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Understanding the risks



T IS a widely held view that older

buildings are not energy efficient and

must be radically upgraded in order

to improve their performance. In reality

the situation is more complicated and

assumptions about poor performance

are not always justified. For example,

as Dennis Rodwell points out in his

article on heritage and sustainability

(see page 3), when HM Courts Service

analysed their records of energy use they

found that ‘…buildings from the early

part of the 20th century and before tend

to use less energy than the equivalent

more recent buildings’. Nevertheless,

opportunities exist to improve the

energy and carbon performance of many

heritage buildings, thereby helping them

to remain viable and useful now and in

the future.

The challenges in striking the right

balance between benefit and harm

can, however, be considerable. The

unintended consequences of getting

energy efficiency measures wrong

(or doing them badly) include:

• harm to heritage significance

altered appearance

loss of features

• harm to human health and

building fabric

poor indoor air quality

condensation and mould growth

decay of building fabric

• failure to achieve the predicted

savings or reductions in

environmental impact.

Getting the balance right is best achieved

through a systematic ‘whole building’

approach. This is a logical process based

on conservation planning principles

that uses the understanding of a

heritage asset, its context, significance

and all the factors that affect energy

use (not least, the people inhabiting

it) as the starting point for devising

strategies for energy efficiency.

Strategies may vary depending on

whether the main aim is to mitigate

carbon emissions, cut fuel bills or

comply with legislation such as the

Building Regulations. Compromises

are inevitable, but the whole building

approach enables informed decisions to

be taken and ensures that improvements

are suitable, well-integrated, properly

coordinated, effective, cost-efficient

and sustainable. It also provides an

effective framework for communication

between all parties involved in the

process, including assessors, designers,

installers and the people who will

use and manage the building.

A ‘Mean, Lean, Green’ philosophy

has evolved for the design, construction

and use of new buildings. This is based

on a hierarchy that begins with the

siting, orientation, form, materials and

construction of the building to optimise

the efficient use of energy and other

resources (‘Mean’). Next comes the

design, management and control of

engineering systems to ensure they can

Shrewsbury Flaxmill Maltings (Grade I, 1797), where Historic England is assessing the effects of internal

wall insulation on the hygrothermal behaviour of brickwork (Photo: Jonathan Taylor, all other images:

Iain McCaig/Historic England)