Dissertation: Thermal Retrofit of 19th Century Building

DT175a Dissertation

Retrofit of a 19th

Century Building ~A strategy for the thermal retrofit of Cuilín House~

(Submission date 11th May 2012)

DT175a – Module: ARCH4258 – Final Year Dissertation

~ Conor Sweeney ~

C08731136

Supervisor: Cathy Prunty

Total Words: 11,612

Main Body: 8,200

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Abstract

This dissertation contrasts two retrofit proposals to be applied to an historic protected

structure in some disrepair. The first using synthetic materials and minimalist

interventions to the existing fabric, the second with a more rounded and intensive

thermal retrofit sensitively tailored to the intricacies of a19th century building’s

dynamics. A strategy for renovation with a mind towards both conservation and

thermal efficiency upgrading is put forward and evaluated against the baseline

proposal, and evaluated from breathability and conservation perspectives, as well as a

detailed analysis of the overall effect both approaches have on the thermal efficiency

of the structure.

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Declaration

I hereby declare that the work described in this dissertation is, except where otherwise stated, entirely my own work and has not been submitted as an exercise for a degree at this or any other university.

_________________________

Student Name

2012

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Acknowledgements

I’d like to thank Sima, Sarah, Dave and all the Studio Staff for their encouragement,

interest and expertise this year, my thesis supervisor Cathy Prunty for her unerring

eye and appreciation for detail, the staff and students of the School of Architecture,

for an interesting, engaging, fun and incredibly busy 4 (or more) years and lastly and

most of all my family for all their support and help, and for giving me the swift kick

up the backside I needed to get my act together to get to this point.

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Table of Contents

Chapter 1 Introduction................................................................................................ 9

1.1 Preamble & Context ............................................................................................ 9

1.2 Aims of the Research ........................................................................................ 10

1.3 Objectives ........................................................................................................... 10

1.4 Cuilín House ..................................................................................................... 11

1.5 Initial Unit 01 Proposal .................................................................................... 12

1.6 Methodology ...................................................................................................... 14

Chapter 2 – Literature Review ................................................................................. 15

2.1 Traditional Buildings - General ....................................................................... 15

2.1.1 Traditional Solid Walls ............................................................................... 15

2.1.1 Timber Sash Windows ................................................................................ 17

Chapter 3 – Fabric Retrofit & Refurbishment ....................................................... 19

3.1 External Walls ................................................................................................... 19

3.1.1 Current Condition ....................................................................................... 19

3.1.2 Condensation Risk Analysis ....................................................................... 19

3.1.3 Breathable Construction.............................................................................. 21

3.1.4 Insulation Selection ..................................................................................... 22

3.1.5 Proposed Intervention ................................................................................. 24

3.1.6 Resultant Wall U-Value .............................................................................. 26

3.2 Replacement Ground Floor .............................................................................. 27


3.2.2 Initial Unit 01 Proposal ............................................................................... 27


3.2.3 Resultant U-Value ....................................................................................... 30

3.3 Existing Cut-Timber Collar Roof ..................................................................... 31





3.4 Existing Timber Sash Windows........................................................................ 35

3.4.1 Current Condition ...................................................................................... 35




Chapter 4 – New Construction ................................................................................ 38

4.1 Circulation Atrium ............................................................................................ 38

4.1.1 Atrium Structural Glass Walls & Roof ....................................................... 38

4.1.2 Radiant Concrete Floor ............................................................................... 39

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Chapter 5 – Thermal Comparison ........................................................................... 40

5.1 Introduction ....................................................................................................... 40

5.1.1 General ........................................................................................................ 40

5.1.2 Heat Losses Generally ................................................................................ 40

5.1.3 Steady State Heat Loss Calculation ............................................................ 41

5.2 Total Transmission Heat Loss .......................................................................... 44

5.3 Total Ventilation Heat Loss .............................................................................. 46

5.4 Total Heat Loss & Demand .............................................................................. 47

Chapter 6 - Conclusion .............................................................................................. 48

Appendix A – U Value Calculations ......................................................................... 51

Unit 01 External Wall Proposal .......................................................................... 52

Rebuilt Suspended Ground Floor ........................................................................ 52

Thermal Retrofit of External Wall ....................................................................... 53

Unit 01 Proposed Roof Refurb ............................................................................. 54

Retrofitted Cut Timber Roof................................................................................ 55

Internal Wall Type 1 (450 Solid Brickwork) ........................................................ 56

Appendix B – BuildDesk Condensation Analyses ................................................... 57

Appendix C – Fabric Heat Loss Calculations ......................................................... 60

Appendix D – Overall Unit 01 Proposal .................................................................. 66

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Table of Tables

Table 1: U-Value Calculation of Unit 01 Wall Proposal 24

Table 2: U-Value Calculation of Proposed Suspended Timber Floor 30

Table 3: U-Value Calculation for Proposed Roof Retrofit 34

Table 4: Possible Actions for thermal upgrade of traditional sash windows and their

resultant U-Value. 37

Table 5: U-Value Calculation for New-Build Concrete Floor @ Atrium 39

Table 6: Summary of Element U-Values. 40

Table 7: Design Internal & External Temperatures 43

Table 8: Example Heat Loss Calculation for external wall in one room. 44

Table 9: Transmission Heat Loss by Space – Unit 01 44

Table 10: Transmission Heat Losses by Space – Deep Retrofit 45

Table 11: Calculation Table of Ventilation Heat Losses – Shallow Retrofit 46

Table 12: Calculation Table of Ventilation Heat Losses – Deep Retrofit 46

Table 13: Total Heat Losses 47

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Table of Figures

Figure 1: Cuilín House and surrounding structures ................................................ 11

Figure 2: Roof Plan of Cuilín House Existing .......................................................... 13

Figure 3: Roof Plan Showing Alterations ............................................................... 13

Figure 4: Section Showing Existing Arrangement .................................................. 13

Figure 5: Section Showing New Arrangement ....................................................... 13

Figure 6: Existing Wall Inner Face: Unplastered section......................................... 19

Figure 7: Sketch of insulation board & external wall dabbing ................................ 19

Figure 8: Wool Strand Diagram ............................................................................. 22

Figure 9: The principle of insulation performing a hygroscopic buffering function,

storing and diffusing moisture from vapour ingress. ..................................... 23

Figure 10: The problems associated with introducing vapour control principles to a

traditional solid wall. .................................................................................... 23

Figure 11: Diagram of Retrofit Wall Buildup. ........................................................ 24

Figure 12: Fractional Areas of Bridging through the insulation and batten plane. .. 26

Figure 13: Existing Floor boards ............................................................................ 27

Figure 14: Missing Floor boards and exposed subfloor / dwarf walls ..................... 27

Figure 15: Unit 01’s Floor Build-Up Proposal ......................................................... 27

Figure 16: Joists and Dwarf Wall separated from External Wall ............................. 28

Figure 17: Proposed Floor Construction – through Joists ....................................... 28

Figure 18: Proposed Floor Construction – through Dwarf Wall .............................. 28

Figure 19: Proposed Retrofit Subfloor Vents & External French Drain ................... 29

Figure 20: Section of Upper Storey ....................................................................... 31

Figure 21: Existing Roof Rafters & Collars exposed internally ................................ 31

Figure 22: 3-D showing existing eaves and roof build-up ....................................... 32

Figure 23: Section showing existing eaves arrangement ....................................... 32

Figure 24: Proposed extension of eaves to allow soffit ventilation ........................ 32

Figure 25: Section through proposed roof construction ........................................ 33

Figure 26: Section through Joists .......................................................................... 33

Figure 27: Recessed window with architrave and panelling .................................. 35

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Figure 28: Flush Sash Window .............................................................................. 35

Figure 29: Draughtproofing measures for sash windows ....................................... 35

Figure 30: Jamb detail: flush window with secondary glazing ................................ 36

Figure 31: Jamb detail: recessed window with secondary glazing .......................... 36

Figure 32: Heat Camera Image showing the heat lost through traditional sash

window (right) and one with secondary glazing (left). ................................... 36

Figure 33: Traditional Sash ................................................................................... 37

Figure 34: 3D of Atrium siting within Cuilin House ................................................ 38

Figure 35: Triple paned structural glass ................................................................ 38

Figure 36: New Build Atrium Floor ........................................................................ 39

Figure 37: First Floor Plan with internal ................................................................ 43

Figure 38: Ground Floor Plan with internal ........................................................... 43

Figure 39: Fractional Areas of materials in the cross-battened wall/roof ............... 51

Introduction

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Chapter 1

Introduction

1.1 Preamble & Context

Energy efficiency in our existing building stock is becoming more and more a

concern as European Union member states commit themselves to newer and ever

more ambitious energy saving and emission reduction targets. By 2020 Ireland is

required under the EU’s Europe 2020 Strategy, as one of its five key aims, to reduce

its greenhouse gas emissions by 20% and to achieve a 20% increase in energy

efficiency over the whole economy compared to 1990 levels.

Europe uses 40% of its energy in heating and cooling its buildings, as such it is an

obvious and necessary goal to approach new refurbishment and restoration projects

with a goal to improving thermal efficiency.

Department of the Environment statistics indicate that over 10 per cent of the existing

dwelling stock in Ireland was constructed pre-1919, and thus fall far below modern

standards of thermal efficiency and thus consume more energy to heat. As the

greenest building is one that has already been built, in terms of embodied energy,

retrofitting historic and traditional buildings to a higher standard of thermal efficiency

is an exercise in sustainability and conservation, as the best way to ensure the comfort

required for their continued use and thus survival.

That being said an appropriate balance must be maintained between building

conservation and energy conservation, due respect must be given to the traditional

elements of older construction and their particular dynamic in any intervention, the

approach taken must balance these aims. The interventions proposed for this protected

building are directly informed by the quality and extent of remaining historical

features in their original positions and are intended as a guide for protected buildings

in a similar state of degradation and historical erosion.

Introduction

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1.2 Aims of the Research

This dissertation aims to propose a thermal retrofit strategy for Cuilín House that will

balance the concerns around the conservation of a culturally significant building, and

the desire for thermal and thus energy efficiency.

This paper will explore and analyse the considerations involved in retrofitting and

refurbishing a 19th century building and to suggest appropriate interventions, informed

by best practice. These interventions will be designed to improve thermal

performance without disrupting or damaging the integrity of the existing fabric, and

preserving the buildings historic features.

1.3 Objectives

This paper will explore the issues and possible problems involved in executing a

thermal intervention to an historic building by;

• Reviewing existing guidance documents on the subject

• Applying thermal retrofit interventions through detail design to the study

building, informed by guidelines and best practice.

• Suggesting technological solutions to improving thermal performance while

maintaining fabric integrity and that of historical features.

• Comparing the finished project to an earlier retrofit proposal of the building in

terms of thermal performance.

Introduction

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1.4 Cuilín House

The sample older building used in this study is Cuilín House, located off Hampstead

Avenue in the mature wooded surrounds of the old Albert College in Glasnevin

Dublin 9.

The building was originally constructed to house the operator of the model farm in

that location, which served as an educational institution from the early 19th century

until the latter half of the 20th. The model farm was among the first of its kind in

Europe and attracted visitors as notable as Prince Albert of the United Kingdom, for

whom the college is named, and the son of Napoleon I of France, as it was seen as a

new departure in the education of farmers and farm workers. The House itself has

been the subject of a number of extensions and demolitions to both its core

arrangement and surrounding structures and is currently at the south-west corner of a

quadrangle of outbuildings of varying ages and levels of use.

Today the complex is used by the Dublin City Council (DCC) Parks Department;

however the house itself is currently in a state of disuse and considerable disrepair. It

is a protected structure not for its intrinsic architectural merit, but for the social and

cultural importance it attained in its role as a pathfinder in the realm of agricultural

education in Ireland and Europe.

Figure 1: Cuilín House and surrounding structures

Introduction

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1.5 Initial Unit 01 Proposal

The proposed demolitions and extensions contained and used in this study are a result

of the development project undertaken by myself and my colleagues in Unit 01, as

part of our Technical Design Studio thesis project in our final year.

I have isolated the original 1830’s house proper for the purposes of this study and

disregarded works to the ancillary buildings. The works proposed by this earlier

project for the main house include the demolition of lean-to single story concrete

structure at the rear (east elevation) of the main house, and the front porch (west

elevation), both of which are later additions to the building.

The largest proposed changes involved the removal of the central part of the east

façade facing into the quadrangle and replacing it with a glazed atrium to perform as a

circulation area, in terms of this study a new modern intervention interacting with a

much older surrounding building.

The overall use of Cuilín House will change to that of office space for the DCC at

ground level and the provision of an exhibition space and office accommodation at

first floor level for use of the community. Full details and explanatory drawings of

Unit 01’s proposals are to be found in Appendix

Introduction

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Figure 2: Roof Plan of Cuilín House Existing Figure 3: Roof Plan Showing Alterations

Figure 5: Section Showing New Arrangement Figure 4: Section Showing Existing Arrangement

Introduction

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1.6 Methodology

The structure of this dissertation is relatively straightforward – reading and comparing

texts such as guidance notes, case studies and other research to inform an approach to

detailing specific elements of the fabric of the building.

In summation, the methodology applied to compiling this paper is as follows:

• Secondary Research: Reading guideline texts and prior research into the areas

directly related to the applications (i.e. case studies and best practice

documents in the field of solid wall insulation.)

• Secondary Research: Reading papers around the concepts and philosophy

underlying the interventions chosen (i.e. the concept and dynamic of

breathability in construction)

• Primary Research: Use of computer programmes for evaluation

• Primary Research: Adapting and applying technologies informed by secondary

research reading to details of prior survey of building.

• Primary Research: Evaluation of proposals through attaching thermal values to

their buildip (i.e. U-Valuation)

• Primary Research: Evaluating the dissertation hypothetical intervention’s

values to those of the baseline Unit 01refurbishment proposal using an

empirical model of comparison (i.e. the heat loss calculation).

Literature Review

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Chapter 2

Literature Review 2.1 Traditional Buildings - General

2.1.1 Traditional Solid Walls

Traditional solid walls are inherently different creatures when it comes to the addition

of internal or external insulation. Condensation risk and interrupting their natural

dynamic is a huge issue in any consideration. There are a number of guidelines and

studies that deal with the complications around internally insulating walls of this

nature.

Guidance from English Heritage (2010) holds that in a traditional wall, the build-up

often contains a variety of materials with different performance characteristics and the

presence of “voids, irregular bonding patterns and concealed timbers” can complicate

any understanding of how energy and moisture interact with the structure. The guide

warns against the reliability of modern theoretical calculations and analytical

computer programmes in the design of a thermal upgrade, and if such a method is

used then “performance should be closely monitored after installation in case of

problems occurring. This guide strongly warns against the use of modern synthetic

insulation materials, as the natural materials in the walls are designed to “breathe”, or

exchange moisture vapour between outside and in. Vapour barriers and other

impermeable materials are to be avoided as they may trap and hold moisture in the

wall.

The UK’s Energy Saving Trust guidelines on the refurbishment of solid-walled

houses (2006) maintains that best practice is to take a U-Value of 0.3W/m2K to be the

goal of internally insulating. However this source seems to deal with more modern

brick and concrete solid walls and much of the guidance is around the idea of a

vapour control layers and synthetic materials, contravening the guidance above.

An article on the subject of breathing in Self Build’s online edition (Morgan, 2008)

expands on the traditional concept of the breathing building versus the modern idea of

“we dare not let moisture into the fabric of our buildings”. Traditional walls of stone

and brick permitted the movement of moisture through and around them and, the

Literature Review

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author states, experience has taught us “modern responses – based on blocking the

passage of moisture where it suits us – it tends not to work.” Morgan also warns

against synthetic insulants in favour of “hygroscopic” materials to effectively store

and buffer moisture in its vapour form - both managing wall moisture content and

passively controlling internal humidity.

Expanding on the role of the wall regulating damp and moisture, the Department of

the Environment’s Guide to Energy Efficiency in Historic Buildings (2010) describes

the way traditional wall materials’ porosity allowed moisture to be absorbed, stored

and later released, echoing other sources. Actual water from rain was absorbed but

owing to the thickness of the wall never made it directly through, where moisture

vapour passed through depending on pressure either side. Repointing may be

necessary and measures taken to avoid rising damp. The guide also pointed out that

chemical DPC’s are unreliable in any rubble filled wall, as the presence of voids can

negate it’s effects.

The Society for the Protection of Ancient Buildings, in their Control of Damp

publication (SPAB, 2009) mentions sheep’s wool and cellulose as effective natural

hygroscopic materials that can help reduce existing condensation issues, as well as

improving thermal performance. This was the first evidence I’d encountered of

internal insulation having a directly positive effect condensation risk as opposed to

merely being designed so as not to have a negative effect. Since the opinion seems to

be that modelling software cannot be relied upon, it will be important to design the

retrofit with a high level of tolerance to any negative condensation effects.

Significantly, one of the only studies that aims to refute the claims made around the

importance of breathability as a consideration in insulation comes from a white paper

produced by Cambridge Architectural Research (2009) commissioned by a synthetic

insulation manufacturer, Kingspan. In the study, they aver that ventilation accounts

for 95% of the vapour transfer from a house with breathable walls and thus the

breathability of insulation products is “at best a side show,in reality… a complete red

herring”. The study claims that as long as the air changes in a volume are above 0.5/h,

condensation (on surfaces) cannot occur, and that all but the most airtight buildings

exceed this.

However, Neil May of Natural Building Co. in his direct rebuttal of the Kingspan

paper (May, 2009) explains that the paper did not deal with the two areas where

breathability is vital: in the case of fabric health where there are building faults, and

Literature Review

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human health through the prevention of moulds and the buffering of internal

humidity. These would seem to be the most directly related issues with this project

and thus confirms the previous sources in that it would be wisest to go with a natural

breathable insulant product with a hygroscopic buffering or storage ability to

compensate.

2.1.1 Timber Sash Windows

Traditional timber sash windows, originally developed in France, Holland and

England in the 17th century, were the most common window type in Ireland for almost

300 years, up to the mid-20th century.

The Department of the Environment, Heritage and Local Government’s Conservation

Guidelines for Windows (DoEHLG, 1996) warn against well-intentioned but poorly

executed replacement windows in refurbishment projects and in cases were a

replacement is necessary, the advice is to copy another window in the building, or

from another building of the same age, as the design and profile of items like the

glazing bars and the presence of horns changed over time. The guidelines warn

against sealing windows hermetically, as condensation is sure to occur. The

guidelines strongly favour the concept of secondary windows as the “most

satisfactory solution to thermal performance”, but suggest the members be painted a

dark colour and placed so as to be concealed behind glazing bars and meeting rail.

English Heritage’s “Framing Opinions: 7 – Timber Sash Windows” (English

Heritage , 1997) states that the reason for the continuing integrity of centuries old

windows lies in the fact the wood is from the heart of the tree, whereas 60’s and 70’s

windows were sapwood, which is permeable and attractive to fungi. The paper

advices anyone looking to maintain or upgrade their sash windows to look for key

points; signs of structural movement deforming the opening and damaging the

window, evidence that the pointing of the frame to the wall reveal is cracked, loose or

missing, exposing the sash box to moisture, difficulty opening the sash could be

caused by overpainting, broken sash cords, seized up wheels – a full health check is

required.

“Framing Opinions:1: Draughtproofing and Secondary Glazing” (English Heritage,

1994) somewhat disagrees with the guidance from the DOE around secondary glazing

Literature Review

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and double glazing – stating that only about 20% of a buildings heat is lost trhough

windows and most of this through infiltration from improper draught proofing. This

paper seems to be out of date though, only describing secondary glazing as a screen

one can remove when not wanted. This guide comes with valuable drawings on how

to detail a weather proofing intervention to a timber sash.

Guidance on historic windows from the Northern Ireland Environment Agency (NIA,

2010) also mentions the English Heritage finding that 90% of window heat loss is due

to draught and finds therefore that draughtproofing is the most effective form of

insulating historic windows, ruling that double glazing is unneccessary. The booklet

states that higher again insulation from sound and cold can be provided with

secondary glazing and counsels that should rot be found, it may only be localised and

the affected areas removed and spliced with healthy members. In regard to secondary

glazing, the concept of reversibility is important, that the unit can be removed if

desired at a later date.

Historic Scotland’s “Sash & Case Windows” guidance document (Historic Scotland,

2008) recommends against fitting proprietary trickle vents into slots cut in the rails of

sash windows, and instead suggests the chamfering the outside edge of the top sash

and insertion of an adjustable grille on the inside and a fixed grilled on the outside to

allow ventilation over the top.

Historic Scotland’s guidelines for “Energy Efficiency in Traditional Homes” (Curtis,

2008) gives tables on a range of options for improving the thermal performance of

sash windows, giving resultant U-values gained through laboratory testing.

Fabric Retrofit & Refurb

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Chapter 3

Fabric Retrofit & Refurbishment

3.1 External Walls

3.1.1 Current Condition

The walls currently appear to be in good

condition externally, aside from needing

some repointing work; they are faced in

cut limestone. Internally the plaster is

missing in many areas exposing the brick

inner facing. As has been said, the

internal composition is in some doubt

over whether or not there is a rubble core,

however the thickness of 470-550 would

imply its presence.

3.1.2 Condensation Risk Analysis

Despite the guidance around condensation risk analysis computer programmes being

unsuitable, I put this to test and was immediately aware that I was dealing with a lot

of unknowns re: the internal makeup of the walls. The software, Builddesk U

calculates condensation risk based on

methodology in BS EN ISO 13788:2002,

which is only reliable “for constructions

containing solely homogeneous layers

(unbridged layers)” – this immediately ruled

out this project due to first and ground floor

joists being embedded in the wall.

More from a curiosity and illustrative point of

view I ran a number of simulations around

Figure 7: Sketch of insulation board &

external wall dabbing

Figure 6: Existing Wall Inner Face:

Unplastered section


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installing a synthetic non-breathable insulant (polyurethane board) internally with a

plasterboard finish (full results in Appendix B).

The results showed that a 20mm layer of polyurethane board would pass the

assessment, but with the proviso that although condensation occurs, the condensate is

expected to evaporate during the summer months. Anything thicker than 20mm

resulted in a fail, as condensate would not completely evaporate and degradation

could occur. As 20mm would only provide a U-value of 0.79W/m²K, this was

insufficient.

Predictably the addition of a vapour barrier (0.6mm polyethylene) on the insulations

warm side or a foil backing to the plasterboard mitigated this problem - allowing

levels of the insulation beyond 100mm. While this is potentially possible in a new

build where joints, bridges and perforations are under a measure of control, it is

wholly inappropriate for a retrofit to an existing building. As Chris Morgan for

SelfBuild writes, “It is common, if not ubiquitous that vapour barriers are penetrated

dozens if not hundreds of times on each build” (Morgan, 2008), these would

constitute pinch-points for interstitial condensation, where the areas around the breach

would bear proportionately much more moisture than the rest of the wall which is

protected. The embedded joists and adjoining internal walls would undoubtedly

experience this increased moisture load too, potentially leading to a structural failure

(May, 2005).

This experiment demonstrates that applying modern doctrines of vapour-impermeable

material and constructions with no thought to the existing walls dynamics could lead

to serious structural and performance issues later.


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3.1.3 Breathable Construction

The actual construction of Cuilín House’s is unclear, but the consensus among the

teams surveying was that it was most probably a limestone faced, rubble-cored

construction with a brick inner face. The quality of the stonework and protected

nature of the building prohibits the use of external insulation solutions and internally

insulating a traditional solid wall requires many considerations around disruption of

moisture movement and risks exacerbating surface and interstitial condensation

problems.

The approach taken in this research is one of breathability, using a natural insulation

material capable of buffering the moisture in the wall in its vapour form and in the

form of condensate, storing it for when weather conditions permit evaporation.

Breathability means that a wall of such thickness working as intended has the ability

to dry and keep itself damp free, the thickness is such that actual water does not

penetrate all the way through the structure, but soaks through the external limestone

layer, particularly through the porous lime mortar, wherefrom it in turn evaporates.

The rubble core acts as a buffer, intending water to pass down its length rather than

passing directly into the internal spaces.

Breathability in the context of external walls is something of a misnomer as it sounds

like it implies air-permeability, a more accurate term would be that the wall sweats

moisture vapour – a sweating wall (Morgan, 2008). The concept is that warm air or

heat will always seek to balance itself and the occupied internal environment of a

building will more often than not contain more moisture vapour than the colder

outside air. This creates an out-flowing dynamic that moisture vapour will tend

towards the low pressure outside through a vapour-open wall. Should interstitial

condensation or other damp-related problems (a retrofit DPC is impractical) occur, the

intervention to the wall will be so designed as to absorb and store the moisture until

evaporation conditions area reached once again.


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3.1.4 Insulation Selection

The prime actor in this concept of buffering internal moisture until conditions permit

it’s release into the atmosphere will be the internal insulation lining. The material will

be required to act as a hygroscopic buffer, absorbing excess moisture and releasing it

when the time is right, as well as allowing moisture vapour from both inner and

external environments pass through it to maintain internal environmental balance.

In this context, I have specified Sheep’s Wool as the sole insulating product for use in

the project – wall, floor and roof.

Recommended for use in traditional

solid walled interventions (SPAB,

2009), wool is a naturally hygroscopic

material. The exterior layer of a wool

fibre is water resistant, while it’s inner

layer is ‘hydrophilic’ (water-loving),

meaning the material can absorb up to

30% of it’s weight in moisture without

feeling damp to the touch, and up to

40% of it’s dry mass without

compromising it’s thermal

performance. Significantly though,

when wool absorbs absorbs moisture from the air, it generates a small amount of heat,

known as the ‘heat of sorption’ (Irish Eco Homes, 2010) this warmth, while not

noticeable inside the building, maintains the temperature above dew-point in damp

conditions preventing interstitial condensation from occuring.

These characteristics make sheep’s wool an appropriate choice for this project, as it

assists moisture and vapour transit through the fabric, rather than attempting to disrupt

and contain it, restricting the walls existing breathable dynamic.

Figure 8: Wool Strand Diagram


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Figure 10: The problems associated with

introducing vapour control principles to a

traditional solid wall.

Figure 9: The principle of insulation performing

a hygroscopic buffering function, storing and

diffusing moisture from vapour ingress.


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3.1.5 Proposed Intervention

The baseline model of comparison, the works proposed in the Unit 01 project,

specified the walls to be repointed externally, internally stripped of remaining plaster

and thoroughly cleaned and re-finished in new lime plaster. This resulted in a U-

Value of 1.44W/m²K.

Unit 01 Proposed Wall U-Value

Layer Thickness (m) Conductivity Resistance

Internal

Surface - - 0.13

Plaster 0.018 0.8 0.02

Clay Brick 0.21 0.77 0.27

Limestone 0.29 1.26 0.23

External

Surface - - 0.04

0.70

Total Element U-Value: 1.44

Table 1: U-Value Calculation of Unit 01 Wall Proposal

Repointing of Lime Mortar

Before mixing it is important that the colour of sand matches the original as much as

practicable and that the mix contains as high an amount of lime as necessary to

achieve the level of permeability to affect evaporation of moisture from the wall.

Figure 11: Diagram of Retrofit Wall Buildup.


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1. Internal Lime Plaster

The internal brickwork surface of the wall is to be re-finished in a lime mortar for the

Unit 01 project and I decided to retain this element for my retrofit proposal, so as to

ensure an even surface for battening. Also from a conservation perspective, a lime

plaster will be a beneficial remnant should the thermal component of the retrofit

require reversing.

The plaster is to be 2-coat as the brick surface is relatively flat. The first coat is an 8-

10mm haired mix of ratio 1:2.5 lime and sand to be scoured and dried for up to three

weeks. Atop this is an 8mm devil or nail coat, performed with a trowel with

projecting nails at each corner to form a key for the finish, which is a thin 2mm 1:1

mix lime:sand to be skimmed smooth.

2. Insulating & Battening:

A batten and counter battening layer is specified to hold the insulation layer –

composed of a vertical series of 50x50mm battens at 400 centres screwed through the

plaster into the brickwork using appropriate sized rawl plugs at 250mm centres. The

counter battening is a horizontal series of 50x50mm battens at 400 screwed to the

vertical. Between each series of battens a 50mm batt of sheep’s wool is tension fitted

ensuring no gaps or room for sagging.

3. Diffusion Membrane:

A polyethylene copolymer membrane is taped to internal face of the battening, this

membrane is a humidity variable diffusion material, regulating the maximum amount

of water vapour that can be transmitted through to the wall at times of high internal

humidity, while still allowing the structure to breath within tolerances – it’s porosity

is selected to match that of the sheep’s wool.

4. Plasterboard:

12.5 Gypsum plasterboard is fixed to the internal battens with 40mm roundhead

galvanised steel plasterboard nails at 150mm centres, to be skimmed and painted using

strictly water-based paint (there is some debate over the use of matt and emulsion

paints and their vapour openness (May, 2005).)


26

3.1.6 Resultant Wall U-Value

It should be noted that there is a health warning

around U-valuating such an old wall, as

assuming homogenous layers and no air gaps is

unreliable. However the contrast from the Unit

01 proposal to existing forms a basis from which

to make before and after comparisons.

The U-value calculation took into account the

bridging from both sets of battens by using

fractional areas, a result of 0.33W/m²K was

found, above the Part L requirement of

0.27W/m²K but well below the requirements for

a material change of use of 0.6W/m²K and an

80% improvement on the Unit 01 proposal.

Figure 12: Fractional Areas of Bridging

through the insulation and batten plane.


27

Figure 14: Missing Floor boards

and exposed subfloor / dwarf walls

3.2 Replacement Ground Floor


The existing suspended timber ground floor is

heavily decayed and entirely missing in some

areas of the house. As was common in the early

19th century, the subfloor was ventilated by the

internal spaces, as opposed to external vents, and

consisted of exposed earth (DOE, 2010). It is

proposed to completely replace the entire floor.

3.2.2 Initial Unit 01 Proposal

The specified replacement floor in the Unit 01

project consisted of an entirely new heavily

synthetically insulated radiant concrete floor.

While this had high thermal performance

credentials (0.14W/m²K), it was at variance with

the traditional breathable nature of the

surrounding structure. It is highly probably that

the subfloor, while only ventilated from the

internal spaces, performed a drying function on the external wall and it was therefore

my judgement an upgraded ventilated suspended timber floor system was more

appropriate for this project.

Figure 15: Unit 01’s Floor Build-Up Proposal

Figure 13: Existing Floor boards


28


The overall deteriorated state of the existing floor presents

an opportunity to eliminate a cold bridge; by using new brick

honeycombed dwarf walls to set the new floor timbers back

from the wall surface. This will protect the timber from

moisture damage and allow the wall insulation and floor

insulation to meet and provide a more complete envelope.

Sheep’s wool is specified to be packed between joists and

around the perimeter.

1. Retrofit Subfloor & Drainage

The exposed earth subfloor was excavated to a level of approximately 400mm below

original subfloor height, lined in well compacted hardcore and a 100mm concrete

subfloor slab was poured. As this brought the subfloor level to below that of the

external ground level, a French trench drain has been specified. 300mm wide, the

depth is determined by the depth of the foundations - so as not to jeopardise

foundation stability, the bottom of the trench cannot go below a figurative 45˚ line

drawn from the top of the foundation (SPAB, 2009).

Figure 16: Joists and Dwarf Wall

separated from External Wall

Figure 17: Proposed Floor Construction –

through Joists Figure 18: Proposed Floor Construction –

through Dwarf Wall


29

Figure 19: Proposed Retrofit Subfloor Vents & External French Drain

2. Subfloor Ventilation

As stated, the original earthen subfloor was unventilated, which is not uncommon in

older buildings. As the potential for ventilating from the internal space is lost by

adding insulation between the joists, retrofit vents have been specified. Measuring

100mmx200mm each, fronted with a stainless steel grill, with an internal insect

repellent mesh, they are installed 600mm from the corners of the walls, and at 2 metre

centres thereafter (Timber Queensland , 2004).

3. Dwarf Walls

The new floor joists are set on honeycombed brick dwarf walls, set a minimum of

100mm from the external walls, allowing the joists to be isolated from forming a

thermal bridge. The honeycomb pattern of the bricks allows ventilation through the

walls. Two courses of brick and a 75x100mm timber wallplate, separated by a DPC.

4. Joists & Insulation

The floor joists are skew nailed atop the wallplate and are to be 50x225 C22 timber at

400 centres as per Eurocode 5. A layer of steel mesh is moulded around the joists to

form a support for the insulation batts between, this mesh to be fixed to the external

wall behind pads of timber to support edge insulation. Between the joists, supported

by the steel mesh is fitted 225mm batts of sheep’s wool insulation, tightly packed.


30

5. Fibreboard and Floor Boards

25mm fibreboard sheathing is nailed atop the joists to prevent any draughts from

below, surviving floorboards are cleaned and re-treated, to be supplemented by new

boards from reclaimed sources where practicable.

3.2.3 Resultant U-Value

The U-value for this construction was calculated as 0.2W/m²K. While this is above

the value of 0.14W/m²K in the original Unit 01 proposal, it is well below the Part L

requirement for buildings other than dwellings of 0.25W/m²K, and I feel far more

appropriate as it does not rule out a drying function being performed on the wall from

the inner side.

Table 2: U-Value Calculation of Proposed Suspended Timber Floor

Rebuilt Suspended Ground Floor

(Through Joists - 12.5%)


Internal Surface - - 0.13

Floorboards 0.03 0.18 0.14

Fibreboard Deck 0.03 0.13 0.19

225x50 C22 Joists 0.23 0.13 1.73

External Surface - - 0.04

Total Resistance: 2.23

U-Value 0.45






Sheep's Wool 0.23 0.04 5.77


Total Resistance 6.27

U-Value 0.16



31

3.3 Existing Cut-Timber Collar Roof


The first floor of the building is more or less a half-

story, in that at present the rafters and collar

constitute the ceiling. Currently the roof is an un-

insulated cut rafter & collar construction with

sarking felt and boarding above, there is no ceiling

board so timber members are exposed internally,

leaving only the sarking and roof tiles as protection

from the elements. There is a high degree of wind

gaps through the structure and the sarking and

boarding is in bad repair. Structural surveys

undertaken prior to our own suggest the rafters and

collar joists to be in good structural condition so it is

my intention to clean, re-treat and re-use these

members as far as practicable.

The initial survey of the building and historical

research indicated the roof has been replaced since

construction, as the pitch is higher in historical

drawings. In addition, the slates are of cement fibre

and certainly not original – I have specified these be

disposed of and natural slate reinstated throughout.

In insulating the roof there was a requirement to ventilate the rafter space and above

the ceiling collar. In its current state this is impossible as the eaves overhang is

approximately 50mm with the fascia board flush against the external wall, precluding

soffit vents.

Figure 21: Existing Roof Rafters &

Collars exposed internally

Figure 20: Section of Upper Storey


32


The proposal in the Unit 01 project was minimalist – to clean and reuse the existing

slates, install batts of sheep’s wool between the joists and collar and to plasterboard

beneath – which gave a u-value of 0.25W/m²K.


As with the floor, I have determined that it

is unwise to close off the loft space to

ventilation through insulating the roof,

however it would be unconscionable to

leave the joists uninsulated as more than

25% of heat loss occurs through the roof. A

possible solution to this is to retrofit more

substantial eaves. By bolting lengths of

timber to the sides of the rafter ends, I have

extended their length creating an overhang

of 200mm - while this is below the

recommended 300mm, I felt an extension of

the eaves of that size would overly change the external appearance of the building.

With the new eaves, soffit vents can be fitted.

Figure 22: 3-D showing existing eaves and roof

build-up

Figure 23: Section showing existing eaves

arrangement

Figure 24: Proposed extension of eaves to allow

soffit ventilation


33

1. Slates.

As stated, the existing fibre cement slates were disposed of, and new natural slates

installed, preferably from reclaimed sources.

2. Battens.

50x50 treated timber battens are nailed along the top of the rafters to create ventilation

space between top of ventilation and the underside of slates, atop these 50x35mm

slating battens are counter-fixed.

3. Breather membrane

This is lapped and taped between the tops of the rafters and the bottom of the battens.

4. Rafters & Insulation

The rafters and collar joists are to be cleaned and retreated after being inspected for

structural integrity. Spaces in between the joists are tension packed with 150mm

sheep’s wool.

5. Insulated Service Cavity & Ceiling

Below the rafters, 50x50 counter battens are fixed at 400 centres to allow a service

cavity and also a second layer of insulation – infilled with 50mm batts of sheep’s

wool, and finished in a 12.5mm plasterboard ceiling.

Figure 25: Section through proposed roof construction Figure 26: Section through Joists


34


The U-Value calculation, performed to take account of the fractional areas of bridging,

resulted in a value of 0.2W/m² - an improvement on the Unit 01 proposal of 0.25, exactly

the requirement for Existing Buildings other than Dwellings in Part L 2008 and

substantially less than the requirement for material change of use in Part L, 35W/m2K.

(Through 50mm Insulation/150mm Insulation - 76.6%)



Plasterboard 0.013 0.25 0.05

Sheep’s Wool 0.05 0.039 1.28

Sheep’s Wool 0.15 0.039 3.85

Fibreboard 0.025 0.13 0.19

Ventilated Cavity - - 0.34

Fibre Cement Slates 0.01 0.45 0.02


Total R: 5.90

U: 0.17

(Through 50mm Insulation/ 150mm Joists - 21.8%)



Sheeps Wool 0.05 0.039 1.28

Timber Joists 0.15 0.13 1.15

Fibreboard 0.025 0.13 0.19




Total R: 3.21

U: 0.31

(Through 50mm Battens/ 150mm Joists - 1.6%)



Timber Battens 0.05 0.13 0.38


Fibreboard 0.025 0.13 0.19




Total R: 2.31

U: 0.43


Table 3: U-Value Calculation for Proposed Roof Retrofit


35

3.4 Existing Timber Sash Windows


The existing windows are the original timber

frame single glazed sliding sashes of varying

sizes. Overall the windows appear to be in

good condition, the paintwork is heavily

degraded but there is no sign of any faults

with the actual timbers. There are a number

of panes of glass missing. A number of

windows have their original timber panelling

and architraving, most are recessed with

angled reveals, and some are flush with the

wall.


The initial proposal was to restore the

timberwork and draught proof the windows.

As this does not affect the U-Value the

laboratory tested U-Value for a traditional

timber single glazed sash window is 5.2W/m²K (Mitchell,

2008).


Restoration & Draught Proofing

The deteriorated paint is to be removed and the timbers

inspected, defective areas are to be spliced with new

timbers, and the window repainted. Missing or damaged

glazing panes are to be removed and replaced where

necessary. Draught proofing is performed through

installation of draught strips and beads with incorporated

draught brushes.

Figure 28: Flush Sash Window

Figure 27: Recessed window with architrave

and panelling

Figure 29: Draughtproofing

measures for sash windows


36

Secondary Glazing

In cases of a recessed window, the fixing frame of the secondary glazing system can

be bolted into the ope wall – where the windows are more flush with the wall,

100x50mm studs on each side of the ope have been used to fix the units timber fixing

frame. Both solutions are reversible. In all cases existing timber panelling and

architraving surrounds are to be removed, cleaned and restored for reinstatement

around the secondary glazing frame.

The glazing system specified is designed to be very discreet, the entire depth of the

frame is less than 40mm and is so designed that the meeting rail is in line with that of

the existing window – rendering it concealed from outside, from inside it’s thin

profile and white finish does not provide a contrast to the existing. The optimum

distance between secondary glass and primary glass is attained, at 150mm, this

ensures optimum thermal and acoustic performance. (RMIT University, 2005)

Figure 32: Heat Camera Image showing the heat lost through

traditional sash window (right) and one with secondary glazing

(left).

Figure 31: Jamb detail: recessed window with

secondary glazing Figure 30: Jamb detail: flush window with

secondary glazing


37


The table below shows the U-value attainable by performing the listed actions on the

window – A minority of the windows do have slender timber shutters, however I

determined that to insulate these would be a damaging act. As the table shows, and

independently laboratory tested (Mitchell, 2008), the resultant U-Value for traditional

sash windows with secondary glazing is 1.6W/m²K while draught proofing can

reduce air infiltration by up to 80%.

Table 4: Possible Actions for thermal upgrade of traditional

sash windows and their resultant U-Value.

Figure 33: Traditional Sash

Window with slimline discreet

aluminium framed secondary

glazing unit.

New Construction

38

Chapter 4

New Construction

4.1 Circulation Atrium

As previously mentioned, the Unit 01

project proposal included the demolition of

the central core of the House, constructing a

new double height circulation area clad

entirely in glass to house the stairwell and

lift and to provide public access to the

house. As this is included in the thermal

efficiency comparison, this chapter deals

with the elements involved and their U-

value.

4.1.1 Atrium Structural Glass Walls & Roof

The walls and roof of the atrium are

frameless glass mounted on spider fixings

fixed to internal steel columns/beams. I

have specified a low emissivity argon-filled

glazing system. The outer pane is 6mm

glass with a low-emissivity coating,

permitting the transmission of the sun’s

short wave radiation at a higher rate than the

long wave radiation generated by the buildings heating system, also reducing glare. A

12mm argon-filled cavity separates the outer pane from the centre pane of 6mm glass,

and a further 12mm cavity separates the centre pane from the inner pane of 10mm

heat soaked toughened glass.

The manufacturers U Value rating for this arrangement is 0.8W/m2K.

Potential overheating will be mitigated by the installation of thermostat connected to

automated louvered glass vents at eaves level.

Figure 35: Triple paned structural glass

Figure 34: 3D of Atrium siting within

Cuilin House

New Construction

39

4.1.2 Radiant Concrete Floor

The steel frame of the new atrium space is supported on a 200mm concrete slab

foundation (thickened to 450mm at edges). Atop this is 30mm sand blinding, a

DPC/Radon barrier and 150mm polyurethane board insulation. A 100mm concrete

floor deck supports the 50mm screed floor, to be finished in granite tile.

The substantial thickness of the slab and screed is to facilitate thermal storage of solar

gains and from the water-based geothermal under floor heating system.

The U-Value for this construction is 0.13W/m²K, in compliance with requirements in

Part L of the Building Regulations.

Concrete Floor @ Atrium Layer

Thickness (m) Conductivity Resistance

Internal Surface

- - 0.17

Granite Tile

0.025 2.2 0.01

Screed

0.5 0.41 1.22

Concrete

0.1 1.15 0.09

Polyurethane

0.15 0.025 6.00

Sand Blinding

0.03 0.15 0.20

External Surface

- - 0.04

7.73

Element U-Value:

0.13

Table 5: U-Value Calculation for New-Build Concrete Floor @ Atrium

Figure 36: New Build Atrium Floor

Thermal Comparison

40

Chapter 5

Thermal Comparison

5.1 Introduction

5.1.1 General

This section aims to calculate the total heat loss from the building under the

conditions in the Unit 01 proposal project, and those demonstrated herein, contrasting

the difference in thermal efficiency between the more conservative refurbishment

proposal and this paper’s proposed thermal retrofit. Below is a table recapping the u-

values of the existing elements associated with both strategies;

Element Baseline Refurb

(Unit 01 Proposal)

Study Retrofit

(Thermal Retrofit)

External Wall 1.44 0.33

Ground Floor 0.14 0.2

Roof 0.25 0.2

Windows 5.2 1.6

First Floor (Joists packed

with Sheep’s Wool) 0.2 0.2

Internal Walls (Solid Brick,

12.5 plasterboard) 1.46 1.46

Table 6: Summary of Element U-Values.

5.1.2 Heat Losses Generally

Total heat loss for a building is derived from total transmission or fabric losses added

to ventilation and infiltration losses for each space in the building. These values

determine the sizing of the heating appliance in each room, and thus the overall

energy load required to heat the building. There are a number of methods used to

calculate this loss used by engineers, The Chartered Institution of Building Services

Engineers (CIBSE) in the UK use a number of increasingly complex methodologies

as a project progresses from outline through design to implementation stage:

• Concept Stage: Rules of Thumb methods

• Design Stage: Steady State Calculation

• Final Design: Dynamic Transient Method

Thermal Comparison

41

The approach taken in this paper is the Steady State method, whereby transmission

and ventilation losses are calculated with a pre-determined design external

temperature, design internal temperature, design air change rate.

5.1.3 Steady State Heat Loss Calculation

In this method, also known as the manual-method, calculation of transmission heat

losses is arrived at by multiplying the element area of a particular building element

within the space, by its u-value, by the design temperature difference, repeating for all

fabric elements in the space being evaluated. Transmission of heat from one internal

space to another where there is a design temperature difference is included, but

naturally this balances itself out as the transmission heat loss from one is a

transmission heat gain in the other.

Calculating ventilation heat loss is performed by multiplying the space volume by the

design temperature difference, by the design air changes per hour, by the specific heat

capacity of air. In a traditional building the target air changes per hour after draught-

proofing measures are undertaken is 0.8ac/h (English Heritage, 2010) – I have used

this value for this study’s retrofit, and a higher rate of 1ac/h for the shallow retrofit to

reflect a less intensive upgrade.

The variables used in the calculation are as follows:

Internal Design Temperature: The temperature level recommended by engineering

and plumbing industry bodies to maintain comfort, determined by the purpose of the

space (e.g. Internal design temperature for a small office = 20˚C).

External Design Temperature: Based on the location of the building, the external

design temperature or heating dry-bulb temperature is not the lowest temperature

expected, but rather “close to lowest”. The following calculations use the 99% design

temperature for Dublin, Ireland tabulated by ASHRAE (American Society of Heating,

Refrigeration and Air-Conditioning Engineers), which means a low temperature that

will be exceeded, statistically speaking, for 88 hours in a typical year.

Design Temperature Difference: Or delta-t is the difference in temperature between

the internal design temperature and the external design temperature.

Thermal Comparison

42

U-Value: a measure of the heat transmission through a building part such as a wall or

roof, with a varied build-up of materials and levels of conductivity, with lower

numbers indicating better insulating properties.

Element Area: Tabulated by measuring the area of external wall or roof within the

space being calculated – taken from the internal dimensions.

Space Volume: The internal volume of the room, from internal dimensions.

Air Changes / per Hour: A measure of how many times the air within a space is

replaced due to ventilation and infiltration – a design value is applied, taking into

account desired and recommended ventilation levels and the control of infiltration

through new wall linings and draught seals.

Specific Heat Capacity: In this case, of air, it is the measurable physical quantity that

characterizes the amount of heat required to raise air temperature by a given amount.

For heating calculations the value of 0.33 is always applied.

Total Transmission Heat Loss: The total heat that is lost from internal spaces

through the fabric of the building in Watts per Hour

Total Ventilation Heat Loss: The total heat that is lost from the internal spaces

through ventilation and infiltration in Watts per Hour

Total Design Heat Loss: The sum of transmission and ventilation heat losses, that

occur over a steady state.

Assumptions used in Design Heat Loss Calculation:

• Assumed to occur at night, where no solar loads act on building

• Building is treated as unoccupied (no internal loads)

• Equipment and appliances are not in operation.

• Lights are off

• Moisture loads ignored

• Heat flow is analysed using static conditions, meaning stable temperatures

over the defined period of time (one hour)

• Heat storage in the fabric is discounted.

Thermal Comparison

43

The following is a summary of the inputs required to calculate:

Design Temperatures

Internal (Watkins, 2011):

Space Type Temp

Office 20˚C

Storage 18˚C

Circulation 16˚C

Exhibition 18˚C

Plant 15˚C

Entrance Hall 15˚C

External (ASHRAE, 1981)

Heating Dry Bulb Temperature for Dublin, Ireland: -1˚C

Table 7: Design Internal & External Temperatures

Figure 38: Ground Floor Plan with internal

and external design temperatures.

Figure 37: First Floor Plan with internal

and external design temperatures.

Thermal Comparison

44

5.2 Total Transmission Heat Loss

Full calculation tables are provided in Appendix B, an example calculation is

demonstrated below:

U-Value x Area of Element x Temperature Difference = Heat Loss through that element

Example:

Component UValue(W/m2) Element Δ

(m2)

Temp. Diff.

(Int-Ext)

Heat Loss

(W/hr)

External Wall 0.33 32.30 21.00 223.84

Table 8: Example Heat Loss Calculation for external wall in one room.

The resulting heat loss is given in Watts per Hour under the design conditions

mentioned previously. Repeated for each element (e.g. external wall, floor, roof) in

each space and added together, the result is the total heat loss under steady state

analysis experienced by the building. The following table is a summary of results in

both the Unit 01 refurb proposal, and the thermal retrofit proposal herein, by space

and in total.

Unit 01 Proposal:

Space

Heat Loss

(W/hr)

1 Conference Room 1808.83

2 Reception 546.94

3 Entrance Hall -13.63

4 Office1 1528.36

5 Office 2 846.08

6 Plant 468.34

7 Exhibition Space 2012.84

8 Exhib. Reception 580.20

9 Lobby 110.38

10 Office 3 1363.67

11 Office 4 755.44

12 Glazed Atrium 2566.32

Total Transmission Heat Loss 12573.78

Table 9: Transmission Heat Loss by Space – Unit 01

The result of the calculation was a total transmission heat loss of 12,500 watts per

hour, or 12.5 Kilowatts per hour (KW/hr).

Thermal Comparison

45

Thermal Retrofit:

Space

Heat Loss

(W/hr)

1 Conference Room 667.50

2 Reception 246.42

3 Entrance Hall -9.78

4 Office1 530.81

5 Office 2 262.76

6 Plant 92.17

7 Exhibition Space 664.62

8 Exhib. Reception 263.01

9 Lobby -54.16

10 Office 3 474.36

11 Office 4 233.86

12 Glazed Atrium 2566.32

Total Transmission Heat Loss 5937.89

Table 10: Transmission Heat Losses by Space – Deep Retrofit

The result of the calculation was a total transmission heatloss of 6,000 watts per hour,

or 6 Kilowatts per hour (KW/hr) : A 53% improvement on the Unit 01 Proposal

Thermal Comparison

46

5.3 Total Ventilation Heat Loss

As stated in 3.1.3, the only different variable in the ventilation heat loss calculation

for both retrofit models is the air change rate – full calculations of ventilation heat

loss are set out below:

Unit 01 Proposal:

Space Vol (m3)

Delta

T AC/H Sp. Ht. Cap. Total (W)

1.Conference 120 21 1 0.33 831.60

2. Reception 44.63 21 1 0.33 309.29

3. Entrance 22.3 17 1 0.33 125.10

4. Office 1 60.2 21 1 0.33 417.19

5. Office 2 41.8 21 1 0.33 289.67

6. Plant 58.2 16 1 0.33 307.30

Ground Floor: 2280.14 Watts

7. Exhibition 159.57 19 1 0.33 1000.50

8. Ex. Reception 38.78 21 1 0.33 268.75

9. Lobby 19.4 17 1 0.33 108.83

10. Office 3 52.4 21 1 0.33 363.13

11. Office 4 36.87 21 1 0.33 255.51

First Floor: 1996.72 Watts

12. Atrium 384 17 1 0.33 2154.24

Ventilation Losses: 6431.11 Watts

Table 11: Calculation Table of Ventilation Heat Losses – Shallow Retrofit

Thermal Retrofit:

Table 12: Calculation Table of Ventilation Heat Losses – Deep Retrofit

Space Vol (m3) Delta T AC/H Sp. Ht. Cap. Total (W)

1.Conference 120 21 0.8 0.33 665.28

2. Reception 44.63 21 0.8 0.33 247.43

3. Entrance 22.3 17 0.8 0.33 100.08

4. Office 1 60.2 21 0.8 0.33 333.75

5. Office 2 41.8 21 0.8 0.33 231.74

6. Plant 58.2 16 0.8 0.33 245.84

Ground Floor: 1824.12 Watts

7. Exhibition 159.57 19 0.8 0.33 800.40

8. Ex. Reception 38.78 21 0.8 0.33 215.00

9. Lobby 19.4 17 0.8 0.33 87.07

10. Office 3 52.4 21 0.8 0.33 290.51

11. Office 4 36.87 21 0.8 0.33 204.41

First Floor: 1597.38 Watts

12. Atrium 384 17 0.8 0.33 1723.39

Infiltration Losses: 5144.89 Watts

Thermal Comparison

47

The Unit 01 entails a ventilation heat loss / load of 6400 watts per hour, or 6.4

Kilowatts per hour (KW/hr), where the thermal retrofit carries a loss of 5100 watts per

hour or 5.1KW/hr, or a 20% improvement on the Unit 01 proposal.

5.4 Total Heat Loss & Demand

Total heat loss is the sum of transmission and ventilation heat loss:

Deep Retrofit Shallow Retrofit Transmission Losses 5937.89W/hr 13085.31W/hr

Ventilation Losses 5144.89W/hr 6431.11W/hr

Total (W/hr) 11082 W/hr 19516W/hr

Total (KW/hr) 11.1 KW/hr 19.5 KW/hr

Table 13: Total Heat Losses

Overall, the thermal retrofit outlined in this paper constitutes a 43 percent

improvement in thermal efficiency on the original Unit 01 thesis proposal, without

compromising the natural balance traditional constructions exist in.

Conclusion

48

Chapter 6

Conclusion

To recap, this dissertation set out to explore and analyse the considerations involved

in thermally retrofitting an historic building, while balancing the considerations

around conservation principles and the requirements of traditional constructions.

The paper has set out a strategy that aims to do the least harm, if not aid the building

fabric in its moisture regulation and thermal functions. Using best practice

recommendations and guidance from prime actors in the area of conservation and

thermal comfort, it has sought to apply the principles learned to the existing fabric of

Cuilín House.

The attaching of u-values to the hypothesised construction, and the comparison to the

base line model through use of the Steady State Heat Loss Method have demonstrated

that the proposal achieved a 53% thermal efficiency increase, while interventions to

the floors, (such as the addition of a trench drain and subfloor ventilation), and walls,

(such as the hygroscopically active insulation) could actually benefit their moisture

control function. Further, conservation principles were satisfied – in that with all but

the replacement suspended floor, every intervention is reversible –and by the retention

of what limited window architraving, moulding and panelling remained, the internal

character has been somewhat restored.

I believe this is a sensitive, non-obtrusive retrofit strategy, it preserves the character of

the traditional windows and the traditional materials throughout, while significantly

improving the prospects for thermal comfort, and thus those of the continued survival

of the building as a used space – the ultimate goal in conservation.

In conclusion, from the perspective of modern architectural technology, where there is

a lot of emphasis on moisture eradication and airtightness, dealing with older walls

requires a shift in thinking, to one of control and regulation of moisture and allowing

the building to breath as it has always done – what seems simple and old often has

hidden qualities and controls.

References

49

References / Bibliography

Bibliography ASHRAE. (1981). Design Conditions for Selected Locations. In ASHRAE Handbook

(p. Appendix ). Atlanta: American Society of Heating, Refrigerating and Air-

Conditioning Engineers.

Cambridge Architectural Research. (2009). Breathability – A White Paper.

Cambridge: Kingspan Insulation Ltd. .

Cambridge University. (2005). Potential for Microgeneration - Study and Analysis.

Cambridge: The Energy Saving Trust.

Curtis, R. (2008). Energy Efficiency in Traditional Homes. Edinburgh: Historic

Scotland.

Department of Environment, Heritage and Local Government. (1996). Conservation

Guidelines - Windows. Dublin: Government of Ireland.

Department of the Environment, Heritage & Local Government. (2010). Energy

Efficiency in Traditional Buildings. Dublin: Government of Ireland.

Eco Warriors Solar (UK) Ltd. . (2010). How it works: Solar Photovoltaics For Your

Home. Retrieved April 18, 2012, from E-W-Solar: http://www.e-w-

solar.com/solarPvHowItWorks.shtml

Energy Saving Trust. (2006). Practical Refurbishment of Solid-Walled Houses.

London: Energy Saving Trust.

English Heritage . (1997). Framing Opinions 5: Timber Sash Windows. Swindon:

English Heritage.

English Heritage. (1994). Framing Opinions 1: Draught Proofing and Secondary

Glazing . Swindon: English Heritage.

English Heritage. (2010). Energy Efficiency in Historic Buildings - Draught Proofing

Windows and Doors. London: English Heritage.

English Heritage. (2010). Energy Efficiency in Historic Buildings - Insulating solid

walls. London: English Heritage.

Historic Scotland. (2008). Sash & Case Windows: A Short Guide for Homeowners.

Edinburgh: Historic Scotland.

References

50

Irish Eco Homes. (2010). Sheeps Wool. Retrieved March 27, 2012, from Irish Eco

Homes: http://www.irishecohomes.ie/

May, N. (2005). Breathability: the Key to Building Performance. London: Natural

Building Co.

May, N. (2009). Breathability Matters: Why the Kingspan White Paper is seriously

misleading . London: Natural Building Co.

Mitchell, D. S. (2008). Energy Efficiency in Traditional Homes. Edinburgh: Historic

Scotland .

Morgan, C. (2008). Breathing Buildings. Dunblane: SelfBuild.ie - Extend & Renovate

Ireland.

Northern Ireland Environment Agency. (2010). Windows: A Guidance Booklet on

Openings . Belfast: Northern Ireland Environment Agency.

RMIT University. (2005). Sound Insulation for Windows. Melbourne: City of

Melbourne.

Society for the Protection of Ancient Buildings. (2009). Technical Q&A 19 : French

Drains. Retrieved April 9, 2012, from SPAB:

http://www.spab.org.uk/advice/technical-qas/technical-qa-19-french-drains/

Society for the Protection of Ancient Buildings. (2009). The Need for Old Buildings

to ‘Breathe’. London: SPAB.

Timber Queensland . (2004). Technical Data Sheet 14 - Sub-floor Ventilation.

Brisbane: Timber Queensland.

Watkins, D. E. (2011). Heating Services in Buildings. Chichester: John Wiley & Sons

Ltd. .

Appendix

51

Appendix A – U Value Calculations

Notes on U-Value Calculations In calculating the U-Value of the external wall

there are a level of unknowns around the

composition of the existing solid wall. The

presence of voids / a rubble core is not accounted

for and thus the result may be more valuable in a

comparison of the effect of internal insulation

compared to leaving the existing in place

The external wall insulation layer is composed of

battens and counter battens with the wool packed

between, thus U-values were taken through the

batten-on-batten route, the batten on insulation

and insulation on insulation layers and the values

added according to their distribution throughout the wall. Similarly the roof is treated

the same where battens run perpendicular along the underside of the joists.

Figure 39: Fractional Areas of materials

in the cross-battened wall/roof

Appendix

52

Unit 01 External Wall Proposal

Through 50mm Batten/50mm Insulation (21.8%)



Plaster 0.018 0.8 0.02

Clay Brick 0.21 0.77 0.27

Limestone 0.29 1.26 0.23


0.70


Rebuilt Suspended Ground

Floor






225x50 C22 Joists 0.23 0.13 1.73


Total Resistance: 2.23

U-Value 0.45






Sheep's Wool 0.23 0.04 5.77


Total Resistance 6.27

U-Value 0.16


Appendix

53

Thermal Retrofit of External Wall

(Through 50mm Batten/50mm Insulation - 21.8%)




Sheeps Wool 0.05 0.039 1.28


Lime Plaster 0.018 0.43 0.04

Clay Brick 0.21 0.77 0.27

Limestone 0.29 1.26 0.23


Total R: 2.44

U-Value: 0.41

(Through 100mm Battens/Battens - 1.6%)






Lime Plaster 0.018 0.43 0.04

Clay Brick 0.21 0.77 0.27

Limestone 0.29 1.26 0.23


Total R: 1.54

U-Value: 0.65

(Through 100mm Wool Batts/Wool Batts - 76.6%)




Sheeps Wool 0.05 0.039 1.28

Sheeps Wool 0.05 0.039 1.28

Lime Plaster 0.018 0.43 0.04

Clay Brick 0.21 0.77 0.27

Limestone 0.29 1.26 0.23


Total R: 3.34

U-Value: 0.30


Appendix

54

Unit 01 Proposed Roof

Refurb

(Through Insulation - 87.5%)




Sheeps Wool 0.15 0.039 3.85

Fibreboard 0.025 0.13 0.19




4.62

0.22

(Through Rafters - 12.5%)




Timber Rafters 0.15 0.13 1.15

Fibreboard 0.025 0.13 0.19




1.93

0.52


Appendix

55

Retrofitted Cut Timber Roof

(Through 50mm Insulation/150mm Insulation - 76.6%)




Sheeps Wool 0.05 0.039 1.28

Sheeps Wool 0.15 0.039 3.85

Fibreboard 0.025 0.13 0.19




5.90

0.17

(Through 50mm Insulation/ 150mm Joists - 21.8%)




Sheeps Wool 0.05 0.039 1.28


Fibreboard 0.025 0.13 0.19




3.21

0.31

(Through 50mm Battens/ 150mm Joists - 1.6%)






Fibreboard 0.025 0.13 0.19




2.31

0.43


Appendix

56

Internal Wall Type 1 (450 Solid Brickwork)



Clay Brick 0.450 0.77 0.58


0.68


Appendix

57

Appendix B – BuildDesk Condensation Analyses

As discussed in 3.1.2, I ran a number of demonstration simulations on refurbishing the

external wall with a synthetic non-breathable insulant to highlight how inappropriate

modern construction theory would be if applied to the walls.

Firstly, determining that a thickness of 50mm insulation would be a good starting

point, I ran an analysis using a solid wall of Limestone at 490mm thickness,

polyurethane board mechanically fixed to the inner face with a dabbed plasterboard

finish internally for a U-Value of 0.55W/m²K, results as follows:

Appendix

58

Reducing the thickness of the polyurethane by 10mm increments, at 20mm thickness

the wall was deemed to have passed the test, in that condensation occurs during the

summer months but was expected to fully evaporate, only giving a U-Value of

0.79W/m²K:

Appendix

59

Adding a foil backing to the plaster board (i.e. on the warm side of the insulation)

ruled out the risk of interstitial condensation at any time with thicknesses up to

100mm and beyond and giving a U-Value of 0.42W/m²K using 50mm polyurethane

board layer:

My contention is that, aside from this tool not taking into account any bridging and

assuming all homogenous layers, the success or failure of the use of synthetic

insulants is wholly determined by the integrity of the vapour barrier or foil layer, and

as it is common for these membranes to be punctured either during construction or

later by occupants nailing through the plasterboard, it is wholly inappropriate to

specify a vapour-barrier based system to the external walls in this case.

Appendix

60

Appendix C – Fabric Heat Loss Calculations

Unit 01 Refurb - Fabric Heat Load :

1. Conference

Component U-Value(W/m2K Element Δ (m2) Temp. Diff.

Heat Loss

(W/hr)

External Wall 1.46 32.30 21.00 990.32

Windows 5.20 5.70 21.00 622.44

Internal Walls 1.46 13.20 2.00 38.54

Floor 0.14 44.50 21.00 130.83

Ceiling 0.20 44.50 3.00 26.70

Fabric Heat

Loss 1808.83 W

2. Reception

Component U-Value Element Δ (m2) Temp. Diff.

Heat Loss

(W/hr)

External Wall 1.46 9.08 21.00 278.39

Windows 5.20 1.40 21.00 152.88

Internal Wall 1.46 11.50 4.00 67.16

Floor 0.14 16.50 21.00 48.51

Fabric Heat

Loss 546.94 W

3. Entrance


Heat Loss

(W/hr)

External Wall 1.46 5.20 17.00 129.06

Floor 0.14 8.26 17.00 19.66

Internal Walls 1.46 27.80 -4.00 -162.35

Fabric Heat

Loss -13.63 W

4. Office 1


Heat Loss

(W/hr)

External Wall 1.46 23.82 21.00 730.32

Internal Wall 1.46 11.55 4.00 67.45

Floor 0.14 22.30 21.00 65.56

Windows 5.20 6.09 21.00 665.03

Fabric Heat

Loss 1528.36 W

Appendix

61

5. Office 2


Heat Loss

(W/hr)

External Wall 1.46 19.68 21.00 603.39

Floor 0.14 15.69 21.00 46.13

Window 5.20 1.80 21.00 196.56

Fabric Heat

Loss 846.08 W

6. Plant


Heat Loss

(W/hr)

External Wall 1.46 17.49 16.00 408.57

Internal Wall 1.46 13.20 -5.00 -96.36

Windows 5.20 1.40 16.00 116.48

Floor 0.14 21.55 16.00 48.27

Ceiling 0.20 21.55 -2.00 -8.62

Fabric Heat

Loss 468.34 W

7. Exhibit Space


Heat Loss

(W/hr)

External Wall 1.46 39.20 19.00 1087.41

Windows 5.20 6.38 19.00 630.34

Floor 0.20 67.80 -2.00 -27.12

Roof 0.25 73.90 19.00 351.03

Internal Wall 1.46 9.87 -2.00 -28.82

Fabric Heat

Loss 2012.84 W

8. Exhib. Reception


Heat Loss

(W/hr)

External Wall 1.46 8.90 21.00 272.87

Internal Wall 1.46 9.87 2.00 28.82

1.46 9.87 4.00 57.64

Roof 0.25 18.15 21.00 95.29

Window 5.20 1.15 21.00 125.58

Fabric Heat

Loss 580.20 W

9. Lobby


Heat Loss

(W/hr)

External Wall 1.46 4.50 17.00 111.69

Internal Wall 1.46 24.24 -4.00 -141.56

Roof 0.25 9.08 17.00 38.59

Window 5.20 1.15 17.00 101.66

Fabric Heat 110.38 W

Appendix

62

Loss

10. Office 3


Heat Loss

(W/hr)

External Wall 1.46 21.29 21.00 652.75

Internal Wall 1.46 11.05 4.00 64.53

Roof 0.25 24.53 21.00 128.78

Window 5.20 4.74 21.00 517.61

Fabric Heat

Loss 1363.67 W

11. Office 4


Heat Loss

(W/hr)

External Wall 1.46 17.54 21.00 537.78

Roof 0.25 17.54 21.00 92.09

Window 5.20 1.15 21.00 125.58

Fabric Heat

Loss 755.44 W

12. Atrium


Heat Loss

(W/hr)

Glazed Wall 0.80 114.30 17.00 1554.48

Glazed Roof 0.80 64.00 17.00 870.40

Concrete Floor 0.13 64.00 17.00 141.44

Fabric Heat

Loss 2566.32 W

TOTAL TRANSMISSION

LOSS: 12573.78 W/hr

Appendix

63

Dissertation Thermal Retrofit

1. Conference

Component

U-

Value(W/m2K

Element Δ

(m2) Temp. Diff.

Heat Loss

(W/hr)

External Wall 0.33 32.30 21.00 223.84

Windows 1.60 5.70 21.00 191.52

Internal Walls 1.46 13.20 2.00 38.54

Floor 0.20 44.50 21.00 186.90

Ceiling 0.20 44.50 3.00 26.70

Fabric Heat Loss 667.50 W

2. Reception

Component U-Value

Element Δ

(m2) Temp. Diff.

Heat Loss

(W/hr)

External Wall 0.33 9.08 21.00 62.92

Windows 1.60 1.40 21.00 47.04

Internal Wall 1.46 11.50 4.00 67.16

Floor 0.20 16.50 21.00 69.30


3. Entrance

Component U-Value

Element Δ

(m2) Temp. Diff.

Heat Loss

(W/hr)

External Wall 0.33 3.10 17.00 17.39

Door 3.00 2.10 17.00 107.10

Floor 0.20 8.26 17.00 28.08

Internal Walls 1.46 27.80 -4.00 -162.35

Fabric Heat Loss -9.78 W

4. Office 1

Component U-Value

Element Δ

(m2) Temp. Diff.

Heat Loss

(W/hr)

External Wall 0.33 23.82 21.00 165.07

Internal Wall 1.46 11.55 4.00 67.45

Floor 0.20 22.30 21.00 93.66

Windows 1.60 6.09 21.00 204.62


5. Office 2

Component U-Value

Element Δ

(m2) Temp. Diff.

Heat Loss

(W/hr)

External Wall 0.33 19.68 21.00 136.38

Floor 0.20 15.69 21.00 65.90

Window 1.60 1.80 21.00 60.48


Appendix

64

6. Plant

Component U-Value

Element Δ

(m2) Temp. Diff.

Heat Loss

(W/hr)

External Wall 0.33 17.49 16.00 92.35

Internal Wall 1.46 13.20 -5.00 -96.36

Windows 1.60 1.40 16.00 35.84

Floor 0.20 21.55 16.00 68.96

Ceiling 0.20 21.55 -2.00 -8.62


7. Exhibit Space

Component U-Value

Element Δ

(m2) Temp. Diff.

Heat Loss

(W/hr)

External Wall 0.33 39.20 19.00 245.78

Windows 1.60 6.38 19.00 193.95

Floor 0.20 67.80 -2.00 -27.12

Roof 0.20 73.90 19.00 280.82

Internal Wall 1.46 9.87 -2.00 -28.82


8. Exhib.

Reception

Component U-Value

Element Δ

(m2) Temp. Diff.

Heat Loss

(W/hr)

External Wall 0.33 8.90 21.00 61.68

Internal Wall 1.46 9.87 2.00 28.82

1.46 9.87 4.00 57.64

Roof 0.20 18.15 21.00 76.23

Window 1.60 1.15 21.00 38.64


9. Lobby

Component U-Value

Element Δ

(m2) Temp. Diff.

Heat Loss

(W/hr)

External Wall 0.33 4.50 17.00 25.25

Internal Wall 1.46 24.24 -4.00 -141.56

Roof 0.20 9.08 17.00 30.87

Window 1.60 1.15 17.00 31.28

Fabric Heat Loss -54.16 W

10. Office 3

Component U-Value

Element Δ

(m2) Temp. Diff.

Heat Loss

(W/hr)

External Wall 0.33 21.29 21.00 147.54

Internal Wall 1.46 11.05 4.00 64.53

Roof 0.20 24.53 21.00 103.03

Window 1.60 4.74 21.00 159.26


Appendix

65

11. Office 4

Component U-Value

Element Δ

(m2) Temp. Diff.

Heat Loss

(W/hr)

External Wall 0.33 17.54 21.00 121.55

Roof 0.20 17.54 21.00 73.67

Window 1.60 1.15 21.00 38.64


12. Atrium

Component U-Value

Element Δ

(m2) Temp. Diff.

Heat Loss

(W/hr)

Glazed Wall 0.80 114.30 17.00 1554.48

Glazed Roof 0.80 64.00 17.00 870.40

Concrete Floor 0.13 64.00 17.00 141.44


TOTAL TRANSMISSION LOSS: 5937.89 W/hr

Appendix

66

Appendix D – Overall Unit 01 Proposal To place the works proposed herein into context, the following are drawings from the

Unit01 proposal for the overal redevelopment of Cuilín House.

Dissertation: Thermal Retrofit of 19th Century Building

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