Future Challenges of Cities in Hot and Humid Climates

Lam Khee Poh, PhD, FRIBA Provost’s Chair Professor of Architecture and Building

Dean, School of Design and Environment 24 October 2017

Future Challenges of Cities in

Hot and Humid Climates

Transforming Cities in Hot and Humid Climates

Towards more Efficient and Sustainable Energy Use

“When you build a thing you cannot merely build that thing in isolation, but must also repair the world around it, and within it so that the larger world at that one place becomes more coherent and more whole; and the thing which you make takes its place in the web of nature as you make it.” Christopher Alexander Architect, Theorist, Educator

Author of “A Pattern Language”,1977, and “The Timeless Way of Building”, 1979.

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Nature of the Built Environment

"It is not the most intellectual of the species that survives; it is not the strongest

that survives; but the species that survives is the one that is able to adapt to and

to adjust best to the changing environment in which it finds itself”. Charles Darwin

Eskimos’ Ice House

Made of ice bricks with thickness of

about 500mm. The indoor temperatures

can be maintained at above －5℃

when the outside temperature is－30℃.

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Egyptian Residence

Brick thickness is more than 400mm.

Due to the big thermal mass, indoor

temperature difference in a day is less

than 6℃, while outdoor temperature

difference is more than 24℃.

Roof Exterior Surface T

Outdoor Air T

Indoor Air T

5

6

Cave Houses

Cave House in

Shaanxi, China

Cave House

in Tunis

Taman Tropika House, Universiti Teknologi Malaysia

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Ossen, D R, et al., Thermal Performance of Prototype Malaysian Traditional Timber House, 9th SENVAR & 2nd ISESEE

2008 International Seminar. Universiti Teknologi MARA (UiTM), Shah Alam, Malaysia on 1-3 December 2008

(60%)

(68.3%)

Brockway, et al, Understanding China's past and future energy demand: An exergy efficiency and

decomposition analysis. Applied Energy, October 2015

(94.6%)

(87.7%)

SADLY it does not work

DAMN YOU

THERMODYNAMICS Always ruining everything

WHO CAN TELL ME

THE FIRST LAW OF

THERMODYNAMICS?

MEN WILL

NATURALLY MOVE

TOWARDS THE

”HOTTEST” GIRL IN

COLLEGE !

Zeroth Law:

You must play the game

First Law:

You can't win

Second Law:

You can't even break even

Third Law:

You can't quit the game

So…..we need more

SCIENCE !

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Building Energy Flow-paths

Clarke, 1985: Energy Simulation in Building Design

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Passive Solar Elements

Clarke J, 1985: Energy Simulation in Building Design

Air Flow Modeling

Wind tunnel experiment to establish the boundary conditions for CFD computational analysis

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National Library Singapore

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149 150 151 156 157 157 153 149

0

50

100

150

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AverageBuilding

GMPlatinumDesign

2006 2007 2008 2011 2012 2013 2014 2015

kW

h/m

2/y

r

Year

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Concurrent Temperature and Air Velocity Profiles

Outside and Inside Building

Wind speed: 3.28 fps (1 m/s). Lower wind speeds give time for heat to accumulate and create heat pool between buildings.

Wind speed: 9.84 fps (3 m/s)

Wind speed: 16.40 fps (5 m/s)

Wind speed: 32.8 fps (10 m/s). Higher wind speeds help

dispersing heat pool between buildings.

Wind speed: 3.28 fps (1 m/s)

Wind speed: 9.84 fps (3 m/s)

Wind speed: 16.40 fps (5 m/s)

Wind speed: 32.8 fps (10 m/s)

Sustainable Urban Development - Tianjin Eco-City

Technology (alone) is not the answer…..

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Tropical City Concept Kampong Bugis Dev’t Guide Plan Proposal 1989

Khee Poh Lam PhD, RIBA Center for Building Performance and Diagnostics School of Architecture

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Tropical High-rise

Bio-Climatic Skyscraper – TRHY

Pinnacle@Duxton – ARC Studio A&U

Pinnacle@Duxton - WOHA

Ground Street Level

Sky Street – 30th Level

Sky Park – 30th Level

Sky Park – 50th Level

“Urban Shades” - Clarke Quay

Singapore’s Energy Policy

Our Approach Challenges

经济竞争

环境持续 能源安全

http://grammarist.com/wp-content/uploads/2014/09/details.jpg

An n-gram is a contiguous sequence of n items from a given sequence of text or speech

[computational linguistics and probability]

The devil is in

the details? God is in

the details?

Design Construction Commissioning Operation

Evaluation, Measurement and Verification

BUILDING DELIVERY PROCESS

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Framework ensures comprehensive and integrative design consideration for high performance and sustainable

solutions

Spatial Diagnostic

methodology for measuring

building performance,

evaluating impacts and establishing benchmarks

Thermal

Indoor Air Quality

Visual

Acoustical

Building Integrity

Knowledge-based Design

Knowledge Production

Codes &

Standards

Indoor – Outdoor Environmental Interaction Occupant Comfort, Health, Well-being

Life-cycle Process

http://ecocitizenworldmap.org/fr/about/the-project/

BUILDING DELIVERY PROCESS T

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Total Building Performance

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Framework ensures comprehensive and integrative design consideration for high performance and sustainable

solutions

Spatial Diagnostic

methodology for measuring

building performance,

evaluating impacts and establishing benchmarks

Thermal

Indoor Air Quality

Visual

Acoustical

Building Integrity

Knowledge-based Design

Knowledge Production

People-centric

Goals

(Liveability)

Limits of

Acceptability

Systems

and

Process

Integration

(Suitability,

Reliability,

Flexibility)

Total Building Performance

Total Environmental Performance

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Environmental Quality & Protection

Material & Waste

Management

Energy

Efficiency

Water

Efficiency

WHITE STRATEGIES

• Micro climate management

• Thermal comfort

• Ventilation

• Eco biodiverse habitat

• Minimize site disturbance

• Alternative transportation

GREEN STRATEGIES

• Energy efficient infrastructure

• & public amenities

• On-site energy generation

• Use of renewal energy

• District cooling plant

• Hybrid ACMV system

BLUE STRATEGIES

• Water efficient features

• Storm water management

• Rainwater harvesting

• Grey water recycling

BROWN STRATEGIES

• Waste management &

segregation

• Waste conveyance system

• On-site refuse processing &

composting

• Use of environmentally friendly

or recycled materials

HOLISTIC APPROACH TO ENVIRONMENTAL SUSTAINABILITY

Net-Zero Energy Building in the Tropics

“Walk the Talk”

SDE 4 – Under Construction

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SDE 4 – Hybrid System Daylight Measurement

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SDE 4 – Hybrid System Thermal Measurement

Olgyay’s bioclimatic chart, adapted

from (Olgyay 1963).

Givoni’s building bioclimatic chart,

adapted from (La Roche 2012)

Schiavon, et al (2014) Web application for thermal comfort visualization and calculation according to ASHRAE

Standard 55 . Building Simulation

Human Centric Design

http://blog.gridium.com/3241/are-your-set-points-sexist/

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SDE 4 – Hybrid System Thermal Measurement

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N=76SDE4|HYBRIDSYSTEM|SUBJECTIVESURVEY

0 1 8

2732

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5

10

15

20

25

30

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VeryUncomfortable Uncomfortable Slightlyuncomfortable SlightlyComfortable Comfortable VeryComfortable

Whatisyourcurrentthermalcomfort?

12%

8%

06

49

20

0

10

20

30

40

50

60

ClearyUnacceptable JustUnacceptable JustAcceptable ClearlyAcceptable

Whatisyouracceptanceofcurrentairmovement?

8%

15

43

26

0

5

10

15

20

25

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ClearyUnacceptable JustUnacceptable JustAcceptable ClearlyAcceptable

Whatisyouracceptanceofcurrenthumidity?

What’s next?

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Study conducted by BCA and NUS from Jan 2014 for 3.5 years

12 September 2017

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