THE IMPORTANCE OF
Iain Fairnington, technical director at A.Proctor Group, considers why airtightness is crucial to good
There is no question that an integral part
of modern building design is energy
efficiency. In the EU, it is estimated that
buildings account for approximately 40%
of energy consumption and are responsible for some
36% of CO2 emissions. Closer to home, around
45% of UK CO2 emissions come from the built
environment, (27% from domestic dwellings and
18% from non-domestic).
The driver for the energy efficiency of our
buildings has primarily come from compliance with
Building Regulations. However, there are significant
benefits in improving energy efficiency, which can
be realised in terms of economic, environmental,
social, and health and wellbeing factors.
Architects, designers and builders are central
to maximising the energy efficiency in buildings.
When considering how a building may lose heat,
46 BUILDING PRODUCTS | JUNE 2018
we are primarily concerned with air leakage, thermal
conduction and thermal barriers.
Airtightness improves energy efficiency
As thermal insulation requirements have increased
over the last few years, the proportion of energy
lost through air leakage has become more evident.
The ever-increasing thermal insulation required
will, however, be rendered largely ineffective unless
the airtightness of the structure itself is addressed.
Air leakage greatly reduces the effect of thermal
insulation; therefore if energy efficiency is to be
improved within buildings, this is the most critical
area to focus on.
In addition to improved insulation, energy
efficient heating systems will also be ineffective if
warm air can escape the building and cold air can
seep in. This is reflected in the fact that total space
heating costs in an airtight construction may be
considerably less than in a leaky one.
Air leakage through cracks, gaps, holes and
improperly sealed elements such as doors and
windows can cause a significant reduction in the
performance of even thermally insulated envelopes.
Architects are increasingly turning to air barrier
membranes as an essential part of the design process
in achieving the most effective means of controlling
and reducing air leaks.
In terms of the energy efficiency of a building,
uncontrolled air flow will almost certainly have
a major impact. Initial heat load calculations for
heating and cooling equipment will usually make
an allowance for a level of natural infiltration or
uncontrolled air flow. The higher the infiltration
rate, the lower the energy efficiency of the building.
Efficiency levels can be affected by both natural and