M2 MMC Nov' '16 cc

Passivhaus - Is it desirable?
Is it affordable?
In 1991 Wolfgang Feist and Bo Adamson applied the passive design approach to a house in Darmstadt, with the objective of
developing a prototype low energy home. The design proved successful both in terms of energy consumption and comfort and
Passivhaus is now considered the ultimate in building performance. Passivhaus fundamentally requires a balance of three
elements: energy, quality and cost - encompassing heating, cooling and thermal comfort which all have to be met cost effectively.
Kingspan Timber Solutions
are pushing the practical
application of new
technologies to create high
performance building
envelopes. Prefabrication
and lean design expertise is
invaluable when dealing with
the enhanced thermal and
airtightness requirements of
passivhaus projects...
Business Unit Director for Kingspan
Timber Solutions, Ian Loughnane, shares
his perspective on the merits of high
performance building envelopes and the
company’s experience of building low energy
homes.
Achieving the design performance as detailed in
the build specification can present challenges -
eliminating the gap between design and as-built
performance is a key issue within the
construction industry. Developers, architects and
engineers are beginning to recognise the impact
of building details and specification in use
energy performance and are keen to promote
best practice.
Though renewable technology has its place,
there is no doubt that the energy performance of
the building’s external fabric is the most cost
effective, reliable and long-term, lowmaintenance
solution. This is what ‘Fabric First’
and Passivhaus principles are all about - high
performance insulation, good airtightness, the
minimisation of thermal bridging and harvesting
the sun's energy through solar gain via southfacing
windows. In essence this means that the
building does the work, rather than relying on
occupiers operating and maintaining costly
renewable energy devices.
Whilst the benefits of the Fabric First principles
are well documented, we still find some projects
that only specify U-values whilst the SAP rating
of a dwelling is driven by the interlinked
properties of U-values, Psi values and
airtightness. This is likely to be because U-
values are readily calculated whilst the overall Y-
value can only be determined once the building
details are known and the individual junction Psi
values input against actual junction length.
Passivhaus is a building standard that is truly
energy efficient, comfortable, ecological and
when the reduction in long term operating costs
are taken into consideration - affordable. It is a
construction concept that follows a set of
rigorous and certifiable principles that have
stood the test of time and practice.
Kingspan Timber Solutions are pushing the
practical application of new technologies to
create high performance building envelopes.
Prefabrication and lean design expertise is
invaluable when dealing with the enhanced
thermal and airtightness requirements of
passivhaus projects, such as the Greenhauses in
Sulgrave Gardens.
Greenhauses represents a significant step
forward in bringing Passivhaus into common use
in the UK, in an affordable and deliverable
format. The development comprises a terrace of
three-storey houses together with two fivestorey
apartment buildings all of which have
been constructed to Passivhaus principles. The
development is completed with four mews
houses with roof terraces. These homes are not
only designed to save residents a significant
amount on energy bills - up to 90% in the case of
the certified units, but also to provide
considerably improved indoor air quality.
To complement the architecture in two adjacent
conservation zones, brick was chosen as the
primary facade material for the buildings. Given
the tight urban nature of the site, minimising the
thickness of the remaining wall build-ups was
key, whilst still attaining the required level of
thermal performance.
Each of the four blocks required a specific
design response so as to meet the challenges
of the planning and architectural context, and
the energy use and heat loss targets of
Passivhaus. Two main construction methods
were used both utilising the high performance
Structural Insulated Panel system (SIPs).
Kingspan TEK ® SIPs produce the primary
structure of the 10 houses, with a concrete
frame insulated with Kingspan TEK® cladding
panels being developed for the 20 apartments.
Both build-ups achieve outstanding thermal
performance with final external wall U-values
of 0.10 W/m2K. The proprietary jointing system
featured on both Kingspan TEK products, in
combination with the additional airtightness
detailing on the project, ensured that air loss is
below the 0.6 air changes per hour @ 50 Pa. To
maintain a constant flow of fresh air,
mechanical ventilation heat recovery (MVHR)
systems were installed, using heat from the
outgoing air to warm the incoming, fresh air.
Building performance evaluation is currently
underway together with occupier wellbeing
research.
The transition to a low-carbon economy
presents our industry with great opportunities
for growth. Environmental considerations will
transform how our buildings are constructed,
what materials are used and the methods
employed. We are now on the cusp of the
predicted ‘sea-change’ and the time is right for
the construction industry to embrace
innovative timber technology and offsite
techniques to develop better buildings at a
rapid rate to enhance lives, minimise the
environmental impact and reduce energy costs
for occupants for many years to come.
36 MMC
Nov 2016 M2