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Passivhaus, If you think it will cost more it will

Presentation at the first South Pacific Passivhaus Conference Auckland. Cost and performance should be seen as constraints as part of the design brief.

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Passivhaus, If you think it will cost more it will

  1. 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. 2. Deja vu 1997 Suggests cost/performance correlation
  3. 3. Deja vu 2003 Market transformation in 6 years
  4. 4. Vienna - mature market
  5. 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. 6. Form Does a cost effective Passivhaus have to look like a Passivhaus?
  7. 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?
  8. 8. Design freedom As free as a bird Freedom of choice
  9. 9. OK, not all birds look so bird like . . .
  10. 10. 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
  11. 11. Compensating for too compact a form by adding fins Guess where this owl lives? Form & heatloss
  12. 12. Irony is allowed in nature (within natural constraints) Punch
  13. 13. Length Depth Height Roof pitch Natural selection is slow & expensive We can model
  14. 14. PHPP Tools Simple scenario tracker © Elemental Solutions
  15. 15. Structural strategy • Easy to make airtight? • Easy to avoid thermal bridges? • Cost efficient? • Perhaps part of the aesthetic? • Using available materials? • etc
  16. 16. Beyond Biomockery 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?
  17. 17. As in nature: structure air barrier insulation wind and weather external structure Image Nick Grant
  18. 18. Not like these Green style over function Image Nick Grant Image Nick Grant
  19. 19. This is good Image Nick Grant
  20. 20. Mike Whitfield super-insulated traditional cruck frame extension This is good Image Nick Grant
  21. 21. Sjölander da Cruz This is good
  22. 22. This is good Cavity wall, (or ICF) floor joists don’t penetrate plaster air barrier Image Nick Grant
  23. 23. Wall/floor junction Adding complexity to standard detail to reduce heat loss Image Nick Grant
  24. 24. Simpler Image Nick Grant
  25. 25. Structural slab Air tight layer Load Image: Architype Simpler still
  26. 26. Fenestration (Sorry! Northern hemicentric) Larger windows with low frame factor, all the same size. Image Nick Grant
  27. 27. Fenestration Smaller windows have more frame and less glass. Image Nick Grant
  28. 28. 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?
  29. 29. Passive Solar; What does free heat cost/kWh? Image Nick Grant
  30. 30. 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)
  31. 31. 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
  32. 32. 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
  33. 33. Design out mechanical shading (UK climate) Image Nick Grant
  34. 34. 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)
  35. 35. No mullions large fixed
  36. 36. Hi drama, low cost Passivhaus by Bjørn Kierulf, Createra, Slovakia Fixed glazing c.a. 30% cheaper than opening windows, much cheaper than sliding doors.
  37. 37. Maximum utility Image Nick Grant
  38. 38. 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?
  39. 39. Simple Services
  40. 40. 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
  41. 41. 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
  42. 42. Passivhaus heating conclusion: Expensive fabric = cheap heating Slide courtesy Alan Clarke, UK Passivhaus Conference 2013
  43. 43. Heating • Radiators Bushbury Passivhaus School Simple radiators with thermostatic valves, one per room, not all rooms. Image Nick Grant
  44. 44. Boiler for 2,400m2 school You sure this is right? Image Nick Grant
  45. 45. Housing Examples
  46. 46. 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
  47. 47. Denby Dale Image Green Building Company
  48. 48. Lancaster Cohousing Project Passivhaus Community Housing Project Andrew Yeats ( Eco Arc Architects ) & Alan Clarke International Passive House Conference 2014
  49. 49. Photo Lancaster Co Housing
  50. 50. Based on Denby Dale/AECB Gold details Image Nick Grant
  51. 51. Post occupancy evaluation, Lancaster Co-Housing co-heating tests etc by Sheffield University
  52. 52. Passivhaus Ledbury Built by Mike Whitfield Image Nick Grant
  53. 53. Passivhaus Ledbury Image Ruth Busbridge
  54. 54. Glasgow-marble floor/foundation Image Ruth Busbridge
  55. 55. Image Ruth Busbridge
  56. 56. Image Nick Grant
  57. 57. Passivhaus Clehonger By Mike Whitfield Image Nick Grant
  58. 58. Image Nick Grant
  59. 59. Image Nick Grant
  60. 60. Passivhaus & artist’s studio In Wales Image Nick Grant
  61. 61. Air barrier outside structure Image Nick Grant
  62. 62. N50 = 0.36 ach Image Nick Grant
  63. 63. Image Rob Davies
  64. 64. Image Rob Davies
  65. 65. Image Nick Grant
  66. 66. Image Nick Grant
  67. 67. Borth Passivhaus £1400/m2 without plot, landscaping and furniture.
  68. 68. 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
  69. 69. Summary Unless you laugh in the face of physics or blow the budget, it won’t not look like a Passivhaus - deal with it