Sustainable Buildings: Improving Energy Efficiency in - - PowerPoint PPT Presentation

Sustainable Buildings: Improving Energy Efficiency in TraditionalBuildings

International Conference Energieke Restauratie Hanze Univeristy, Groningen 19 September 2013 Soki Rhee-Duverne Architectural Conservator Building Conservation Research Team

Structure

Part 1

• Background to English

Heritage

• Policy drivers for energy

efficiency

• Our philosophy and

approach. Part 2

• Research;
• Publish guidance notes and

provide training.

Who are we?

• English Heritage (officially the Historic Buildings and

Monuments Commission for England) is an executive non-departmental public body (NDPB) of the British Government and is an executive agency of the Department for Culture Media and Sport (DCMS), advising the Secretary of State on managing the historic built environment.

• As an NDPB we are semi-autonomous giving us the

ability to provide independent advice.

• Our sponsers include DCMS, Department of

Environment, Farming and Rural Affairs (DEFRA) and Communities & Local Government (CLG).

• We are the UK

Government’s statutory advisor and a statutory consultee on all aspects

• f the historic

environment and its heritage assets.

• This includes archaeology
• n land and in the sea,

historic buildings and areas, designated

• landscapes. This involves:

Our remit…

• Management of EH Estate: over 400 sites and monuments; &

and the National Monuments Records.

• Grant aid: to organisations for the conservation of historic

buildings, monuments and landscapes.

• Advisory: to central Government on heritage protection and

listing applications; & management of register of listed buildings and ancient scheduled monuments.

• Advisory local councils on case work, planning issues and

managing change.

• Influencing Government policy: planning and building

regulations.

• Guidance & training: to professionals and homeowners.
• Research: under the framework of the National Heritage

Protection Plan.

English Heritage cycle…

How to adapt to increasing pressures on historic environment by climate change…

Policy drivers…

Carbon Legislation

• Climate Change Act 2008
• Energy Acts 2008, 2010 & 2011

Key strategies & policies

• Carbon Plan 2011
• Green Deal & Energy Company

Obligation

• Energy Performance Certificates

Key targets

• GHG reduction targets of 50% by 2020

& 80% by 2050 from 1990 levels.

• New build homes to be zero carbon by

2016 & all new non-domestic buildings by 2019.

• & by 2050 all buildings are to be near

to zero GHG emissions by 2050. Carbon emissions

• Domestic housing is responsible for
• approx. 25% of UK’s GHG emissions.

1.49

Carbon emissions - how big a contribution does the

historic environment make?

Pre - 1919 dwellings Post - 1919 dwellings Commercial and industrial buildings Other sources BUILDINGS

Housing stock…

Housing stock

• 22.4 million dwellings in

England, of which 22% were built before 1919.

• Approximately 6.5

million solid wall buildings without insulation in England.

Carbon emissions attributable to pre-1919 buildings…

Listed dwellings Dwellings in Conservation Areas Other dwellings Pre 1919 dwellings not in Conservation Areas

Historic and Traditional Buildings…

Historic Traditional

Part of the solution… no exclusion for older buildings

• English Heritage needs to offer

practical solutions…or risks being seen as part of the problem.

• Concerns: aesthetics/cultural

significance & technical

• Heritage value: loss of

traditional features and change in appearance

• Technical unknowns: solid wall

insulation, quality control…

Adaptation concerns…

• Loss of features
• Altered

appearance

• Decay of fabric

Older homes are different…

• Thermal Mass
• Breathing buildings

What are the risks?

• Trapped MOISTURE!!

What do you need to consider?

• Adequate ventilation

“Insulate tight, ventilate right”

• Use hygroscopic materials
• Minimise barriers to

moisture flow

Constructive Conservation: It’s all about achieving the right balance…

• Achieving the optimum

balance between improving energy efficiency and preserving the cultural significance.

• Adaptive Re-use: as buildings

adapt with time

• Functions change
• Meet new requirements eg.

H&S, energy efficiency.

Conservation Principles

• Understand origins, evolution

and associations of a place in its context.

• Evaluate significance, as a whole

and its elements.

• Identify how significance is

vulnerable.

• Devise strategies to safeguard

significance.

• Implement options that cause least

harm to significance.

• Record & evaluate outcome.

Whole building approach…

• Understand:
• heritage values/significance of the building;
• condition of the building fabric and building services;
• energy use related to building occupation and
• peration;
• energy performance of the building envelope and

building services;

• behaviour of the building fabric in response to heat

and moisture;

• user requirements and needs.

Whole building approach…every dwelling can improve its thermal performance

• Identify opportunities to improve energy efficiency and

sustainability and devise energy conservation measures from passive interventions such as draught proofing, to active measures such as changes in services, controls; to operational measures such as how a building is used.

• Evaluate the effectiveness and value for money of such

measures;

• Assess their impact on heritage values/significance;
• Assess the technical risks (e.g. increased risk of condensation);
• Implement the optimum strategy and monitor the outcome.

Research…

Carbon challenge research…

Aim: Develop the evidence base to enable more informed decisions to be made on improving the thermal and energy efficiency of traditionally constructed buildings.

• Understand better & find suitable

carbon adaptation solutions.

Background…

UK Government Regeneration Programmes: Pathfinder Programme

Environmental Change Institute, Oxford University (2005)

What are the problems?

• Lack of data / insufficient evidence:
• actual performance of whole buildings and

individual building elements

• material properties of traditional building

materials.

• Lack of informed guidance which are

appropriate/sympathetic for traditional buildings

• Uncertainties in current models and over-reliance
• n default data.

“

“All models are wrong but some are useful…”

Energy Performance Certificates

We challenge the presumption that old buildings are inherently inefficient and that they require the levels of upgrading indicated by current modelling techniques.

Source: EHCS

Victorian Brick Terrace Houses…

Why?

• Pre-1919 brick terrace housing with solid walls most

common traditional building type in England.

• 22% of English dwellings are built before 1919 (English

Housing Survey, CLG, 2010)

• The thermal performance of pre-1919 dwellings with

solid wall construction is perceived as poor & to test that assumption.

• Establishing the actual performance can contribute

towards a more rational approach and inform debate on the energy efficiency of traditional buildings.

Gathering evidence base to inform refurbishment decisions / carbon solutions…

• Thermal performance
• f traditional building

elements;

• Whole-house thermal

performance and impacts of interventions;

• Technical risks of

insulation;

Approach

0.0 0.5 1.0 1.5 2.0 2.5 3.0 Englefield: Plaster + wallpaper/paint Englefield: Drylined with plasterboard + paint/wallpaper Englefield: Bare painted brick Englefield: Cement render Shrewsbury: Plaster + wallpaper/paint Walsall: Plaster + wallpaper/paint Walsall: Drylined with (insulated) plasterboard + paint/wallpaper U-value, W/m2K Measured Calculated with brick @ 1.2W/mK 0.77W/mK 0.56W/mK 0.44W/mK

Fieldwork Measured v. Modelled Laboratory testing

Thermal performance of traditional building elements

• U-values indicators of thermal performance and are used in

calculations to assess energy & carbon performance of

• buildings. They are the basis for Standard Assessment

Procedures (SAP) from which Energy Performance Certificates (EPC’s) derive from.

• However, current understanding of U-values are based on

default assumptions about building performance and have not been tested against real buildings.

Windows research: carbon solutions

Various testing options Before and after repair

What is a U-value?

• It is a measure of the rate of heat flow through a

material.

• It is expressed in W/m2K and shows the amount
• f heat loss in Watts per square metre of

material when there is a temperature difference between inside and outside

• The lower the U-value the better the insulation is

provided by the material.

Thermal performance assessment of traditional windows

Estimates of the whole window U-values and reduction in total heat loss through the window with various

• ptions

Option Reduction in heat loss U-value (W/m2K) Whole window with single glazing 4.3 Heavy curtains 41% 2.5 Shutters 58% 1.8 Modern roller blind 38% 2.7 Roller blind with low E film on outside 57% 1.9 Honeycomb blind 51% 2.1 Secondary glazing 58% 1.8 Secondary glazing and shutters 62% 1.6

Thermal performance of traditional brick walls…

In-situ U-values of solid brick walls

Thermal conductivity testing

Thermal performance of traditional brick walls…

Objectives

• To better understand the thermal characteristics of

traditional brick walls in-situ U-values of 18 solid brick walls and lab tests to obtain thermal conductivity values.

• To test assumptions made about performance of
• lder building by measuring real buildings by comparing

results with standard industry data and building software models.

Comparison with industry standards: thermal performance is underestimated by a third…

Drylined!

Measured v. Modelled: accurate thermal conductivity data is vital for U-value calculations

0.0 0.5 1.0 1.5 2.0 2.5 3.0 Englefield: Plaster + wallpaper/paint Englefield: Drylined with plasterboard + paint/wallpaper Englefield: Bare painted brick Englefield: Cement render Shrewsbury: Plaster + wallpaper/paint Walsall: Plaster + wallpaper/paint Walsall: Drylined with (insulated) plasterboard + paint/wallpaper U-value, W/m2K Measured Calculated with brick @ 1.2W/mK 0.77W/mK 0.56W/mK 0.44W/mK

Findings…

• Underestimation of thermal performance of traditional walls by a

third;

• Importance of accurate thermal conductivity data for U-value

calculations (main discrepancy between in-situ measurements & calculated values is due to lack of known physical properties)

• Influence of variation of physical properties (density, texture,

structure) of brick:- eg. correlation between lower densities & better thermal insulation;

• Important to maintain a house in a good state of repair. Influence of

moisture on thermal conductivity, wet thermal conductivity was 1.5-3 times greater than dry values. Damp walls = poor thermal insulation.

Whole house thermal performance before & after interventions and assessment of technical risk

Overall Project Aims

1) To determine the improvement in thermal performance of the building envelope after energy efficiency interventions by establishing:

• Heat loss coefficients in W/K (building envelope inc.

ventilation) & heat loss parameters W/m2K (building size);

• SAP ratings, energy and carbon reduction;
• ‘Buildability’ issues, cost & payback period and viability of

Green Deal model. 2) To investigate the risk of moisture problems within the walls after installation of insulation and compare a vapour open (“breathable”) with conventional vapour control system (impermeable).

New Bolsover Model Village...

Condition

Energy Efficiency Improvements

Two insulation systems were used for internal wall insulation:

• 1. On the ground floor – PIR (polyisocyanurate)

insulation with aluminium foil/kraft paper facings

• n both sides and plasterboard in two variants:

– Type A: 65mm insulation and plasterboard – Type B: 55mm insulation, battens to provide service zone and plasterboard.

• 2. On the first floor - a vapour permeable system

based on wood fibre insulation:

– Type C: lime plaster applied to brick, 100mm wood wool fibre insulation, finishing coat of lime plaster.

Windows

• Replaced plastic coated aluminium windows with

single glazed timber windows conforming to original design.

• Installed 2 types of high specification secondary

glazing:

• low-e secondary glazing
• secondary glazing system using a slim profile

vacuum glazing, essentially triple glazing

Loss of original windows in most properties…

Existing windows

Plastic coated aluminium double- glazed Plastic coated aluminium single- glazed

Secondary glazing

One window secondary glazed with 6.5mm vacuum IGUs Vertical siding Horizontal sliding

Whole house thermal performance testing: Co- heating test

Before After

Measured energy efficiency SAP rating: E (47) Measured energy efficiency SAP rating: D (66)

Air perm: 13 m3/h.m2 Air perm: 10 m3/h.m2

Savings…

Before After Savings Energy KWh/yr 29,730 17,025 12,705 (40% reduction) Carbon kg/yr 6051 3532 2519 (42% reduction) Cost £ 1070.72 674.19 396.53 Heat loss coefficient W/K 348 177 49% improvement SAP rating E 47 D 66

49% improvement

348 177

Monitoring of risk

Objective:

• To assess the condensation risk at the interface
• f fabric and the 2 insulation systems:
• PIR insulation with VCL – closed system
• Wood fibre insulation – vapour permeable
• To assess what are the benefits of vapour open
• vs. vapour tight systems?

The internal insulation systems represent the two alternatives. Three approaches are being used to assess risk:

• 1. Long term monitoring from start of intervention
• 2. Modelling – WUFI
• 3. Laboratory testing with testing the systems used

at Bolsover and mineral wool system installed in EST Solid Wall Insulation case study house.

Breathable vs. Vapour Control…

1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8

Ongoing: Monitoring condensation risk...

Monitoring Methodology

• Calculations and experience shows the risk of condensation is

greatest at interface between masonry and cold side of insulation.

Exterior Interior

Insulation layer

Simplest solution is to measure RH/T at interface. Also, wooden blocks used for “proxy” moisture measurements.

WUFI Modelling

• Underway using WUFI 2-D;
• Gather actual material property test data for

hygrothermal models rather than relying on reference values.

Laboratory Investigations

Carry out measurements in an environmental chamber under controlled conditions to investigate both thermal performance & moisture risk.

Issues…

Problem arising from lime plaster levelling coat:

• Council was advised to remove existing plaster by suppliers;
• Exposing an inner face of brickwork which required more plaster

than anticipated in manufacturers specs of 9mm; but for older buildings with uneven wall surfaces, this is perhaps unrealistic?

• Insufficient curing and/or retention of moisture? Manufacturer’s

specs suggested 1mm/day for drying but we feel this only allows for the builders to work with. And under what conditions?

• Lack of familiarity/skills from contractors with working with lime.

Insulation

Original Wall

First floor: wood-wool system

Lime plaster levelling coat Lime plaster finishing coat

Conclusions…

• Industry standards and models significantly

underestimate the thermal performance of traditional buildings;

• Suggests that Government predictions of carbon

savings may be missed;

• Though significant improvements in thermal

performance and energy efficiency can be achieved by fabric upgrade, more than is currently predicted by SAP, we would argue that there are many significant reasons to suggest a degree of caution…

Conclusions…

• Issue of technical risk from moisture and

potential damage to the fabric;

• Danger of over-insulating & building in new

problems from a lack of ventilation causing unhealthy environments for buildings and people;

• Potential loss of historic interiors;
• High cost and long payback period;
• Loss of space;
• Disruption;
• Lack of appropriate skills, poor manufacturer’s

specs and poor site supervision.

Conclusions

• Updating services & good maintenance = just

as effective & more affordable?

• Understand the building, what is appropriate,

what are the implications for any interventions?

Other research…

Launched in November 2011 “Danger that retrofit of traditional buildings would be carried out without proper assessment and understanding of traditional buildings and without the necessary processes or skills”. Responsible retrofit report published 2012

Future research

• Relationship between energy performance and building condition: what is

the effect of repair on the thermal performance before and after repointing?

• Air in small cavities: what is the effect of insulation on subfloor

ventilation/rafter level?

• Energy saving from building services: what are the most appropriate and

energy efficient types of heating systems that meet the needs of historic buildings and their users?

• What is the influence of radiant heat exchange on thermal comfort?
• What is the influence of wall insulation on thermal inertia?
• What is the role of traditional lath and plaster in vapour control?
• Thermal conductivity of materials
• Window reveals and insulation

Climate change and your home…

• Our dedicated website

covering:

• Climate Change in Context;
• Climate Impacts;
• Saving Energy; and
• Further Information.
• It can be customised and

includes our latest research findings www.climatechangeandyourhome.

• rg.uk

Guidance Library…characterisation, climate

change, energy…

Historic Environment: Local Management HELM www.helm.org.uk

Thank you for listening!

Contact details: soki.rhee-duverne@english-heritage.org.uk