The Relative Impact of Building Form on
Energy Consumption
Multiple Unit Residential Buildings (and Offices)
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
Energy Codes over time
Site Energy Use (1975 = 100)
90A-1980
90.1-1989
90.1-1999
100 90-1975
90.1-2004
90.1-2010
90.1-2013
80
MNECB-1997
60
SB-10 2012
NECB-2011
TGS-2014
40
ASHRAE 90.1
MNECB/NECB
20
This graph is illustrative only
0
1970
1980
1990
2000
2010
2020
2030
3
Energy Use Intensity (kWh/m²-yr)
Today’s Energy Use of All Canadian Buildings
– By Year of Construction
400
• Energy consumption
is for year 2009
350
• Most older building
300
have been
250
renovated with
newer HVAC
200
• Most older building
150
have a “computer on
100
every desktop”
50
• Why is this
happening?
0
Before 1920 1960 1970 1980 1990 2000 2005
1920
to
to
to
to
to
to or later
1959 1969 1979 1989 1999 2004
• data does not come
with explanation
Year Building was Constructed
Ref: Survey of Commercial and Institutional Energy Use – Buildings 2009, NRCAN
4
What was studied?
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
5
Floor plates developed around realistic suite
layouts
Double loaded
corridors
6
7
0°
90°
180°
270°
North
Square
Bar
‘L’
‘U’
‘H’
8
Wall Constructions – Effective R-Values
R-4.3
R-8.9
R-13
9
Glazing Constructions
All glazings used argon
gas fills in Aluminum
frames with 9 mm thermal
breaks
10
Glazing Constructions
Centre-of-Glass
ID
DESCRIPTION
U-VALUE
2
IGU-1
IGU-2
IGU-3
IGU-4
IGU-5
IGU-6
Double Glazed, high solar
heat gain low-e (surface #3)
Double Glazed, low solar
heat gain low-e (surface #2)
Double Glazed, high solar
heat gain low-e (surface #3)
& high solar gain low-e on
surface #4
Double Glazed, low solar
heat gain low-e (surface #2)
& high solar gain low-e on
surface #4
Triple Glazed, high solar
heat gain low-e on surfaces
#2 and #5
Triple Glazed, low solar heat
gain low-e on surfaced #2
and #5
*all glazing cavities are
Argon filled
RSI-Value
W/m ·°C
°C-m²/W
1.55
0.65
1.40
Total Window System
(CSA Rated Size)
SHGC
U-VALUE
2
RSI-Value
SHGC
W/m ·°C
°C-m²/W
0.62
2.39
0.42
0.56
0.71
0.39
2.26
0.44
0.35
1.46
0.68
0.55
2.31
0.43
0.50
1.38
0.72
0.36
2.24
0.45
0.33
1.26
0.79
0.50
2.04
0.49
0.46
1.17
0.85
0.33
1.96
0.51
0.30
11
Metrics used to evaluate results
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)
12
Space Heating Load Intensity – Floorplate
and Orientation
34,000
33,500
33,000
32,500
32,000
Square
31,500
Bar
31,000
'L'
'U'
30,500
'H'
30,000
29,500
29,000
0°
90°
180°
Orientation of Floorplate
270°
13
Space Heating Load Intensity – Floorplate
and Orientation (to scale)
40,000
35,000
30,000
Square
25,000
Bar
20,000
'L'
'U'
15,000
'H'
10,000
5,000
0
0°
90°
180°
270°
14
Space Cooling Load Intensity – Floorplate
and Orientation
35,000
30,000
25,000
Square
20,000
Bar
'L'
15,000
'U'
'H'
10,000
5,000
0
0°
90°
180°
270°
15
Space Heating Load Intensity – Number of
Floors
40,000
35,000
30,000
25,000
Square
Bar
20,000
'L'
15,000
'U'
'H'
10,000
5,000
0
0
2
4
6
Number of Floors
8
10
12
16
Space Heating Load Intensity – “L”
Floorplate envelope to area to floor area
35,000
1
30,000
0.8
25,000
0°
20,000
0.6
90°
15,000
0.4
180°
10,000
270°
5,000
0.2
Envelope to Building Floor Area Ratio
1.2
40,000
Envelope to Building Floor Area Ratio
0
0
0
2
4
6
Number of Stories
8
10
12
17
Building Form Conclusions
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
18
Annual Cooling Load Intensity and Window
Performance
30%WWR
55%WWR
90%WWR
90,000
Annual Cooling Load Intensity [Wh/m2]
80,000
70,000
60,000
50,000
40,000
30,000
20,000
10,000
0
0.3
0.35
0.4
0.45
0.5
0.55
Solar Heat Gain Coefficient [SHGC] of Windows
0.6
0.65
19
Annual Cooling Load Intensity and Window
Performance
30%WWR
55%WWR
90%WWR
90,000
Annual Cooling Load Intensity [Wh/m2]
80,000
70,000
60,000
50,000
40,000
30,000
20,000
10,000
0
IGU-1
U-2.39
SHGC-0.56
IGU-3
U-2.31
SHGC-0.50
IGU-5
U-2.04
SHGC-0.46
IGU-2
U-2.26
SHGC-0.35
IGU-4
U-2.24
SHGC-0.33
IGU-6
U-1.96
SHGC-0.30
20
Annual Cooling Load Intensity and
Wall+Window System SHGC
90,000
80,000
85% WWR & 0.52 SHGC,
70,000
60,000
50,000
40,000
30% WWR & 0.30 SHGC
or
90% WWR & 0.11 SHGC
30,000
20,000
55% WWR & 0.52 SHGC,
or
90% WWR & 0.33 SHGC,
10,000
-
0.00
0.10
0.20
0.30
Wall+Window SHGC
0.40
0.50
0.60
21
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
Heating Load Intensity vs. Wall+Window
Average R-value
60,000
50,000
40,000
30,000
20,000
Can you see a pattern??
10,000
-
3.00
4.00
5.00
6.00
Window + Wall R-value
7.00
8.00
9.00
23
Heating Load Intensity vs. Wall+Window
Average R-value
60,000
Wall A - R4.3
50,000
Wall B - R8.9
Wall C - R13
40,000
30,000
20,000
10,000
-
3.00
4.00
5.00
6.00
Window + Wall R-value
7.00
8.00
9.00
24
Heating Load Intensity vs. Window to Wall Ratio
and Wall Performance
30%WWR
55%WWR
90%WWR
Annual Heating Load Intensity [Wh/m²]
60,000
50,000
40,000
30,000
less than R-7 opaque walls
20,000
This is putting “lipstick on a pig”
Cooling loads increase significantly
10,000
0
0.4
0.6
0.8
1
Wall Construction U-Value [W/m²-°C]
1.2
1.4
25
Heating Load Intensity and IGU
Performance (truncated scale)
30%WWR
55%WWR
90%WWR
34,000
Annual Heating Load Intensity [Wh/m2]
33,000
32,000
31,000
30,000
29,000
28,000
27,000
26,000
25,000
24,000
IGU-4
U-2.24
SHGC-0.33
IGU-2
U-2.26
SHGC-0.35
IGU-6
U-1.96
SHGC-0.30
IGU-3
U-2.31
SHGC-0.50
IGU-1
U-2.39
SHGC-0.56
IGU-5
U-2.04
SHGC-0.46
26
Putting it All Together – Heating and Cooling
Energy Consumption
Annual Energy Consumption for Heating and
Cooling (kWh/m²)
60.0
Envelope - 90% WWR, R13, IGU-1
(U-2.39, SHGC-0.62)
50.0
Envelope - 90% WWR, R4.5, IGU-2
(U-2.26, SHGC-0.39)
40.0
Envelope - 90% WWR, R13, IGU-5
(U-2.04, SHGC 0.5)
30.0
Envelope - 55% WWR, R13, IGU-2
(U-2.26, SHGC-0.39)
20.0
Envelope - 55% WWR, R13, IGU-5
(U-2.04, SHGC 0.5)
10.0
Envelope - 30% WWR, R13, IGU-2
(U-2.26, SHGC-0.39)
Envelope - 30% WWR, R13, IGU-4
(U-2.26, SHGC-0.39)
0.0
0°
90°
180°
Building Orientation
270°
Envelope - 30% WWR, R13, IGU-6
(U-1.96, SHGC-0.33)
27
Putting it All Together – Heating and
Cooling Energy Cost
Annual Energy Cost for Heating and Cooling
($/m²)
4.00
Envelope - 90% WWR, R13, IGU-1
(U-2.39, SHGC-0.62)
3.50
Envelope - 90% WWR, R4.5, IGU-2
(U-2.26, SHGC-0.39)
3.00
2.50
Envelope - 90% WWR, R13, IGU-5
(U-2.04, SHGC 0.5)
2.00
Envelope - 55% WWR, R13, IGU-5
(U-2.04, SHGC 0.5)
1.50
Envelope - 55% WWR, R13, IGU-2
(U-2.26, SHGC-0.39)
1.00
Envelope - 30% WWR, R13, IGU-2
(U-2.26, SHGC-0.39)
0.50
Envelope - 30% WWR, R13, IGU-4
(U-2.26, SHGC-0.39)
0.00
0°
90°
180°
Building Orientation
270°
Envelope - 30% WWR, R13, IGU-6
(U-1.96, SHGC-0.33)
28
Corroborating Study by Ryerson University
“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
29
Corroborating Study by Ryerson University
30
Conclusions
• Envelope performance is key
• When the envelope is poor massing and orientation can improve
energy performance
• Great envelope performance allows freedom in massing/orientation
Number of
Stories
Opaque Wall
Thermal
Performance
Envelope
Parameters
Presence and
type of balcony
Floor Plate
Geometry Floor Plate
Orientation
Relative impact of Architectural
Feature on Heating Loads
Window
Thermal
Performance
Window-Wall
Ratio
Window Thermal
Performance
(solar gains only)
Floor Plate
Geometry
Presence of
Balconies
Number of
Stories
Relative impact of Architectural
Floor Plate
Feature on Cooling Loads
orientation
Envelope
Parameters
Opaque wall and
Window thermal
conductance
Window-Wall
Ratio
31
Cautions…
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)
32
And one more Quote…
“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
33