BUILDING TO PASSIVHAUS STANDARDS WITH KNAUF INSULATION - 22.11.10
An ambitious project, one of the first certified PassivHaus
homes in the UK, has used an array of new build insulation products
from Knauf Insulation’s portfolio to achieve outstanding energy
efficiency.
The Denby Dale PassivHaus in West Yorkshire, has been built to
use 90% less energy for space heating than the average UK dwelling
– with a space heating need of only 15 kWh/m2/year. The three
bedroom property is the first UK PassivHaus to be built using
cavity wall construction and was built to a tight budget of
£141,000.
The project was led and managed by Green Building Company, which is
the construction division of Passivhaus product specialists Green
Building Store. “We wanted to build a PassivHaus using
British construction techniques, with, as far as possible,
materials you could find in any local builder's yard. We decided to
go down the cavity wall path because of familiarity and arrived at
the design for several reasons including: planning restrictions,
thermal store, cost, and maybe most important of all,
buildability,” explains Bill Butcher, Project Leader.
Excellent performing insulation is obviously fundamental to
Passivhaus construction and the Denby Dale house has 300mm DriTherm
32 Ultimate cavity slabs in the walls, 500mm Earthwool CarbonZero
Loft Roll 44 in the roof void (both of which incorporate ECOSE®
Technology) along with 225mm of high-performing Polyfoam Floorboard
Standard insulation in the floor. “We're fully filling the
cavity with glass mineral wool insulation for the walls above
ground, because it is easier to fill the cavity - fitting around
the ties and openings– and it's easier to install,” comments Bill
Butcher.
Glass mineral wool was specified over rigid insulation to ensure
a tight thermal fit. DriTherm Cavity Slabs are flexible
enough to eliminate air gaps and prevent heat loss due to their
inherent ability to knit together at joints between the
slabs. If rigid insulation is used and fitted badly with too
many gaps, air movement around and between the insulation boards is
increased, which can drastically reduce its insulation
value.
DriTherm Cavity Slabs are BBA Certified for all exposure zones
and formally guaranteed for 50 years to prevent the transmission of
liquid water from the outer masonry leaf to the inner masonry
leaf.
In addition to its thermal performance glass mineral wool also
has other sustainable features. In manufacture it uses a high
content of recycled glass bottles and requires less overall energy
consumption than some alternative products, resulting in less
carbon emissions. In addition, it can be recycled at the end of a
building’s life and has zero GWP and zero ODP. ECOSE®
Technology further extends these established green credentials as
it is manufactured with 70% less energy than traditional binders
and the products contain no dye or added formaldehyde – providing
the ideal solution to the eco-friendly house.
PassivHaus Planning package (PHPP) software was used with the
early design to ensure that the Green Building Company kept the
space heating needs at or below 15kWh/m2/annum – the prerequisite
for PassivHaus certification. Modelling different materials in the
online PassivHaus Planning Package has dramatic effects on the
figure depending on which type of wall insulation and window
configurations have been inputted.
“Two and half years ago we decided to build a low energy home
for our retirement and it was important to use high performing, and
cost-effective materials– as we were on a fairly tight budget . We
hope that our house will be a template for other PassivHauses in
the UK using methods and materials familiar to the UK construction
industry whilst still adhering to PassivHaus performance criteria,”
explains Geoff Tunstall, homeowner.
-ENDS-