FEATURE TIMBER & PASSIVHAUS
Maximising Energy Efficiency
MEDITE VENT and SMARTPLY PROPASSIV proved to be a winning combination for the first oak frame Passivhaus to be built in the heart of Wiltshire, South West England.
B
uilt by award-winning construction company Erigo
control properties, used as structural sheathing in timber frame
Developments, ‘Seldom Seen’, a private detached
buildings. These features eliminate the need for additional air and
residence, was at the time of completion the first house
vapour control layer (AVCL) membranes. Its coating also provides a
in Wiltshire to meet the Passivhaus standard. It still ranks
durable, smooth surface perfect for the use of airtight tape at the panel
as only the eighth certified Passivhaus in the South West of England. Designed around a traditional oak frame and finished in oak cladding, the house was strategically sympathetic to its rural Area of Outstanding
joints. SMARTPLY’s in-house speciality surfacing technology provides this integrated vapour barrier, which delivers high and constant vapour resistance across the whole surface.
Natural Beauty (AONB) setting. The combination of MEDITE VENT and SMARTPLY PROPASSIV helped to achieve its Passivhaus status. “At the time, there was nothing else on the market that fulfilled
For this project, the timber frame was in-filled with Icynene Sprayfoam insulation, with SMARTPLY PROPASSIV lining the interior, alongside plasterboard facing the room. MEDITE VENT was installed on
its role in this location,” said Rebecca Thursby, Director of Erigo
the exterior of the spray foam, which was then topped with Tyvek wrap
Developments. “We used an oak frame to create the external envelope
and finished with the timber cladding.
and then choose both MEDITE VENT and SMARTPLY PROPASSIV to
MEDITE SMARTPLY’s entire product range, including MEDITE VENT
achieve the level of airtightness required to meet the Passivhaus
and SMARTPLY PROPASSIV, is manufactured with FSC-certified Irish
standard. We managed to get the airtightness down to 0.38 ACH @ 50
timber, from their own sustainably managed forests, demonstrating a
Pascals, which is very good.”
clear supply chain and manufacturing process.
To reach Passivhaus standard, a building must achieve an airtightness
Being conscious of how this industry impacts the environment is
level of 0.6ACH (air change per Hour) at 50 Pascals or less. In other words,
also something that Erigo Developments takes very seriously. Erigo is an
the volume of uncontrolled air leakages in one hour must be less than
award-winning construction company that puts an exceptionally strong
0.6 times the overall building volume when the difference in air pressure
focus on being environmentally responsible. The company demonstrates
between the indoors and outdoors is 50 Pascals. In this case, Pascals
this by selecting carbon responsible materials and always aiming to
indicates the air pressure difference between inside the building and
achieve zero non-hazardous waste to landfill in all of their projects.
outside the building for the airtightness test. Reaching an airtightness level of 0.38 can be considered a remarkable achievement. Perfect for use in low energy buildings, MEDITE VENT is a high
“We’ve made a commitment that we’re only going to build to a Passivhaus standard going forward, and to build with carbon responsible materials,” adds Rebecca. “I think everyone needs to do their bit to combat
performance, breathable sheathing panel, suitable for use in timber
climate change. I think that building regulations need to go further in terms
frame structures. It boasts high racking strength in excess of Category 1
of power requirements and what’s needed from houses now to achieve
requirements, and high vapour permeability alongside weather resistance.
energy efficiency. That way, everyone knows what they can do in order to
Its extremely low vapour diffusion factor helps to prevent condensation
reduce their energy demands. There also needs to be more incentives in
and because it is manufactured with no added formaldehyde, it contributes
place to make people choose carbon responsible materials.”
to both a healthier working environment for installing contractors and a More at www.erigodevelopments.co.uk
healthier living environment for building occupants.
mdfosb.com/en/products/smartply-propassiv
This intelligently formulated panel is teamed with SMARTPLY
mdfosb.com/en/products/medite-vent
PROPASSIV, an airtight structural OSB/3 panel with integrated vapour
Timber Construction Magazine
Spring 2021
30
www.timbermedia.co.uk
@Timber_Media
