This document analyzes energy consumption data from six mid- to high-rise residential buildings before and after enclosure rehabilitation. It found that while enclosure retrofits improved building enclosures, they did not necessarily reduce total energy use, as service systems had a greater influence on energy consumption. On average, the buildings saw a 4.8% reduction in total energy use after rehabilitation, but results varied, with savings of up to 16.8% in one building and increased usage of 13.8% in another. The study concluded that energy improvements require coordinated efforts between enclosure and service system engineers.

1. Energy Consumption
in Mid- to High-rise Residential Buildings
both before and after Enclosure Rehabilitation
– a Top-Down Approach
Eric Burnett, Warren Knowles, Graham Finch and
Marcus Dell

2. Multi-Unit Residential Building Energy Study
! Energy consumption of over 60 mid- to high-rise Multi-Unit
Residential Buildings (MURBs) constructed between 1974 and
2002
! Half of study buildings underwent a full-scale building
enclosure rehabilitation
! These studies were done with the support and funding of the
following organizations:
CMHC SCHL

3. Objectives
Part of a larger survey to assess the impact of
Enclosure Rehabilitation on MURB’s in urban BC.
Six buildings were chosen, common features were:
! > 9 floors
! similar residential suites
! condo or strata – not rental or social housing
! at least two years of energy data pre- and post-rehab
Compare and evaluate the performance of these buildings
making NO assumptions (Top-Down analysis) and try to
assess the affects on energy consumption

4. Top-down vs. Bottom-up Analysis
Top down:
! Annual bulk energy billed known
! Simplistic Metering of site energy consumption
(individual suites for electrical, common areas for gas and electrical )
! Seasonal conversion efficiencies of equipment not known
! No or minimal assumptions
Bottom-up:
! Detailed information often available (occupants, service systems,
etc.)
! Better data - smart metering, precise weather records, etc.
! Modeling software available

5. Understanding Energy Use in MURBs
Parking Garage
Exhaust Fans
Common Areas
Parking Garage
Building
Energy
Distribution
Gas
- To heat ventilation air
for make-up air supply
- To heat domestic hot water
- To heat pool/hot-tubs
- Suite fireplaces (if equipped)
- Pilot lights for above
Electricity
Common
Areas
- Interior lighting
- Elevators
- Ventilation fans and motors
- Parking garage exhaust fans
- Water distribution pumps
- Baseboard heaters
- Recreation areas/pool pumps
- Exterior lighting
- Communication
- Controls
Suites
- Baseboard heaters
- Lighting
- Appliances
- Miscellaneous Electric Loads
- Plug loads
- Exhaust fans
Gas Boiler to Pool
heat pool &
hot-tubs
Suites
Elevator Shaft
Common Hallway Corridors
Stairwell
Shaft
Electric Baseboard
Heaters in all
Suites
Gas fireplaces in
some Suites
Air flow through
open windows
Air exhausted using
bathroom/kitchen fans
& windows
Air leakage of heated
ventilation air through
elevator and stairwell shafts Ventilation air is heated
using gas-fired make-up
air unit (MUA)
Heated ventilation air supplied to each floor common corridor (pressurized)
Heated
Ventilation air
from corridor
Domestic Hot
Water is heated
using Gas
Some Gas & Electric
Heat at Common Areas
Typically Unheated
Leakage of heated
ventilation air into shafts
Rec. Areas
Enclosure air-leakage
Elevator pumping

6. Metering Considerations
! Gas readings – one meter for DHW, MUA, fireplaces, etc.
! Electrical readings – one meter for suites (sometimes individually),
appliances, conditioning, lighting, MEL, etc
! Electrical readings – one meter for common areas (elevators,
stairways, corridors, lighting, etc.
! Readings taken at <62 day intervals. Billing monthly therefore some
estimates or guesses.
Data had to be:
! Correlated – for irregularities and gross statistical error
! Normalized - monthly and annually
! Standardized – 12 months of equal duration, in kWh

7. Monthly Energy Consumption – Building #62
Building #62 is used as the sample building
to demonstrate the following:
! How the nature and the format of data is important – histogram .v.
smooth continuous lines
! The baseline and the variable portions of each fuel
! The effect of a Service System adjustment (SSA)
! The impact of the remediation/rehabilitation period

8. Distribution of Energy Costs in MURBs
Total
Consumed
By
Owner,
59.5,
29%
Total
120,000
100,000
80,000
Consumed
By
Strata,
146.9
,
71%
Electric
Baseboard
Heating,
24.8,
42%
Rehabilation - May 2004 to May 2005
Plug
and
Appliances
(Suite),
18.7,
31%
Lights
(Suite),
15.9,
27%
Owner Paid
Electric
Baseboard
Heating,
0.3
,
0%
Fireplaces,
37.7
,
26%
Ventilation
Heating,
39.7
,
27%
Equipment
and
Ammenity
(Common),
28.3
,
19%
Lights
(Common),
3.7
,
3%
DHW,
32.9
,
22%
Elevators,
4.2
,
3%
Strata Paid
60,000
40,000
20,000
0
Jan-98
May-98
Sep-98
Jan-99
May-99
Sep-99
Jan-00
May-00
Sep-00
Jan-01
May-01
Sep-01
Jan-02
May-02
Sep-02
Jan-03
May-03
Sep-03
Jan-04
May-04
Sep-04
Jan-05
May-05
Sep-05
Jan-06
May-06
Sep-06
Jan-07
May-07
Sep-07
Jan-08
May-08
Sep-08
Total Energy Consumption (kWh/month)
Monthly Consumption Comparison
Total Electricity
Gas
Baseline Pre: 18,000 kWh/,month
Baseline Post: 10,500 kWh/month
Pre DHW Upgrade and
Repiping

9. Note
! Two distinct types of Energy Use:
Baseline Energy
Variable Energy
! Below the baseline the energy use is effectively constant
! Above the baseline the energy use varies – roughly as the winter
takes hold and heating is required
! The heating season is not defined by the extent of variable energy
however. Both gas and electricity are still needed for DHW and for
space heat ( baseboards and fireplaces still run, pilot lights, etc.,may
not be turned off.
! The variable energy

10. 0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
Jan-98
May-98
Sep-98
Jan-99
May-99
Sep-99
Jan-00
May-00
Sep-00
Jan-01
May-01
Sep-01
Jan-02
May-02
Sep-02
Jan-03
May-03
Sep-03
Jan-04
May-04
Sep-04
Jan-05
May-05
Sep-05
Jan-06
May-06
Sep-06
Jan-07
May-07
Sep-07
Jan-08
May-08
Sep-08
Total Energy Consumption (kWh/month)
Monthly Suite Electricity Consumption
Suite
Electricity
Baseline Pre: 16,000 kWh/month Baseline Post: 14,500 kWh/month
Rehabiliation - May 2004 - May 2005

11. 0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
45,000
50,000
Jan-98
May-98
Sep-98
Jan-99
May-99
Sep-99
Jan-00
May-00
Sep-00
Jan-01
May-01
Sep-01
Jan-02
May-02
Sep-02
Jan-03
May-03
Sep-03
Jan-04
May-04
Sep-04
Jan-05
May-05
Sep-05
Jan-06
May-06
Sep-06
Jan-07
May-07
Sep-07
Jan-08
May-08
Sep-08
Total Energy Consumption (kwhr/month)
Monthly Common Area Electricity Consumption
Common
Electricity
Baseline Pre: 32,500 kWh/month
Pre DHW Upgrade and
Repiping
Baseline Post: 27,500 kWh/month
Rehabilitation - May 2004 - May 2005

12. 0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
Jan-98
May-98
Sep-98
Jan-99
May-99
Sep-99
Jan-00
May-00
Sep-00
Jan-01
May-01
Sep-01
Jan-02
May-02
Sep-02
Jan-03
May-03
Sep-03
Jan-04
May-04
Sep-04
Jan-05
May-05
Sep-05
Jan-06
May-06
Sep-06
Jan-07
May-07
Sep-07
Jan-08
May-08
Sep-08
Energy Consumption - kWh/month
Monthly Energy Consumption Comparison
Electricity - Suites
Electricity - Common

13. Building #62 – Annual Energy Data
062 - Bellevue Place
ANNUAL SUMMARY CONSUMPTION ANALYSIS AND DISTRIBUTION
Gas Electrictiy Electricity Electricity Total Energy Annual
Total/Year Suites Common Total Building HDD
Years of
Data
Time Period kwhr kwhr kwhr kwhr kwhr 18C
Aug 1998 - Jul 1999 SSA 493,244 514,762 438,385 953,147 1,446,391 2,804
Aug 1999 - Jul 2000 SSA 490,708 455,222 426,045 881,267 1,371,975 2,812
Aug 2000 - Jul 2001 1 556,741 431,754 458,559 890,313 1,447,055 2,929
Aug 2001 - Jul 2002 2 520,929 488,741 475,544 964,285 1,485,214 2,884
Aug 2002 - Jul 2003 3 466,472 438,817 436,783 875,599 1,342,072 2,629
Aug 2003 - Jul 2004 433,409 458,328 372,074 830,402 1,263,810 2,567
Aug 2004 - Jul 2005 Rehab 271,099 483,111 383,842 866,953 1,138,051 2,630
Aug 2005 - Jul 2006 4 336,165 455,838 391,295 847,133 1,183,297 2,685
Aug 2006 - Jul 2007 228,903 496,384 394,686 891,070 1,119,973 2,806
Aug 2007 - Jul 2008 5 308,602 500,325 377,538 877,863 1,186,465 3,037
Average of 7 years 407,317 467,169 415,211 882,381 1,289,698 2,791
Standard Deviation 110,231 29,473 36,715 43,771 133,305 149
Coefficiant of Variation 27.1% 6.3% 8.8% 5.0% 10.3% 5.3%
**Data outside one standard deviation (highlighted in blue) have been eliminated in the averages below
Pre-Upgrade Avg 1, 2 3 514,714 453,104 456,962 910,066 1,424,780 2,814
SD Pre-Upgrade 45,454 31,064 19,430 47,528 74,125 162
CV Pre-Upgrade 8.8% 6.9% 4.3% 5.2% 0.052 5.8%
Post-Upgrade Avg 4, 5 322,383 478,081 384,417 862,498 1,184,881 2,861
SD Post-Upgrade 19,490 31,457 9,727 21,730 2,240 249
CV Post-Upgrade 6.0% 6.6% 2.5% 2.5% 0.002 8.7%
MONTHLY BASELINE
(DETERMINED GRAPHICALLY)
ANNUAL BASELINE
Note
1 Drop rehab years and data > one SD variation
2 Drop years with Service System Adjustment
3 2-years either side of Rehab.

14. ANNUAL
BASE
LINE
TOTAL
ANNUAL
ENERGY
TOTAL
VARIABLE
ENERGY
Gas
(kWh/year)
Suite
Electric
(kWh/year)
Common
Electric
(kWh/year)
Gas
(kWh/
year)
Suite
Electric
(kWh/year)
Common
Electric
(kWh/year)
Gas
(kWh/
year)
Suite
Electric
(kWh/year)
Common
Electric
(kWh/year)
Pre-­‐
Enclosure
Retrofit
216,000
192,000
390,000
514,714
453,104
456,962
298,714
261,104
66,962
Post-­‐Enclosure
Retrofit
126,000
174,000
330,000
322,383
478,081
384,417
196,383
304,081
54,417
%Change
42%
9
15
37
-­‐6
16
34
-­‐16
19
%
Change
RelaJve
to
Total
603
1.3
4.2
13.5
-­‐1.8
5.1
7.2
-­‐3
0.9

15. Building Details
Building
Number
No. of
Floors
No. of
Suites
Suite Space
Heating
Ventilation
System
Domestic Hot
Water
Percent Total
Energy Savings
#62 21 55 Electric
baseboards &
fireplaces
Gas-heated
make-up air
Gas-fired boiler 16.8%
#20 10 58 Electric
baseboards &
fireplaces
Gas-heated
make-up air
Gas-fired boiler 4.0%
#7 15 128 Electric
baseboards
Gas-heated
make-up air
Gas-fired boiler -1.6%
#18 22 186 Electric
baseboards
Gas-heated
make-up air
Gas-fired boiler -13.8%
#19 10 94 Hydronic
baseboards
Gas-heated
make-up air
Gas-fired boiler 6.6%
#17 12 68 Gas fireplaces
and electric
baseboards
Unconditioned
make-up air
Electrically
heated
10.7%

16. Proportion of Gas Energy to Total Energy
Building # #62 #20 #7 #18 #19 #17
Pre-Rehabilitation
36% 66% 43% 41% 68% 19.4%
Post-Rehabilitation
27% 66% 44% 44% 69% 18.4%

17. Changes in Energy Consumption
4.8%
0.9%
13.4%
-9.0%
8.1% 8.2%
3.4%
13.7%
10.9%
9.1%
18.5%
9%
20.0%
15.0%
10.0%
5.0%
0.0%
-5.0%
-10.0%
-15.0%
7 11 17 18 19 20 21 28 32 33 62 Typ Avg
% Total Energy Pre-Post Savings
- Weather Normalized
- Buildings 11, 21, 28, 32, 33, shown for reference

18. Conclusions General
! Enclosure Retrofit is usually successful in that the enclosure performs
better than before, BUT not necessarily when the measurement is in
purely energy terms.
! The service systems can have a greater influence on energy use than the
enclosure.
! It should be emphasized that energy improvements should be made by
the service system engineers and the building enclosure engineers
working together.
! The two are inextricably involved but differ in timing (when), costs
(immediate v cumulative), and stake (owner v energy supplier).

19. Conclusions Specific
! Heat produced from different energy sources in different
locations does mix.
! It is debatable that HDD is an entirely reliable indicator of
the weather in higher buildings as orientation, wind, solar
and snow and sleet have an impact

20. Thank you

21. Discussion

22. Aug 2001 - Jul 2002 2 520,929 488,741 475,544 964,285 1,485,214 2,884
Aug 2002 - Jul 2003 3 466,472 438,817 436,783 875,599 1,342,072 2,629
Aug 2003 - Jul 2004 433,409 458,328 372,074 830,402 1,263,810 2,567
Aug 2004 - Jul 2005 Rehab 271,099 483,111 383,842 866,953 1,138,051 2,630
Aug 2005 - Jul 2006 4 336,165 455,838 391,295 847,133 1,183,297 2,685
Aug 2006 - Jul 2007 228,903 496,384 394,686 891,070 1,119,973 2,806
Aug 2007 - Jul 2008 5 308,602 500,325 377,538 877,863 1,186,465 3,037
Average of 7 years 407,317 467,169 415,211 882,381 1,289,698 2,791
Standard Deviation 110,231 29,473 36,715 43,771 133,305 149
Coefficiant of Variation 27.1% 6.3% 8.8% 5.0% 10.3% 5.3%
**Data outside one standard deviation (highlighted in blue) have been eliminated in the averages below
Pre-Upgrade Avg 1, 2 3 514,714 453,104 456,962 910,066 1,424,780 2,814
SD Pre-Upgrade 45,454 31,064 19,430 47,528 74,125 162
CV Pre-Upgrade 8.8% 6.9% 4.3% 5.2% 0.052 5.8%
Post-Upgrade Avg 4, 5 322,383 478,081 384,417 862,498 1,184,881 2,861
SD Post-Upgrade 19,490 31,457 9,727 21,730 2,240 249
CV Post-Upgrade 6.0% 6.6% 2.5% 2.5% 0.002 8.7%
Gas (kWh/
month)
Suites
Electric
(kWh/
month)
Common
Electric
(kWh/
month)
Gas (kWh/
year)
Suites Electric
(kWh/ year)
Common
Electric (kWh/
year) Gas (kWh)
Suites
Electric (kWh)
Common
Electric (kWh)
TOTAL ANNUAL ENERGY
Gas
(kWh)
USAGE
Suites
Electric
(kWh)
Common
Electric
(kWh) SUM
Pre-Enclosure Retrofit 1, 2, 3 18,000 16,000 32,500 216,000 192,000 390,000 298,714 261,104 66,962 514,714 453,104 456,962 1,424,780
Post-Enclosure Retrofit 4, 5 10,500 14,500 27,500 126,000 174,000 330,000 196,383 304,081 54,417 322,383 478,081 384,417 1,184,881
% Change 42% 9% 15% 42% 9% 15% 34% -16% 19% 37% -6% 16%
6.3% 1.3% 4.2% 7.2% -3.0% 0.9% 13.5% -1.8% 5.1%
*total refers to the average for all years of the total energy in the building: This value is 1,424,780 kWh
% Overall Savings 16,8%
Overall Savings (kWh/ year) 239,899
MONTHLY BASELINE
(DETERMINED GRAPHICALLY)
% Change Relative to the total*
ANNUAL BASELINE
TOTAL ANNUAL VARIABLE ENERGY
(TOTAL ANNUAL - ANNUAL BASELINE)

23. Study Buildings
! Located in Lower Mainland and Victoria