Thermal Comfort & Environment

© Swanke Hayden Connell Architects, Nov 2006 Climate Change

GETTING HOT UNDER THE COLLAR? WHAT’S THE SET-POINT?

Dr Nigel OselandSwanke Hayden Connell Architects

November 2006


Introduction

• “Boston summers are warm and

sunny. Dress light and take

advantage of the balmy 80-90 °F

(27-32°C) by taking lunch in one

of our many city parks.

• … however, bring along a jersey

or jacket for indoors as the

conference centre will maintain a

comfortable 66 °F (19°C)”

American Society of Heating, Refrigerating

and Air-Conditioning Engineers

Boston Summer Conference (1997)


Agenda

• Outdoor temperature increasing

• Indoor temperature affects satisfaction and productivity

• Increase of 1°C set-point in summer = 5% energy saving (Gifford

Engineers)

• some models predict up to 15% savings

• What is the appropriate set-point temperature in offices

• why are ISO, CIBSE and BCO different?

• 24 Degree Forum

• Can/will we adapt to higher temperatures?

• Can/will our buildings adapt?


UKCIP – Summer Temperature Change

(UKCIP02 Climate Change Scenarios (2005)


Dissatisfaction & Importance

Based on 68 buildings and 7200 responses

0

5

10

15

20

25

30

0 10 20 30 40 50 60

Dissatisfaction (%)

Imp

ort

an

ce R

an

kin

g

PC

VentPeople Noise

Winter Temp

Summer Temp

Privacy

Quiet Space

Desk Space

EmailChair

Layout

Equip NoiseDaylight

0

5

10

15

20

25

30

0 10 20 30 40 50 60

Dissatisfaction (%)

Imp

ort

an

ce R

an

kin

g

PC

VentPeople Noise

Winter Temp

Summer Temp

Privacy

Quiet Space

Desk Space

EmailChair

Layout

Equip NoiseDaylight

Important but Satisfied

Important and Dissatisfied


Productivity – Tin Plate Production

95

100

105

40

50

60

Output

TemperatureRel

ativ

e O

utpu

t %

Ext

ern

al T

empe

ratu

re °

F

Jan Mar May Jul Sep Nov Jan

95

100

105

40

50

60

Output

TemperatureRel

ativ

e O

utpu

t %

Ext

ern

al T

empe

ratu

re °

F

Jan Mar May Jul Sep Nov Jan

Vernon (1919)


Productivity – Typist Study

**

20 °C*

* *

40

30

20

10

0

1 2 3 4 5Days

Mea

n no

. of

lin

es t

ype

d in

1 h

our

**

20 °C*

* *

40

30

20

10

0

1 2 3 4 5Days

Mea

n no

. of

lin

es t

ype

d in

1 h

our

24 °C24 °C

Wyon (1974)

9°C


Productivity – Typist Study

**

20 °C*

* *

40

30

20

10

0

1 2 3 4 5Days

Mea

n no

. of

lin

es t

ype

d in

1 h

our

**

20 °C*

* *

40

30

20

10

0

1 2 3 4 5Days

Mea

n no

. of

lin

es t

ype

d in

1 h

our

24 °C24 °C

Wyon (1974)


Productivity: Data Processing

Kroner, Stark-Martin & Willemain (1992)

Pro

du

ctiv

ity

chan

ge(

%)

20

10

0

-10

-20

-30

-40

-4 -3 -2 -1 0 1 2 3 4

Move to new building

Time (weeks)

5 6

16%


Environmental Responsive Workstation


Productivity: Data Processing

Kroner, Stark-Martin & Willemain (1992)

Pro

du

ctiv

ity

chan

ge(

%)

20

10

0

-10

-20

-30

-40

-4 -3 -2 -1 0 1 2 3 4

Move to new building

Time (weeks)

5 6

16%

3%


Standards - ISO 7730 Calculation

• Thermal sensation is related to the thermal balance of the human body

• Thermal sensation can be predicted from 6 key variables:

• air temperature

• mean radiant temperature

• air velocity

• relative humidity

• physical activity (metabolic rate)

• clothing insulation

• Met & clo looked up in charts

• highly subjective

• variable due to personal preference

Air temperature

Radiant temperature

Metabolism

Air velocity

Humidity

Clothing


Standards - ISO 7730 Calculation

• 6 variables calculate the Predicted Mean Vote (PMV)

• 7-point thermal sensation scale

• Corresponds to Predicted Percentage Dissatisfied (PPD)

• 3 categories of PMV/PPD:

• PMV: A = -0.2 to +0.2, B = -0.5 to +0.5, C = -0.7 to +0.7

• PPD: A = <6%, B = <10%, C = <15%

• “It can be difficult to verify that the PMV conforms to the Class A category (0,2 PMV +0,2)”

• “It is an advantage if some kind of individual control of the thermal environment can be established”


Standards - Temperature

(met)

(1.2)

Clothing: Winter = 1 clo (suit), Summer = 0.5 clo (trousers & short-sleeve shirt)

ISO 7730 (2005)


Standards - Temperature

ISO 7730 (2005)

Standard Winter Summer

ISO 7730 22±2°C 24.5±1.5°C

CIBSE 2006* 22±1°C 23±1°C

ASHRAE 55** 22.5±2.5°C 25.5±1.5°C

BCO 2005 20±2°C 22±2°C* Clothing: Winter = 0.85 clo, Summer = 0.7 clo, Activity = 1.2 met

** Clothing: Winter = 1.0 clo, Summer = 0.5 clo, Activity = 1.0-1.3 met, humidity = 50%

• Standards and Guidance but no upper temperature Legislation


Standards – Temperature Offset

ISO 7730 (2005)

0.15 clo = 1°C


History of Suits


Vernacular Clothing


Seasonal Clothing


Cool Biz Clothing


Clothing Development


24 Degree Club

• CoreNet 24 Degree Forum want change to BCO specification

• Increase of 1°C = 5% energy saving from less cooling in summer

• for typical office work, densities and loads

• Calls for change in clothing and workstyle

• attitude and culture issue

• demise of suit, new fabrics/fashion required

• Why not 26°C or 27°C?

• Productivity studies indicate manual and mental performance

starts to decrease above 27°C (Wyon)

• The TUC recently called for a maximum working

temperature of 30°C


Behavioural Adaptation

• “If a change occurs such as to produce discomfort, people react in ways which tend to restore their comfort.”

• Modify internal heat generation:• type of activity - siesta• vigour • drinks/food

• Modify rate of body heat loss:• clothing & chair insulation• posture

• Modify thermal environment:• thermostat• ventilation/fan/window• window blinds

• Select different environment:• within building• other locations


Adaptation & PMV

Oseland, Humphreys, Nicol, Baker and Parsons (1998)

Availability oflocal cooling

desk fan

ceiling fan

opening window

Consumption ofdrink/food

cold drinks

warm drinks/food

Revised temperatureNote: no account is taken of the effect of posture, activity vigour or fit of clothing.

+ 2.8 K

+ 2.2 K

+ 1.1 K

+ 0.9 K

- 0.9 K

Variation inactivity non-sedentary

high stress

- 3.4 K

remove tie/collar

chair option

Y

Y

Y

N

N

N

N

Ability to adjust clothing

Y YN

add jumper/cardigan

remove jacket

Starting temperature

Example: If assuming 1.2 met and 1.0 clo then use a starting temperature of around 22°C.

- 2.6 K

+ 0.8 K

- 2.2 K

+ 2.2 K

0.3 K

Y

YN


Adaptation

• “Extended acceptable environments may be applied for occupant-controlled, naturally conditioned, spaces in warm climate regions or during warm periods, where the thermal conditions of the space are regulated primarily by the occupants through the opening and closing of windows.

• Field experiments have shown that occupants of such buildings could accept higher temperatures than those predicted by the PMV.” (ISO)

• “Higher temperatures may be acceptable if air-conditioning is not present … if temperatures

of 25°C is not exceeded for 5% of annual occupied period.” (CIBSE)

ISO 7730 (2005)


Adaptation - ASHRAE

ASHRAE (2004)UK running mean = 20°C, Jul mean max = 22°C, Jul 2006 highest = 36.5°C

Mean monthly outdoor temperature (°C) 35302520151050

30

28

26

24

22

20

18

Neu

tral

tem

pera

ture

(°C

)


Adaptation - CIBSE

CIBSE (2006)UK running mean = 20°C, Jul mean max = 22°C, Jul 2006 highest = 36.5°C

Outdoor running mean temperature (°C) 35302520151050

30

28

26

24

22

20

18

heated/cooled

Neu

tral

tem

pera

ture

(°C

)-free running


Adaptive Algorithm

SCATS, Nicol et al (2000)

• BA Waterside:• 30 staff on one floor, surveyed Aug – Oct 2000

• No increase in discomfort

• 224 kWh saved during study, potential 448 MWh saving for whole building

Comfortable Too Cold Too Warm

0

10

20

30

40

50

-3 -2 -1 0 1 2 3

Pre Set-point

Post Set-point

Pre Adaptive

Post Adaptive

0

10

20

30

40

50

-3 -2 -1 0 1 2 3

Pre Set-point

Post Set-point

Pre Adaptive

Post Adaptive


Adaptive Behaviour

• Expectations (Leaman, DeDear):• forgiveness factor / tolerance

• organisation to building match

• behavioural settings

• Control & Feedback (Leaman & Bordass):• ability to operate / change

• intuitive systems

• low burden, minimal negotiation

• confirmation of action

• rapid response

• Context effect (Rohles, Oseland):• colour

• furnishings

• “meat-locker effect”

Bordass & Leaman (2006)


Adaptive Behaviour

• 30 subjects

• Monitored over 2 weeks in winter

• Same clothing and activityOseland (1995)

Operative temperature (˜C)

3

2

1

0

-1

-2

-3

14 16 18 20 22 24 26 28

cold

hot

neutral

Mea

n re

port

ed t

herm

al s

ensa

tion

Chamber

Office

Home


Early Sustainable Buildings

• Controls too complex• too automated or

• not intuitive, not user-friendly

• New/untried technology

• Limited modeling

• User apathy• no sustainable appetite


Adaptive Attributes Effect Design feature Positive adaptive attributes

1 2 3 4 5 6 7 8 9

10 11 12 13

Openable windows Adjustable blinds Locally controlled ceiling fan Desk fan Local building services controls Workstation flexibility Furniture design Shallow plan Cellular rooms Good views Well chosen surface finishes Day-lighting and task lighting Good ergonomic design

Negative adaptive attributes

1 2 3 4 5

Uniformity of physical conditions Deep plan High occupant density External noise Central building services controls

Oseland, Humphreys, Nicol, Baker and Parsons (1998)


Work Location

• Temperatures reach 47°C on Central line in July

• Option to work from home:

• reduce travel time

• reduce pollution

• less energy consumption

• alleviate discomfort – travel and office

• more individual control over temperature

• quiet and concentration, less disruptive

• less stress

• increased productivity

• support local community


Energy Use

• Energy Consumption (Econ 19):

• office ~ 8,000 kWh/year @ 14 m²/desk

• home ~ 22,000 kWh/year

• home-working ~ 3,000 kWh/year (14%) extra

• 80% reduction in energy use overall

(Dept of Employment, 1997)

• if homework only and vacate office

Industrial 125M, 23%

Service 75M, 14%

Transport 163M, 30%Domestic

175M, 32%

Agriculture 5M, 1%

UK CO2 Emissions = 550 Million Tonnes


Carbon Footprint

• Say 220 days per annum at work

• car = 8 miles car, train = 64 miles,

tube = 6 miles per day

• ~ 2,000 kg carbon

• ~ 6,000 kg if used car only

• “to stop global warming everyone

needs to reduce their emissions by

2,500 kg per year”


Building Utilisation

• 14 million sq ft of office space available in London (CBRE)

• 9.6 million sq ft (69%) old stock

• but increase in new speculative

• Adaptive reuse -

convert to “lifestyle” apartments:

• less travel

• Reduced city pollution

• option to pop home, choice

• avoid working hottest part of day

• bring community back into city


Legacy Stock


Adaptable Buildings

Office Hotel Hospital Flat Room

13 m² office

1600 x 800 mm desks

6-person Meeting

12-person Meeting

Single Room

Double Room

6-person ward

4-person ward

2-person flat

1-person flat

Single Room

Twin Bedsit

14

.4 m

7.2 m


Adaptable Buildings


Adaptable Reuse


Demand for Large Floorplates

Northgate

HQ2

More House

201 Bishopsgate

10 Bishops Square


Vicious Circle of Blame

Property Environment Group (1992)

Occupiers“We would like to have sustainable

offices, but few are being built”

Constructors“We can build

sustainable offices, but the developers don’t ask for them”

Investors“We would fund

sustainable buildings , but there is no

demand for them”

Developers“We would ask for sustainable offices,

but the investors won’t pay for them”


Vicious Circle of Blame

Property Environment Group (1992)

Occupiers“We would like to have sustainable

offices, but few are being built”

Constructors“We can build

sustainable offices, but the developers don’t ask for them”

Investors“We would fund

sustainable buildings , but there is no

demand for them”

Developers“We would ask for sustainable offices,

but the investors won’t pay for them”


Conclusion

• Clearly indoor temperature affects satisfaction and productivity

• International Standards predict comfort up to 26°C

• by changing clothing

• National Guidance recognises adapt to higher temperatures

• by providing adaptive opportunities through workstyle and building design

• Allowing higher indoor temperatures means more sustainable cooling

• saves energy on AC or supports more sustainable design solutions

• Office carbon emissions minimal compared to travel

• Reduce travel by:

• encouraging flexible working

• utilising empty office space


Building Evolution


THANK YOU

Dr Nigel OselandSwanke Hayden Connell Architects

[email protected]

[email protected]

Thermal Comfort & Environment

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