Clearview National October 2014 - Issue 155 | Page 61

HARDWARE& SECURITY

Roto Frank gives
an insight into
what is Passivhaus
If someone mentions Passivhaus to you, how do you react? Are
you so knowledgeable about the subject, you immediately launch
into a discussion about U-values and air changes per hour?
»»It seems there are still a lot
of people within the fenestration industry
who only have a basic understanding of the
concept. Roto Frank, specialists in door and
window hardware, thought they would offer a
bit of a refresher, and have spoken to some of
the leading lights of the Passivhaus movement
to see what’s going on right now in the world
of energy efficient buildings.
First of all, they asked Nick Grant, Principal
of sustainable building consultants Elemental
Solutions and one of the people who helped
start the Passivhaus movement in the UK,
should we call it “Passivhaus” or translate it to
“passive house”?

‘There was a lot of
discussion about the name’
“There was a lot of discussion about
the name,” explains Nick. “Originally,
the Passivhaus Institute wanted us to use
the English translation, but many in the
sustainable building community thought
“passive house” to be confusing because it
implies a house – my first three projects were
schools, so you can see how it didn’t really
fit.
“There was also a chance of confusion
with passive solar and passive vent, both of
which are different concepts. So by using
“Passivhaus” it’s clear what we are talking
about.”

What makes a building
a Passivhaus?
One way to say it might be that it’s a very
well insulated, draught free building that
doesn’t need very much energy at all to heat
it in winter or to cool it in summer. At the
same time, it’s constantly ventilated so the air
is always fresh, even when it’s too cold
and windy to open a window.

can be found on every continent – including
an environmental research station in the
Antarctic.
What about windows
and doors?
Most importantly for the fenestration
industry is the very specific
requirements placed on windows
and doors. They need to have
very low U-values – not just
in their glazing, but as overall
units. To achieve the target figure
of 0.85 W/(m^2.K) requires the
use of triple glazing, usually with
argon-filled voids, plus warm edge technology
and thermally-broken frames. The size and
positioning of windows is also important, in
order to take advantage of solar gain.
The result of all this is a massive reduction
in the need for energy in comparison with
a conventional building. According to one
figure, a true Passivhaus requires at least 75%
less energy than a current standard UK new
build.
The idea that a Passivhaus has to be
heated solely by warming the vent air is a
misconception, says Nick Grant. “Many of
us don’t use the vent air for a whole host
of reasons,” he explains. “There is a myth
than you can’t have radiators. In fact, many
Passivhaus experts choose to use them or use
other methods of heating.”
So long as the energy consumption and rate
of ventilation fall within the requirements,
a building can be accredited as a Passivhaus.
Roto Frank has provided hardware for several
new-build projects, and also a Victorian
house, which wa ́ѡ