Table of Contents Table of Contents
Previous Page  3 / 54 Next Page
Show Menu
Previous Page 3 / 54 Next Page
Page Background





Analysis of the embodied energy and

materials of historic buildings provides

important indicators:

• it prioritises a holistic evaluation of

the long-term energy investment as

well as performance in use of all older


• it broadens perception of the

value of our built heritage beyond

delimited cultural criteria to embrace

environmental resource, societal

factors and usefulness

• it highlights the potential for

mainstreaming retrofit measures

beyond a restricted heritage sector,

up-scaling traditional methods

in tandem with appropriate new


• it facilitates the development of

manifold options for balancing

energy-related objectives with those

of heritage significance, ones that are

normal and affordable rather than

specialist and expensive.

In short, understanding sustainability

requirements provides a major opportunity

for the heritage sector to expand its field

of activity and influence in concert with

the mainstream retrofit sector.



An important starting point is to address

negative assumptions regarding the

energy performance of our existing

building stock, especially older buildings

constructed using traditional materials

and techniques.

The conventional criteria for

identifying and calculating thermal

performance across the built

environment rely on simplistic thermal

transmittance or U-values, ignore

factors such as thermal inertia, and

employ standardised and generally high

assumptions concerning acceptable

indoor temperature levels. The variation

in performance as well as human comfort

levels experienced between buildings

of diverse constructional types is not

taken into account, the behavioural

patterns of building occupants as

well as their tolerance of variabilities

is ignored, and the results obtained

from different energy certification

systems – all of which are modelled

theoretically – can vary significantly.

The current measurement criteria

combine to undervalue the thermal

performance of older buildings and

create an expectation that intensive

levels of intervention are required to

make them energy efficient, ones that

anticipate conflict with their heritage

significance while proving less effective

than assumed. Additionally, there is

no industry-agreed methodology for

calculating and comparing the embodied

materials and energy of diverse typologies

of buildings by age and construction or

of interventions into them, and life-

cycle parameters and analyses are either

neglected or poor.

In 2007, based on research of

energy consumption data across a broad

cross-section of its building stock, the

Ministry of Justice in England confounded

preconceptions by demonstrating that its

oldest, pre-1900 buildings use the least

energy. The research also demonstrated that

the performance of these older buildings

was not approached in new construction

until the 1990s and 2000s, decades during

which energy use was still eight per cent

higher per square metre than for the

pre-1900 buildings. As the architect Jon

Wallsgrove has written: ‘This innovative

research... has shown that the conservation

of our architectural heritage is directly

compatible with energy conservation, rather

than being diametrically opposed, as some

environmental fundamentalists believe’.

In the light of these and related

findings both at home and abroad,

priority has been attached by the historic

environment agencies and others across

the United Kingdom to the research

and promotion of benign interventions

and limiting detrimental impacts on

the historic and traditional building

stock. Notable in this regard is the

ongoing applied research by Historic

England (formerly English Heritage) and

Historic Environment Scotland (formerly

Historic Scotland), the Building Research

Establishment, Changeworks, the Society

for the Protection of Ancient Buildings

(SPAB) and the Sustainable Traditional

Buildings Alliance (STBA), and research

conducted in historic cities including

Bath, Bristol and Edinburgh.

Austwick, Lancashire: house conversion. Heritage significance subsumes appearance and material fabric. In

this case, whereas the material fabric has been retained by overlaying solar panels, the building’s appearance

has been seriously compromised. Advances are being made in the production of solar roof tiles, also shingles

and slates, which protect the overall as well as detailed appearance of historic buildings but require

substitution of the fabric. The heritage impact methodology outlined in this article facilitates informed and

transparent decision-making in situations where choices have to be made. (All photos: Dennis Rodwell)

Thermal image composition showing heat loss from Bute House, Edinburgh (Image: Kal Murray, Eco Surveys)