuring protocols may not match reality……
• Equipment rating conditions are very different from operating conditions.
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5. Simulate to identify trends
Wall to Roof Ratio 1:2 Wall to Roof Ratio 2:1
16,750 16,750
16,250 16,250
MJ/annum
MJ/annum
15,750 15,750
15,250 15,250
14,750 14,750
14,250 14,250
W:R=1:2 FWR 17% - 85% W:R=1:2 Window U / SC W:R=2:1 Window U/SC W:R=2:1 FWR 17%-85%
W:R=1:2 Wall Insul RSI 1.8-8.0 W:R=1:2 Roof Ins RSI 2.1-15 W:R=2:1 Wall RSI 1.8-8 W:R=2:1 Roof RSI 2.1-15
15,620 m2 regional high school – Screening Tool School archetype
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6. Common Commercial Building Tools
• Commercial buildings require multi-zone analysis
addressing the following systems:
• heating ventilating and air conditioning;
• service water heating;
• electric power distribution and metering provisions;
• electric motors and belt drives, and;
• lighting.
• Simulation tools commonly used in Canada:
• DOE-2; EE4 (DOE-2.1E); eQuest (DOE-2.2); Ecotect; TAS; TRNSYS;
Energy Plus; IES <VE>; ESP-r.
• Commercial HVAC sizing tools:
• TRACE (Trane); HAP (Carrier)
• US DOE Tools listing (345 individual tools):
• http://www.eere.energy.gov/buildings/tools_directory/
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7. Fair and Consistent Evaluations
• ASHRAE 90.1-1999 • MNECB/CS 1999
• Energy Cost Budget Method Article • Statement of Intent (page ii)
11.1.2 • “In general, the purpose of
• “The energy cost budget and the performance compliance
the design energy cost procedure is not to develop
calculations are applicable an accurate prediction of
only for determining annual energy use for space
compliance with this heating. Rather, the purpose is
standard. They are not to develop fair and
predictions of actual energy consistent evaluations of the
consumption or costs of the effects of deviations (in
proposed design after whatever direction) from
construction. …” MNECB prescriptive
• 90.1-2004 similar. requirements.”
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8. Relative Comparison Method
• Both MNECB and ASHRAE 90.1
compare a proposed building and
a reference building;
• Both buildings operated under
standardized conditions;
• Similar equipment is ignored;
• Elevators – note changes w/ 90.1 Appendix G.
• BUT…building design follows
multiple additional standards;
• ASHRAE 55 – 2004 (Comfort);
• ASHRAE 62.1 – 2004 (Ventilation);
• Local building code imperatives.
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9. Major Simulation Variables
• Weather;
• 1996 CWEC (Environment Canada) 30 year average used for EE4.
• Occupancy conditions;
• Occupant densities;
• Schedules;
• Occupancy hours;
• Plug loads.
• Service per person;
• Ventilation air;
• Hot water.
• Heating, Ventilation, and Cooling system representations;
• Limited number of HVAC systems in MNECB / EE4 – interpretation required;
• If correct systems are present, controls options may not be available.
• Geometric building entries.
• MNECB conditions (EE4) – no building self-shading, no off-site shading.
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10. MNECB School Occupants & Fans
MNECB Schedule D (School) Occupants
1.1
1
Weekdays
0.9
Portion of Total Capacity
0.8
Weekend
0.7 & Holiday
0.6 Week Day
0.5 Fans
0.4
0.3
0.2
0.1
0
1 3 5 7 9 11 13 15 17 19 21 23
Hour
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11. BC School Occupants
Credit: EnerSys Analytics
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12. Differing Service Amounts
ASHRAE 62.1 – 2004 MNECB 1997
• Hours of use/day (BC): 14 • Hours of use/day: 16
• Occupant Density • Occupant Density:
• Classroom: age +9 yrs – 2.9 m2/occ • All classrooms – 8 m2/occ
• Lecture class – 1.5 m2/occ
• Lecture Hall (fixed seats) – 0.7 m2/occ
• Ventilation Air (L/s/occ) • Ventilation Air (L/s/occ):
• Classroom age +9 yrs – 6.7 L/s/occ • All classrooms – 8.0 L/s/occ
• Lecture class – 4.3 L/s/occ
• Lecture Hall (fixed seats) – 4.0 L/s/occ
• 100 m2 classroom • 100 m2 classroom:
• Lecture class; • All classrooms the same;
• 65 occupants; • 13 occupants;
• 280 L/s outdoor air. • 100 L/s outdoor air.
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13. EE4/DOE-2 Software Conditions
• Nature of DOE-2 analysis:
• Hourly time step
• Air side space conditioning only – no radiant effects;
• Evenly mixed air temperature – no stratification;
• Pure systems – single system per zone, schedules at zone;
• Sequential: Loads; Systems; Plant; Economics – system interactions
incompletely captured;
• Adiabatic environment – each zone isolated unless links are created.
• Specific EE4 limitations
• No geometric relationships;
• Ventilation based on occupancy class (not population), floor area, and fan
schedules;
• Window analysis based on U-value and solar heat gain coefficient only (not
able to model spectrally selective glass);
• Infiltration excluded – set at 1/10th current good practice.
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14. What to do next?
• For existing buildings;
• Measure occupancy times & patterns;
• Cross reference occupancy with utility data.
• Develop simulation models reconciled with real
data.
• Use reconciled simulation models to test benefits
of proposed efficiency upgrades.
• For new buildings & major retrofits:
• Design using the Integrated Design Process;
• IDP provides quality assurance on design;
• Design sessions take place in facilitated
workshops with energy simulation support.
• Owner participates “live” on the design team;
• Owner hires energy simulator directly;
• Remove potential for conflicts between design
approaches;
• If possible, simulate occupancy with custom
schedules representing real occupancy patterns.
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15. A good energy simulator….
• Sees the whole forest not just the
trees;
• Has HVAC design experience,
AND/OR strong knowledge of how
the simulation software models work
– interprets well;
• Understands building science behind
window, wall, and roof performance;
• Looks for cross system impacts of
individual efficiency measures.
• Documents assumptions and inputs.
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16. Thank You
Stephen Pope, OAA, MRAIC
Sustainable Building Design Specialist
Natural Resources Canada / CANMET Energy Technology Centre
Sustainable Buildings & Communities / Commercial Buildings Section
580 Booth St., 13th Flr, D5, Ottawa ON K1A 0E4
tel. (613) 947-9823 cell (613) 324-1642, fax (613) 996-9909
email - spope@nrcan.gc.ca, web - http://www.sbc.nrcan.gc.ca
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