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

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-

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

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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)

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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

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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

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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

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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

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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…

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“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…

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