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Multiple Unit Residential Buildings (and Offices)
The Relative Impact of Building Form on Energy Consumption
Steve Kemp, P.Eng. M.A.Sc. Partner, MMM Group
Introduction Wanted to answer the following questions:
• How important is building massing and form to the energy performance?
• Various studies have examined the effect of shapes, fenestration and shading strategies on the energy use of buildings
• However, studies identifying the combined impact of these design parameters are rarely found especially in the context of Canada
• There are disagreements among researchers about the importance of geometry on energy performance of office buildings
• How important is the envelope to the energy performance?
• Are there any patterns to aid designers?
2
0
20
40
60
80
100
1970 1980 1990 2000 2010 2020 2030
Site
Ene
rgy
Use
(197
5 =
100)
ASHRAE 90.1
MNECB/NECB
90-1975 90A-1980 90.1-1989 90.1-1999
90.1-2004
MNECB-1997
NECB-2011
90.1-2010 90.1-2013
Energy Codes over time
This graph is illustrative only
SB-10 2012
TGS-2014
3
Today’s Energy Use of All Canadian Buildings – By Year of Construction
• Energy consumption is for year 2009
• Most older building have been renovated with newer HVAC
• Most older building have a “computer on every desktop”
• Why is this happening? • data does not come
with explanation
Ref: Survey of Commercial and Institutional Energy Use – Buildings 2009, NRCAN
0
50
100
150
200
250
300
350
400
Before1920
1920to
1959
1960to
1969
1970to
1979
1980to
1989
1990to
1999
2000to
2004
2005or later
Ener
gy U
se In
tens
ity (k
Wh/
m²-y
r)
Year Building was Constructed
4
Investigate the relative impact the choice of residential building form on heating and cooling demands
• Originally, 3 building heights, 5 floor plates, 4 orientations
Also decided to investigate enclosure performance
• 3 constructions (insulation values), 6 window types and 3 window to wall ratios
• three balcony configurations (results not shown today) • no balcony, cantilevered balcony and thermally broken
What was studied?
5
Floor plates developed around realistic suite layouts
6
Double loaded corridors
7
8
0°
Square
Bar
90° 180° 270°
‘L’
‘U’
‘H’
North
Wall Constructions – Effective R-Values
9
R-4.3 R-8.9 R-13
Glazing Constructions
10
All glazings used argon gas fills in Aluminum frames with 9 mm thermal breaks
Glazing Constructions
11
ID DESCRIPTION
Centre-of-Glass Total Window System (CSA Rated Size)
U-VALUE RSI-Value SHGC
U-VALUE RSI-Value SHGC
W/m2·°C °C-m²/W W/m2·°C °C-m²/W
IGU-1 Double Glazed, high solar heat gain low-e (surface #3) 1.55 0.65 0.62 2.39 0.42 0.56
IGU-2 Double Glazed, low solar heat gain low-e (surface #2) 1.40 0.71 0.39 2.26 0.44 0.35
IGU-3
Double Glazed, high solar heat gain low-e (surface #3) & high solar gain low-e on surface #4
1.46 0.68 0.55 2.31 0.43 0.50
IGU-4
Double Glazed, low solar heat gain low-e (surface #2) & high solar gain low-e on surface #4
1.38 0.72 0.36 2.24 0.45 0.33
IGU-5 Triple Glazed, high solar heat gain low-e on surfaces #2 and #5
1.26 0.79 0.50 2.04 0.49 0.46
IGU-6 Triple Glazed, low solar heat gain low-e on surfaced #2 and #5
1.17 0.85 0.33 1.96 0.51 0.30
*all glazing cavities are Argon filled
Heat and cooling energy “load intensity” • Annual heating and cooling energy that will need to be provided by
HVAC systems, therefore: • Boiler efficiency not included • Chiller efficiency not included • Distribution (pumps/fans) not included • Internal (lights/appliances) gains not included
• Goal was to provide results that were HVAC neutral and only attributable to the performance of the envelope and building form
Normalized by building area (energy load / area) • Allows comparisons between parameters that affect the building size
(e.g. number of floors)
Metrics used to evaluate results
12
Space Heating Load Intensity – Floorplate and Orientation
13
29,000
29,500
30,000
30,500
31,000
31,500
32,000
32,500
33,000
33,500
34,000
0° 90° 180° 270°Orientation of Floorplate
Square
Bar
'L'
'U'
'H'
Space Heating Load Intensity – Floorplate and Orientation (to scale)
14
0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
0° 90° 180° 270°
Square
Bar
'L'
'U'
'H'
Space Cooling Load Intensity – Floorplate and Orientation
15
0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
0° 90° 180° 270°
Square
Bar
'L'
'U'
'H'
Space Heating Load Intensity – Number of Floors
16
0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
0 2 4 6 8 10 12Number of Floors
Square
Bar
'L'
'U'
'H'
Space Heating Load Intensity – “L” Floorplate envelope to area to floor area
17
0
0.2
0.4
0.6
0.8
1
1.2
0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
0 2 4 6 8 10 12
Enve
lope
to B
uild
ing
Floo
r Are
a Ra
tio
Number of Stories
0°
90°
180°
270°
Envelope to Building Floor Area Ratio
Heating Loads • Orientation and floor plate have only minor effect • Number of stories (surrogate for envelope to floor ratio) has a larger
effect, reducing the heating load intensity
Cooling Loads • Self-shading massing reduces cooling loads, only minor effect on
heating • Number of stories increase the cooling load intensity
Building Form Conclusions
18
Annual Cooling Load Intensity and Window Performance
19
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
90,000
0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65
Annu
al C
oolin
g Lo
ad In
tens
ity [W
h/m
2]
Solar Heat Gain Coefficient [SHGC] of Windows
30%WWR 55%WWR 90%WWR
Annual Cooling Load Intensity and Window Performance
20
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
90,000
IGU-1U-2.39
SHGC-0.56
IGU-3U-2.31
SHGC-0.50
IGU-5U-2.04
SHGC-0.46
IGU-2U-2.26
SHGC-0.35
IGU-4U-2.24
SHGC-0.33
IGU-6U-1.96
SHGC-0.30
Annu
al C
oolin
g Lo
ad In
tens
ity [W
h/m
2]
30%WWR 55%WWR 90%WWR
Annual Cooling Load Intensity and Wall+Window System SHGC
21
-
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
90,000
0.00 0.10 0.20 0.30 0.40 0.50 0.60Wall+Window SHGC
30% WWR & 0.30 SHGC or 90% WWR & 0.11 SHGC
55% WWR & 0.52 SHGC, or 90% WWR & 0.33 SHGC,
85% WWR & 0.52 SHGC,
Overall envelope (window and wall) system R-value is strongly affected by WWR
Wall system (wall + windows) overall R-value is strongly affected by WWR
22
-
10,000
20,000
30,000
40,000
50,000
60,000
3.00 4.00 5.00 6.00 7.00 8.00 9.00Window + Wall R-value
Heating Load Intensity vs. Wall+Window Average R-value
23
Can you see a pattern??
-
10,000
20,000
30,000
40,000
50,000
60,000
3.00 4.00 5.00 6.00 7.00 8.00 9.00Window + Wall R-value
Wall A - R4.3Wall B - R8.9Wall C - R13
Heating Load Intensity vs. Wall+Window Average R-value
24
Heating Load Intensity vs. Window to Wall Ratio and Wall Performance
25
0
10,000
20,000
30,000
40,000
50,000
60,000
0.4 0.6 0.8 1 1.2 1.4
Annu
al H
eatin
g Lo
ad In
tens
ity [W
h/m
²]
Wall Construction U-Value [W/m²-°C]
30%WWR 55%WWR 90%WWR
less than R-7 opaque walls
This is putting “lipstick on a pig” Cooling loads increase significantly
Heating Load Intensity and IGU Performance (truncated scale)
26
24,000
25,000
26,000
27,000
28,000
29,000
30,000
31,000
32,000
33,000
34,000
IGU-4U-2.24
SHGC-0.33
IGU-2U-2.26
SHGC-0.35
IGU-6U-1.96
SHGC-0.30
IGU-3U-2.31
SHGC-0.50
IGU-1U-2.39
SHGC-0.56
IGU-5U-2.04
SHGC-0.46
Annu
al H
eatin
g Lo
ad In
tens
ity [W
h/m
2]
30%WWR 55%WWR 90%WWR
Putting it All Together – Heating and Cooling Energy Consumption
27
0.0
10.0
20.0
30.0
40.0
50.0
60.0
0° 90° 180° 270°
Annu
al E
nerg
y Co
nsum
ptio
n fo
r Hea
ting
and
Cool
ing
(kW
h/m
²)
Building Orientation
Envelope - 90% WWR, R13, IGU-1(U-2.39, SHGC-0.62)
Envelope - 90% WWR, R4.5, IGU-2(U-2.26, SHGC-0.39)
Envelope - 90% WWR, R13, IGU-5(U-2.04, SHGC 0.5)
Envelope - 55% WWR, R13, IGU-2(U-2.26, SHGC-0.39)
Envelope - 55% WWR, R13, IGU-5(U-2.04, SHGC 0.5)
Envelope - 30% WWR, R13, IGU-2(U-2.26, SHGC-0.39)
Envelope - 30% WWR, R13, IGU-4(U-2.26, SHGC-0.39)
Envelope - 30% WWR, R13, IGU-6(U-1.96, SHGC-0.33)
Putting it All Together – Heating and Cooling Energy Cost
28
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
0° 90° 180° 270°
Annu
al E
nerg
y Co
st fo
r Hea
ting
and
Cool
ing
($/m
²)
Building Orientation
Envelope - 90% WWR, R13, IGU-1(U-2.39, SHGC-0.62)
Envelope - 90% WWR, R4.5, IGU-2(U-2.26, SHGC-0.39)
Envelope - 90% WWR, R13, IGU-5(U-2.04, SHGC 0.5)
Envelope - 55% WWR, R13, IGU-5(U-2.04, SHGC 0.5)
Envelope - 55% WWR, R13, IGU-2(U-2.26, SHGC-0.39)
Envelope - 30% WWR, R13, IGU-2(U-2.26, SHGC-0.39)
Envelope - 30% WWR, R13, IGU-4(U-2.26, SHGC-0.39)
Envelope - 30% WWR, R13, IGU-6(U-1.96, SHGC-0.33)
“Determining the effect of building geometry on energy use patterns of office buildings in Toronto” - Tomina Ferdous and Mark Gorgolewki
Office Building Archetype, study including daylighting energy savings
Corroborating Study by Ryerson University
29
Corroborating Study by Ryerson University
30
• Envelope performance is key • When the envelope is poor massing and orientation can improve
energy performance • Great envelope performance allows freedom in massing/orientation
Conclusions
31
Floor Plate Orientation
Floor Plate Geometry
Presence and type of balcony
Number of Stories
Window Thermal
Performance
Opaque Wall Thermal
Performance
Window-Wall Ratio
Envelope Parameters
Floor Plate orientation
Number of Stories
Presence of Balconies
Floor Plate Geometry
Opaque wall and Window thermal
conductance
Window Thermal Performance
(solar gains only)
Window-Wall Ratio
Envelope Parameters
Relative impact of Architectural Feature on Heating Loads
Relative impact of Architectural Feature on Cooling Loads
These results are from “models” Models are always wrong – they are necessarily approximations of reality, and inputs into the model are always the weakest link However… “If we had observations of the future, we obviously would trust them more than models, but unfortunately… … observations of the future are not available at this time.” Tom Knutson and Robert Tuleya (climate modelers)
Cautions…
32
“What is the use of having developed a science well enough to make predictions if, in the end, all we’re willing to do is stand around and wait for them to come true?”
Sherwood Rowland Nobel Laureate in Chemistry for his work on ozone depletion
And one more Quote…
33