Passivhaus buildings can be cost-effective and have flexible designs if certain principles are followed. Constraints like energy efficiency, size and cost should be embraced rather than seen as limitations. Simple structural strategies like continuous insulation and airtight designs can reduce thermal bridging and construction complexity. Limiting window area and using fixed glazing where possible cuts costs versus mechanical shading or opening windows. Keeping mechanical systems simple with basic radiant heating keeps costs low compared to complex ventilation setups. Past housing examples like Denby Dale show Passivhaus can be achieved at standard costs when principles are followed.

1. Passivhaus, If you think it will cost more it
will
Inaugural South Pacific Passive House Conference
Auckland 2015
Nick Grant
Elemental Solutions
UK Passivhaus Trust
@ecominimalnick

2. Deja vu
1997
Suggests cost/performance correlation

3. Deja vu
2003
Market transformation in 6 years

4. Vienna - mature market

5. Constraints
“Here is one of the few effective keys to the design
problem — the ability of the designer to recognize
as many of the constraints as possible — his
willingness and enthusiasm for working within
these constraints. Constraints of price, of size, of
strength, of balance, of surface, of time and so
forth.”
“I have never been forced to accept compromises
but I have willingly accepted constraints.”
— CHARLES EAMES

6. Form
Does a cost effective Passivhaus have
to look like a Passivhaus?

7. Value Engineered
(3.5 billion year design time)
Why do they always look like birds?
What can we guess about
this bird just by looking at it?

9. Design freedom As free as a bird
Freedom of choice

10. OK, not all birds look so
bird like . . .
kiwibird.org

11. Form factor double whammy
• = Heat loss area/useful floor area
• Higher FF = more wall and roof =
more cost
• Higher FF = more insulation =
even more cost
• More insulation = thicker walls =
bigger footprint = even more cost
• Before we even think about
complexities of build, shading etc
Passive House Design, Vallentin & Gonzalo

12. Compensating for
too compact a form
by adding fins
Guess where this owl
lives?
Form & heatloss

13. Irony is allowed in nature
(within natural constraints)
Punch

14. Length
Depth Height
Roof
pitch
Natural selection is slow & expensive
We can model

15. PHPP Tools Simple scenario tracker
© Elemental Solutions

16. Structural strategy
• Easy to make airtight?
• Easy to avoid thermal bridges?
• Cost efficient?
• Perhaps part of the aesthetic?
• Using available materials?
• etc

17. Beyond Biomockery
www.fishing.net.nz
warm blooded animal has
structure on inside
cold blooded animal has
structure on outside
if you want to build an
insulated building, where does
the structure go?

18. As in nature:
structure
air barrier
insulation
wind and weather
external structure
Image Nick Grant

19. Not like these
Green style over function
Image Nick Grant
Image Nick Grant

20. This is good
Image Nick Grant

21. Mike Whitfield super-insulated traditional cruck frame extension
This is good
Image Nick Grant

22. Sjölander da Cruz
This is good

23. This is good
Cavity wall, (or ICF) floor joists don’t penetrate plaster air barrier
Image Nick Grant

24. Wall/floor junction
Adding complexity to standard detail to reduce heat loss
Image Nick Grant

25. Simpler
Image Nick Grant

26. Structural slab
Air tight layer
Load
Image: Architype
Simpler still

27. Fenestration
(Sorry!
Northern
hemicentric)
Larger
windows with
low frame
factor, all the
same size.
Image Nick Grant

28. Fenestration
Smaller
windows have
more frame
and less glass.
Image Nick Grant

29. 44
Windows - performance
44
Uwindow=1.8 W/m2K
Poor Installation;
Traditional mullions
Installation free of thermal bridges;
Simplified design
Uwindow=0.8 W/m2K
For UK Building Regulations, the performance of these two
windows can be considered the same:
But with Passivhaus, you have to calculate them
individually
How could you optimise the window performance through design?

30. Passive Solar;
What does free heat cost/kWh?
Image Nick Grant

31. Gains 4000 kWh/a - losses 1863 kWh/a
Window area 36m2
= 59 kWh/m2.a
- About £6‘saved’ per m2 window per year @ 80p/kWh*
- Gets worse the more glass you add! (utilisation factor,
solar shading, additional mass - all cost)
- BUT, free if you needed the window area anyway.
- *(3% discount rate, 20 year life, £400/m2 window cost, 100% utilisation – YMMV)

32. MK9 2HP
MK9 2HP
Larger overhang to shade
May need external blinds
Structure more challenging
Difficult cill detail
Extra thermal bridge at cill
Dirt from splash
Loss of wall space
Glass to floor
Image Nick Grant

33. Glazing to ground omitted
• More daylight
• Better summer comfort
• More useful space
• Big cost & time savings
• Architect likes it!
Image Nick Grant
Image Juraj Mikurcik Architype

34. Design out mechanical
shading (UK climate)
Image Nick Grant

35. m2 window cost in UK
Double Passivhaus
Overcost/m2
Floor area
Additional
Build cost
PVC High
Quality
£180 £240 £12 + 1%?
Timber High
Quality
£230 £310-450 £16-£43 + 1-3%
Calculation based on a current Passivhaus Project, Cae Duff
26m2 windows and doors
134m2 TFA (PH methodology so c.a. 150m2 GIFA)

36. No mullions large fixed

37. Hi drama, low cost
Passivhaus by Bjørn Kierulf,
Createra, Slovakia
Fixed glazing c.a. 30% cheaper
than opening windows, much
cheaper than sliding doors.

38. Maximum utility
Image Nick Grant

39. However:
• Add 50% glazing area
• Add extra shading to deal with subsequent overheating of extra
glass.
• Add sliding doors (tilt&slide +55%, lift & slide +105%)
• Add steel structure to accommodate sliding doors
• Make all windows opening even if not required (c.a. 30% cheaper
for fixed depending on manufacturer)
Result: + 10 to 15% on total build cost?

40. Simple Services

41. Alan Clarke
Thermal
store
Solar
pump
Stove
pump
Heating
pump
Heating
manifold
Pipes to
gas boiler
Solar
controls
Under-floor
controls
DHW
pump
Alan Clarke
Typical Green Building Services

42. All that kit: £20,000
Life of 20 years: £1000/year + fuel +
maintenance.
Heat + hot water: 5,000kWh/year
Gas @ 6p/kWh: £300/year

Slide courtesy Alan Clarke, UK Passivhaus Conference 2013

43. Passivhaus heating conclusion:
Expensive fabric = cheap heating
Slide courtesy Alan Clarke, UK Passivhaus Conference 2013

44. Heating
• Radiators
Bushbury Passivhaus School
Simple radiators with thermostatic valves, one per room, not all rooms.
Image Nick Grant

45. Boiler for 2,400m2 school
You sure this is right?
Image Nick Grant

46. Housing Examples

47. m2 build costs in UK
Self build costs Homebuilding & Renovating Mag from RICS
2014
91-160m2 house in East of England, NW, SW or Scotland
Builder/subbies Main contractor
Standard Good Excellent Standard Good Excellent
£960 £1164 £1514 £1010 £1226 £1593
Passivhaus projects that I know
Denby Dale 1186*
Wahrunga 1570
Clehonger 1400
Borth 1400
Lancaster 1505
*Excluding fees
N.B. The basis area and what is excluded varies by project

48. Denby Dale
Image Green Building Company

49. Lancaster Cohousing Project
Passivhaus Community Housing Project
Andrew Yeats ( Eco Arc Architects ) & Alan Clarke
International Passive House Conference 2014

50. Photo Lancaster Co Housing

51. Based on Denby Dale/AECB
Gold details
Image Nick Grant

53. Post occupancy evaluation,
Lancaster Co-Housing co-heating tests
etc by Sheffield University

54. Passivhaus Ledbury
Built by Mike Whitfield
Image Nick Grant

55. Passivhaus Ledbury
Image Ruth Busbridge

56. Glasgow-marble floor/foundation
Image Ruth Busbridge

57. Image Ruth Busbridge

59. Image Nick Grant

60. Passivhaus Clehonger
By Mike Whitfield
Image Nick Grant

61. Image Nick Grant

62. Image Nick Grant

63. Passivhaus & artist’s studio In
Wales
Image Nick Grant

64. Air barrier outside structure
Image Nick Grant

65. N50 = 0.36 ach
Image Nick Grant

66. Image Rob Davies

67. Image Rob Davies

68. Image Nick Grant

69. Image Nick Grant

70. Borth Passivhaus
£1400/m2 without plot, landscaping and furniture.

71. Housing Lessons
• Keep the thermal envelope really simple
• keep the services really simple
• Glaze for daylight not ‘free heating’
– ‘Free’ solar gains cost about $1/kWh
– Staying warm is easy, staying cool is harder
• Timber works great
• Masonry also great

72. Summary
Unless you laugh in the face of physics or blow
the budget, it won’t not look like a Passivhaus -
deal with it