Incorporating Occupant

Behaviour Into New

Building Design

Liam O’Brien, PhD Assistant Professor, Civil & Environmental Engineering

PI, Human Building Interaction Laboratory

Carleton University

2

12 Ottawa House Load Comparison

Non-HVAC: Appliances, lighting, hot water

(Saldanha, Beausoleil-Morrison, 2012)

Factor

of 4

# of occupants is a

reasonable good

predictor; but hard to

predict during design

3

Background

3

5 identical Danish houses; Source: Gram-Hanssen (2010)

• Family #3 thought they were

very energy-conscious

4 Assumed occupant behaviour affects design

5 Occupant Behaviour and Passive Buildings

Occupant behaviour is even more significant

in passive buildings

Occupant Uncertainty and NZEB Design

Energy Use

Pro

bab

ility Renewable energy generation

capacity for 50% chance of achieving net-zero energy

90% chance of achieving net-zero energy

Uncertainty from occupant behaviour

Occupant effects: 10 to 1000%

7 Manual Shade Control

7

Uncertainty about blinds control

(Christoph Reinhart, 2004)

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9 Understanding Occupant Shade Control

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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

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10 Understanding Occupant Shade Control

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“Seduced by the View”

(Urban Green Council, USGBC, 2013)

12

What’s been said of occupants:

are illogical

act in response to random, external events

take decisions to use switches or controls only after an event has

prompted them to do so (rather than in advance of it)

often wait for some time until taking action and typically when they

reach a ‘crisis of discomfort’

over-compensate in their reactions for relatively minor annoyances

take the easiest and quickest option rather than the best, for their

immediate benefit

consciously or otherwise, leave systems in their switched state,

rather than altering them back again later, at least until another crisis

of discomfort is reached.

Leaman (1999)

Path of Least Resistance: “Desire Path”

Occupants will take the path of least

resistance, so we might as well consider

this from the beginning of design.

Results from a survey on residential

blind use

(Veitch, Mancini, Galasiu, Laouadi, 2013)

IAQ

Thermal

Comfort

Acoustic

Comfort

Visual

Comfort Privacy

Quality

of View Activity

Type Social

Constraints

Past

Experiences

Anticipated

Conditions

Occupancy

Type

Clothing

Level

Light-

switching

Fan use Operable

windows MacGyvered

solutions

Reposition

& Rotate Change

Activity Level Eat/drink

Thermostat

Adjustment

Cost

Implications

Environmental

Conscience

Energy

Literacy

Ease of

Adaptation Systems’

Simplicity

Black

Box

Culture

16

Agenda

1. Background theory

2. Case studies that exemplify occupant

behaviour

3. Three-tiered approach

1. Design with passive features

2. Implement smart controls

3. Directly influence occupant behaviour

17

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 green buildings

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Occupants are Creative

If discomfort occurs, occupants will adapt

themselves or the building

The Human Energy Balance

2/1/2014 20

ASHRAE Comfort Chart

2/1/2014 21

22

Adaptive Comfort

(only applies to buildings with natural/hybrid ventilation)

23 EcoTerra EQuilibrium House, Eastman, QC

2.84 kW (peak)

Building-

integrated

photovoltaic-

thermal system

Passive solar

design:

Optimized

triple glazed

windows and

mass

Ground-

source heat

pump

23

24

Don’t ignore localized comfort

Comfort is more than air temperature.

ASHRAE recommends concrete/tile floors to be maintained at 26-29°C if

they are likely to be stood on with bare feet.

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Other occupant adaptations

Dark shades

significantly

reduce heat-

rejection

capability

Can be

thermally

worse than no

shades at all

26 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)

5 kW electric heater

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Education of occupants was critical

EcoTerra garage

heater

EcoTerra setpoints

NREL RSF

cleaning schedule

But we must rely

less on researcher

intervention!

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 house Average existing

Canadian house

Second fridge and freezer in

EcoTerra basement

EnerPos, Reunion Island, France

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Seek efficient means

to deliver comfort

(Garde and Lenoir)

No significant air-conditioning required

Comfort can be maintained through natural ventilation and fan use alone

(Garde and Lenoir)

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Comfort is key: thermal, visual, acoustic

EnerPos clothing level

ASHRAE recommends 0.5 clo in summer; 0.34

clo was measured in EnerPos

Open

windows

allow both air

and sound

through

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Load monitoring in EnerPos

Equipment cost about 3% of

the total building costs

After 6 months of operation, it

was discovered that 13% of

EnerPos’ energy use was for

the elevator!

Why? The lighting.

ASHRAE Comfort Tool

NREL RSF, Golden, Colorado

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RSF Interior Design

Photography or Photorealistic

Renderings for Visual Comfort Analysis

So

urc

e: B

ren

t H

uch

uk

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Comfort and energy are tightly linked

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

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Acoustic Comfort

Acoustic comfort

is routinely

ranked low in

green buildings.

Hard surfaces

Open concept

Low ventilation

rates

Natural ventilation

Acoustic Comfort

Newsham, Birt, Arsenault, Thompson, Veitch, Mancini, Galasiu, Gover, Macdonald, Burns (2012)

Design for comfort and occupant

behaviour

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

Occupant

Behaviour

Smart Controls

Fixed/Passive Design

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

Occupant

Behaviour

Smart Controls

Fixed/Passive Design

Robust Design

System (building) Deviation

from target

Signal

Noise (e.g., occupant

behaviour)

Design parameters

Definition: An engineered system that is

designed to have greater tolerance for a wide

range of conditions while still performing as

desired.

Fixed/Passive Design

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Bi-directional robust design

BuildingOperating conditions

Occupant(s)

Performance

Comfort conditions

Adaptive actions

PO(x)

x

PB(x)

x

PP(x)

x

POC(x)

x

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Robust Design Example

Variation on Lightswitch-2002 algorithm to reflect observed inactivity of occupants

Shades closed if Isolar,workplane > 50 W/m2 and solar penetration depth > 1.0 m

Reopen after X days, where X is a normal distribution (μ = 3 days; σ = 3 days) if occupant is present

Lights are controlled to achieve 500 lux or greater on workplane

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0.8 m

Glare-free zone 3.0 m

3.0 m

Ωmin for no glare

Solar noon,

June 21Ωmax

= 70° Fixed shading device

1.0 m

Robust Design

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Robust Design

50

10 %

Robust Design

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Robust Design

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0.8 m

Glare-free zone 3.0 m

3.0 m

Ωmin for no glare

Solar noon,

June 21Ωmax

= 70° Fixed shading device

1.0 m

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Interior Design: Chair

An upholstered chair can add about 0.2 clo

(equivalent level to thin pants)

This shifts the comfort temperature by about

1.1°C

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Interior Design: Desk A computer monitor that is perpendicular to a

window is theoretically optimal for daylight

glare prevention.

(Osterhaus, 2005)

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Interior Design: Desk One study found that giving occupants full

range of rotation eliminated daylight glare for

97% of occupied time.

Sample Robust Design Solutions

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Occupants have diverse

preferences

Traditional controls neglect

these and assume “one-size-

fits-all”

They are also conservative to

prevent complaints

Controls can be designed to

learn from occupant

override/habits

Reinhart and Voss (2003)

Design

guidelines

Desig

n g

uid

elin

es

Haldi and Robinson (2010)

Occupant

Behaviour

Smart Controls

Fixed/Passive Design

Smart Controls

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Example of learning controls: Nest

The Nest thermostat

Learns your schedule

Learns your preferred

temperature

Attempts to make slight

energy-saving shifts unless

override occurs

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Smart Controls does not necessarily

mean complex

Occupancy sensors for

perimeter offices often

increase energy use over

manual switch. Why? If conditions are sufficiently daylit,

people may not turn their lights on. This

more than compensates for those who

forget to turn them off at end of day.

A simple switch can reduce lighting

energy by 60% relative to occupancy

sensors

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Perceived control and social dynamics

Cohen et. al (1998):

manual controls

(windows, blinds,

lights) in open-plan

offices tend to “lapse

into default states that

minimize conflict and

inconvenience but are

not optimal, e.g. ‘blinds

down, lights on.’”

Social dynamics play an important role

in comfort and behaviour

Clothing level

Lights

Shades/blinds

Fans

Thermostats

Noise/speech

Private office Open-plan office

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Perceived Control vs. Actual Control

Studies have shown that people are much more comfortable if they sense they are control, even if they are, in fact, not.

Ideally, people should have the power to easily control their comfort.

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http://redchalksketch.wordpress.com/category/facade/facade-

consultant/emmer-pfenninger-partner-ag/

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Perceived control and social dynamics

Bordass, Bromley, Leaman (1993). User and occupant controls in office buildings

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Approaches to individualized comfort

CBE, UC Berkeley

Personal fan at head level

Hands heater above keyboard

Foot heater Task lighting

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Building energy

billing systems are

like going grocery

shopping without

being able to see

the prices till after

check-out. –

Source unknown

Occupant

Behaviour

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Occupant Feedback

Thermostat misconceptions

(Urban, 2013)

Thermostat is an on/off

switch

Thermostat is a dimmer

switch

Thermostat is an accelerator

Turning down the thermostat

has little or no effect on

energy consumption

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Influence of sub-metering on indoor

temperature selection

Upgrading homes to

submetering reduces

energy use by ~30%

Submetering added

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Influence of sub-metering on indoor

temperature selection

Submetered

occupants were less

willing to take further

adaptive measures:

they were at their

comfort limit

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Building Dashboard Guidelines

Provide context (historical and/or

understandable metrics)

Sub-meter as much as possible –

individuals must see their personal

impact

Real-time or frequent updates

Interactive

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Validation for Adaptive Actions

Window opening signals can

“…validate and leverage the

behavior of those who

naturally like to have their

windows open.” - Ackerly and Brager, 2011

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Energy Savings and Clothing Level

If occupants have

minimal constraints on

clothing level, heating

and cooling energy can

be reduced by as much

as 40%! (Newsham,

1997)

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Clothing Level and Social Constraints Shopping Mall:

Offices:

Morgan and de Dear (2003)

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Clothing Level and Social Constraints

Casual Friday in the office:

Morgan and de Dear (2003)

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Japanese Cool Biz initiative

Initiative to increase A/C setpoint to 28°C

Allow staff to wear less formal clothes

Use of desk fans

Flextime to avoid afternoon heat

Move desks away from windows (solar exposure)

Breaks and cold drinks Resulted in 1.14 million ton

CO2 emission reduction

2/1/2014 74

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In Summary…

Occupant behaviour has a profound influence

on building performance

Occupants are not the excuse but the

solution to high-performance buildings

Comfort cannot be expressed with a single

metric – it is complex

Case studies and software tools are

invaluable for influencing design

Occupant behaviour should be considered

up-front in design.

Acknowledgements

Burak Gunay

PhD Candidate

Brent Huchuk

MASc Candidate

Austin Selvig

MASc Candidate Ryan Kuhne

MASc Candidate

Aly Abdelalim

PhD Candidate Sara Gilani

PhD Candidate

Laura Scrimgeour

Research Assistant

Isis Bennet

Research Assistant

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Two-day conference – 70 technical

presentations on wide variety of

building performance topics @ St.

Brigid’s Centre

Industry-conference reception @

Bridgehead Roastery

8 workshops @ Carleton

We are looking for a few more

partners

THANK YOU – QUESTIONS? Liam O’Brien – liam.obrien@carleton.ca