Green Building Design

Dr. Liam O’Brien

Dept. of Civ&Env Engineering

Carleton University

Agenda

1. Introduce course

2. Major issues

3. Case studies

4. Review syllabus, course schedule

5. Office hours

6. Labs

7. AC&SE CEAB survey – please remind me!

2

My Background

B.Eng., Aerospace Engineering

M.A.Sc., Aerospace Engineering

Product design

Evaluating the sustainability of

engineering activities

PhD, Building Engineering Thesis: Development of a design

tool for solar houses

Consulting on over a dozen

building projects

Started at Carleton in 2011 for

new Architectural Conservation

and Sustainability Engineering

program

3

Human Building Interaction Laboratory4

Occupant

Behaviour

Smart Controls

Fixed/Passive Design

Simulation, BIM, and visualization research

• Occupant behaviour field

studies

• Advanced/learning/smart

controls for lighting and

blinds

• Model-predictive controls

• Building performance

visualization

• Occupant modelling

• Building information

modelling and data

visualization

• Natural ventilation

• Occupant comfort

• Design of offices and

homes for occupants

8 researchers (civil, mechanical, enviro, architecture, psychology, computer

engineering); ~12 industry and gov’t partners

International research community on NZEBs and occupant behaviour

Research: design processes,

tools, visualization

Teaching

GREEN HIGH

PERFORMANCE BUILDING

DESIGN

6

Learning outcomes of GBD

Understand the anatomy of a building and how different

components affect environmental impact and occupant

health and comfort

Know how to perform basic calculations – enough to

make informed design decisions – at least at the

conceptual design stage

Be able to walk through a building and relate course

theory to them

Understand the design process and the roles of all major

design parties

7

Learning outcomes of GBD

Be aware of and develop skills using software tools

Develop skills to identify symbiotic relationships between

components and understand and apply integrated design

Understand the strategies that can/should be

implemented at the various design/life-cycle stages

Understand different approaches to building

codes/standards and how to apply them

8

Topics with less detail

LEED

Water systems

9

Building anatomy10

(Notes on board)

Context for Canadian buildings11

Single detached

houses

7,566,000 units (1.2 billion m2)

Row/attached houses 1,453,000 units (200 million m2)

High-rise residential 4,104,000 units (368 million m2)

Commercial/institutional 717.1 million m2

Commercial/institutional Residential

Internal vs. envelope load dominated

buildings Internal load dominated buildings: the majority of

energy is used for equipment, lighting, and process

loads. A mild climate or low surface area to volume

ratio minimizes heat transfer through the envelope

and minimizes heating/cooling loads (e.g., large

commercial buildings)

Envelope load dominated buildings: internal loads

are insignificant compared to heating and cooling

loads caused by high heat transfer through the

envelope (e.g., detached houses)

(notes on board)

12

Energy vs. GHG emissions for buildings13

Sector energy use by country14

Energy inequality

GHG abatement by cost-

effectiveness

Building types: classified by occupancy

patterns and space uses

Residential: houses, townhouses, multi-unit

residential buildings (MURBS – e.g.,

apartments, condos)

Commercial: office, retail, institutional

(schools, universities, gov’t, hospitals)

17

3 + 2 pillars of “Green” Buildings18

Green Buildings

Build

ing E

nve

lop

e

HV

AC

Rene

wa

ble

s

Co

ntr

ols

/op

era

tion

s

Occup

an

ts/e

ng

ag

em

en

t

Integrated Design High-performance buildings do not work well

and are very expensive if integrated design is

not practiced!

19

From this…. to this.

Integrated vs. conventional design

Conventional Design

ProcessIntegrated Design Process

Involves team members

only when essentialInclusive from the outset

Less time and collaboration

in early stages

Front-loaded - time and energy

invested early

Decisions made by fewer

peopleTeam influences decisions

Linear process Iterative process

Systems often considered

in isolationWhole-systems thinking

Emphasis on up-front costs Life-cycle costing

Typically finished when

construction is complete

Process continues through post-

occupancy

ROADMAP FOR THE INTEGRATED DESIGN PROCESS – Busby Perkins and Will, and Stantec

Design team

Process is iterative, but approx. order

of design should be:

1. Massing,

orientation

2. Envelope design,

layout and finishes

3. Daylighting

4. HVAC

5. Renewables

22

Example of integrated design: how much insulation?

Simulation facilitates integrated design considerations

23

Insulation level

Bu

ildin

g c

ap

ita

l co

st

Point where peak heating

load drops and smaller

HVAC system can be

chosen

Smaller HVAC system

Larger HVAC system

Toolbox for design

Case studies, rules of thumb

High-Performance Building Magazine, SABMag,

ASHRAE Journal

Simple tools: single-system, simplified

models

RETScreen, HOT2000, Screening Tool, PV

Watts, MIT Design Advisor

Detailed integrated tools

EnergyPlus, eQUEST, TRNSYS

24

Example tools for passive building design

Climate Analysis/Visualization

• Climate Consultant

• Sustainable by Design

• Ecotect

Systems and Components

• RETScreen

• LBNL Window/Therm

• ParaSol

• WUFI; WUFI Passive

• SketchUp (also good for

geometry generation for other

tools)

• TRNSYS

• IA-QUEST; CONTAM

Building Level (residential)

• HOT2000/HOT3000

• PHPP

• BEOpt

• RESFEN

Comprehensive database of tools here:

http://apps1.eere.energy.gov/buildings/tools_directory/

25

Building Level (all)

• EnergyPlus/OpenStudio

• ESP-r

• COMFEN

• Screening Tool

Daylighting

• DAYSIM

• SPOT (sensor position

optimization tool)

Relationship between building subsystems

Mutualistic: subsystems #1 benefits subsystem #2 and vice versa. (HVAC and Envelope)

Commensalistic: subsystem #1 benefits subsystem #2, but subsystem #2 has no effect on subsystem #1. (Windows and walls)

Parasitic: subsystem #1 exploits subsystem #2 with nothing in return. (large east-facing windows and HVAC)

+

+

Net-Zero Energy Housing &

EcoTerra Case Study

Liam O’Brien

EcoTerra EQuilibrium House

2.84 kW (peak)

Building-

integrated

photovoltaic-

thermal system

Passive solar

design:

Optimized

triple glazed

windows and

mass

Ground-

source heat

pump

28

Net-Zero Definitions1. Electricity imports = Site electricity exports

(boundary at house’s electrical meter)

2. Electricity imports = site + off-site electricity

exports (boundary expanded to include off-site

generation)

3. Primary energy use = primary energy use

offset (boundary expanded to fuel source)

4. Zero life-cycle energy (boundary includes

materials)

5. Zero net operating GHG emissions

6. Zero operating or life-cycle costs

Net-Zero Measurement Period

All definitions pertain to

the period of a year

During this period, all

usual weather conditions

are experienced – good

and bad.

This is suitable for all

houses without long-

term storage

The testing period would

usually be the first 1-2

years.

NZEH Design Objectives

Achieve predicted NZE for least cost (capital

or life cycle)

Use simple and robust systems

Don’t sacrifice too much on comfort

Practice integrated design

Objectives of Net-Zero Concept

Self-sufficiency

Implied zero net impact on environment

Encourages state-of-the-art development of

technologies and construction techniques

Encourages both energy efficiency measures and

renewables (NZE necessarily includes

renewables)

Simplicity; understandable by lay person (e.g., vs.

LEED)

Universality (e.g., no dependency on climate

zones, etc.)

Underlying Fundamental Concept

Energy Efficiency Measures

(“negawatts”) On-site Energy Collection

Objective: Find the path to the performance goal with

the least resistance (cost, complexity).

Energy

Savings

The Optimal Mix

Energy efficiency

measures provide

diminishing returns

At some point, it’s

cheaper to move

forward with

renewable energy

systems (based on

additional $/kWh)

PVEnergy Efficiency

Measures

Economically

Optimal

EcoTerra House Timeline

Design Team

Engineering,

R&D, and

Systems Design

Andreas Athienitis

and graduate

students,

Concordia

University

Architectural

Design

Masa Noguchi,

Architect

Builder (and

technicians/trades)

Alouette Homes

Assembly of Modules

• Prefabricated homes can reduce cost of BIPV through integration

• The house was delivered in five modules; with the basement pre-poured

BIPV/T roof construction in Maisons Alouette’s

factory as one system – a first

Warm/hot air

flow from

BIPV/T

Sun

Air intakes

in soffit

Building

integrated PV arrays

Air cavity

Key features of EcoTerraTM House

Passive Solar Heating Large south-facing

windows (RSI 1)

Passive Charge Concrete Slab & Brick Wall

Motorized Blinds

BIPV/T PV panel Cooling

Drying Clothes

DWH heating

Ventilated Concrete Slab heating

Geothermal HP Forced-Air Space

heating/cooling

DWH heating

Ventilation Fan

Return Air

Exhaust Air Interior

Brick Wall

Well Water

Outdoor

Air Inlet

BIPV/T System

A/W Heat

ExchangerGeothermal Heatpump

(source is

well water)

Ventilated Slab

Supply Air

DHW

Preheat

Tank

DHW

Tank

Electrical Heater

Potable Water

Non-potable Water

Desuper-

heater from Heatpump

Circulator

Air Flow

Direction

Water Flow

DirectionWell Water

HRV

Fresh Air

Exhaust Air

Exhaust

Dryer

Passive Charge Slab

(direct solar gain)

Drain Water Heat Recovery

Variable

Speed Fan

Damper

Key features of EcoTerraTM House

80 meter boreholes

3-ton, 2-stage heat

pump

Major envelope parameters: EcoTerraTM

Heated Volume: 671.4 m3

Heated floor area (with basement): 230 m2

Two bedrooms

Ceiling Area: 87.06 m2 Exposed Wall Area: 219.73 m2

Glazing area:

North: 0.65m2

South: 20.9 m2

East: 6.67 m2

West:5.2m2

South Glazing to Floor Ratio: 9.1% (42% of south façade)

Air-tightness: 0.85 ach @ 50 Pa (measured)

(0.047 ach under typical conditions)

Roof RSI- 9.1 ; Walls RSI- 6.3

Basement floor RSI - 1.5; basement walls RSI - 5

Wall Constructions/Thermal Mass

Thermal mass

locations (high-

density concrete):

Basement floor

slab: 4” (10 cm);

ventilated

Main floor slab

(south half): 6” (15

cm)

Dividing wall

(bottom 3 ft of main

floor): 10” (25 cm)

Innovative Technologies

Building-integrated

photovoltaic/thermal

(BIPV/T) system that

was built in factory as a

manufactured model.

Hollow core thermal

storage system in floor

connected to BIPV/T.

Ventilated Slab

115

89

76

64

38

Normal Density Plain ConcreteSteel Deck (Canam P-2436, galvanized steel)Ventilation Channel (cavity)

Metal Mesh (e > 5mm)Rigid Insulation

Water/vapor Barrier

Gravel (earth)

Unit in mm

Th

_cn

c

Concrete

Air

Site/Shading Analysis

Vegetation was cleared to prevent shading on south façade and roof

Major Decisions Form - 1 vs. 2 storeys, shape, aspect ratio

Envelope – windows, opaque construction

insulation

Thermal mass – location, type, quantity

Heating/cooling/ventilation – type, distribution

Domestic hot water – heating source/recovery

Controls – interface, control zones, schedules

Renewables – type, quantity, storage

The NZE goal provides one more reason

to practice integrated design

Key Design Objectives

Energy efficient design –

airtight, optimal insulations

levels.

Passive solar design – south

facing windows to reduce

winter heat loads and mass

to prevent overheating;

active control also studied.

Building-integrated solar:

BIPV/T; geothermal heat

pump.

Demand

side

Supply

side

Integrated

Design

High-Level Design ProcessRules of thumb and experience

for passive solar, form, fabric

1-day follow-up meeting to

discuss ventilated slab

Proposal of design by architect

2-day design charrette mainly for

design of solar collector, thermal

storage

Aloutte in-house design for

lighting, forced-air system,

electrical, etc.

Design CharretteMembers: University research team (energy systems

design), architect, builder, municipality representative,

PV expert, utility representative, GSHP distributor

Advance work:

• proposed architectural drawings, predicted plug

loads (lighting, appliances, etc.)

• Major geometry fixed beforehand to reduce size of

design space

During:

• Parametric simulations (HOT2000) to size insulation,

windows, form.

• Design day calculations (Mathcad) performed to

assess passive solar performance and thermal

comfort.

• BIPV/T thermal output estimated

• PV sized to achieve desired net-energy level; priority

to reach target while maintaining affordability. 45°

slope assumed.

• GSHP chosen and sized (by distributor) in charette;

later downsized to account for passive solar

performance.

Detailed design by architect

Control system design by

commercial building controls

company and researchers

Passive Solar Strategies

Size window area and mass to avoid overheating.

Aspect ratio, form; passive solar design rule of thumb

– aspect ratio of 1.2 – 1.3 – get more south façade

but minimum practical depth is 8 m.

Higher ceiling height on first floor – 9’ - 10’.

Need to size mass to prevent overheating

Exterior shading?

Mass – where? Distributed mass on floor and walls is

better than thick mass in one location; active and

passive storage.

Passive Solar Design: EcoTerra House50

One-day follow-up meeting: Slab Design

Meeting objective: determine how to

actively store heat for space heating

from BIPV/T roof.

Approach: brainstorming, followed by

parametric analysis with different slab

materials, channel geometry, thickness,

and insulation.

Ventilated slab position in basement

floor so that:

Basement is cooler; enabling greater heat

storage capacity and lower minimum BIPV/T

outlet temperature threshold

Construction/ductwork easier

115

89

76

64

38

Normal Density Plain ConcreteSteel Deck (Canam P-2436, galvanized steel)Ventilation Channel (cavity)

Metal Mesh (e > 5mm)Rigid Insulation

Water/vapor Barrier

Gravel (earth)

Unit in mm

Th

_cn

c

Design Approaches

Simultaneous consideration of active and passive

approaches at the early design stage (similar to

combined building – HVAC simulation).

For example, the GSHP distributor sized the system

without considering the passive solar performance.

The distributed suggested 3.5-4 ton; 3 was used

(while 2.2 would have been sufficient).

Other Key Design Decisions

Solar DHW system would have been expensive and

added complexity. Instead, the its cost was reallocated

to a larger PV array.

Original plan was to use GSHP to completely heat water

but instead, BIPV/T and desuperheater pre-heat DHW

and a second tank with electric heater is used to bring

temperature up to 55°C.

Awning added to upper floor windows because there is

little thermal mass there.

How much insulation?

Space Heating vs. Wall Insulation

4800

4900

5000

5100

5200

5300

5400

5500

5600

5700

5800

6 8 10

Wall (RSI)

He

ati

ng

En

erg

y (

kW

h)

• Note that benefit in going from 6 to 8 RSI is

twice that of going from 8 to 10 RSI

• Diminishing returns

Insulation: parametric study results

Purpose: quickly establish most significant

affects and point at which return on

investment in minimal.

(based on HOT2000 calculations)

Thermal analysis – clear winter day

(similacase)Case Window

area (% of

south face)

and R-value

Mass (cm

concrete

on first

floor)

Aspect

Ratio

Heating

Type

Energy

consumption

kWh

Max room

temp.

C

1 30 (RSI 1) 5 cm 1.3 conv 54 24

2 40 (RSI 1) 5 cm 1.3 conv 51 27

2a 40 (RSI 1) 20 cm 1.3 conv 36 25

3 40 (RSI 1) 20 cm 1 conv 39 24.5

4 50 (RSI 1) 20 cm 1.3 conv 27 28.5

5 50 (RSI 1) 20 cm 1.3 Radiant-

conv.

26 (50 on

avg day)

28

6 50 (RSI 0.6) 20 cm 1.3 Radiant-

conv.

46 (69 on

avg day)

27

Passive Solar/Daylighting “Efficiency”

Solar Gains

Heat Loss

Daylight

Airflow

Useful

Overheating

Glare

Displaced

Lighting

Ventilation

Air

Leakage

Increased

Heating

Reduced

Cooling

Solar on

Occupants

57

Good passive

solar/

daylighting

design is

complex.

Sample

Performance

Lag

Temperature

Swing

Source: Chen, Y. et al (2010)

58

Sample Passive Solar Performance

Spikes mostly from garage heater

Only minimal heat

in morning at time

of setpoint

increase

Temperature

briefly falls below

setpoint before

nighttime setback

The demand profile can be analyzed to modify control strategies

for energy savings. E.g. change time of nighttime setback

Sample Passive Solar Performance

Indicates that

heating is being

supplied by GSHP

Stratification of 2-3°C occurs between rooms and peaks around

13:00-14:00.

Potential energy savings are possible with a more advanced

control system for circulation fan.

Why Solar Buildings: Diverse Forms

Photovoltics (PV)

Efficiency: 3 - 25%

Daylighting/

Passive Solar

Efficiency: 5 - 20%

PV/Thermal

Efficiency: up to 80%

Solar Thermal

Efficiency: up to 70%

• Quantity

• Timing

• Comfort

• Form

61

The 4 Pillars of Solar Energy Harvesting62

Storage

Orienta

tion

Conver

sion

Solar Conversion Efficiency

EnergySolar Incident

Energy UsefulEfficiency

63

Roof Design: Constraints/Considerations PV modules should extend along the length of the

roof (sloped direction) for integration

Voltage and current outputs had to match inverter

Collectors limited to south roof areas

Slope selected to optimize combined electrical and

thermal output

Width had to fit house width

The municipality required metal roof

Shading (trees, neighbours, etc.) should be avoided

A slope of 40 degrees or greater is needed to fully

shed snow

50 degree slope

Avalon Discovery 3 - March 21st Shadow Patterns

Shading study seems accurate for Avalon

Roof Design: Modules and the Inverter The number of modules

should be selected so that the

array power output is just

under the capacity of the

inverter.

The configuration (number of

modules per string) must also

be compatible with the

inverter.

1 2 3 4 5

5

6 74% 98%

7 86%

8 100%

9 76%

10

Mo

du

les/S

trin

g

Strings

Roof Design: Type

Gable Hip Cross-Gable

Visualization

Average Annual Solar Radiation

on Roof (kWh/m2) 1481 1481 1214

% Shaded Annually

0 0 18 %

Optimal Panel Layout

% Area Covered by Cells

80 % 66 % 76 %

Roof Design: Intermediate Solution

30° slope (changed from 45° for shipping)

9 meters wide

Amorphous Silicon modules (low efficiency but

large area)Extension added for

electrical compatibility

(19 →21 modules; 10

meters)

Hybrid Solar Collectors

Doubling-up can increase yields, but not

double them.

Semi-transparent PV

Photovoltaic/thermal at Concordia

University

71

Solar Fraction: Fraction of Total Energy

Provided by Solar Energy

So

lar

Fra

ctio

n

0

1

Solar Collector Area

“Net-zero”

Thermal energy needs

72

Green Building Challenges

1. Daily incongruence between solar

availability and demand.

Peak

demand

occurs

outside of

daylight

hours.

73

Loads and Generation Profiles74

Curved

street pattern Load

Genera

tion

24 hr12 hr

Undiversified

Net

Load

Genera

tion

24 hr12 hr

Net

Rectilinear

street pattern

Green Building Challenges

2. Seasonal incongruence between solar

availability and demand.

Peak energy demand is in the winter, but peak

solar availability is in the summer. Therefore,

you have to store the energy for ~6 months.

75

Green Building Challenges

3. Geometrical limitations: shading from

neighbouring obstructions, limited space,

unfavourable orientations.

Solar collector positioned

near-south (S30°W) and

above shadows from

neighbours

Vegetation cleared to ensure no

winter solstice shading of roof

76

Green Building Challenges

4. Complex systems rarely perform to their full

potential; simpler is better

Month

ly g

enera

tion (

kW

h)

• Summertime

performance is

close to predicted

• Wintertime

performance is

much worse

because of snow

cover

77

Site/Shading Analysis

Overhang Design

• No window shading

during winter

solstice (required by

CMHC).

• Majority of south-

facing windows

shaded by fixed

overhang on

summer solstice; but

not in shoulder

seasons.• Overheating can occur in shoulder seasons when outdoor

temperature is warm but sun is low.

o Retractable awnings are used on upper floor to minimize

unwanted gains. (only on upper windows because of lack

of thermal mass here)

o Interior shades are less effective because not all solar

gains are rejected; but also offer privacy.

78

-10

-5

0

5

10

15

20

25

0

10

20

30

40

50

60

70

80

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Me

an T

em

pe

rau

tre

(C)

Sola

r A

ltit

ud

e a

t n

oo

n (d

eg.

)

Solar Altitude

Mean Temperature

1-2 month lag

Building Performance Simulation 79

• Building geometry & envelope

• Controls

• HVAC

• Lighting

• Occupants

• Renewable energy systems

Weather

data

Model• Energy use

• Energy generation

• Temperatures

• Pressures

• Airflow

• Air quality

• Acoustics

• Daylight

• Thermal comfort

• Visual comfort

Outputs

Boundary

conditions

Time/Effort/Detail

Accu

racy

Elements of Building Simulation

(Clarke, 2001)

80

The Power of Performance Simulation

• Test new strategies

• Examine many

design possibilities

• Performance path

for building

performance

standards

• Meet current

expectations of with

absolute targets

like Net-Zero

A*SHGC (m2)

Ove

rha

ng

(d

ep

th a

s a

fra

ctio

n o

f gla

zin

g h

eig

ht)

5 10 15 20 25

0.05

0.1

0.15

0.2

0.25

0.3

1

1.1

1.2

1.3

1.4

1.5

1.6

1.7

x 104

Window size (m2)

81

200 400 600 800 1000 1200 1400 1600 1800 2000

200

400

600

800

1000

1200

1400

1600

1800

2000

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

8 9 10 11 12 13 14 15 16

Me

an S

had

e P

osi

tio

n (F

ract

ion

C

lose

d)

Time of Day

South East

South West

North East

North West

Building Simulation: Visualization

NREL RSF Building

82

Light shelves/

Sunshades

No Light shelves/

Sunshades

Waldorf school in West Virginia

NREL RSF daylight rendering

Annual daylight

availability

The Challenges of Building Simulation

• Designers cannot

control how well the

building is built

• Designers cannot

control how the

building is used

• Excessive data

availability

• Simulation does not

replace designers;

it’s just a tool

83

0

1000

2000

3000

4000

5000

6000

7000

Abon

dance

Alo

uette

Alsto

nvale

Ava

lon

CH

ESS

Ech

o H

aven

Min

to

Now

Riv

erdal

e

Win

nipeg

Predicted Measured Extrapolated from data

Model Details (EnergyPlus)

For early stage design, grouping windows is appropriate; however they were

explicitly modeled since the house is designed.

Ground boundary conditions applied.

EnergyPlus does not calculate solar

gains for windows below z=0.

Thermal Zoning

Having more zones is more conservative in

characterizing the risk of stratification.

Only mechanical airflow was considered.

Future work could consider natural airflow using an airflow

network of CFD.

Overhangs;

lower roof

modeled as

shading

surfaces

Mid-height

massive wall

Roof

(unconditioned)

Upper Zone

Garage Zone

North Zone

South Zone

Basement Zone

Preliminary Results

0

100

200

300

400

500

600

700

800

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Hea

tin

g L

oad

(kW

h)

Simulation Results

Monitored (occupied) Results

Occupied and monitored

period

Tools Used and Their Purpose

HOT2000 (required): used for whole house

annual energy analysis.

RETScreen (required): used for design of

renewables (PV, in this case).

MathCAD: design day analysis of passive

solar performance and design of BIPV/T and

ventilated slab.

RETScreen Demo

HOT3000 Demo

Design Approaches: Simulation

Period

Yearly simulation: necessary for net energy

determination, economic analysis and proper

optimization.

Design day simulation: useful for understanding

daily dynamics (e.g. passive solar performance).

91

Solar Design Days for Passive Solar Behaviour

0

5

10

15

20

25

30

35

40

00h3

0

02h3

0

04h3

0

06h3

0

08h3

0

10h3

0

12h3

0

14h3

0

16h3

0

18h3

0

20h3

0

22h3

0

time

Tem

pera

ture

(C

)

0

2

4

6

8

10

12

So

lar

Ga

in o

r H

ea

tin

g L

oa

d (

kW

)

South Zone Temp

Solar Gain

Heating Load

Peak Indoor Temperature: 25.6°C

Daily Purchased Heating:

64.24 kWh

Annual Purchased Heating: 12,441 kWh

0

5

10

15

20

25

30

35

40

00h3

0

02h3

0

04h3

0

06h3

0

08h3

0

10h3

0

12h3

0

14h3

0

16h3

0

18h3

0

20h3

0

22h3

0

time

Tem

pera

ture

(C

)

0

2

4

6

8

10

12

So

lar

Ga

in o

r H

ea

tin

g L

oa

d (

kW

)

Peak Indoor Temperature: 25.6°C

Daily Purchased Heating:

38.0 kWh

Annual Purchased Heating: 9,804 kWh

Glazing and thermal mass added

Cold

Sunny D

ay

-40%

-21%

Zero

heating

load at

time of

high

total grid

load

HOT 2000 Preliminary analysis

Space Heating vs. Window Area

1200

2200

3200

4200

5200

6200

7200

8200

9200

9.0 11.0 13.0 15.0 17.0 19.0 21.0 23.0 25.0

Window Area as % of Floor Area

Heati

ng

En

erg

y (

kW

h)

84.4

84.6

84.8

85

85.2

85.4

85.6

85.8

86

EG

H r

ati

ng

Solar Heat Gain Space Heating Load Heating Load w/ GSHP EGH Score

Heating - Gas

Heating - GSHP

EGH

Solar gains

Simulation Approach: Annual

Annual data can be overwhelming if not

presented properly

-10000

-5000

0

5000

10000

15000

20000

12

93

58

58

77

11

69

14

61

17

53

20

45

23

37

26

29

29

21

32

13

35

05

37

97

40

89

43

81

46

73

49

65

52

57

55

49

58

41

61

33

64

25

67

17

70

09

73

01

75

93

78

85

81

77

84

69

He

atin

g/C

oo

lin

g E

ne

rgy

(W)

Heating

Cooling

93

Simulation Approach: Annual

• If presented properly, annual results are ideal

o We want to confirm that the building performs well

under all expected conditions

Space Heating vs. Wall Insulation

4800

4900

5000

5100

5200

5300

5400

5500

5600

5700

5800

6 8 10

Wall (RSI)

He

ati

ng

En

erg

y (

kW

h)

94

Integrated Design: Major Questions

What parameters have the greatest impact

on design?

What model aspects deserve the most

attention?

What if…?

95

Rules of Thumb vs. Simulation

Rules of thumb:

“The thermal mass

should be 9 times

the area of south-

facing glass.”

“Do not exceed 6”

in thickness for

thermal mass

materials”

96

Good starting point

Usually limited to

relating only 1-2

variables

Limited to pre-

conceived

configurations/technolo

gies

Only predicts good

design characteristics;

not performance

When Rules of Thumb Fail97

Solar obstructions

Advanced technologies

Non-standard controls

Non-standard use of

space

PV Array

Trees (opaque)

Trees (opaque)

Trees (50% transmittance)

Parametric Analysis

Establish trends

Determine the

most critical

parameters

98

4,000

5,000

6,000

7,000

8,000

0.05 0.2 0.35 0.5 0.65 0.8

Co

mb

ine

d h

eat

ing

and

co

oli

ng

en

erg

y (k

Wh

/ye

ar)

Window-to-wall ratio

WWR1 (South)

WWR3 (North)

WWR4 (West)

WWR2 (East)

Parameter Interactions99

Example of a weak interaction

Example of a strong interaction

System Interactions

10

0

Full FactorialFractional

Each circle represents a unique case.

Each dimension represents a design decision.

Subsystem Coupling/Decoupling

Envelope &

Base Loads

BIPV

BI Solar

DHW

Energy Efficient

Measures

Solar

Thermal

(space

heating)

Good

prospects for

Decoupling

Moderate

Prospect for

Decoupling

Poor Prospects for

Decoupling

Passive Solar

Heating/Cooling

BIPV/T

Geometry,

Thermal

Geometry,

Demand,

Thermal

10

1

Why Solar Buildings? Source Close to Sink

10

2

But Canada’s best solar potential is near population centres

Solar Footprint of Toronto

Roofs Only (21% of area)

10% Conversion Efficiency

Solar Footprint

of Toronto

If all energy is

converted and

all land is used

Energy Flows and Boundaries

Externalities: health, quality of life, ecosystems

NetZEB: Lessons Learned

Liam O’Brien, Subtask B Co-leader (with Andreas Athienitis)

Assistant Professor, Civil & Environmental Engineering

Carleton University

Objective/Background

Present anecdotes from four international

case studies that can be generalized as

lessons learned.

The buildings were used as archetypes

Details can be found in our book: Modelling,

Design, and Optimisation of Net-Zero Energy

Buildings

EcoTerra, Eastman, Quebec LEAF House, Italy EnerPos, Reunion Island,

France

NREL RSF, USA

Don’t ignore localized comfort

Comfort is more than air temperature.

Seek efficient means

to deliver comfort

EnerPos, Reunion Island

No significant air-conditioning required

Comfort maintained through natural ventilation and fan use alone

Comfort is key: thermal, visual, acoustic

Thermal

Comfort

Acoustic

Comfort

Indoor Air

Quality

Visual

Comfort

Energy

Fixe

d a

nd

mo

vab

le

sola

r sh

adin

g

Heating/cooling

Heating/cooling

Daylightin

g

design

Openness for daylight penetration

Ventilatio

n and

outdoor a

ir

require

ments

Surf

ace

fin

ish

es: d

ust

co

llect

ing

vs. s

ou

nd

ab

sorb

ing

Natural ventilation

and outdoor noise

Acoustics is repeatedly ranked low for high-performance buildings

The 1:10:100 Ratio of Building Costs

1:10:100

Energy Costs

Rent

Salaries

Bottom line: Don’t sacrifice comfort for energy savings; BUT they are not

mutually-exclusive – market reports indicate “sustainable features” are

desirable.

11

0

Comfort is key: thermal, visual, acoustic

EnerPos clothing level

ASHRAE Recommends 0.5 clo in summer; 0.36

clo was measured in EnerPos

Open

windows

allow both air

and sound

through

Occupants are Creative

If discomfort occurs, occupants will adapt

themselves or the building

Other occupant adaptations

Dark shades

significantly

reduce heat-

rejection

capability

Can be

thermally

worse than no

shades at all

Know your occupants: anticipate diversity

Design for flexibility. Example: EcoTerra

Garage was turned into a workshop

Basement was converted to bedroom

Occupants are retired (not middle-aged with two

kids)

Design for comfort and occupant

behaviour

But no future opportunities for adjustment; so get it right!

Design for comfort and occupant

behaviour

But extreme care must be taken to not irritate occupants

Design for comfort and occupant

behaviour

But disaggregate as much as possible

Plug loads add up

Heat Pump21.3%

DHW11.7%

HRV/Air Cleaner

7.2%

BIPV/T Fan & Pump1.4%

Aux Garage Heater7.3%

Controls2.2%

Aux HP Heater1.0%

Lighting, Appliances, Plug Load

34.5%

Fan, Misc Equip13.2%

EcoTerra houseAvg. existing

Canadian house

EcoTerra basement

If you can’t measure it, you can’t

manage it Sub-meter as much as

possible and make data

readily available (including

to occupants).

After 6 months of

operation, it was

discovered that 13% of

EnerPos’ energy use was

for the elevator. Why? The

lighting.

Commissioning is Essential

Efficiency has its limits

Redesign studies showed that efficiency

measures tended to approach their upper

limits of practicality.

-12000

-10000

-8000

-6000

-4000

-2000

0

2000

4000

6000

8000

10000

12000

14000

Ba

se

Ca

se

(a

s b

uilt

)

Re

move

d a

ir c

lean

er

an

dre

du

ce

d fa

n u

se

Re

move

Div

ide

rs

Sh

ad

ing

Co

ntr

ol

Ba

se

me

nt a

nd W

all

insu

latio

n

Ad

de

d P

V

Ele

ctr

icit

y U

se

(k

Wh

/ye

ar)

Controls

Equipment

HRV/Air Cleaner

DHW

Heat Pump: Cooling

Heat Pump: Heating

Lighting, appliances, andplug loads

PV generation

Keep it simple

LEAF House mechanical systems schematic

Roof Design

• 30° slope (changed from 45° for module shipping

constraints) • Constraint could be removed through panelized construction

• Amorphous Silicon modules (only 6% efficiency but large

area)

Extension added for

electrical compatibility

(19 →21 modules)

12

4

The NetZEB goal is a game-changer

0 is an arbitrary number

But it is challenging and forces integrated design

with energy as a central goal – for designers and

occupants

$13 of PV per continuous Watt

This realization justified snipping backlight power

in all phones

Building performance simulation is a

life-cycle tool; not just for design

NREL RSF – model used to commission

building

Can be used to evaluate more sophisticated

operations

114

89

76

63

38

Normal density plain concrete (125mm (5"))

Steel deck (0.7mm (1/32") galvanized steel)

Ventilation channel (air cavity)

Metal mesh (8mm (1/4"))

Vapor barrier

Insulation (50mm(2") EXPS, RSI-1.7(R10))

Gravel backfill

125

Locations

of TC

TC-1

TC-2

TC-3 TC-5

TC-4

Education of occupants was critical

EcoTerra garage

heater

EcoTerra setpoints

NREL RSF

cleaning schedule

But we must rely

less on researcher

intervention!

Use of multiple tools is prevalent: for

features and for model resolution

Don’t overlook significant interactions; but

don’t be afraid to decouple for some situations

Design day/short/simple simulations

are valuable

But remember: it’s only a moment/day in time.

Design day/short/simple simulations

are valuable

Tools cannot model everything!

Closing thoughts

Comfort is king

For NetZEBs, subtleties count

The road to achieving NetZEB just starts at

construction

Simulation is invaluable, but care must be

taken

Controls Systems Design

Controls are key to low-energy design.

For example, the best use of the BIPV/T thermal

energy must be determined.

Small changed to the setpoint schedule can affect

whether auxiliary heating (COP=1) is used instead of

the GSHP (COP=3.6)

Collaboration between Regulvar (commercial

building controls company) and Concordia.

Two step process:

Concordia generated pseudocode

Regulvar implemented algorithms into the control

system

Strengths of Design Process

Proper integrated design with formal

design charette

Many experts included in design

process

Excellent co-operation between all

stakeholders (e.g. builder and

researchers/designers).

Limitation of Design Process

Ducting design was un-integrated. Could

have been better with improved

communication between engineers and

builder. Result: indirect ducting with

moderate heat loss between BIPV/T and

loads.

Fragmented models; unable to capture

some effects of interactions.

Should have had one “owner” for the

design of each major subsystem.

ECOTERRA PREDICTED AND

MEASURED PERFORMANCE

DATA

Pre-construction Predictions

Unoccupied Year – Monitored Data

-150

-130

-110

-90

-70

-50

-30

-10

10

Space Heating

Water Heating Appliances Lighting Cooling

Solar Electricity

Solar Thermal

Ground Source HP

Ene

rgy

De

nsi

ty (

kWh

/m2

)

Energy Consumption and Production Density

National Average

R-2000 Home

ÉcoTerra

-300.00

-250.00

-200.00

-150.00

-100.00

-50.00

0.00

National Average

R-2000 Home ÉcoTerra

Ene

rgy

De

nsi

ty (

kWh

/m2

)

Total Annual Enegy Densities

Reasons for Discrepancies

Occupancy daytime heating setpoints (22.5°C) is less energy-conscious

than designed for (21°C). (simulation shows this affects heating load by ~

20%)

Significant heat losses (~ 5°C drop) occur in the ducting from BIPV/T to

loads. Prediction of BIPV/T performance was optimistic.

Air cleaner was unexpected (consumes ~400 kWh/year)

Additional installed lighting (daylighting poorer than expected)/second fridge.

Snow cover and inverter downtime hurt PV electrical production. (~30%

worse than expected)

Garage heating consumes a predicted 2000 kWh/year (2/3 of the heat pump

energy consumption!)

Dryer not properly installed on BIPV/T ducting (system does not work as

expected because of duct design).

0

1000

2000

3000

4000

5000

6000

7000

Abon

dance

Alo

uette

Alsto

nvale

Ava

lon

CH

ESS

Ech

o H

aven

Min

to

Now

Riv

erdal

e

Win

nipeg

Predicted Measured Extrapolated from data

Electrical consumption for lights and applianceskW

h/y

ear

Recommendations: Operational

Temperature control setpoints:

If possible, delay daytime increase until after sunrise to permit solar

gains to do some of warming.

Set auxiliary (electric) heater on GSHP to have higher temperature

threshold (i.e. higher than difference between day and nighttime

setpoints).

Garage electric resistance heater:

Minimize use to when garage is occupied

Ventilation and circulation:

Circulation rate should be controlled by temperature differences between

rooms; not always on.

Ventilation rate should be reduced – saves energy and prevents dryness

of air (owners mentioned this issue).

Air cleaner could be removed/bi-passed.

Recommendations: Design

Ductwork should be simplified to reduce pressure drops and allow

faster flow rate in BIPV/T roof. This will allow greater flow rates (and

quantifies of extracted energy).

A greater roof slope would enhance show-shedding ability and

increase surface area.

Use of BIPV/T air in garage – usefulness threshold is much lower in

garage since it is maintained at a cooler temperature.

Possible use of lower roof section for solar energy collection, if more

aggressive targets are set.

Higher daylight levels through larger non-South windows. Cost of

additional heat loss should be balanced with daylighting.

MODELING AND REDESIGN

Redesign Strategies

Kitchen Appliances, Lights, Laundry, 5084.0,

31%

Actuators, 0.2, 0%

Sump Pump, 0.8,

0%

Water Filter, 0.0, 0%

Well Pump, 6.0, 0%

Alarm System, 83.6, 1%

DHW, 1425.2, 9%HRV/Air

Cleaner, 1260.4,

8%

Inverter, 18.0, 0%Controls, 390.4, 2%

Garage Heater, 1965.5, 12%

BIPV/T Fan, 69.4, 0%

Aux. Heater, 263.0, 2%

Heat Pump, 3151.8, 19%

HP Circulation Fan, 2509.1, 16%

Best first steps: biggest energy

consumers. Operations before

physical systems.

Better control over circulation fan

Less energy-intense source for

garage heat

Roof re-design for higher

performance

Additional PV/higher efficiency PV

Remove air cleaner

Daylighting

Envelope improvements

Assumption: Appliance loads cannot be reduced though the re-design

Upgrade #1: Smarter airflow controls

Issue: fan is currently on (low-speed) all the

time. Significant stratification only occurs in

early afternoon. Mean ΔT = 0.45°C

Solution: turn fan on only if temperature

between thermal zones exceeds 2°C.

Result: Fan is on for 32.8% of year; mean ΔT

= 1.40°C. Energy savings of 1690 kWh.

Modest effect on comfort.

Upgrade #2: Smarter airflow controls

Issue: air cleaner (in line with

HRV) is arguably unneeded

(house is far from pollution

sources)

Solution: Remove it.

Result: 429 kWh savings.

Upgrade #3a: Garage heating

Issue: Garage is used as

workshop; electric resistance

heating unexpected added.

Predicted 2660 kWh heating load.

Solution: Supply heat with GSHP

(assumed setpoint 12°C during

daytime only; as requested by

owners)

Result: 1920 kWh savings (over

electric resistance heater)

PV Upgrade

0 10 20 30 40 50 60 70 80 9080

85

90

95

100

105

110

115

120

Roof Slope (deg)

An

nu

al E

lectr

icity G

en

era

tio

n (

kW

h/m

2)

Snow Modeled

Snow Ignored

Under ideal conditions, PV performance is relatively insensitive

to slope.

With snow considered, higher slopes (>40-45 deg.) are better.

Higher slopes also mean a greater area for the given house

footprint.

Time of generation (especially thermal energy) must be a

consideration.

Upgrade #4: Increased PV efficiency

and slope Issue: Slope is slightly below

optimal and accumulates snow

Solution: Increase slope to 40°

and double nominal PV efficiency

to 12.6%.

Result: Predicted additional

4320 kWh/year of generation.

THE FUTURE OF NET-ZERO

ENERGY AND OTHER “BIG

PICTURE” TOPICS

Net-Zero Energy Buildings in the Future

NZE will become more feasible with:

More efficient appliances and lighting

More efficient and economical renewable energy

systems

Better building-occupant interaction

Energy monitoring, display, and interface

“Net-zero ready” – focus on envelope upgrade

appliances, lighting, renewables later.

Problems with Net-Zero Energy

Somewhat arbitrary definition. So what if it’s

90% or 110% of the way there?

Focus is exclusively on energy; no recognition

of comfort, health, water, other resources, social

considerations (e.g., affordability)

Probably not economically optimal; diminishing

returns on energy efficiency and renewable

energy generation. Incentives would be better

spent by distributing them equally.

Problems with Net-Zero Energy

NZE is a marketing label with no requirements

for monitoring

Occupants can impact energy use by 50% so

when can you call a house net-zero? After

design? After occupancy?

The definition is very home-centric; zero regard

for neighbours and co-operation

No consideration of temporal effect of electricity;

what if everyone has peak generation at one

time and peak consumption 6 months later?

Problems with Net-Zero Energy

Is the universal definition fair? Some climates

much more cooperative (e.g., on Reunion

Island, they often don’t use heating or cooling

and the days are all about 12 hours long)

No recognition of spatial considerations

Urban areas pose more constraints, but are likely

more sustainable (less transportation and land use)

Net-zero energy standard could lead to more urban

sprawl

Societies/Organizations/Projects

IBPSA-Canada (free to join; discussions of

starting Ottawa Chapter)

ASHRAE Carleton Student Chapter ($20/year

for students, but free monthly dinners and

magazine!; see my website for application

form)

Canada Green Building Council (CaGBC) –

Emerging Green Builders (EGBs) ($35/year)

Design competitions galore

SAB Mag (free industry magazine)

1/7/2015

156