Why choose Passivhaus? April 2013

Why Choose
Passivhaus?
Tanisha Raffiuddin
Passivhaus Trust
Passivhaus Trust The Foundry, 5 Baldwin Terrace, London N1 7RU Tel: 0207 704 3502
Email: info@passivhaustrust.org.uk Web: www.passivhaustrust.org.uk Twitter: @PassivhausTrust
Underhill House: Seymour-Smith Architects
15th April 2013
The Challenge
There are two major challenges presently facing the UK construction industry:
1. Building regulations are tightening,
requiring more energy-efficient
buildings, and targeting zero carbon
new homes by 2016.
2. Many conventional buildings designed
and built in the past few years are
demonstrating a performance gap in
terms of:
a. energy use
b. ventilation and indoor air quality
c. thermal comfort and overheating
Denby Dale – Photo: Green Building Store
Passivhaus: holistic approach
A quality-assured and certified
process
Achieving the Passivhaus standard requires a holistic approach throughout the
whole process; this ensures it will perform as intended.
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The use of Passive House Planning Package (PHPP)
Design assumptions accord with those used in PHPP
Conductivities satisfy relevant EN standards
Windows: internal surface temp <17°C & g-value >0.5
Pressure tests undertaken in accordance with EN 13829
MVHR satisfies PHI’s strict performance requirements
MVHR commissioned in accordance with requirements
Written declaration from contractor
Photographic construction record of the project kept
Comprehensive construction drawings and documentation
Primary energy calculations include details of: heating
system, hot water distribution, renewable technology,
appliances and lighting.
Oakmeadow School: Architype
Proven, measured performance
The actual performance of Passivhaus buildings in use has been measured.
Figures show that the average heat energy use is 15kWhr/m2/yr or less.
Data from the first UK
Passivhaus buildings
also shows:
1. Heating energy use
of 15kWhr/m2/yr.
2. Consistent
temperatures
3. High occupant
satisfaction
Passivhaus measured performance. Passive House Institute
Beyond Part L
1. 15kWh/m2/yr
2. Maximise insulation and minimise thermal bridges
3. Airtightness
4. MVHR
5. PHPP
6. Quality Assured Process
Why choose 15kWh/m2/yr?
This is the most cost-effective approach over the lifetime of the building.
Below 15 would push
costs too high for benefits
to pay for themselves
Above 15 would mean a
larger heating system
and additional costs and
complexity.
Lifecycle costs: Feist (editor), Economy of Energy Efficiency, working group on
cost efficient Passive Houses, 42, Passive House Institute, Darmstadt, 2013
2011 Measured performance
Primary Energy: 100.19 kWh/(m².yr)
(Everything, including space/water heating)
Space Heating: 8.86 kWh/(m².yr)
Y Foel, the first Certified PH project in the UK
North Wales (2006/7)
Why maximise insulation,
minimise thermal bridges?
By insulating the fabric and thermal bridges:
• Heat loss is reduced
• Surfaces are warmer
• Condensation & mould growth is eliminated
• Space heating energy demand is reduced
• CO2 emissions are reduced in a simpler, more
effective way than bolt-on renewables
Wimbish Passivhaus: Samuel Ashfield Photography
Measured performance:
Primary energy demand: 80 kWh/m²/yr
Space heating demand 14.8 kWh/m²/yr (£130/yr gas bill)
Internal temperatures never below 20°C or over 26°C
Canolfan Hyddgen, the first Non-domestic PH project in the UK
North Wales (2008)
Why be so airtight?
Through careful measures, reducing holes in the fabric to a minimum, airtightness
can be reduced below 0.6ACH, compared to typical levels 10 times higher.
Benefits of greater airtightness include:
• Reducing heat loss
• Minimising draughts
• Reducing noise from outside
• Preventing the damage caused by moist air
condensing on the structure as it leaves
• Allowing a controlled ventilation strategy
Craigrothie Passivhaus
Evidence of performance
Y Foel: Constant indoor temp, Consistent relative humidity between 40 and 60%.
Why use MVHR?
MVHR can transfer heat from the stale outgoing air to the fresh incoming air,
therefore making the building much more energy efficient.
MVHR performs best:
• With attention to detail during the design and installation
• With clear, accessible controls and maintenance plans for
occupants
• At airtighness levels of 3m3/m2/hr and below
• Using highly efficient fans and systems
Y Foel MVHR filters: Mark Tiramani
“The MVHR has been a great success.
There are no lingering smells, and
bathroom mirrors, if they get steamed
up at all, clear quickly. Three months
after we moved in we changed the
paper filters; a simple five minute job,
and the user control on the MVHR unit
reminds you when to do it.”
Adam Dadeby, Resident and CEPH
Designer, Totnes Passivhaus
Why use triple glazing?
Three layers of low-e glazing, insulated frames, insulated spacers and
optimised insulation, typically with a U-value of 0.8W/m2K
Benefits of Passivhaus windows:
• Reduces heat loss further
• Warm surfaces
• Better use of space close to the windows
• No condensation
• Reduced noise from outside
NB Windows can and should be opened, when needed.
Denby Dale – Photo: Green Building Store
“Unlike older houses the temperature in
winter is much the same throughout
the house. Wall to wall, floor to celing.
None of the internal surfaces ever get
cold, not even the windows. So there is
no condensation. Even when it’s -5°C
outside it is still comfortable to sit on
the window banks and use the window
as a backrest.”
Mark Tiramani, Occupant, Y Foel
Why use PHPP?
PHPP is a spreadsheet modelling tool, which is sophisticated enough to
consider the design variables that matter, but simple enough to be understood.
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Builds users knowledge of how buildings work
Allows freedom to experiment with design
forms, orientation, materials etc
Helps to balance aesthetic and functional
aspects within Passivhaus framework
Builds confidence to present ideas to others
Provides evidence to support and argue the
case for new ways of doing things
Fran Bradshaw: Anne Thorne Architects
Underhill House: Seymour-Smith Architects
Plummerswood, GAIA Architects
Why invest in Passivhaus?
Extra capital costs can typically be between 3-8%, offset by lower running costs.
However, experienced designers have managed to build at no extra cost.
Extra capital costs:
Insulation, high performance triple glazed windows,
ventilation with heat recovery.
Savings:
Reduced cost of heating systems, heating bills typically
reduced by 90%
PLUS extra value:
High build quality; health and lifestyle benefits
Bushbury Hills Primary School: Architype
Passivhaus QA
Quality assured process with Certification for:

Buildings
- Through UK based certifiers
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Products / Components
- Through Passive House Institute
- Is a demonstration of performance but not
required (except for MVHR systems)
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Designers / Consultants
- Through CEPH courses
- List of CEPH designers / consultants on the
PH Trust website
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Tradesmen / Installers
- Through Certified Tradesman courses
Addressing myths
It is important that common concerns about Passivhaus are addressed:
1. There are openable windows!
2. It’s a German standard, but adapted for the
UK and used worldwide
3. It’s uses specific data for the UK climate
4. It enables design choice
5. It ensures the MVHR will work
6. You can address other sustainability issues
Crossways: Richard Hawkes
To summarise
Simple and robust – high quality,
easy controls and maintenance
Low energy – low bills, low emissions
Good thermal envelope –
constant comfortable temperature, no
overheating
Better airtightness – no drafts
MVHR – better indoor air quality, positive
impact on occupant health
Triple glazing – warm surfaces, more
usable area
Quality assured – you get what it
says on the tin
Certified – it will perform as intended
Oakmeadow Primary School, Architype Architects
Denby Dale, Green Building Store
Crossway, Hawkes Architecture
Plummerswood, GAIA Architects
Art Studio, Conker Conservation
Hadlow Rural Regeneration Centre, Eurobuild
“We were surprised how fresh
and airy it turned out to be. It is
very liberating not having to
think about keeping warm. The
house just seems to take care
of you.”
Adam Dadeby, Resident,
Totnes Passivhaus
What next?
• Join the Passivhaus Trust
www.passivhaustrust.org.uk
• Come to the Open days in November
http://www.ukpassivhausconference.org.uk/home
• Do the training and build a Passivhaus building
www.passivhaustrust.org.uk