Dissertation a

SID: 1108442

Anglia Ruskin University

BSc (Hons) Construction Management

‘How to Improve the Thermal Efficiency of

Listed Residential Buildings’

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May 2014

Declaration by the Author

This work is composed of my original work, and contains no material previously

published, produced or written by another person or organisation except where due

reference has been made. I have clearly stated the contribution of others to the

production of this work as a whole. I have read, understood, and complied with the

Anglia Ruskin University academic regulations regarding assessment offences,

including but not limited to plagiarism.

I have not used material contained in this work in any other submission for an

academic award or part thereof.

I acknowledge and agree that this work may be retained by Anglia Ruskin University

and made available to others for research and study in either an electronic format or

a paper format or both of these and also may be available for library and inter-library

loan. This is on the understanding that no quotation from this work may be made

without proper acknowledgement.

Candidates signature ………………………..……………………….…………

Candidates Student Number……………………………………………………

Date ……………………………………………..………………………………..

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Acknowledgements

I would like to thank Anglian Ruskin University for allowing me the opportunity to

study Construction Management. My supervisor Sunny Nwaubani who as supported

me throughout this module with advice and guidance. The knowledge and expertise

provided by Dayle and Andy has been very helpful. Their ‘Conservation of Historic

Buildings’ short courses have been invaluable in helping me to complete my

dissertation. Thank you to the participants who took the time to fill in my

questionnaires. I am grateful to my family for encouraging me and helping me remain

focused over the last three years. Finally, I would like to thank my father for inspiring

to investigate the topic of this dissertation.

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Abstract

This dissertation investigates the reasons why listed building should be

thermally upgraded. It discusses the barriers to improving the thermal

efficiency of listed buildings, and the methods that can be used to improve

their thermal performance.

The literature review discusses the advice given in various guide books

relevant to the topic. It also discusses current legislation on listed buildings

and energy efficiency. The literature review is supported by a survey of

construction professional that specialise in listed buildings. This is conducted

to gain an understanding of the methods they prefer to use when upgrading

the thermal efficiency of listed buildings.

The findings of the research suggest that there are two major barriers

associated with retrofitting listed buildings in order to make them more

thermally efficient. These are the listed building legislation and the risk of

decay from damp. The results of the survey generally correlate with the

advice given in the literature review.

The conclusions propose that heritage conservation is about the management

of change in order that the heritage value in a building is preserved. Before

applying for planning permission to make alterations to a listed building, a

detailed investigation should be conducted to show how the alterations could

affect the building in the present and in the future.

Key Words:

Legislation

Regulations

Conservation

Conduction

Convection

Decay

Insulation

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Contents

1.0 List of Figures and Charts..............................................................................vii

2.0 Introduction......................................................................................................1

2.1 Limitations....................................................................................................2

2.2 Aims and Objectives.....................................................................................3

2.3 Structure.......................................................................................................3

3.0 Literature Review............................................................................................5

3.1 Listed Buildings and Conservation Act 1990................................................5

3.2 Building Regulations Part L1B......................................................................8

3.3 Conservation Principles................................................................................9

3.4 Problems with Historic Buildings................................................................11

3.5 Insulation Materials....................................................................................14

3.6 Walls...........................................................................................................16

3.7 Windows.....................................................................................................18

3.8 Floors.........................................................................................................23

3.9 Roofs..........................................................................................................25

4.0 Research Methods........................................................................................27

4.1 Literature Review..........................................................................................27

4.2 Questionnaire................................................................................................27

5.0 Ethics Statement...........................................................................................30

5.1 Participants Information Letter....................................................................30

5.2 Participants Consent Form.........................................................................31

5.3 Ethics Tick Sheet........................................................................................32

6.0 Results..........................................................................................................33

7.0 Conclusions and Recommendations.............................................................44

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7.1 Conclusion..................................................................................................44

7.2 Recommendations.....................................................................................45

8.0 Further Research..........................................................................................47

9.0 References....................................................................................................48

10.0 Bibliography.................................................................................................49

11.0 Appendices..................................................................................................50

11.1 Appendix A – Questionnaire....................................................................50

11.5 Appendix B –Participant Information Letter.............................................57

11.6 Appendix C – Participant Consent Form.................................................58

11.7 Appendix D – Tutorial Sheet ...................................................................59

11.7 Appendix E – Original Illustrations...........................................................60

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1.0 List of Figures and Charts

Fig 1 – Traditional Stone Wall 12

Fig 2 – Traditional Solid Wall 12

Fig 3 – Moisture Ingress 13

Fig 4 – Insulation Materials 15

Fig 5 – Insulation Stopping at Joist 17

Fig 6 – Insulation Covering Joist 17

Fig 7 – Traditional Glazing Bar 21

Fig 8 – Modern Glazing Bar 21

Fig 9 – Traditional Glazing Bar with Slim Unit 22

Fig 10 – Suspended Timber Floor with Foam Boards 24

Fig 11 – Suspended Timber Floor with Quilts 24

Fig 12 – Cold Roof 25

Fig 13 – Warm Roof 26

Chart 1 – What natural insulation materials would you prefer to use? 33

Chart 2 – What mineral insulation materials would you prefer to use? 34

Chart 3 – What petrochemical insulation materials would you prefer to use? 35

Chart 4 – What composite insulation materials would you prefer to use? 36

Chart 5 – What methods would you most prefer to improve the thermal

efficiency of a cold pitched roof?

Chart 6 – What methods would you most prefer to improve the thermal

efficiency of a warm pitched roof?

Chart 7 – What methods would you most prefer to improve the thermal

efficiency of solid masonry wall?

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37

38

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Chart 8 – What methods would you most prefer to improve the thermal

efficiency of a wattle & daub/lathe & plaster wall?

Chart 9 – What methods would you most prefer to improve the thermal

efficiency of solid masonry/concrete floor?

Chart 10 – What methods would you most prefer to improve the thermal

efficiency of a suspended timber floor?

Chart 11 – What methods would you most prefer to improve the thermal

efficiency of a window?

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40

41

42

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2.0 Introduction

The title of this project is “How to Improve the Thermal Efficiency of Listed

Residential Buildings”.

It is now widely accepted that human activity is the major cause of global warming.

Increasing emissions of greenhouse gases such as methane and carbon dioxide are

making global temperatures rise. As a result sea levels are expected to rise and

weather to become more extreme. (PRT, 2010, p.1) A landmark report by the IPCC

(International Panel of Climate Change) says scientists are 95% certain that humans

are the "dominant cause" of global warming since the 1950s. (BBC, 2013) Fuel

poverty is another major problem in the UK, often with the most vulnerable people

bearing the brunt. Energy is increasing by an average of 16% year on year between

2004 and 2008. (PRT, 2010, p.1)

The UK contributes 1.73% of the total global carbon emissions, making it the 9th

largest contributor in the world. (European Commission, 2012) 44 -48% of the UK’s

carbon emissions is accounted for by the built environment. Approximately 27% of

these emissions are produced by domestic buildings and about 22% by public and

commercial buildings. 20% of these domestic buildings were constructed before

1919. Another 20% were constructed between 1920 and 1939. Space and water

heating is responsible for around 75% of carbon emissions produced by dwellings

with the rest coming mostly from lighting and appliances. (English Heritage, 2012)

Climate change is inevitable, but if we want to minimise its future impact we must

make our buildings more energy efficient and more capable of withstanding our

increasingly erratic weather patterns. (PRT, 2010, p.1)

The UK is committed to an 80% reduction of carbon emissions by 2050. Much

attention has been focused on designing new builds to be more energy efficient,

however because 70% of the UK’s building stock by 2050 will be buildings that exist

now, surely more investment should be spent on improving the energy efficiency of

our existing buildings. However, adapting buildings once they are already built is

inherently more difficult as there would not be an allowance for alterations in the

design of a building. (PRT, 2010, p.1) Still, this is a problem that must be addressed,

as the only other alternative is to demolish the building and start again which is

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counterproductive, creates a lot of waste and uses up precious energy that could be

saved. It also wastes the embodied energy that went in to constructing the original

building. (English Heritage, 2012, p.7)

This is particularly so for the UK’s stock of listed buildings and those in conservation

areas. It is particularly complicated to improve the energy efficiency of buildings with

historic or architectural interest, as statutory requirements restrict what alterations

may be made. This raises the question of which methods can be used to improve

their energy efficiency within legislative boundaries?

Many listed buildings actually have energy efficient features and design because

they were built at a time when energy was relatively more expensive. (English

Heritage, 2012, p.7) Traditional buildings very often had a high thermal mass, which

meant they were good at naturally regulating the internal temperature, so it would be

warmer at night during winter and cooler in the day during summer. (The PRT,

2010, p.11)

However in this day and age we see it as a necessity to heat our homes during the

winter for personal comfort. The trouble is that old buildings will quickly absorb this

heat into the fabric of the building, rather than letting it heat the occupants. (M.G.

Cook, 2009, p.33) Consequently, to keep the heat inside the building some may

resort to modern methods, such as installing insulation on the inside or the outside of

external walls. The trouble with this method is the insulation acts as a barrier to

moisture and as traditional building materials are very porous so anything stopping

the moisture escaping will trap it in the building fabric, resulting in mould and decay.

(SPAB, 2013, 2013, p.37-38) Therefore, we need new methods of improving the

energy efficiency of listed buildings. Otherwise people will not be inclined to live in

them and keep them maintained, without occupancy they will fall in to a state of

disrepair and we will lose our heritage. (M.G. Cook, 2009, p.16)

2.1 Limitations

The scope of the study will have to be limited due to many contributing factors such

as time, resources and word count. Therefore the research will only cover listed

buildings in the UK, meaning that listed building regulations for other countries will

not be taken in to account. Neither will considerations particular to warmer or colder

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environments than the UK be considered. The research will not cover historic

buildings which are not listed as these do not have barriers such as statutory

protection. Only residential buildings will be covered as commercial and industrial

building etc will have separate requirements. As the majority of carbon emissions

from listed buildings are a result of heating, the dissertation will only cover thermal

efficiency. Also, this will only mean for the actual fabric of the build, not services such

as space and water heating. Neither will it cover energy efficiency such as renewable

energy sources or more efficient energy systems.

2.2 Aims and Objectives

Aim:

This dissertation will investigate barriers to improving the thermal efficiency of listed

buildings and buildings in conservation areas. It will discuss the recommended

methods of improving thermal efficiency and investigate what methods professionals

in the industry prefer to use. At the end of the dissertation advice will be given on the

process of upgrading the thermal performance of listed buildings.

Objectives:

Investigate the current statutory regulations for listed buildings and energy

performance standards for existing dwellings.

Review current literature on methods of retrofitting listed/historic building for

energy efficiency.

Survey companies and professionals who specialise in listed buildings to yield

quantitative data.

Analyse the data in conjunction with information from the literature to come to

a conclusion and recommendations.

2.3 Structure

The study will be structured in the standard way, using the following chapter layout:

• Literature Review

• Methodology

• Ethical Guidelines

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• Results and Analysis

• Conclusion

• Recommendations

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3.0 Literature Review

There are a number of organisations who have published material on retrofitting

listed buildings for energy efficiency and sustainability. Two major organisations are

English Heritage and the Society for the Protection of Ancient Buildings (SPAB).

They provide advice on all matters to do with heritage conservation.

English Heritage is an executive non-departmental public body of the British

Government sponsored by the Department for Culture, Media and Sport (DCMS). It

advises on the conservation of the historic environment in England and has the

responsibility of registering and enforcing the protection of listed buildings and

ancient monuments. (English Heritage, 2014)

The Society for the Protection of Ancient Buildings is a registered charity that is

involved in all aspects of the survival of buildings which are old and interesting. They

offer conservation advice and training and produce technical publications, providing

practical guidance on the repair and care of old buildings. (SPAB, 2009)

Energy efficiency is becoming a key issue for those who work with historic buildings.

Research has been carried out on the performance of various traditional buildings

materials. Historic Scotland has produced reports on the performance of sandstone

construction, while English Heritage is currently looking at brick construction. SPAB

have taken the responsibility for researching most other walling types, including

wattle & daub panelling, cob, limestone, slate, granite etc. (SPAB, 2009)

There are also many official statutory documents relating to conservation principles

and building regulations. The literature is concerned with the Listed Buildings and

Conservation Act 1990 and it also discusses the relevance of the Buildings

Regulations Approved Document L1B - Conservation of fuel and power.

3.1 Listed Buildings and Conservation Act 1990

Section 1 of the Planning (Listed Building and Conservation Areas) Act 1990

imposes the duty on the Secretary of State to approve a list of buildings with

“special” architectural of historic interest in order that the planning authorities can

protect them. This enforcement comes in the form of listed building consent,

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conservation area control and scheduled monument consent. (HM Government,

2014, p.2)

Listed building consent is required when a development could affect the character of

or special architectural or historic interest of a listed building.

There are certain grades that a listed building can be given, these are the following:

• Grade I - Buildings that are of exceptional interest

• Grade II* - Buildings that are particularly important and of more than special

interest

• Grade II- Buildings that are of special interest (English Heritage, 2012, p.22)

Architectural Interest:

A building may be regarded as having special architectural interest based on its own

merit for having exceptional visual quality in its design, decoration or craftsmanship.

A building may also have special interest because it is an exceptional example of a

particular building type or technique, such as a building that demonstrates

technological innovation. (English Heritage, 2012, p.24)

Historic Interest:

A building can be regarded as having special historic interest if it illustrates important

aspects of the nation’s economic, cultural, or military history. It may be particularly

characteristic of the local region, or it may symbolise a particular era of industry. The

building may even have ties with nationally recognised people.

It is the policy of the Secretary of State that only those buildings that are most

representative or most significant examples of their type that should be listed. When

a number of buildings of similar type or quality survive it is necessary to compare

them in order to choose which ones to list. (English Heritage, 2012, p.24)

Age and Rarity:

One of the major considerations for listed buildings is how rare it may be. The older a

building is the less surviving examples there are likely to be and therefore the more

likely the building is to be listed.

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The generic principles used are listed below:

• Before 1700 - All buildings where most of the original fabric is intact are listed.

• 1700 to 1840 - Most buildings are listed.

• After 1840 - A greater proportion of these buildings have survived as more

were built, therefore stricter selection is needed.

• After 1945 – Very careful selection is required for buildings after this period,

they are usually only listed if of outstanding quality and under threat. (English

Heritage, 2012, p.25)

Group Value:

Another consideration the Secretary of State will take in to account is the value of

groups of buildings that demonstrate communal history and character. Where there

is a historical functional relationship between buildings it can shed light on how

society functioned in the past. (English Heritage, 2012)

When conservation officers decide whether to grant planning consent on a listed

building they take in to account the desirability of preserving the building, its setting

and/or features that make it of special architectural or historic interest. In this

instance conservation does not mean preservation, in the sense the building cannot

be altered in any way. Instead it means the careful management of change, so as

not to compromise the integrity of the interest. The significance of a building can be

harmed or lost through alteration or destruction. Heritage assets are irreplaceable;

therefore any damage or loss will need clear and convincing justification. (English

Heritage, 2012)

If a development will cause substantial harm to or total loss of significance to a listed

property, local planning authorities should refuse consent. The exception to this rule

is when there is substantial public interest that outweighs the damage or loss. The

following exceptions also apply:

The particular nature of the heritage asset inhibits all reasonable use of the

property

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No viable use of the heritage asset can be arranged through appropriate

marketing that will facilitate its conservation; and

It is shown to be impossible for conservation to be funded by grants or some

form of charitable or public ownership; and

The damage or loss is outweighed by the benefit of putting the property back

into use. (English Heritage, 2012, p.25)

When a development proposal will lead to less than substantial harm to the

significance of a listed property, the harm should be weighed against the public

interest, including safeguarding its most viable use. A balanced judgement is

required regarding the scale of harm or loss against the significance of the heritage

asset. It is up to the relevant planning body to decide whether the consequences of

development are justifiable given the significance of the building. (English Heritage,

2012, p.26)

3.2 Building Regulations Part L1B

The Building Regulations govern the standard for alterations to thermal elements of

existing buildings. The guidelines are set out in the Approved Document L1B -

Conservation of fuel and power.

The building regulations come in to effect for a variety of circumstances, the ones

that concern alterations are:

• “When certain changes or renovations are made to thermal elements”,

thermal elements are external walls, floors or roofs”.

• “When changes are made to controlled fittings or services”, controlled fittings

are windows, external doors, roof lights and roof windows. Controlled

services are space heating and hot water systems, mechanical ventilation

and cooling, and fixed artificial lighting”. (HM Government, 2014, p.7)

Section 3.6 of the Approved Document L1B - Conservation of fuel and power

(existing dwellings) states “There are exemptions from the energy efficiency

requirements that may apply to building work to existing dwellings”:

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Buildings which are:

• “Listed in accordance with section 1 of the Planning (Listed Buildings and

Conservation Areas) Act 1990”;

• “In a conservation area designated in accordance with section 69 of that Act”; or

• “Included in the schedule of monuments maintained under section 1 of the Ancient

Monuments and Archaeological Areas Act 1979.”

For these buildings, the exemption applies only to the point that compliance with the

energy efficiency requirements would excessively alter the character or appearance.

(HM Government, 2014, p.8)

The Building Regulations state:

The application of the energy efficiency requirements in accordance with the

provisions of the approved document L1B and up to, but not beyond, the point at

which:

i) “Unacceptable alteration to the character and appearance of historic buildings will

be likely to occur.”

ii) “The ability of traditional buildings to ‘breathe’ to control moisture and potential

long-term decay problems is likely to be unacceptably impaired.”

When considering work on a building that falls into one of the planning exemptions

listed in section 3.6, the objective should be to increase energy efficiency as far as

possible without damaging the character or appearance of the building. Materials

should not be used that would be detrimental to the resilience of the building. (HM

Government, 2014, p.8)

3.3 Conservation Principles

English Heritage’s conservation principles identify certain considerations that should

be addressed when proposing alterations to listed buildings. The four major

principles that English Heritage promote are minimum intervention, compatibility,

reversibility and authenticity.

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When alterations to improve energy efficiency are proposed, regard should be given

to:

• Understanding the building to avoid any alterations that could damage the property.

• Minimising disturbance to existing fabric.

• Making it possible to reverse any changes without damaging the existing fabric in

the process. (English Heritage, 2012, p.22)

The following tests need to be satisfied when considering alterations:

• There is sufficient information on the building to fully comprehend the possible

impacts of alteration on the significance of the building.

• The proposal will not materially damage the significant features of the building.

• The proposal will be of sufficient quality and workmanship that will be valued both

in the present and in the future.

• The long-term consequences of the proposal can be demonstrated to be benign

and the design should allow for any solutions in the future. (English Heritage, 2012,

p.25)

Minimum intervention:

All works on a building should be kept to as little as possible to retain the maximum

amount of historic fabric and the significance it holds.

Compatibility:

All changes should be made using materials and techniques that are compatible with

the traditional fabric. Modern materials can be quite rigid, therefore to ensure it

weathers like the original material it should be slightly weaker. Also modern materials

tend to be less permeable and when used alongside original fabric it can accelerate

decay, so a solution should be found to guarantee this will not occur.

Reversibility:

Where changes are detrimental to the significance of a building they should be

reversible. This means that if the significant features are temporarily obscured, in the

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future the historic fabric can be returned to its original state without being damaged.

This principle can be applied from individual repairs to major extensions.

Authenticity:

All development to a building should appear authentic and respect the history of the

fabric.

This implies that:

• All new work should appear as if it was built at the same time as the old.

• All the phases that a building has gone though in its past history should be clearly

visible.

• Restoration should be avoided where it is based on speculation, apart from

instances where documentary and/or physical evidence of previous form is available.

• Nothing of important significance should be removed. (English Heritage, 2012,

p.27)

3.4 Problems with Historic Buildings

Most buildings until the early twentieth century had solid walls; in fact around 1 in 5

homes in the UK have solid walls. (SPAB, 2013, p.11) Traditional solid walls were

constructed from bricks, stone or even cob (earth and straw). Where mortar was

used it was generally made from lime and sand. This type of mortar was a lot more

porous than modern mortars. When the building was rendered a lime mix was

normally used and it may have then been lime washed. (SPAB, 2013, p.13) These

traditional materials are very good at ‘moisture buffering’ which means that when it

rains; moisture is easily absorbed in to the wall and when the rain stops it will

evaporate. Inside, walls were plastered with lime or even clay. The moisture created

inside from human activity was absorbed in to the wall and gradually released. Open

flues, chimneys and draughts also helped to disperse internal humidity. This way

moisture within the structure remained in equilibrium and kept the interior dry. (PRT,

2010, p.20)

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Fig 1 – Traditional Stone Wall Fig 2 – Traditional Solid Wall

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The traditional construction materials such as stone and brick used in solid walls also

produced a high thermal mass. This means it is good at storing heat and slowly

releasing it during cooler temperatures. This helps moderate temperature

fluctuations and keeps the interior at a steady temperature. (SPAB, 2013, p.10)

Unfortunately in the UK the temperature inside old buildings is quite uncomfortable

compared to modern living standards. It also takes a long time for dense masonry

walls to heat up in the first instance, which therefore means a lot more energy is

used. (PRT, 2010, p.20)

In modern buildings the solution would be to install insulation to reduce heat loss in

the building. Insulation materials have low thermal conductivity so when installed in a

building it slows down the rate of heat transfer through the external walls. However,

most modern insulation materials are made from impermeable materials. This

interferes with the buildings natural ability to breathe. It holds water in the building

fabric, making them damp, unhealthy and less thermally efficient. Damp walls are

less thermally efficient because water is a better thermal conductor meaning heat

can pass through much easier. SPAP research suggests that 40 per cent more heat

is lost through damp walls than dry ones. Where timbers are embedded in to the

external walls it can cause rot and eventually structural failure of an entire floor.

(SPAB, 2013, p.11)

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This diagram shows how the traditional

breathable materials used in solid wall

construction easily absorbed and released

moisture and evaporated rising damp. (SPAB,

This diagram shows a typical suspended

timber floor which became common place

from the mid-nineteenth century. By this time

many buildings were constructed from brick.

(SPAB, 2013, p.12)

This diagram shows how traditional

solid walls are not compatible with

impermeable modern materials as

moisture becomes trapped in the wall.

(SPAB, 2013, p.13)

Fig 3 – Moisture Ingress

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3.5 Insulation Materials

All alterations to upgrade the thermal efficiency of historic buildings should be

compatible with the existing structure, particularly with the need for permeable fabric

that ‘breathes’. Natural insulation materials are generally the best for allowing the

building to breathe and are also very good at absorbing and releasing moisture

which buffers the changes in humidity. (English Heritage, 2012, p.35) Typical

examples include wool, hemp, flax and recycled newspaper (cellulose). Some

mineral insulation products are also breathable but they are not good at absorbing

water as they slump and the air pockets fill with water. (SPAB, 2013, p.53)

Generally more than one type of insulation is used within one building as the most

appropriate solution should be sought for each section of the building. (English

Heritage, 2012) Insulation comes in quilts, batts, boards or as loose fill. Quilts come

in long lengths, batts and boards are rigid and come in shorter lengths. They are

usually cut to lengths using a knife or saw respectively. Loose fill is pumped in by

professional installers. (SPAB, 2013, p.49)

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The chart overleaf compares the main types of insulation products. It indicates the

form they take, common uses, thermal performance, embodied energy and cost.

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Fig 4 – (SPAB, 2013, p.52)

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3.6 Walls

Generally internal or external insulation of the external solid walls on a listed building

is unacceptable. However, in some cases where the building has external rendering

or cladding that is in such bad condition that it needs to be replaced, external

insulation can be installed underneath without affecting the character of the building.

Internal insulation can also be installed if the plasterwork needs to be replaced.

(English Heritage, 2012, p.52)

External insulation is the better option out of the two, as it keeps the wall warm by

keeping the heat inside. This can potentially eliminate the risk of interstitial

condensation as water vapour will not condense on warm surfaces. Internal

insulation causes the opposite by preventing the heat inside the building from

warming up the masonry. As a result, the temperature of the wall can drop to ‘dew

point’, which is the point where water vapour will condense. Moisture will build up

inside the wall and this is known as interstitial condensation. (SPAB, 2013, p.47)

Another great risk with internal insulation is the point where the insulation stops is

around the floor joists. Traditionally floor joists were embedded in to the wall, thus

creating a thermal bridge. The insulation would encourage condensation at these

points, which could lead to the joists rotting and the whole floor could collapse. In an

effort to stop this, some retrofits may involve lifting floorboards and continuing the

insulation down between the joists. (SPAB, 2013, p.110)

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Fig 5 – Insulation Stopping at Joist Fig 6 – Insulation Covering Joist

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To reduce the amount of moisture entering the wall most internal insulation systems

incorporate a vapour control layer which is designed to stop water vapour passing

through to the wall. Unfortunately they rarely provide a vapour tight layer and are

very susceptible to breaches. In fact they even contribute to interstitial condensation.

When wind driven rain soaks in to the core of the wall it cannot evaporate in to the

room because the vapour control layer stops it. (PRT, 2010, p.25)

Timber Framed Walls:

Insulation to timber framed wattle and daub walls is unlikely to receive planning

approval, particularly when the timber frame is visible. However when the wattle and

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This diagram shows internal insulation

stopping at the floor and ceiling, creating a

thermal bridge where the joist is set in to

the masonry. This attracts moisture that can

rot the timber. (SPAB, 2013, p.110)

This diagram shows internal insulation that

has been continued around the joist to

minimise the thermal bridge. (SPAB, 2013,

p.110)

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daub infill panels are in such bad condition that they need replacing, it may be

possible to replace them with ‘hemp-crete’ panels which are made from a mixture of

hemp and lime. (English Heritage, 2012) This lightweight concrete has good

breathing characteristics which will help reduce heat loss by reducing conductivity.

Casting it in-situ will also make it a lot more air tight around the timber frame. Where

panels can’t be replaced any large gaps between the frames can be filled with

insulation quilt. (SPAB, 2013, p.118 - 119)

3.7 Windows

Windows are one of the most important parts of the building to consider when

improving overall thermal performance. This is because glass is not a particularly

good insulator, especially single glazed panels with no air gap. One of the first

checks to carry out is to see if the window panes have a good seal and the frame fits

tight in the reveal. Timber framed windows can easily go out of shape over time,

causing gaps to materialise around seams. If this is the case, a professional joiner

can make fairly in-expensive repairs to rectify the problem. They will also repair any

other defects such as splits in the timber. If the windows have original shutters the

opportunity should be taken to repair them as well. (PRT, 2010, p.30)

The simplest and least invasive method to improve the thermal performance of old

windows is to install curtains, blinds or shutters. In the majority of cases they will

already be fitted anyway. Taking embodied energy in to account they can be just as

energy efficient as double or secondary glazing. They are also very efficient at

keeping a building cool during the summer months by preventing heat from entering

the building. (PRT, 2010, p.30)

Curtains:

Heavy curtains interlined with fleece are very efficient at reducing heat loss through a

window. They should be hemmed in-situ so they are in contact with the floor and the

ceiling to stop draughts either end. They should also be hung close to the wall to

reduce the gap in between. If a radiator is situated underneath a window, the warm

flow of air can escape behind the curtain. By placing a shelf above the radiator, this

can be stopped. Sometimes introducing a pelmet to the top of the curtain can also

close of draughts. (SPAB, 2013, p.80-81)

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Thermal Blinds:

Thermal blinds incorporate insulating material and reflective layers which minimise

thermal conductivity. A metal runner is screwed to the window frame and magnets

around the edge of the blind hold it to the frame, thus creating an effective seal.

(SPAB, 2013, p.81)

Shutters:

Being made out of wood, shutters work well as insulators. Ideally, a rubber seal or

brush strip should close off the point where they meet. Because traditional shutters

are only used during the night, they cannot help with energy-efficiency during the

day. If the originals are missing but the window is still designed to have shutters, an

ideal solution is to use glazed shutters, which can be closed during the day. The

incorporation of double glazed units within the shutters can further enhance the

thermal performance of a single glazed window. (SPAB, 2013, p.81)

Secondary Glazing:

Secondary glazing is an extra sheet of glass/plastic which is placed behind the

existing window. (PRT, 2010, p.31) They can come in glass and plastic forms, some

panels are fixed and others can open. The fixed versions are held on by a self-

adhesive magnetic strip, whilst others have two panes that slide past each other on a

track. Vents are usually installed in the frame to aid ventilation in the air gap,

otherwise condensation can build up.

Secondary glazing can dramatically improve airtightness and reduce heat loss

through conductivity, especially when low-e glass is specified. (SPAB, 2013, p.81)

There should be an air gap of at least 200mm between the two panes to make a

sufficient reduction in heat loss. Although, this would make it impracticable to install

secondary glazing around window seats or windows with shutters as it may impair

their use (PRT, 2010, p.31)

Surprisingly, plastic sheets are much more discreet than glass as in comparison they

are so lightweight they do not need a trim. (SPAB, 2013, p.87) In the case of glass

panels, to conceal the secondary glazing, the trim should not protrude beyond the

width of the window frame. (PRT, 2010, p.31) In which case, fixed panel glazing is

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the more likely choice as the types that open have thicker trims because of the track.

They also have a bar across the middle of the window to divide the panels. To be

hidden it would have to sit behind the mullions on the window. (SPAB, 2013, p.85-

86)

However a fixed panel would not suit windows which are regularly opened to aid

ventilation as they cannot be opened. Fixed panels are much easier to clean and

maintain and they can be removed during the summer to take advantage of solar

gain. However, SPAB comments that depending on the size of the windows and how

many there are; this can be a very labour intensive task. It may require more than

one person to lift out the panels. (SPAB, 2013, p.85) It may also contravene fire

safety regulations. This is one instance where plastic sheets are a good alternative

because they are so lightweight. (SPAB, 2013, p.87)

Double Glazing:

Double glazing is a combination of two sheets of glass with a gap in between to

make a single unit. The space around the edge is sealed and the air gap is generally

filled with argon gas. (PRT, 2010, p.31) This arrangement leads to unit thicknesses

between 24 – 28mm. Most traditional windows have shallow rebates as they were

only designed to accommodate a single sheet of glass which was held in place with

putty. Therefore it would seem impossible to fit double glazing in to the rebate of old

windows. (SPAB, 2013, p.88)

Traditional glazing bars vary in size but

this example is 15mm deep with

handmade glass 3mm thick. The glass is

held in with putty. (SPAB, 2013, p.88)

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Fig 7 – Traditional Glazing Bar

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Modern glazing bars are

usually 24mm to 28 mm

thick with deep rebates to

allow for thicker units.

(SPAB, 2013, p.88)

Yet there is a new

generation of double

glazing units which are much slimmer and can be used in some traditional glazing

bars. Although, they are limited to the rebate depth of individual windows. These

varieties are filled with low conductivity gases such as krypton or xenon making them

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just as efficient at only 10 - 12mm thick. They can even come with an outer layer of

handmade glass to suit the style and age of the house. Other options include

vacuum-filled units but these come with spacers between the panes which are

clearly visible. It is important to bear in mind that twice the amount of glazing will be

added to the window, so the extra weight can strain the hinges and unbalance

sashes. (SPAB, 2013, p.89)

Slim-profile units as evidenced here will

fit within the rebate of some traditional

glazing bars. As before, the glass can be

held in place with putty. (SPAB, 2013,

p.88)

3.8 Floors

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Fig 9 – Traditional Glazing Bar with Slim Unit

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Ground floors in old houses were traditionally either solid or suspended in

construction. Solid floors were made from stone flags, bricks or tiles laid directly on

to compacted earth. Suspended floors are formed of timber board nailed to joists

with ventilation underneath. (PRT, 2010, p.25)

The point of ventilating under floorboards was to allow air to circulate and reduce the

build-up of moist air which could rot the timbers. Unfortunately this created draughts

in the gaps between the floorboards, a problem which is now solved with tongue and

groove floorboards. (English Heritage, 2012, p.54) In the case of traditional

floorboards the gaps can be draught proofed with all manner of materials including

draught strips, string, expanding foam, silicone, papier-mâché and even thin strips of

wood. (SPAB, 2013, p.130) With draught proofing installed heat loss will be reduced

through convection. Unfortunately this still won’t stop the considerable heat loss that

occurs through suspended floors, so sometimes insulation is required. (English

Heritage, 2012, p.54)

When there is only a shallow void beneath the floor boards it becomes necessary to

lift them up to install the insulation. In most cases permission would not be granted to

lift up historic floorboards because of the risk of damage. However if it is allowed,

then it must be done with great care, especially with tongue and groove as the

tongue can easily spit off. Skirting may also need to be removed. (English Heritage,

2012) Floorboards that were not cut using a sawmill had varying thicknesses and all

had a specific place in order to create a flush surface. Therefore it is very difficult to

relay these types of floorboards as each one has to be numbered. (SPAB, 2013,

p.131)

Insulation is usually installed between the floor joists and either rigid insulation or

quilts are generally used. Common types of rigid insulation that are used include foil

faced foam board or wood fibre boards for their superior k-values and hygroscopic

properties respectively. To hold in rigid insulation, battens are screwed to the base of

the joists for the insulation to rest on. Insulation quilts on the other hand are held up

with netting running underneath the joists. (SPAB, 2013, p.132)

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Fig 10 – Suspended Timber Floor with Foam Boards

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This diagram shows foam boards being suspended by battens in between the joists of a

suspended ground floor. The air bricks allow ventilation in to the underside of the floor.

(SPAB, 2013, p.132)

This diagram shows insulation quilt being supported underneath the floor using garden

netting. (SPAB, 2013, p.132)

3.9 Roofs

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Fig 11 - Suspended Timber Floor with Quilts

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Cold Roofs:

For cold roofs, insulation is generally laid horizontally across the top of the ceiling, in

between and maybe on top of the joists. There are two main types that are used for

this, either quilts or loose fill insulation. Loose-fill insulation is pumped in with a long

hose to fill the roof space to the desired thickness. This is not recommended where

the roof space is draughty as the cellulose fibres can easily be blown around, making

the insulation bed vary in thickness. (SPAB, 2013, p.49)

It is common to have poorly detailed roof eaves in old buildings and sometimes

insulation can block ventilation at the eaves. But this does not mean insulation

should stop before the eaves or thermal bridging will occur at the end of the joists.

The insulation should run up to the wall plate without blocking eaves ventilation.

(SPAB, 2013, p.64)

This diagram represents a cold roof. The roof space remains uninhabited and the rafters are

exposed. There is ventilation at the eaves and insulation is laid above the ceiling. (SPAB,

2013, p.60)

Warm Roofs:

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Fig 12 – Cold Roof

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For warm roofs, the insulation is generally fitted along the rafters. There are various

versions of this, these being under the rafters, in between or on top. Either quilts or

batts can be used and the same fixing principles of netting and battens are used.

Insulation above the rafters is referred to as ‘sarking’. This is generally the best

solution as it minimises the condensation risk by keeping the roof warm. It is also

creates the least disturbance as most of the work can be carried out on the roof. This

is important if the roof space has historic plaster on the underside. The trouble with

this method is the extra thickness of the insulation would raise the level of the roof,

posing problems for the eaves and verge. A temporary roof covering is also needed.

When installing insulation in between the rafters a ventilated cavity of 50mm must be

left above the insulation. This means if the rafters are less than 80mm then there

won’t be enough space. If the planning officers allow it, it is possible to attach

battens to the underside of the rafters to increase the depth. (SPAB, 2013, pp.67-69)

This diagram represents a warm roof. The roof space has become a warm occupied room.

Insulation is installed along the rafter line and covered up by plasterboard. (SPAB, 2013, 4.0 Research Methods

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Fig 13 – Warm Roof

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The methodology chapter will discuss the way in which data will be collected for the

dissertation and the reasons why those techniques were chosen. It will explain how

the chosen methods of research will answer the main question of the dissertation.

4.1 Literature Review

The literature review has to be one of the ways that data is gathered. The purpose of

the literature review is to inform the reader of the problems and barriers involved with

upgrading the thermal efficiency of listed residential buildings. Literature such as

books, journals, articles and websites are freely available. All that is necessary is to

find appropriate material from reputable sources, which could be analysed in order to

investigate the research questions. A selection of literature will be used so

information can be drawn from different perspectives. In order to obtain reputable

information, most of the literature will come from guide books from official

organisations, which there are plenty of regarding alterations to listed buildings.

Following the literature review will be the results of the questionnaire, which will be

based on the methods stated in the literature review.

4.2 Questionnaire

In order to investigate what methods construction professionals prefer to use for

improving the thermal efficiency of listed buildings, the decision was made to create

a questionnaire. It would be emailed to various professionals in the construction

industry who deal with listed buildings. Along with the questionnaire will be an

explanation of why they are being invited to participate and what the data would be

used for. Emailing the questionnaire rather than personally delivering it to the

participants will lessen the ethical risks. It also means they can quickly email the

completed questionnaire back rather than having to wait for it to be posted.

The kind of construction professionals that the questionnaire will be sent to include

construction managers, construction consultants and conservation officers. The aim

is to focus on people who are involved in retrofitting projects on listed buildings from

the beginning to the end. These professionals would have the most practical

experience with listed buildings and would therefore have the most reliable opinions.

Before sending out the questionnaire a pilot study should be undertaken. The pilot

study will involve asking people to fill in the questionnaire as best they can and

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asking them if the questions were understandable and if they could answer them

easily. The final questionnaire will be formed around the feedback gained through

the pilot study.

The questionnaire asks the participants to answer 11 closed questions by writing a

number in each box corresponding to their preferred materials/methods for improving

the thermal efficiency of a listed residential building. The highest number would be

their most preferred option and the lowest number would be their least preferred

option. The results will be visually represented on bar charts so the best scoring

methods/materials can be clearly seen.

The participants are told that they can leave the boxes blank if they would never use

that particular material/method or have not heard of it. This also included the boxes

labelled ‘Other’, so if this was left blank it would mean they could not think of any

other material/methods to use on that part of the building or that they wouldn’t use

anything else other than what was stated in the questionnaire.

If they cannot pick a preference between any materials/methods, maybe because

they are just as good as each other, then they are allowed to put the same number in

each box. The participants will also be given the opportunity to write any comments

they may have in a box provided at the bottom of each question.

The first four questions are focussed on insulation materials. They are split up in to

different types of insulation, these being natural, mineral, petrochemical and

composite insulation. These types of insulation were based on the chart titled fig 4

which will also be used to aid the analysis of the results. The participants will be

asked to rank each type of insulation in order of preference. This has been made

easier by splitting insulation into types, as there is less too consider, rather than all

being listed in one question.

The rest of the questions are focused on particular methods. They are split up in to

different sections of the buildings, like it is in the literature review. The participants

will be asked what methods they would use to improve thermal efficiency in each

section of the building; this also takes in to account different types of structure. The

questions are aimed at cold pitched roofs, warm pitched roofs, solid masonry walls,

wattle and daub/lathe and plaster walls, solid masonry/concrete floors, suspended

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timber floors and windows. The questionnaire is designed to cover all possible

structures, to understand what methods professionals prefer using in different

circumstances.

By finding out the opinions of professionals the results can be compared with the

information in the literature review and a balanced conclusion can be made to the

principle question of the dissertation, how to improve the thermal performance of a

listed residential building?

To receive an accurate result on the questionnaire it is important to put the

insulation/methods into different lists. This allows the participants to personally

consider the disadvantages and advantages of each option. Being asked to make

their own choices will provide a more diverse result. Replying with the most

commonly used products would probably produce a similar outcome. The

information will be collected on a bar chart as it is easy to distinguish which options

score higher than others. The larger the bar shows the more favoured choice. This is

why the questionnaire asks the participants to show their preferred decision with

the highest number and the least favoured with the lowest number.

5.0 Ethics Statement

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The questionnaire and the subsequent data raise ethical issues. So to eliminate

these issues, certain ethical considerations were observed and dealt with before

inviting the participants to take part in the investigation.

The participants who were invited to take part in the questionnaire were a mixture of

employees in the construction industry with positions relevant to the project. They

are of different genders, age and experience but none are:

• Under the age of 18

• Unable to consent

As no one was under the age of 18, no CRB check was necessary for the study.

The questionnaire (see Appendix A) was distributed via email, together with an

explanation of what was being investigated and why. In the email the participants

were asked to refer to the Participant’s Information Letter (see Appendix B) attached

for further information about the purpose of the study and an outline of what their role

would be within it. Should they wish to participate, they were asked to fill in and sign

the attached Participant Consent Form (see Appendix C) and email a copy back to

me.

5.1 Participant Information Letter

Within the Participant Information Letter:

Reassurance is given that the participant’s/company’s reputation will not be at

risk as no names or businesses will be mentioned in the final dissertation and

confidentiality will be upheld at all times.

Reassurance is given that in order to manage the risk of anonymity; all data

gathered through the study will be saved on an encrypted memory stick and

then destroyed once the project is completed.

The participant is made aware that the data will not be used for any other

purposes other than to support the recommendations in the dissertation.

So as not to put any pressure on the participants to agree to take part in the

questionnaire, the participants are informed that all answers to questions are

entirely voluntary.

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The participants are made aware that they can withdraw from the study at any

time and if they should wish to do so, they should fill in the withdrawal section

of the consent form and email it to me.

The researchers contact details were provided should the participants have

further questions or wish to withdraw themselves from the study.

Contact details of the supervisor and for the university were also provided in

case the participants should want to talk to the relevant senior faculty

members.

5.2 Participants Consent Form

Within the Participant Consent Form:

The participant is made aware that by signing the form he/she was agreeing

to their data being used in the dissertation.

A withdrawal section at the bottom of the form is left for any participants who

wish to withdraw from the study. Filling in this section would mean their

information would be destroyed and not used in the dissertation.

5.3 Ethics Tick Sheet

WILL YOUR RESEARCH STUDY? YES NO1 Involve any external organisation for which separate research ethics clearance No

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is required (e.g. NHS, Social Services, Ministry of Justice)?2 Involve individuals aged 16 years of age and over who lack capacity to consent

and will therefore fall under the Mental Capacity Act (2005)?No

3 Collect, use or store any human tissue/DNA including but not limited to serum, plasma, organs, saliva, urine, hairs and nails? Contact Dr Matt Bristow.

No

4 Involve medical research with humans, including clinical trials? No5 Administer drugs, placebos or other substances (e.g. food substances,

vitamins) to human participants?No

6 Cause (or could cause) pain, physical or psychological harm or negative consequences to human participants?

No

7 Involve the researchers and/or participants in the potential disclosure of any information relating to illegal activities; or observation/handling/storage of material which may be illegal?

No

8 With respect to human participants or stakeholders, involve any deliberate deception, covert data collection or data collection without informed consent?

No

9 Involve interventions with children under 18 years of age? No10 Relate to military sites, equipment, weapons or the defence industry? No11 Risk damage or disturbance to culturally, spiritually or historically significant

artefacts or places, or human remains?No

12 Involve genetic modification, or use of genetically modified organisms? No13 Contain elements you (or members of your team) are not trained to conduct? No14 Potentially reveal incidental findings related to human participant health

status?No

15 Present a risk of compromising the anonymity or confidentiality of personal, sensitive or confidential information provided by human participants and/or organisations?

Yes

16 Involve colleagues, students, employees, business contacts or other individuals whose response may be influenced by your power or relationship with them?

No

17 Require the co-operation of a gatekeeper for initial access to the human participants (e.g. pupils/students, self-help groups, nursing home residents, business, charity, museum, government department, international agency)?

No

18 Offer financial or other incentives to human participants? No19 Take place outside of the country in which your campus is located, in full or in

part?No

20 Cause a negative impact on the environment (over and above that of normal daily activity)?

No

21 Involve direct and/or indirect contact with human participants? Yes22 Raise any other ethical concerns not covered in this checklist? No

6.0 Results

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The results of the questionnaire are founded on the opinions of 10 professional

within the construction industry that specialise in listed buildings. The analysis for the

results of questions 1 - 4 uses information taken from the chart titled Fig 4.

Chart 1 - What natural insulation materials would you prefer to use?

Cellulose

Cork (ex

panded

)

CottonFla

xHem

p

Monolithic l

ime/h

emp m

ix

Reed board

Shee

p’s wool

Wood fiberb

oardOther

0.00

2.00

4.00

6.00

8.00

10.00

12.00

The most popular Natural Insulation material was Flax. This choice is

understandable as it is a fairly standard natural insulation product however it is

somewhat surprising that sheep’s wool was not the favourite as it costs nearly the

same as flax but has a better thermal performance. To achieve a U-Value of

0.25Wm2K, flax needs a thickness 170mm yet sheep’s wool only needs a thickness

of 150mm. For the same reason it is surprising cotton was not used by any

participants in the survey. It would make more sense that cork was not chosen as it

is not used in the UK.

The three most popular choices were insulation rolls. What may have affected this

result is the fact most listed buildings cannot have insulation on the walls but are

more likely to have it in the roof and rolls generally can’t be used on walls. Insulation

rolls may also be more popular because they come in long lengths, which reduce the

amount of sections needed to fill the entire length of a cavity.

Chart 2 - What mineral insulation materials would you prefer to use?

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0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

The most popular Mineral Insulation material was Cellular glass closely followed by

Glass Fibre and Calcium Cilicate Board. This is an unexpected result as glass fibre

has the best thermal performance out of the 3 materials; it is the cheapest alternative

and the most versatile. For this same reason it is surprising stone mineral wool did

not score higher. However glass fibre quilts are known to slump over time which can

reduce their performance, this may mean the participants were considering the

longevity of the material. It is not surprising that Aerogel was not used by any of the

participants because it is cutting-edge material developed by NASA and it is

therefore very expensive, making its payback period very long.

Chart 3 - What petrochemical insulation materials would you prefer to use?

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Expanded polystyrene

Extruded polystyrene

Phenolic foam boards

Polyurethane, polyisocyanurate

board & spray foam

Recycled plastic bottle fiber wool

Other0.00

1.00

2.00

3.00

4.00

5.00

6.00

The most popular Petrochemical Insulation material was Phenolic foam boards. This

is a predictable result as it has a very low conductivity partially due to its foil backing

out and only a thickness of 80mm is needed to achieve a u-value of 0.25Wm2K, so

this is particularly helpful where space is at a premium. Unfortunately this also

means it comes with a higher price tag so it may not necessarily have a short

payback period. It is interesting that phenolic foam boards just like flax cannot be

used as exterior wall insulation. Again this implies that this is not an important

requirement because rarely can it be permitted to install wall insulation on a listed

building.

Chart 4 - What composite insulation materials would you prefer to use?

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Multi-foils Vacuum insulated panels Other2.50

2.60

2.70

2.80

2.90

3.00

3.10

As there were only two choices for this question and there were relatively little

participants, the result is not that reliable. Vacuum insulated panels have a much

better thermal performance and are very versatile but because they are quite

sophisticated they are also very expensive.

The case for multifoil’s is the complete opposite, in fact mutlifoil’s are generally only

meant to be used a supplementary product. Therefore given that the benefits of

multifoil are dependent on what they are used in conjunction with; it would seem that

vacuum insulated panels are the best insulation material in their own right.

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Chart 5 - What methods would you most prefer to improve the thermal efficiency of a

cold pitched roof?

Insulation quilts Insulation batts Loose-fill Insulation Other0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

The preferred type of insulation was insulation quilts. This conforms to the favourite

insulation materials in the first two questions, as they too came in quilt form. It seems

probable that participants may have made their selection of materials based on the

fact that they come as quilts. This implies that the participants were considering the

ease of use of the insulation material in their assessment and not just their beneficial

properties. This is something to consider when judging the results. It is not surprising

the participants have not used loose-fill insulation as this requires specialists to blow

in the insulation from a pipe.

It could be argued that insulation quilts are the simplest type to install because there

is no need for precise cutting to fit them in to awkward spaces. For example

joists/rafters not being equal distances apart, a common trait in old buildings. Quilts

are also much easier to manage as they roll up; it is easy to get them in to tight roofs

spaces for example.

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Chart 6 - What methods would you most prefer to improve the thermal efficiency of a

warm pitched roof?

Insulation above rafters

Insulation below rafters

Insulation between rafters

Other0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

The preferred method of insulating a pitched warm roof was insulation above the

rafters. This may be because of the reasons stated in the literature review. This

solution minimises the risk of condensation as it keeps the roof structure warm and

there is no necessity for an air gap to provide ventilation.

It may also be the preferred option because most listed that have a habitable room in

the roof space would also have historic plasterwork. This would be destroyed if

insulation were installed between or underneath the rafters. But this threat is taken

away when insulation is installed above the rafters as the roof tiles only need to be

removed and reinstalled after the insulation is fitted. This option is more time

consuming but more likely to get planning approval. Another reason could be

because of increasing popularity in having exposed wooden beams.

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Chart 7 - What methods would you most prefer to improve the thermal efficiency of

solid masonry wall?

Internal insulation External insulation Render Other0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

The preferred method of insulating an external masonry wall was render. This may

be because in most cases the participants have not installed insulation on the

exterior wall of listed buildings for all the reasons mentioned in the literature review.

However, many listed buildings have render that may be in bad condition. Therefore

it is very likely that planning consent would be given in these cases to re-render the

building using traditional materials or equivalents.

Internal insulation being the least favoured corresponds with what was stated in the

literature review. Internal insulation prevents the heat inside the building from

warming the masonry. As a result, the temperature of the wall would reach dew point

and moisture will condense inside the wall.

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Chart 8 - What methods would you most prefer to improve the thermal efficiency of a

wattle & daub/lathe & plaster wall?

External render Replacement panels

Internal insulation Other0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

The preferred method to upgrade the thermal efficiency of a timber framed wall was

internal insulation. This is at odds with the results for a masonry wall however it still

may be a better alternative than completely removing the panels, which may be of

historic value.

External render probably scored the least as timber framed buildings such as those

of Tudor origin have exposed frames. Therefore rendering it would mean covering up

the character of the building and to remove the render in the future could damage

the structure underneath. However if there are records showing that the structure

was rendered in the past it may be given consent.

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Chart 9 - What methods would you most prefer to improve the thermal efficiency of

solid masonry/concrete floor?

Install a wooden floor

Install a carpet Insulation Other0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

The preferred method to upgrade the thermal efficiency of a timber framed wall was

internal insulation. This was likely to be the highest scorer as it is probably the

cheapest and simplest way of insulating a solid floor. It also causes the least amount

of disruption to the building. It was not likely that the other two methods would be the

most popular as the extra depth would likely affect the skirting and the bottom of

doors.

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Chart 10 - What methods would you most prefer to improve the thermal efficiency of

a suspended timber floor?

Draught proofing Insulation batts/boards

Insulation quilts Other0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00

The preferred method to upgrade the thermal efficiency of a timber framed wall was

internal insulation. This correlates with the graph for solid floors as once again the

participants have chosen the method that is the cheapest, simplest and has the least

impact on the building. This shows that the participants prefer to try the simplest

methods first before the more invasive methods, perhaps because it may not always

be necessary. It is not surprising the two insulation types scored the same as there is

little difference in benefit between the two.

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Chart 11 - What methods would you most prefer to improve the thermal efficiency of

a window?

Install curtains, shutters or blinds

Install secondary glazing

Install slim profile double glazing

Other 0.00

1.00

2.00

3.00

4.00

5.00

6.00

The preferred method of upgrading the thermal efficiency of a window was to install

curtain, shutters or blinds. This is a predictable result as they offer significant

benefits. They are cheap, probably the most visually acceptable and quick and easy

to install. It is not surprising that slim profile double glazing scored the least as it is a

brand new product that is relatively untested, so it is likely the participants have not

even used it before.

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7.0 Conclusions and Recommendations

7.1 Conclusion

The investigations in the literature review found that there are two major barriers

associated with retrofitting listed residential buildings in order to make them more

thermally efficient. These are the listed building regulations and the risk of decay

from damp. These two barriers are connected as it is the inherent risk of decay from

damp which is why listed buildings are protected by the law.

When proposing an alteration to a listed building, planning permission must be

obtained. It is particularly difficult to get permission to upgrade the thermal efficiency

of a listed building as any alterations could affect its special architectural or historical

significance. However it is up to the relevant local planning body to decide whether

the development is justifiable, given the possible loss or damage to the significance

of the listed building.

Heritage conservation does allow change so long as the heritage value remains

intact. Also because heritage conservation is carried out for the sake of public

interest, it means conservation officers will take in to account the views of the public

when deciding whether to grant permission.

There are many ways a listed building can be thermally upgraded but to get planning

permission, for each method chosen, there should be an investigation in to how the

alterations might affect the building in the present and in the future.

There are two main ways to improve the thermal efficiency of a listed building, either

by insulating the fabric to reduce thermal conductivity or improving air tightness to

reduce thermal convection. The trouble with these methods is they also restrict the

movement moisture in the air and the fabric of the building. Old buildings were built

to breathe as the original construction materials are very porous so this means

moisture can easily get trapped in the building, which can lead to damp and

therefore decay.

As the listed building regulations would unlikely allow any alterations that could result

in decay to the building it makes it difficult to improve the thermal efficiency of a

listed building. The best ways to mitigate the risk of damp is to use natural insulation

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materials that are more porous than other types so they allow the movement of

moisture through the fabric. The other way is to provide controlled ventilation to allow

the movement of moisture through the air.

The literature review also discovered that the building regulations state, that if

planning consent is given to develop on a listed building then the developer has the

duty to increase energy efficiency as far as is realistically obtainable without

damaging the character or the appearance.

From the results of the questionnaire it seems that insulation quilts were the most

popular form of insulation. One reason this could is that because damp is more

associated with wall insulation, roof insulation and floor insulation may be more

favoured and insulation quilts are generally not used for walls as it would be difficult

to hold it up. Insulation quilt are also easier to install in roofs in general.

For the most part, insulation on external wall was not favoured, which makes sense

given all the problems that can arise from applying it. For floors the participants

generally preferred the cheapest options. This makes sense as it would be a waste

to spend out insulating the floor when its thermal efficiency could be upgraded to

sufficient standard through cheap and simple means, such as draught proofing or

installing a carpet.

7.2 Recommendations

For anyone thinking of altering a listed building to make it more thermally efficient, it

would be advisable to think about how the methods used will affect the building

before asking for planning permission. The kind of methods which are less risky will

be more likely to be given consent. These include simple installations such as carpet

fitting and draught proofing. It would also be beneficial to use the more simple

methods before committing to insulation or other drastic procedures, as it may be

that only simple changes are necessary, saving time and money. For the same

reasons it would be reasonable to focus on areas of the building that lose heat more

rapidly, such as the windows.

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However if the decision is taken to use insulation it is always best to choose the most

breathable types, natural insulation is probably the best for this. In order to decide

which material to use, it would be sensible to compare the thermal efficiency of the

insulation with the price, to see how long the payback period will be. Also think about

the most appropriate form of insulation for the structure and where it will be installed.

It may also be worth considering how thick the insulation needs to be to perform at a

reasonable standard. If space is at a premium, it might be worth investigating

insulations that require less depth.

It is important to remember that if the decision is taken to develop a listed building, if

granted planning permission, the developer has the duty to improve the thermal

efficiency as is reasonably obtainable. So the developer has to be committed to

improve every possible aspect of the building. Possible methods that may be given

planning permission were stated in this project. The research also shows the kind of

methods preferred by the professionals, so perhaps the methods that were least

favoured should be avoided.

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8.0 Further Research

Further research could include:

Researching the advantages and disadvantages of different

materials/methods and which ones suit different circumstances. This will

make it simpler to decide what option to take.

Expanding the investigation to see how energy efficient lighting and

space/water heating systems can reduce the amount of energy used in the

first instance, rather than solely focusing on reducing heat loss. It could also

take in to account the amount of embodied energy produced by different

insulation materials.

Researching renewable energy sources which could help provide energy for

the building in a sustainable manner.

Expanding the investigation to provide more general advice on installing

insulation etc. This might include the risks involved and the precautions to

take before making alterations.

Researching government grants that can be used to fund projects on listed

buildings such as the Green Deal or the Heritage Lottery Fund. This may

make it possible to retrofit a building that would have otherwise fallen in to a

state of disrepair.

Researching thermal imaging which can be used to find out where most of the

heat loss is occurring in a building. This means the developer could focus on

upgrading these weak spots.

Expanding the investigation to cover the other categories of building such as

commercial and industrial. This will be important to consider this as larger

buildings require more energy to be heated.

Case studies to evidence the methods that have been used on different types

of building and how the thermal efficiency was affected. This too will help

justify the option to take for any particular building.

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9.0 References

Planning (Listed Buildings and Conservation Areas) Act 1990. London: HMSO.

HM Government, 2010. Approved Document L1B Conservation of Fuel and Power. [pdf] HM Government. Available at: < http://www.planningportal.gov.uk/uploads/br/BR_PDF_AD_L1B_2011.pdf> [Accessed].

The Society for the Protection of Ancient Buildings (SPAB)., 2013.Old House Eco Handbook: A Practical Guide for Energy Efficiency & Sustainability. London: Frances Lincoln Ltd.

The Princes Regeneration Trust (PRT)., 2010. The Green Guide for Historic Buildings: How to Improve the Environmental Performance of Listed and Historic Buildings. Norwich: TSO (The Stationery Office).

M.G. Cook., 2009. Energy efficiency in Old Houses. Ramsbury: The Crowood Press Ltd.

English Heritage, 2012. Energy Efficiency and Historic Buildings. [pdf] English Heritage. Available at: < https://www.english-heritage.org.uk/publications/energy-efficiency-historic-buildings-ptl/eehb-partl.pdf> [Accessed].

European Commission, 2012. National Library of Guidelines. [online] Available at: < http://edgar.jrc.ec.europa.eu/overview.php?v=CO2ts1990-2011> [Accessed].

English Heritage, 2014. National Library of Guidelines. [online] Available at: < http://www.english-heritage.org.uk/> [Accessed].

The Society for the Protection of Ancient Buildings (SPAB), 2009. National Library of Guidelines. [online] Available at: < https://www.spab.org.uk/> [Accessed].

BBC, 2013. National Library of Guidelines. [online] Available at: < http://www.bbc.co.uk/news/science-environment-24292615> [Accessed].

All illustrations were created by the Author.

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10.0 Bibliography

The Society for the Protection of Ancient Buildings (SPAB)., 2013.Old House Eco Handbook: A Practical Guide for Energy Efficiency & Sustainability. London: Frances Lincoln Ltd.

The Princes Regeneration Trust (PRT)., 2010. The Green Guide for Historic Buildings: How to Improve the Environmental Performance of Listed and Historic Buildings. Norwich: TSO (The Stationery Office).

M.G. Cook., 2009. Energy efficiency in Old Houses. Ramsbury: The Crowood Press Ltd.

English Heritage, 2012. Energy Efficiency and Historic Buildings. [pdf] English Heritage. Available at: < https://www.english-heritage.org.uk/publications/energy-efficiency-historic-buildings-ptl/eehb-partl.pdf>

English Heritage, 2008. Conservation Principles Policies and Guidance: For the Sustainable Management of the Historic Environment. [pdf] English Heritage. Available at: < https:// http://www.english-heritage.org.uk/publications/conservation-principles-sustainable-management-historic-environment/conservationprinciplespoliciesguidanceapr08web.pdf>

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11.0 Appendices

A

Improving Thermal Efficiency in Listed Residential Buildings

Please read the instructions below before commencing the questionnaire:

Please answer questions 1-11 by writing a NUMBER in each box corresponding to your

preferred material(s)/method(s) for improving the thermal efficiency of a listed

residential building. The HIGHEST number will be your MOST preferred and the LOWEST

will be your LEAST preferred. Please put them in order of preference.

You may leave boxes blank if you would never use that particular material/method or

have not heard of it, this includes the boxes labeled ‘Other’. If you can’t pick a

preference between any number of materials/methods you may put the same number

in each box. Please write any comments you may have in the boxes provided.

1- What natural insulation materials would you prefer to use? Please write a number

between 10 and 1 according to your preference.

Comments -

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CelluloseCork (expanded)CottonFlaxHempMonolithic lime/hemp mixReed boardSheep’s woolWood fiberboardOther

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2- What mineral insulation materials would you prefer to use? Please write a number

between 8 and 1 according to your preference.

Aerogel

Calcium silicate board

Cellular glass

Glass fiber

Lightweight expanded clay aggregate

Stone mineral wool

Vermiculite

Other

Comments -

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3- What petrochemical insulation materials would you prefer to use? Please write a

number between 6 and 1 according to your preference.

Expanded polystyrene

Extruded polystyrene

Phenolic foam boards

Polyurethane, polyisocyanurate board & spray foam

Recycled plastic bottle fiber wool

Other

Comments –

4- What composite insulation materials would you prefer to use? Please write a

number between 3 and 1 according to your preference.

Multi-foils

Vacuum insulated panels

Other

Comments –

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5- What methods would you most prefer to improve the thermal efficiency of a cold

pitched roof? Please write a number between 4 and 1 according to your preference.

Insulation quilts

Insulation batts

Loose-fill Insulation

Other

Comments –

6- What methods would you most prefer to improve the thermal efficiency of a warm

pitched roof? Please write a number between 4 and 1 according to your preference.

Insulation above rafters

Insulation below rafters

Insulation between rafters

Other

Comments –

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7- What methods would you most prefer to improve the thermal efficiency of solid

masonry wall? Please write a number between 4 and 1 according to your preference.

Internal insulation

External insulation

Render

Other

Comments –

8- What methods would you most prefer to improve the thermal efficiency of a wattle

& daub/lathe & plaster wall? Please write a number between 4 and 1 according to

your preference.

External render

Replacement panels

Internal insulation

Other

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Comments –

9- What methods would you most prefer to improve the thermal efficiency of solid

masonry/concrete floor? Please write a number between 4 and 1 according to your

preference.

Install a wooden floor

Install a carpet

Insulation

Other

Comments -

10- What methods would you most prefer to improve the thermal efficiency of a

suspended timber floor? Please write a number between 4 and 1 according to your

preference.

Draught proofing

Insulation batts/boards

Insulation quilts

Other

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Comments –

11- What methods would you most prefer to improve the thermal efficiency of a

window? Please write a number between 4 and 1 according to your preference.

Install curtains, shutters or blinds

Install secondary glazing

Install slim profile double glazing

Other

Comments –

Thank you for taking the time to complete this questionnaire, it is very much appreciated.

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B

Taylor Betts7 Stanford Road

Canvey IslandEssex

SS8 0DGMobile: 07472 686104

Email: [email protected]

26th January 2014

Dear Sir or Madam

My name is Taylor Betts and I am studying Construction Management at Anglia Ruskin University. I am undertaking a survey investigating the barriers to improving energy efficiency in listed residential buildings. Your experienced opinion is of great interest to me.

I have designed a questionnaire hoping you will be able to aid me in this study. No names or businesses will be mentioned and confidentiality will be upheld at all times. I would be very appreciative if you could find the time to fill in the questionnaire and send it back to me. Thank you.

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If you are willing to assist me, please would you mind signing the participant consent form and either email or post it to me for the study to go ahead. All funding is financed by me. Agreement to participate in this research should not compromise your legal rights. All results of the study will be analysed and used to support the recommendations stated in the dissertation. If you wish to withdraw from the study, please fill in the withdrawal section of the consent form and contact me at any time so I can remove your answers from the survey.

My tutor Sunny Nwaubani is available for any further information. (Email: [email protected])

Thanking you in advance for your help.

Yours Faithfully,

Taylor Betts

C

Participant Consent Form

NAME OF PARTICIPANT:

Title of the project: “Investigating the Barriers to Improving Energy Efficiency in Listed Residential Buildings”

Main investigator and contact details: Taylor Betts 07472 686104 [email protected]

Members of the research team: Taylor Betts, Sunny Nwaubani

1. I agree to take part in the above research. I have read the Participant Information Sheet which is attached to this form. I understand what my role will be in this research, and all my questions have been answered to my satisfaction.

2. I understand that I am free to withdraw from the research at any time, for any reason and without prejudice.

3. I have been informed that the confidentiality of the information I provide will be safeguarded.

4. I am free to ask any questions at any time before and during the study.

5. I have been provided with a copy of this form and the Participant Information Sheet.

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Data Protection: I agree to the University1 processing personal data which I have supplied. I agree to

the processing of such data for any purposes connected with the Research Project as outlined to me.

Name of participant (print)………………………….Signed………………..….Date………………

Name of witness (print)……………………………..Signed………………..….Date………………

YOU WILL BE GIVEN A COPY OF THIS FORM TO KEEP--------------------------------------------------------------------------------------------------------------------------

If you wish to withdraw from the research, please complete the form below and return to the main investigator named above.

Title of Project:

I WISH TO WITHDRAW FROM THIS STUDY

Signed: __________________________________ Date: ____________________

1 “The University” includes Anglia Ruskin University and its partner colleges

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