architects • engineers

integrated sustainable design

mechanical engineering

natural ventilation design

passivhaus consultancy

healthy building design

landscape design

permaculture design

building monitoring

research & development

Exeter OfficeExeter Bank Chambers67 High StreetExeterDevonEX4 3DTTel. 01392 279220Fax. 01392 279036

Bideford Office18 Market Place

BidefordDevon

EX39 2DR(Registered Office)Tel. 01237 474952Fax. 01237 425669

Climate Ready Design Exeter Extra Care Project

David Gale RIBA

Gale & Snowden Architects & Engineers

e c o b u I l d 2 0 1 3designing for adaptation: considerations for an uncertain future

Our Team

• Exeter City Council, Client, Structural and Civil Engineers

• Gale & Snowden Architects, Mechanical Engineers, Landscape Architects

• Exeter University

• Jenkins HansfordPartnership - QS

Low Energy Design Permaculture Design

Passivhaus Certified Healthy Buildings

Project Starting Point

• New build 50 flats and communal facilities

• Restrictive site

• Shading of external courtyard space making it unusable

• Institutional building with central corridor

• Natural cross ventilation not possible

Shading diagram June 21st 18.00

MethodologyAnalysis• Future climate

• Literature research

• Risk Assessment

• Case studies

• Ongoing IES thermal modelling (Integrated Environmental Solutions)

• PHPP (Passive House Planning Package)

• Integrated team studio working

• Sites assessment

• Climate change adaptation strategies

• Cost benefit analysis

Modelling of building in IES and PHPP

Passivhaus Care

Home, Cologne,

Germany

Design for Future ClimateClimate Change – An Overview

We need to adapt our

buildings to cope with

higher temperatures,

more extreme weather

and changes in rainfall

• Since the 1960s the average temperature in UK has risen

• Average summer temperature increase of 4-6 degree by 2100

predicted for the South West of the UK

• Increase in UV radiation

• Events of extreme rainfall and flooding have become more

frequent and this trend is predicted to increase

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Change in Average Temperature Since 1850

Design for Future ClimateClimate Change

Building designers typically use weather data that is based on

past experience to predict the future performance of a building.

The building is then

designed to maintain

optimum comfort and

(ideally) to use minimal

energy over the lifetime of

the building.

Ignoring the evidence that

the climate is changing.

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Typical Design Temperature Range

Design for Future ClimateClimate Change

Building designers typically use weather data that is based on

past experience to predict the future performance of a building.

This project used

probabilistic future

weather data from Exeter

University’s Prometheus

Project which was derived

from the latest climate

projections for the UK

(UKCP09).

The projections are

probabilistic in nature

instead of deterministic so

as to allow users to

assess the level of risk.

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Typical Design Temperature Range

Predicted Change

in Average Temperature

A Climate Risk Radar was

used to visualise

building’s exposure and to

communicate risks to

clients.

Risks are building type

and project specific.

Risks are rated for their

probability and impact.

Design for Future ClimateAssessing the Risks

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Potential for mitigation through inclusion of thermal Mass

User group vulnerability -staff/visitors

User group exposure to health hazards

Requirement for maximum internal temperature

User group vulnerability -customers/clients

User group adaptable capacity

Use of building during extreme heat waves

Required daylight provison and glazing ratio

Mitigation measures in landscape design

Potential for mitigation through increased ventilation rate

Potential for mitigation through building fabric design

Weather exposure/wind loadsMaterial sensitivity to UV exposure

Future finacial viability of energy intensive building type

Sensitivity to UV exposure

Increased seasonal rainfall

Increased storm intensity

Potential mitigation measures in landscape design

Sensitivity to seasonal water shortage

Sensitivity to flooding

Water sensitive landscape requirements

Future finacial viability of high water use building types

Potential for rain/grey water storage

Following detailed analysis of building’s exposure to climate

change related risks, the 2030, 2050 & 2080 @ 50 percentile

with high CO2 emission scenario was chosen

Overheating criteria adopted = < 1% of hours above 25°C for

all accommodation

• User group vulnerability

• Increased internal temperatures

• Increased external temperatures

• Changing rainfall patterns

• Localised air pollution

Climate Change Adaptation Design

• High levels of Dementia care

• Cluster design

• Usable soft-centre courtyard

• Connection to others

• Community and privacy

low energy - healthy - integrated landscape – non institutional

Design for Future ClimatePHPP Overheating Analysis

IES dynamic modelling

and PHPP were used to

assess various ventilation,

shading and construction

strategies using current

and future weather data.

Overheating Classification

According to PHI (PB 41)

h>25°C Classification

>15% catastrophic

10-15% poor

5-10% acceptable

2-5% good

0-2% excellent

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4.3 Heavyweight/ no extra shading/ ventilation rate 2 ach

Design for Future ClimatePotential Impact from User Behaviour

In a Passivhaus night

cooling is especially

effective and great care

needs to be taken not to

overestimate achievable

ventilation rates.

Studies by the PHI in

Germany found that

during summer average

ventilation rates in cross

ventilated flats were

between 0.5 and 0.8 ach.

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1.3 Heavyweight/ no extra shading/ windows tilted at night (0.3 ach)

4.3 Heavyweight/ no extra shading/ ventilation rate 2 ach

A Heavyweight construction with a ventilation strategy that

achieves an average air change rate of 2 is likely to maintain

good summer comfort until 2080.

If this ventilation strategy is compromised because users do not

operate the building as expected and eg only tilt their windows

at night, then the same building will struggle to maintain good

summer comfort in 2030 and fail already in 2050.

Passive Adaptation 4 Heat1. Passive• Cross ventilation

• Super insulated envelope

• Intelligent ventilation control

• Extracting heat at source

• Mass vs light weight

• Living plants / landscape

• Solar shading

Cross flow vent 10-15% over heating improvement over

single sided ventilation

Overheating Criteria not to exceed 1% occupied hours over 25oC

Super-insulated, air tight envelope helps to stabilise

internal temperatures and reduce solar gain

penetration 3 – 6% improvement

Intelligent window control 4% improvement

Mass vs light weight 2-4% improvement with mass

Local shading 2% improvement

Relocation of internal heat gains from

plant outside thermal envelope 5%

improvement

Green microclimate reduce

summer temperatures by 3oC

Evaporation / Transpiration

Green roofPleasant shaded spaces for cooling

Less 1.5oc by microclimate

Active Adaptation 4 Heat2. People centred• Management / staff heat

stress awareness and training

• Drinking points

• No cooking in flats during heat waves

• Room ceiling fans

3. Active design• Heat extraction at

source

• Temperature sensor warning system for vent control

• MVHR coupled with ventilation control

• MVHR ground cooling

Early warning temperature system to aid

intelligent window ventilation control

MVHR Activated during heat

waves for minimum fresh air

Windows closed when external air temperatures

are hotter than inside 2-4% reduction

Ceiling mounted fans increase air

movement and sweat evaporation

Heat extract at source

Supply air reduced by 10oC in summer combined with

closing windows above 22-25oC reduces overheating

to zero 2080

Close loop ground to brine heat exchanger

Drinking point to aid hydration

Adaptation 4 Air Pollution Healthy design• Good ventilation rates

• Thermal comfort

• Filtration of pollutants and pollen using MVHR when needed

• Removal of CO2 by MVHR

• Non-VOC materials

• Plants used to help clean air

• Cleanable surfaces to reduce dust mites infestation

• Radial wiring to reduce EMFs

Plants remove VOCs & CO2

MVHR removes VOCs & CO2

VOCs

CO2

MVHR with pollen filter for affected users

MVHR at night for security on ground floors

Smoke / smog particulates filtered by MVHR

Mosquito insect mesh on opening windows in summer

Pollen

MVHR provides good air quality in bedrooms at night when windows are shut

VOCs

Building and Landscape design working together to provide healthy environments

Courtyard design provides fresh air

microclimate

Adaptation 4 RainfallWater strategies• Water retention via

planting and landscape design

• Irrigation SUDs system

• Rainwater collection

Oversized gutters and downpipes

Wetter winters dryer summers – future rain files need adapting for designers

Rain water harvesting tank on flat roof:

Option A – ground and plants irrigation only

Option B – as A plus flushing WCs, Sluices and laundry

For flushing WCs

For sluice rooms

Storage point at ground level

Water attenuation by rootsRainwater storage crate system =

underground swale irrigation system

Lower collection point for overflow

SUDS / Attenuation system

External area left for rain water harvesting tankRain water harvesting under ground option B

Aquaculture

Integrated LandscapeLandscape

• Thermal comfort

- cooling, shading

• Water

- collection and reuse

• Biodiversity

• Health & well being

• Plants choice - species suited to challenging conditions, winds, drought, occasional flooding

• Minimise hard surfacing

Roof Garden

Cooling effect

Health and Welfare

Biodiversity

Adaptation for Heat, Rainfall, and Air pollution,

Green roof

70-200cm substrate

Sedum, herb, grasses

Biodiversity.

Reduce peak runoff.

Reduce annual runoff

by50-60%

Cooler surfaces

Improve air qualityDeciduous

climbers

growing up

balconies

local shading

Green microclimate reduce

summer temperatures by 3oC

Evaporation / Transpiration

Pleasant

shaded

spaces for

cooling

Permeable paving to allow percolation

into soils

Rainwater collection

For reuse in garden

areas

Layered structure

to planting,

deciduous canopy

for summer

shading

Sequence of rainwater storage crates for natural

percolation to planting and pumped irrigation

Courtyard fresh air

micro-climate

Internal planting remove

VOC’s and CO2,

Design to allow flooding into

central planting shallow swale

Life Cycle CostingCumulative Energy Related Costs

Cumulative energy

costs for an Extra

Care facility,

built to 2010

Building Regulation

requirements, for

heating, cooling

and additional future

investments

required to maintain

adequate comfort

conditions over the

lifetime of the

building.

All costs have been discounted at 5% to represent present value. An

annual increase in fuel costs of 4% has been allowed for and a reduction of

heating demand of 30% from 2050 to 2080 has been included.

Life Cycle CostingCumulative Energy Related Costs

Cumulative energy

costs for an Extra

Care facility,

built to Passivhaus

Standard, for

heating, cooling

and additional future

investments

required to maintain

adequate comfort

conditions over the

lifetime of the

building.

All costs have been discounted at 5% to represent present value. An

annual increase in fuel costs of 4% has been allowed for and a reduction of

heating demand of 30% from 2050 to 2080 has been included.

Life Cycle CostingCumulative Energy Related Costs

Comparison of

Cumulative Energy

costs:

Payback of additional

initial investment

after approx.

13 years

All costs have been discounted at 5% to represent present value. An

annual increase in fuel costs of 4% has been allowed for and a reduction of

heating demand of 30% from 2050 to 2080 has been included.

South Elevation

North Elevation

Adaptability of cluster design

• operate clusters together or independently

• division of building functions

• division of ownership

• conversion to dwellings

Opportunities

Simple, low cost measures incorporated at the

beginning of the design process can create robust, low

energy buildings, future proof against climate change

Adoption of Passivhaus standards combines low

energy buildings with excellent summer comfort

An integrated project team applying good practice

building physics is key to enable architecture to perform in

present and future climates

Swim4Exeter

(D4FC 2)

60% Energy reduction and excellent

summer comfort without air

conditioning

Challenges

Lack of guidance

Weather file selection

Compatibility with

current good practice

guidance

Late consideration of

climate change risks

PassivOffices

(D4FC 2)

Low energy use and excellent

summer comfort without air

conditioning

Summary of findings

• Early consideration

• Employ sound building

physics

• Thermal modelling

• Building layout designed

for cross ventilation

• Well insulated & airtight

• Design for microclimates

• Simplicity

Air conditioning can be avoided into 2080 with a passive approach

The Climate Change Adaptation work has directly influenced the

design of the building

Thank You

Swim4Exeter

(D4FC 2)

60% energy reduction and excellent

summer comfort without air

conditioning Exeter Extra Care

(D4FC 1)

Vulnerable user group

Air conditioning could be avoided into

2080 with a passive approach

PassivOffices

(D4FC 2)

Low energy use and excellent

summer comfort without air

conditioning