Choosing adaptation interventions – the whole is greater than the sum of its parts

Adapting UK dwellings to reduce overheating during heat waves

Principal Investigator: Prof Li Shao De Montfort University

Co-Investigator: Dr Chris Goodier Loughborough University

Researcher: Stephen Porritt De Montfort University

2010: cooler Britain; warmer world

2010 in UK• Coldest

year since 1986

• Coldest December on record

2010 Globally– (2nd) warmest

• Met Office• NOAA • NASA

Extreme weather

2010: Colder Britain; Hotter World

PP1 – Aim

• Assess and rank passive adaptations for common UK dwellings to reduce overheating during heat waves

Building on previous work

Dwelling Selection & Construction Details

Modern Detached

1930s Semi

Victorian Terraced

1960s Flats

Cross-referenced with English House Condition Survey and Energy Saving Trust databases

Adaptations (Interventions)

• Increased loft insulation

• Internal wall insulation

• External wall insulation

• Cavity wall insulation

• Internal blinds

• Curtains

• External shutters

• Fixed shading over windows

• Solar reflective walls

• Solar reflective roof

• Changing window opening rules

• Night ventilation by opening ground floor windows

• Low-e triple glazing

Weather data

Three Approaches considered:

• Morphed future weather files Based on UKCIP02

• Mediterranean weather files (Milan, Rome etc.)

• Real heat wave years from the UK (e.g. 2003)

Ranking: Overheating exposure of dwelling types

1. 1960s top floor flats 2. 2007 detached

3. 1930s semi4. Ground floor flats5. end terraced6. mid terraced

Implication for the elderly:

Result: Single Adaptation Example

Result: Single Adaptation Example

Result: Single Adaptation Example

Findings: Single adaptations

• External shutters are the single most effective intervention (typically 50% reduction of overheating) for 3 of the 4 house types

• The exception is the terraced (due to solar heat transmission through solid walls. Light walls (and external insulation) are better

• The value of behavioural (zero cost) adaptations

Combined Adaptations

The limitation of single adaptation ranking

Challenges for assessing combining adaptation

• Computation• Analysis• Making results

available to others

8192 Simulations(94,208 total)

Combined Adaptations Example

Combined Adaptations Example

Combined Adaptations Example

Combined Adaptations Example

Combined Adaptations Example

Findings: Combined Interventions

• Overheating can be eliminated using the passive adaptations

• Low-cost adaptations often lead to greater winter energy use

• Many adaptations could reduce winter energy use by over 40%

• Use toolkit to pick

Semi, terraced & ground floor flats

Cost/Performance

Typical cost example for a Semi : • £3k • 85% reduction of overheating • 20% reduction of winter energy use

Similar costs for terraced and G floor flats

Or• £10k for • 95% reduction of overheating • 40% reduction of winter energy

Semi, terraced & ground floor flats

Top floor flats & 2007 Detached:“harder to treat”

• Overheating exposure could not be eliminated

• Costs many times higher for same level of overheating reduction

• 2007 detached: hard to reduce winter energy use

£23k for detached vs £3k for semi

Top floor flats & 2007 DetachedAdaptation cost increases for elderly

Top floor flat: • £13k daytime unoccupied (family)• £17k for daytime occupied (elderly)• overheating reduced to similar level• similar reduction of winter energy

use

2007 Detached: • Similar cost increase for elderly

In contrast to semi, terraced, G floor flats:

• Insignificant cost difference

Q: 2007 detached overheats.What if a terraced is highly-insulated like a

2007 detached?

For comparison, 2007 detached house worst overheating exposure: 715 DH

End-terraced Annual carbon emission

Overheating exposure (degree-hours)

Base case: 14,584 Kg 288

Highly insulated (as 2007 detached):

5,946 Kg (a) External wall insulation: 481 (b) Internal wall insulation: 617

Essential to Integrate adaptation with mitigation in retrofit design,and new build,

encouraged by policy

A:

PP1 – Retrofit web toolkit

Web tool demonstrationStephen Porritt

PP1 – Thank You

Retrofit web toolkit:

Questions or comments:

Stephen Porritt:Li Shao:

www.iesd.dmu.ac.uk/crew

sporritt@dmu.ac.uklshao@dmu.ac.uk

Ground vs top floor flats

• Very different adaptations for different floors

• Use toolkit to pick compatible adaptations

External vs Internal Insulation

• External insulation consistently outperforms internal insulation

• internal insulation could lead to worse overheating in some cases

• internal insulation has a role to play if combined correctly with other interventions (use the toolkit)

PP1 – Summary

• Large range in overheating exposure, for example:

• Dwelling type: Top floor flat over 4x mid terraced house• Orientation: Mid terraced house west-facing living rooms

3x north-facing living rooms• Occupancy: Detached house daytime occupied 2x daytime

unoccupied

• Best adaptation is often external shutters, though solar reflective coating on the walls is more effective for the end terraced house

• Some dwellings can be treated effectively at moderate cost (ground floor flat, terraced houses). Others are much more expensive to treat and overheating cannot be totally eliminated at any cost (modern detached, top floor flat)

PP1 – Summary

• If older houses (e.g. terraced) are retrofitted for reducing carbon emissions without considering summer use, overheating will increase to that of modern houses and they will be harder to treat

• Overheating exposure can be significantly greater for residents who have to stay at home during the daytime (e.g. elderly or infirm)

• Elderly and infirm residents should not, where possible, be housed in the most vulnerable dwellings (e.g. top floor flats)

• Validation monitoring has been carried out in addition to the simulations and construction of the web toolkit

• Rigorous selection of dwelling types, baseline construction and insulation for simulation models

• Selection of weather data – 2003 heat wave is expected to be an every year event by the 2040s

• Single adaptations provide an insight, but combined adaptations show how overheating AND energy use can be reduced

• Adaptation and Mitigation must be considered together

• The retrofit toolkit can be used to:• Evaluate stock• Prioritise retrofit schedule• Select adaptations and compare different solutions

PP1 – Summary