PassivHaus - the solution for low energy building? Colin Powell BA(Hons) DipArch Msc RIBA gcp :...

PassivHaus - the solution for low energy building?

Colin Powell BA(Hons) DipArch Msc RIBA

gcp : architecture : energy : sustainable design

Content• PassivHaus primer – a brief outline• (why) Do clients want PassivHaus• The problems for PassivHaus design – myths and reality• Knowledge based design – don’t be frightened by numbers• Challenges for the designer• Engaging the user – achieving performance in use


gcparchitecture : energy : sustainable design

Effective sustainable design requires a detailed knowledge of building science, technology and construction

Our core skills as architects provides our clients with a depth of understanding that informs our advice on energy and sustainability

Our consulting business provides the specialised knowledge of sustainable and low energy design needed to help our clients achieve their ambitions

i n t r o d u c t i o n


PassivHaus is a design standard for producing buildings with very low energy demand

Developed in Germany in 1991, now being used around the world as a tried and tested standard

Not only applicable to housing, it can be used for large and small buildings and refurbishment

q u i c k o u t l i n e


Standard applicable to all building typesPassivHaus focusses on building energy calculated through a rigorous calculation method

Not only applicable to housing, it can be used for large and small buildings

EnerPHit standard applies PassivHaus principles to refurbishment and retrofit

offices

schools

housing

student residence



• Exceptionally high thermal insulation

• High performance triple glazed windows

• Thermal-bridge-free construction

• Very low air permeability – airtight building envelope

• Comfort ventilation with highly efficient heat recovery

continuous thermal insulation typically >300mm thick

larger windows to the south forbeneficial solar gains

continuous air barrierTo prevent air leakage

ventilation system deliversfresh air to main activity spaces

ventilation with Heat recover to save energy



Govt. Agenda for Carbon Reduction – Climate Change Act

35% Reduction in CO2 by 2020

Increasing energy costs and prospect of increasing energy instability

Planning and statutory targets for energy and carbon

l e g i s l a t i v e a g e n d a f o r c h a n g e

DECC – monthly retail price indices

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

0

20

40

60

80

100

120

140

160

180

200Fuel price indices in the domestic sector in real

terms 1992 to 2012

Coal and smokeless fuels

Electricity

Gas


Clients want reliable solutions that deliver real benefits

Suspicion of complex renewable technologies that may not deliver reduced energy

Resistance to sustainability measures that are counter-intuitive

Need for solutions that are simple and robust

We are increasingly finding that sustainability is an important driver to occupiers and investors;• Occupier concern over energy use and running cost• New taxation (e.g CRC)• Sustainable buildings give occupiers tangible costs

savings (£5.2m saved in past 4 years)• Holds long term property values with investors• Now a contractual requirement for our whole supply

chain

(Sarah Cary – Sustainable Development - British Land)

r e a l - w o r l d i s s u e s

In our previous offices, energy costs were over £23,000 per annum and rising fast. Energy costs in the new office are projected to be a credit of £2,000 per annum and rising in line with energy costs, representing a £25,000 per annum saving on the old office.

(John Walkerdine - Interserve )


Stable internal temperatures without cold surfaces or draughts

Reduced risk of overheating

Controlled ventilation can reduce the risks of respiratory disease

Thermal performance and air-tightness through rigorous quality control at design and construction stage

Image courtesy of International PassivHaus Association

I t s n o t j u s t a b o u t m o n e y “We think each person lifted out of fuel poverty will save the health service about £250 a year. Data suggests there are 20% more deaths in Oldham in winter than in summer because of extra respiratory illnesses and heart problems [linked to cold homes]. If you get a cold winter and people cannot heat their homes, you get more people suffering and turning up in A&E”(Guardian Nov.13 – ‘Actively cutting energy bills in Oldham – Welcome to the Passivhauses’)


Exeter City Council

Hastoe Housing Group

Interserve

University of East Anglia

Leicester City Council

Circle Housing

Gentoo

Diocese of Worcester

University of Bradford

London Borough of Tower Hamlets

Carmarthenshire Council

East Midlands Housing Association

Raynsway Properties

Estimated over 500 completed projects by end 2013 a rate of growth consistent with Germany 20 years ago(NHBC Foundation July 2012)

W h y a r e c l i e n t s c h o o s i n g P a s s i v H a u s ?

“healthy buildings”

“addresses fuel poverty”

“reduced management & maintenance”

“future proof”

“not eco-bling”

“demonstrates CSR”

“fabric first”

“massive cost saving”

“tried & tested”

“opportunity for higher revenue”

“right thing to do”


M y t h s a n d R e a l i t y

You can’t open the windows

PassivHaus needs no heating

Sealed buildings are unhealthy

Mechanical ventilation wastes energy

PassivHaus overheats in summer

PassivHaus are too complex

PassivHaus are too simple

Windows can be opened for comfort and cooling, buildings will recover more quickly after closing

PH do need heating – just very little – a single towel-rail or perhaps a big dog?!

Proper ventilation is designed-in and works even in cold months when you want to keep the windows closed

Efficient, well-designed Heat Recovery Ventilation saves 10 times the energy it uses

Shading and cooling are key parts of the design process and certification criteria

PH often use less technology and simpler systems

Sometimes you just can’t win!(there are plenty of examples to refute this)


M y t h s a n d R e a l i t y

You can’t open the windows

PassivHaus needs no heating

Sealed buildings are unhealthy

Mechanical ventilation wastes energy

PassivHaus overheats in summer

PassivHaus are too complex


Windows can be opened for comfort and cooling, buildings will recover more quickly after closing

PH do need heating – just very little – a single towel-railor perhaps a big dog?!

Proper ventilation is designed-in and works even in cold months when you want to keep the windows closed

Efficient, well-designed Heat Recovery Ventilation saves 10 times the energy it uses

Shading and cooling are key parts of the design process and certification criteria

PH often use less technology and simpler systems

Sometimes you just can’t win!(there are plenty of examples to refute this)

?**!


The energy we use is affected by different factors• Age of the building

E n e r g y i n b u i l d i n g s – u s i n g n u m b e r s t o i n f o r m d e s i g n

62%18%

13%

3%3% Home Energy

HeatingHot WaterAppliancesLightingCooking

Energy use – average all UK homes


The energy we use is affected by different factors• Age of the building• Lifestyle• Purchasing decisions

E n e r g y i n b u i l d i n g s

32%

22%

29%

9% 8% Home Energy

HeatingHot WaterAppliancesLightingCooking

Energy use – new home to current regulations

E n e r g y i n b u i l d i n g s – u s i n g n u m b e r s t o i n f o r m d e s i g n


Heat loss from the building has to be balanced with energy (heat) in to maintain comfort

We can calculate where this heat is lost by modelling

S o w h e r e d o e s a l l t h e e n e r g y g o ?





walls13.2

roof9.2

floor4.0

windows24.2

ventilation

48.0

Current Regs - elemental energy loss – kWh / m2

Therm.bridges

2.7





walls13.2

roof9.2

floor4.0

windows24.2

ventilation

48.0

Current Regs - elemental energy loss – kWh / m2

Therm.bridges

2.7

balancing

heat in

74 kWh / m2


• Understanding from elemental analysis enables optimises solutions

• Implications for building design from site layout to construction

U n d e r s t a n d i n g t h e n u m b e r s h e l p s i n t a r g e t i n g s o l u t i o n s

walls8.4

roof5.2

floor3.3

windows13.7

ventilation

5.6

Therm.bridges

0.0 balancing

heat in

14 kWh / m2

PassivHaus - elemental energy loss – kWh / m2


• Increased cost for construction is invested in the building fabric and insulation

• Typically 5-10% more expensive (recent studies show this reducing)

• Payback period around 20 years (but energy costs increasing)

• Protection against fluctuating fuel costs and future uncertainty

Illustration of energy cost savings for a 3-bed detached house

A n d p r o v i d e s c o m p e l l i n g a r g u m e n t s f o r c l i e n t s


• Understanding the main factors that influence performance

• Site factors are significant and need to be considered

• Building form can make life easier – or more difficult

• Complex buildings may need more complex solutions – adaptive buildings that adjust with occupancy

C h a l l e n g e s f o r t h e d e s i g n e r


• Construction type needs to be considered from the outset

• Traditional construction is possible – but will demand new understanding from constructor

• New materials and constructions may be worthwhile

• Clear coordination between design and construction team is vital

C h a l l e n g e s f o r t h e d e s i g n e r


• Success of the project will rely on a good briefing for the end-user

• PassivHaus needs to be ‘driven’ and will take time to acclimatise - the user and the building

• Explaining the reason for controls is as important as knowing what they do

• Understanding seasonal variations will ensure comfort in different conditions

E n g a g i n g t h e u s e r

On hot summer days keep the

windows closed !

Heating by towel rails – press boost if you need some

extra warmth

Keep the ventilation on

auto and press boost if things

get steamy

The boiler is small and won’t be

running very much – don’t worry it’s

not broken!



!

thank you


www.gcparch.co.uk

[email protected]

PassivHaus - the solution for low energy building? Colin Powell BA(Hons) DipArch Msc RIBA gcp :...

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