Sustainable by Design - Extra Care for Exeter

Climate Ready Design Exeter Extra Care Project David Gale RIBA Gale & Snowden Architects & Engineers

ecobuIld 2013 designing for adaptation: considerations for an uncertain future

architects • engineers integrated sustainable design mechanical engineering natural ventilation design passivhaus consultancy healthy building design landscape design permaculture design building monitoring research & development

Exeter Office Exeter Bank Chambers 67 High Street Exeter Devon EX4 3DT Tel. 01392 279220 Fax. 01392 279036

Bideford Office 18 Market Place Bideford Devon EX39 2DR (Registered Office) Tel. 01237 474952 Fax. 01237 425669

Our Team • Exeter City Council, Client, Structural and Civil Engineers • Gale & Snowden Architects, Mechanical Engineers, Landscape Architects • Exeter University

Low Energy Design

Passivhaus Certified

Permaculture Design

Healthy Buildings

• Jenkins Hansford Partnership - QS

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

Analysis • • • • •

Methodology

• • • • •

Passivhaus Care Home, Cologne, Germany

Modelling of building in IES and PHPP

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

Design for Future Climate Climate Change – An Overview • 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

Temperature Change (degree C)

Change in Average Temperature Since 1850 1 0.8 0.6 0.4 0.2 0

We need to adapt our buildings to cope with higher temperatures, more extreme weather and changes in rainfall

Design for Future Climate Climate Change

Building designers typically use weather data that is based on past experience to predict the future performance of a building.

10

8

Ignoring the evidence that the climate is changing.

7

6 5 4 3 2

We are here.

Temperature Change (degree C)

9

The building is then designed to maintain optimum comfort and (ideally) to use minimal energy over the lifetime of the building.

1 Typical Design Temperature Range 0 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100

Design for Future Climate Climate Change

Building designers typically use weather data that is based on past experience to predict the future performance of a building.

10

8 7

6 5 4 3 2

We are here.

Temperature Change (degree C)

9

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).

Predicted Change in Average Temperature

1 Typical Design Temperature Range 0 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100

The projections are probabilistic in nature instead of deterministic so as to allow users to assess the level of risk.

Design for Future Climate Assessing the Risks Potential for mitigation through inclusion of thermal Mass User group vulnerability Potential for rain/grey water storage 25 staff/visitors Future finacial viability of high water User group exposure to health use building types hazards 20 Water sensitive landscape Requirement for maximum internal requirements temperature 15 User group vulnerability Sensitivity to flooding customers/clients 10 Sensitivity to seasonal water shortage Potential mitigation measures in landscape design

Increased storm intensity

Increased seasonal rainfall Sensitivity to UV exposure Future finacial viability of energy intensive building type Material sensitivity to UV exposure

5 0

A Climate Risk Radar was used to visualise building’s exposure and to communicate risks to 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 loads

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

Risks are building type and project specific.

Risks are rated for their probability and impact.

• 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 Climate

Hours above 25 deg C in %

PHPP 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>25째C >15% 10-15% 5-10% 2-5% 0-2%

Classification catastrophic poor acceptable good excellent

Design for Future Climate Potential Impact from User Behaviour

20 % in % C in deg C 25 deg above 25 Hours above Hours

18 16 14

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

12 10 8

4.3 Heavyweight/ no extra shading/ ventilation rate 2 ach

6 4 2 0 2010

2030

2050

2080

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.

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.

Passive Adaptation 4 Heat Overheating Criteria not to exceed 1% occupied hours over 25 oC

1. Passive

Cross flow vent 10-15% over heating improvement over single sided ventilation

• Cross ventilation • Super insulated envelope • Intelligent ventilation control • Extracting heat at source • Mass vs light weight • Living plants / landscape • Solar shading

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 Less 1.5oc by microclimate

Local shading 2% improvement

Evaporation / Transpiration

Pleasant shaded spaces for cooling Relocation of internal heat gains from plant outside thermal envelope 5% improvement

Green microclimate reduce summer temperatures by 3oC

Green roof

Active Adaptation 4 Heat MVHR Activated during heat waves for minimum fresh air

2. People centred • Management / staff heat stress awareness and training • Drinking points • No cooking in flats during heat waves • Room ceiling fans

Windows closed when external air temperatures are hotter than inside 2-4% reduction

Early warning temperature system to aid intelligent window ventilation control Drinking point to aid hydration

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

3. Active design • Heat extraction at source • Temperature sensor warning system for vent control • MVHR coupled with ventilation control • MVHR ground cooling

Healthy design

Adaptation 4 Air Pollution MVHR provides good air quality in bedrooms at night when windows are shut

VOCs

Plants remove VOCs & CO2 MVHR removes VOCs & CO2

VOCs

Courtyard design provides fresh air microclimate MVHR with pollen filter for affected users

CO2 Smoke / smog particulates filtered by MVHR

Pollen

Mosquito insect mesh on opening windows in summer MVHR at night for security on ground floors Building and Landscape design working together to provide healthy environments

• 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

Adaptation 4 Rainfall Rain water harvesting tank on flat roof: Option A – ground and plants irrigation only Option B – as A plus flushing WCs, Sluices and laundry

Oversized gutters and downpipes

Water strategies • • •

For flushing WCs

Water retention via planting and landscape design Irrigation SUDs system Rainwater collection

SUDS / Attenuation system

For sluice rooms

Storage point at ground level Rain water harvesting under ground option B External area left for rain water harvesting tank

Water attenuation by roots Rainwater storage crate system = underground swale irrigation system Lower collection point for overflow

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

Aquaculture

Integrated Landscape

Landscape

Adaptation for Heat, Rainfall, and Air pollution, Evaporation / Transpiration Roof Garden Cooling effect Health and Welfare Biodiversity Rainwater collection For reuse in garden areas Deciduous climbers growing up balconies local shading Courtyard fresh air micro-climate Internal planting remove VOC’s and CO2,

Permeable paving to allow percolation into soils Sequence of rainwater storage crates for natural percolation to planting and pumped irrigation

Layered structure to planting, deciduous canopy for summer shading

Green roof 70-200cm substrate Sedum, herb, grasses Biodiversity.

Reduce peak runoff.

Reduce annual runoff by50-60% Cooler surfaces Improve air quality

Pleasant shaded spaces for cooling Design to allow flooding into central planting shallow swale Green microclimate reduce summer temperatures by 3oC

• 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

Life Cycle Costing Cumulative Energy Related Costs

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.

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.

Life Cycle Costing Cumulative Energy Related Costs

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.

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.

Life Cycle Costing Cumulative 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

Challenges

Simple, low cost measures incorporated at the

Lack of guidance

beginning of the design process can create robust, low energy buildings, future proof against climate change

Weather file selection

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 PassivOffices (D4FC 2) Low energy use and excellent summer comfort without air conditioning

Compatibility with current good practice guidance Late consideration of climate change risks

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

PassivOffices (D4FC 2) Low energy use and excellent summer comfort without air conditioning

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