Effect of Building Shape And Neighborhood Design On Solar

Potential And Energy Performance

NSERC Smart Net-Zero Energy Building Strategic Research Network

Réseau De Recherche Stratégique Du sur les bâtiments a consommation

énergétique net zéro

Caroline Hachem, PhD, B. Arch, MSc. Arch., MSc. Eng.

Postdoctoral fellow, NSERC Smart Net-zero Energy Buildings Strategic

Research Network Concordia University

Vancouver

Edmonton Calgary

Toronto

Halifax Montreal

Ottawa

Lat 53 N Degree-days 5212

PPVV ppootteennttiiaall ooff CCaannaaddaa aanndd SSNNEEBBRRNN 29 researchers from 15 Universities, NRCan, Hydro Quebec, Gaz-Metro, building industry leaders

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�  Building design plays a key role in influencing energy consumption of neighbourhoods.

�  Some design parameters can significantly affect the solar potential and energy performance of houses and neighborhood ►► They should be implemented since the ddeessiiggnn ssttaaggee.

This presentation assumes that we have the possibility to design a whole solar neighborhood, or a cluster of buildings in a neighborhood.

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TOWARDS NET ZERO ENERGY COMMUNITIES

Path Towards Net Zero Energy Neighborhood

DDeennssiittyy

Energy efficiency measures

BBuuiillddiinngg sshhaappee

Solar Potential

SSiittee llaayyoouutt

Integration of PV or PV/T

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A holistic systematic design approach for

solar neighborhoods is required

PPrrooggrraamm

11.. HHoouussiinngg ddeessiiggnn   Building envelope   Geometrical parameters   Roof design-ready for the iinntteeggrraattiioonn ooff ssoollaarr ccoolllleeccttoorrss

22.. NNeeiigghhbboouurrhhoooodd ddeessiiggnn   Road layout   Density: Row and spacing effects

3.. TToowwaarrddss MMiixxeedd UUssee NNeeiigghhbboouurrhhooooddss

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BUILDING DESIGN

45% reduction

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Insulation and South Window Effect

DDwweelllliinngg SShhaappeess

  Trade-off between using higher insulation and larger south facing window area.   Optimal value of insulation is selected to balance between the increase in cost and

energy saving.

45% reduction

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Insulation and South Window Effect

DDwweelllliinngg SShhaappeess

Effect of window properties

Reduction of 40% Reduction of 50%

Hea

ting

load

(kW

)

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Insulation and South Window Effect

DDwweelllliinngg SShhaappeess

Orientation

Aspect Ratio

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DDwweelllliinngg SShhaappeess

  0°-30° - increase of heating load by 8%   30°-60° - increase of heating load by 30%

Increase of heating load

by 30%

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Orientation DDwweelllliinngg SShhaappeess

L

  The aspect ratio should be selected to compromise between heating and cooling loads

Expected to be higher with larger windows on West and East

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13

DDwweelllliinngg SShhaappeess Aspect Ratio

S

30° 30°

30°

30°

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Orientation Solar neighbourhood design

Important to design the larger facade of the building with a near

south orientation

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�  Deviation from rectangular shape leads to increase in heating load, however Ø  Proper design of facades and windows can reduce the energy use Ø  Non rectangular shapes may counterbalance the increase of heating load

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DDwweelllliinngg SShhaappeess Geometry

Heating consumption is

reduced dramatically for

shapes like U and H when the south

window constitutes 50% of the façade.

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�  Deviation from rectangular shape leads to increase in heating load, however Ø  Proper design of facades and windows can reduce the energy use Ø  Non rectangular shapes may counterbalance the increase of heating load

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DDwweelllliinngg SShhaappeess Geometry

DR=1/2   DR=3/2  DR=1  

0

500

1000

1500

2000

2500

3000

3500

Rectangle L (DR=1/2) L (DR=1) L (DR=3/2)

heat

ing

Loa

d 8% 19%

25%

Depth  Ratio  (DR)  

Number  of  shading  facades  Reducing the energy use

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DDwweelllliinngg SShhaappeess Geometry

�  BBuuiillddiinngg sshhaappeess lliikkee iinn sshhaappeess,, HH aanndd TT sshhaappeess hhaavvee llaarrggeerr ssoouutthh ffaacciinngg rrooooff aarree ffoorr tthhee ssaammee fflloooorr aarreeaa aanndd tthheerreeffoorree hhaavvee tthhee ppootteennttiiaall ttoo iinntteeggrraattee llaarrggeerr PPVV ssyysstteemm..

Living area

BBeenneeffiittss ooff nnoonn rreeccttaanngguullaarr sshhaappeess

Living area

Living area

Living area

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DDwweelllliinngg SShhaappeess Geometry

�  LLiivviinngg aarreeaass iinn sshhaappeess lliikkee LL ,, UU aanndd TT sshhaappeess hhaavvee lleessss ddeepptthh →→ppeenneettrraattiioonn ooff ssoollaarr rraaddiiaattiioonn wwhhiicchh iiss bbeenneeffiicciiaall ffoorr ddaayylliigghhtt aanndd ppaassssiivvee hheeaatt

Living area

BBeenneeffiittss ooff nnoonn rreeccttaanngguullaarr sshhaappeess

Living area

Living area

Living area

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DDwweelllliinngg SShhaappeess Geometry

Reduction of wasted space for circulation

and vestibules, which can save land

area

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DDwweelllliinngg SShhaappeess Geometry

(a) (b)

20% more roof area

Different tilt angle Optimal radiation

for summer and winter

�  OOppttiimmaall ttiilltt aannggllee aapppprrooxxiimmaatteess tthhee llaattiittuuddee ooff tthhee llooccaattiioonn �  OOppttiimmaall oorriieennttaattiioonn iiss nneeaarr ssoouutthh

TTiilltt AAnnggllee

PPhhoottoovvoollttaaiicc IInntteeggrraattiioonn

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OOrriieennttaattiioonn

PPhhoottoovvoollttaaiicc IInntteeggrraattiioonn

Reduction of 12%

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NEIGHBORHOODS

  Solar community concepts allow for: Ø  non-rectangular or rectangular house shapes and designs, Ø  appropriate BIPV roof designs, Ø  optimal design passive solar gains.   These designs affect significantly the peak demand and the peak

generation of electricity.

(c)

(a)

U2

U1

U5 U4

U3 U2

U1

U5 U4

U3 U2

U1 U5 U4

U3

U2

U1 U5

U4 U3 U2

U1 U5

U4 U3 U2

U1 U5

U4 U3

(b)

U3 U2 U1 U1 U3 U2 U1 U3 U2

Solar neighbourhood design: Optimizing solar potential

Hachem C., A. Athienitis, P. Fazio, (2011), Investigation of Solar Potential of Housing Units in Different Neighborhood Designs, Journal of Energy and Buildings, Volume 43, Issue 9, Pages 2262-2273.

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Road layout

Difference of heating load ≤3%

S S

Solar access principles are not applied: openings are toward the street (north facing)

Increase of heating load by 60%

Increase of heating load by 7%

Increase of heating load by 60%

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�  The average heating load is not significantly affected by the layout of streets provided solar access is respected.

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Solar neighbourhood design

Example of trade -off between different building shapes, land area and energy efficiency

S 45°

POA r

(a) (c) (b)

Road layout

660

680

700

720

740

760

780

800

820

0

500

1000

1500

2000

2500

3000

3500

R R(O-45) V-SW45

Loa

d (k

Wh)

Average Heating

Average Cooling

Total Area of land

S

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Solar neighbourhood design

Density- Effect of Spacing

0

100

200

300

400

500

600

700

A D 2D

Cooling consumption (kWh)

Heating consumption (kWh)

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�  up to 35% reduction of heating load can be achieved in attached units

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Solar neighbourhood design

Living area Living area

Height

≈2 times Height

The distance between rows is dependent on the height of the shading buildings (about 2 times)

(a)

(b)

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Density- Effect of Spacing

Solar neighbourhood design

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Seasonal thermal storage

BIPV Systems

BIPV Systems

District heating

Solar collectors

Generation of 62% of the total energy use

Generation of 80% of the total energy use

�  Some house shapes (e.g L-shape) are more beneficial in a specific site layout.

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olar Neighbourhood Design

Shape of housing units a)  General site considerations b)  Minimizing total area for a given

functional area . c) Energy considerations ‒ Passive and Active solar design. General o  Orientation: within the optimal

range. Otherwise, trade-offs in shape design should be made.

o  South facing window area. Rectangular shapes: Aspect ratio ‒ of 1.3 to 1.6 should be applied . Self -Shading shapes (like L shape) o  Number of shading facades o  Ratio of shading to shaded façade

widths (depth ratio), and o  Angle enclosed by the wings. Roofs (default hip roof): Key effects : surface area, tilt angle and orientation.

S

30° 30°

30°

30°

Design Guidelines

S

Rectangular shapes: Self -Shading shapes:

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Two shading wings

Living area

Living area

Height

≈2 times Height

S

30° 30°

30°

30°

Design Guidelines

Positioning of housing units on a site. a) Straight road (east west direction) Low density- Detached units o  Apply passive solar design for shapes. Minimum

distance between adjacent units (bylaws) High density- Attached units o  Attached units are recommended for increased density.

For non-convex shapes configurations, the depth ratio and number of shading facades should be considered.

b) Curved Road Low density- Detached units o  Planar obstruction angle (POA) o  Orientation around the curve High Density - Attached units o  Similar observations as for straight road. Additional

design issues should be addressed. c) Row Configurations Low density ‒ Detached units o  Distance between rows of 1.5 - 2 times the height of the

shading building. High density ‒ Attached units o  The same design recommendations as detached units.

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EExxaammppllee ooff DDeessiiggnn

S

Garage covering the south facades

No windows on south facades, aspect ratio is small

Suggested modification

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Thank You…