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Building an even better Passivhaus School

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Presentation at the 19th International Passivhaus Conference in Leipzig. An overview of some key lessons gained building 3 passivhaus primary schools with the same team. The Architect is Architype who specialise in buildings to the Passivhaus or Passive House Standard.

A key lesson was that internal heat gain assumptions have a large impact on design decisions when targeting the passivhaus energy targets. The third school in this series had the lowest cost, highest comfort and lowest energy consumption.

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Building an even better Passivhaus School

  1. 1. Building a Better Passivhaus School 19th International Passivhaus Conference Leipzig 2015 Nick Grant Alan Clarke Elemental Solutions @ecominimalnick @AR_Clarke
  2. 2. Three Schools One Team Oakmeadow Bushbury Hill Wilkinson © Dennis Gilbert/VIEW Team: Architype, Thomas Vale, E3, Ion Acoustics, Price and Myers, Elemental Solutions www.architype.co.uk 2012 RIBA West Midlands Winner2012 UK Passivhaus Trust Awards 2012 RIBA Special Award winner
  3. 3. Oakmeadow (no extra budget for Passivhaus) Image Courtesy Architype
  4. 4. Images Courtesy Architype
  5. 5. Bushbury Hill (no extra budget for Passivhaus) Image Nick Grant
  6. 6. Image Nick Grant
  7. 7. Image Nick Grant
  8. 8. Pending Image Courtesy Architype. © Dennis Gilbert/VIEW Wilkinson (10% less budget than the others)
  9. 9. Structural slab Air tight layer Load Image: Architype Basic construction the same Timber frame Cellulose insulation OSB air barrier Level access Floating slab on 250mm EPS
  10. 10. Image Courtesy Architype. © Dennis Gilbert/VIEW On site: October 2012, Complete: December 2013
  11. 11. Image Courtesy Architype. © Dennis Gilbert/VIEW Client: Wolverhampton City Council Value: £5,000,000 (€6,800,000)
  12. 12. Image Courtesy Architype. © Dennis Gilbert/VIEW TFA: 2395m2 Kids: 420
  13. 13. Image Courtesy Architype. © Dennis Gilbert/VIEWImage Courtesy Architype. © Dennis Gilbert/VIEW
  14. 14. Images Courtesy Architype. © Dennis Gilbert/VIEW
  15. 15. Key Lessons • IHGs – higher than in German schools • Fenestration – less is more • Ventilation – proof of original concept plus simplifications • Kitchen – mature solutions refined • Heating – one small boiler and radiators • DHW – losses dominated so electric used • BMS – still not resolved, do we need one? • Occupant feedback crucial for learning
  16. 16. IHG due to KiddyWatts Average for UK examples 5.7 m2 /child Average for German examples 10.5 m2 /child Difference in body heat = +1.32W/m2 + 5-6 kWh/(m2 .a) of useful heating (Against 15kWh/(m2 .a) target) Image; Nick Grant
  17. 17. IHG
  18. 18. Meant Less South Glazing Image Courtesy Architype. © Dennis Gilbert/VIEWImage Nick Grant
  19. 19. Can Afford More Shading Image Courtesy Architype. © Dennis Gilbert/VIEW
  20. 20. Image Courtesy Architype. © Dennis Gilbert/VIEW
  21. 21. Minimised Glazing to Ground Image Architype. Juraj MikucikImage Nick Grant • Reduced cost • Less winter heat loss and summer gain • More useful space • Better daylight
  22. 22. Higher IHG ‘cheat’; So how much did heat demand increase with less solar gain?
  23. 23. Wilkinson gas use 1 year Special needs school Pre Passiv BREEAM Excellent Oakm eadow (inc’ DHW ) Bushbury (inc DHW ) W ilkinson (Electric DHW ) ImageArchitype
  24. 24. Electricity Image Architype Wilkinson (inc Electric DHW) Oakmeadow Bushbury Lowest of group but still higher than hoped. Note St Luke’s has window ventilation
  25. 25. Energy Use First Full Year Gas for space heating 9.1 kWh/(m2 .a) Gas for kitchen DHW 1.2 kWh/(m2 .a) Electricity 51 kWh/(m2 .a) PE 144 kWh/(m2 .a) High electric use not yet diagnosed but prime suspect is accidentally connected heater battery in kitchen vent and BMS control fault of MVHR. Good summer comfort indicates internal gains are as anticipated.
  26. 26. Summer Comfort Greatly Improved “The questionnaire survey of staff members in 3 passivhaus schools found that Wilkinson classrooms were on average, better rated in terms of thermal comfort and indoor air quality.” Chryssa Thoua, Architype. KEEN Project to be published 2015 with graphs & data. KEEN Post occupancy monitoring as part of Knowledge Exchange and Enterprise Network (KEEN) project between Architype and Coventry University, led by the University of Wolverhampton and funded by European Regional Development Fund (ERDF) and Architype.
  27. 27. Cascade vent used in all 3 schools Works well, simple control, lower cost MVHR First floor ventilation schematic Image Architype, Chryssa Thoua
  28. 28. Summer vent Leave MVHR running in summer? •Better air quality •Easy to understand •Simpler WC vent Graph courtesy Architype, Chryssa Thoua ppmCO2
  29. 29. German Primary School window
  30. 30. Not allowed in UK! Alan Clarke Passivhaus Building Services design & occasional stuntman
  31. 31. Full commercial kitchens
  32. 32. Key points for kitchen vent • All electric – no combustion products • Variable speed air flow – comfort • Robust 50% heat recovery delivers comfort. 12°C fresh air is fine in kitchen, don’t need 17°C Wilkinson improvements: • Eliminated heating coil & so frost coils • Electric heater fitted (against our advice) as fall back measure but was to be isolated 
  33. 33. Kitchen Vent Download the paper and presentation: www.elementalsolutions.co.uk
  34. 34. The Heating System • One boiler for 2,400m2 building (84kW, <25kW demand) • No weather compensation • Radiators and TRVs You sure this is the right boiler? You sure this is the right boiler? Four times the size they needed apparently Four times the size they needed apparently Image Nick Grant
  35. 35. Hot Water • With gas, circulation losses dominated, over 60% • Local electric but only 7 units for whole school • 8mm copper pipe for longer pipe runs so less heaters • 2.7kWh/(m2 .a) PE standing loss • Instantaneous gas in kitchen (c.a. 1.2kWh/(m2 .a) 1.7 litres/minute ‘sprays’Proof of concept test rig
  36. 36. BMS/BEMS “Critics of BMS would do well to remember how building services were controlled in the past. The simple controls that used to be the norm – such as time clocks and thermostats – were often either never adjusted or they were subject to unauthorised tampering, resulting in huge amounts of energy being wasted. What solved the problem was the introduction of building management systems. This is one reason why such systems are now the dominant form of HVAC control in non- domestic buildings.” Trend website
  37. 37. BEMS • Claimed to save energy. • Say £50k install, £5k/a tech support contract, sensor & actuator testing etc • Gas bill £1.5k/a so potential ROI=?? • See papers by Prof Axel Bretzke Frankfurt
  38. 38. One bit logic problem BMS allows us to do clever things e.g. WC vent in summer using MVHR 1 & 0 swapped in BMS logic – extract air damper to hub space shut in winter mode. •Spotted because of cool supply air (due to vent imbalance) •High fan power all winter (and noisy!)
  39. 39. BMS 2020? “Critics of simple controls would do well to remember how building services were controlled in the past. The complex BMS controls that used to be the norm were often either never adjusted or they were subject to unauthorised tampering, resulting in huge amounts of energy being wasted. What solved the problem was the introduction of simple thermostats and timers. This is one reason why such systems are now the dominant form of HVAC control in non-domestic buildings.”
  40. 40. A light switch, KISS (Safety gear optional) Image Nick Grant
  41. 41. Schools Conclusions • Higher IHG assumption led to more comfortable building & paradoxically lower heating demand • Design simplification takes time and courage but can save money and improve performance • If something can go wrong it will but if it isn’t installed it can’t go wrong. • Thanks for listening!

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