As featured in Livinglife 10 by Livingroom Estate Agents,
Guernsey.
Around 50% of all energy generated goes towards supplying
buildings. Widespread application of the PassivHaus design would
have a dramatic impact on energy conservation; one Guernsey family
enlisted the help of Aslett Naftel to take on a very worthwhile
project.
A Passive House is an extremely well insulated, virtually airtight
building that is primarily heated by passive solar gain, with any remaining heat demand being
provided by a highly efficient MHRV (Mechanical Heat Recovery
Ventilation) System. Effective window orientation, high performance
triple-glazing, super-insulation, an airtight building shell, solar
panels and the balanced energy recovery ventilation make possible
extraordinary reductions in energy use and carbon emission. The
PassivHaus Standard was created out of a desire to bridge the gap
between 'designed' performance and 'in-use' performance of
buildings.
David Aslett of Aslett Naftel Chartered Architects and Chartered
Surveyors showed Livinglife around James and Katie Whitford's house
in the heart of St Saviour. The project is at a stage of
development which allows you to see just how it is going to save
energy. Insulation is key, and the first thing you notice is the
material from which the building is constructed. The use of SIPs
(Structural Insulated Panels) would exceed current Building
Regulation requirements alone, but they are covered with additional
thermal insulation on either side, making the construction
extremely thermally efficient and avoiding 'cold bridges'. SIPs are
lightweight and relatively quick to put up; their manufacture and
transportation are far less energy intensive than those involved in
the production of concrete blocks. The house exterior is in the
process of being finished; it looks as though it has been covered
with cement rendering but it is in fact a Wetherby Insulated Render
System.
The front door is striking: it is high-tech, solid and draught
proof. Complying with the PassivHaus standards, windows are
triple-glazed and airtight; they are orientated on the south
elevation in order to maximise passive solar heat gain. Meanwhile,
the north elevation is virtually imperforate, thus minimising heat
loss on this more shaded side. Great attention has been paid to the
installation of the windows, to prevent air leakage at the junction
of frames and structure.
At the heart of the house is 'mission control' - the hub for all
the eco technologies. These include an MHRV (Mechanical Heat
Recovery Ventilation) system. According to David, 'The clients have
employed lots of technologies but what's exciting is what they've
left out - most notably, a conventional central heating system.'
This hub, which also serves as a utility room, has been positioned
to be proximate to the guest WC/shower room, the family bathroom
and the master bedroom en-suite, keeping pipe runs to a minimum -
another energy saver.
The house is comprised of two sections: the front 'block' is open
to guests while the second is the more private family space. The
first block has an open-plan kitchen, dining area and living room,
with lots of glass to make the most of natural light. An appealing
feature is a built-in, cosy reading nook in the living area. A
staircase with a glass balustrade leads to an upstairs playroom, in
the gently sloping eaves of the building.
Walking through to the family quarters, past the bathrooms, are
three south-facing bedrooms downstairs, featuring bold
floor-to-ceiling doors. A second staircase takes you to the master
bedroom suite. This has a generously proportioned home office/study
and a bedroom with a huge window covering two-thirds of the far
gable wall, looking out over rural St Saviours. Like the playroom,
this room is in the eaves and has special FAKRO roof lights which
are specifically PassivHaus compliant. Throughout the building, all
fixed lighting is low energy LED. The en-suite bathroom is situated
above the utility room, again avoiding any excessive pipe
runs.
This house will soon be ready for pressure testing to ensure that
it is in compliance with PassivHaus criteria. This involves sealing
the front door, installing a fan and pumping air into the building
until it is at a level above atmospheric pressure. The crucial
factor is the length of time required for the pressure to return to
equilibrium.
The will to create a Passive House has to be client driven: the
construction cost is likely to be around 15% higher than a more
conventional build. Once the foundations are in place, however, the
structure can go up quickly and you will not have to install an
expensive central heating system. When you move into your house its
energy consumption will be less than a quarter of that of an
average new build so of course, in the long run, it will save you
money - and the knowledge you are helping to save the world is
priceless. 'It is very much the spirit of the age,' says David.
'For clients, contractors and suppliers, environmental issues are
the most important thing - it's become far more mainstream.'
www.aslettnaftel.com
