"WARM low energy building practice: Focus on Passivhaus Principles"

WARM: Low Energy Building Practice

What is Passivhaus?- Certifying in the UK

peter warm BSc CEng MCIBSE MIE

˜WARM: Low Energy Building Practice

Oct 2010 Southampton

Sustainable Construction Network



Passivhaus – a Comfort standard?

• No draughts • No cold radiant• No summer overheating• Fresh air always• Whole house warm - no hypothermia• Fuel Poverty eliminated

- all by simply improving the build quality


Passivhaus standard

Air-tightness 0.6ach @ 50Pa

Surface temp

(windows)

>17degC

Summer overheating

Max 10% >25degC

Vent ~30m3/hr.person

Heating 15kWh/m2K @20C

Primary Energy 120kWh/m2yr

Energy

Comfort

Comfort

Energy

Comfort

Comfort


Passivhaus – Simplicity

• Extra Insulation

• Extra panes of glass

• A full ventilation system

• And clever design………….– Site layout – Insulation and thermal bridges– Solar gain and protection– Airtightness and Ventilation


Somewhere around here is optimum.

After: Dr Wolfgang Feist, Passivhaus Institute, 1997

Life Cycle Energy Analysis

0

5000

10000

15000

20000

25000

Building Regulations Low Energy Autonomous House(off the grid)

Cu

mu

lati

ve

En

erg

y In

pu

t (8

0y

rs)

kW

h/m

2

Fuel

Embodied - maintenance

Embodied - Construction


Cephus Project - 2001CEPHUS project


Why Passivhaus?


Co-Heating – the test (no-one wants to hear about)

• Electric heaters inside building maintain constant temperature.

• Ventilation rate measured daily by CO2 release• Solar gain measured by solarimeter• External temperature measured• Two weeks unoccupied usual

• Heat balance calculated: result is Fabric loss in Watts/C


Results for 16 dwellings

0

50

100

150

200

250

Dwellings

Dw

ell

ing

he

at

los

s (

W/K

)

Measured heat loss

Predicted heat loss

Source: Centre for the Built Environment, Leeds Metropolitan University


Why don’t our buildings perform?


Thermal bypass

thermal insulation

inside outside

air barrier

porous insulant



More gaps and voids


Thermal bridging


Thermal bridging


Passivhaus standard

Air-tightness 0.6ach @ 50Pa

Surface temp

(windows)

>17degC

Summer overheating

Max 10% >25degC

Vent ~30m3/hr.person

Heating 15kWh/m2K @20C

Primary Energy 120kWh/m2yr

Energy

Comfort

Comfort

Energy

Comfort

Comfort


Why Certify?

• Quality, Quality Quality

• Avoids “greenwash” – Independent Check

• Feedback loop present

• Take advantage of Certifiers experience


Certification Process

Shapecheck


Certification

• Shape check – pre planning

• Design Check – pre construction

• Final Certification – after building built and tested


PHPP

• Detailed energy balance model:

• Excel sheet, hence built from scratch by certifier

26.3

13.2

8.5

14.810.3

05

10152025303540

Losses Gains

KW

h/m

2.y

r

Fabric losses Ventilation losses Internal heat gains

Solar heat gains Heating energy


Form factorEffect of Massing

y = -16.918x + 6.1667

R2 = 0.7681

1

2

3

4

5

0.00 0.05 0.10 0.15 0.20 0.25 0.30

Average U value inc glazing

Fo

rm h

ea

t lo

ss

fa

cto

r


Form factorEffect of Massing

1

2

3

4

5

0.00 0.05 0.10 0.15 0.20 0.25 0.30

Average U value inc glazing

Fo

rm h

ea

t lo

ss

fa

cto

r

Uwall


Weather data file

• Currently 5 regions:– Glasgow; Manchester; Birmingham; London;

Plymouth

• Will be 22 regions with BRE data:– Same as SAP degreeday regions

• Meteonorm software can generate data

• Crucial agree non standard weather data with certifier early on


Initial target

• Suggest aim for 12/13 kWh/m2

• Gives a margin of error for:– Unexpected Thermal Bridges– Window Choice– General Calculation errors


Windows

• PHPP is complex as the window heat loss is complex too.

• No such thing as a window type U-value

• How window is built into wall critical


Windows

Ug Uf is




Best glass (Ug = 0.5 W/m2K) and Average frame ( Uf = 1.4W/m2K)

Uwindow=1.8 W/m2K

Poor Installation;

Traditional mullions

Installation free of thermal bridges;

Simplified design

Uwindow=0.8 W/m2K


3 types of certification

Building• Tested and calculated using PHPP, by a person/organisation

appointed by the German Passivhaus Institute (PHI)

Component• A component such as windows is certified as having certain

values that can be used directly in PHPP. Currently direct with PHI or appointed bodies.

Designer• This certification shows that a person has undergone

sufficient training and passed an exam to demonstrate their understanding of Passivhaus principles


Who can certify?

• Can Certified Designers certify their own designs?– No– Certification per normal building certification routes – Assurance to clients

• Do you have to be a Certified Designer to design a certified building?– No– A Certified Designer has demonstrated ownership of

the skills– Lower risk of failing from client perspective


Certification

• No site visits

• Design certified

• Certification then requires certificates for:– Airtightness– MVHR commissioning– Conductivity certificates– Window Schedule and Thermal data– Site supervisor declaration


Documentation required 1












Examples












Perrryfields


Perrryfields


Schools – 5 primary in UK


Retrofit - EnerPHit

• Same calculation as newbuild

• But:– 25 instead of 15 kWh/m2 heating demand– 1.0 instead of 0.6 achr @50 Pa airtightness– Alternatively can certify using Passivhaus

components


What does PH cost?

• PHI: 5-10% of build cost, decreasing with experience to 5% (over BRegs):– Consultancy/Training– Materials : MVHR & windows– Certification

• Certification: Single house <£2k, but no consultancy included, huge reductions on estates


What does PH cost?


£0

£200

£400

£600

£800

£1,000

£1,200

£1,400

£1,600

Basic Code 3Scheme

Code 4 energy Passivhaus (Code 4 energy)

Bu

ild

co

st

£ /

m2

design charges

services and LZCs

windows and doors

timber frame

common costs

Costs re CSH

Source: Randall & Simms QS: 20 units St Ive


Who does certification ?

• BRE• Scottish Passive House Centre• Inbuilt• Mosart• WARM

• PHI• Hans Eek


AECB CarbonLite Training

• 1 day Understanding the PassivHaus standard– 25thOctober NEWCASTLE– 15thNovember LONDON– 22ndNovember BRISTOL

• 2 day Using PHPP software for low energy design– 26/27thOctober NEWCASTLE– 16/17thNovember LONDON– 23/24thNovember BRISTOL

• 1 day 2D Thermal Bridging– 28thOctober NEWCASTLE– 18thNovember LONDON– 25ndNovember BRISTOL

www.aecb.net or www.peterwarm.co.uk

http://www.aecb.net/

http://www.peterwarm.co.uk/


Thanks to the crew

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"WARM low energy building practice: Focus on Passivhaus Principles"