Kurnitski rehva aicarr-seminar-mce-28.03.2012

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nZEB presentation in Milano ComfortExpo 28.3.2012

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Kurnitski rehva aicarr-seminar-mce-28.03.2012

  1. 1. REHVA – AICARR Seminar on Zero Energy Buildings Milan, 28 March 2012 nZEB Buildings: experiences andcase studies from Central and North Europe Jarek Kurnitski SITRA Jarek.Kurnitski@sitra.fiFederation of European Heating, Ventilation and Air-conditioning Associations
  2. 2. nZEB buildings• Many pilot projects across Europe which may be called as nZEB buildings• Variation in the definitions and performance levels• Primary energy (simulated) typically between 50-100 kWh/(m2 a) if all energy use included (plug loads/user electricity incl.)• Some buildings with measured data• Buildings may be extremely complicated which may have implications in operation and maintenance• Simple and reliable solutions based on high performance components and careful system design another nZEB trend Jarek Kurnitski 28.3.2012 © Sitra
  3. 3. nZEB case studies• nZEB office buildings in France, Netherlands, Switzerland and Finland• Reported in REHVA Journal (3/2011 and 2/2012) Jarek Kurnitski 28.3.2012 © Sitra
  4. 4. nZEB case studies – presentation outline• Two buildings in more detail - One from Central Europe, another North Europe - Some technical concepts similar – suit for both climate - Some different – depending on climate - Simulated and measured energy performance - nZEB extra cost• Some key technical concepts based on nother buildings• Can common features of nZEB office buildings be identified?• Performance specification recommendations for nZEB Jarek Kurnitski 28.3.2012 © Sitra
  5. 5. System boundary – REHVA nZEB definition System boundary of net delivered energy System boundary of delivered energy Solar and internal 15.0 PV electricity, from which 6.0 used heat gains/loads in the building and 9.0 exported NET ENERGY NEED (47.2 kWh/(m2 a)) NET ENERGY NEED Appliances BUILDING TECHNICAL (47.2 kWh/(m2 a)) (users) SYSTEMS 10,8 Lighting Boiler DELIVERED ENERGY 3.8 heating 3.8/0.9 = 4.2 Space Fuel 4.2 21,5 heating Free cooling 1,1 Heating of 11.9 cooling 0,6 4.0/10 = 0.4 3,2 air in AHU Compressor cooling Cooling in 21.5 appliances Electricity 33.8 Net delivered energy room units 7.9/3.5 = 2.3 Cooling of 10.0 lighting Ventilation 5.6 10 air in AHU Appliances 21.5 Heat exchange Lighting 10.0 through the (Sum of electricity 39.8) building envelope EXPORTED ENERGY Electricity 9.0 Primary energy: 4.2*1.0 + (33.8-9.0)*2.5 = 66 kWh/(m2 a) • Electricity use of cooling, ventilation, lighting and appliances is 39.8 kWh/(m2 a) • Solar electricity of 15.0 kWh/(m2 a) reduces the net delivered electricity to 24.8 kWh/(m2 a) • Net delivered fuel energy (caloric value of delivered natural gas) is 4.2 kWh/(m2 a) and primary energy is 66 kWh/(m2 a) Federation of European Heating, Ventilation and Air-conditioning Associations
  6. 6. Paris, Elithis Tower(Hernandez REHVA Journal 3/2011) © Sitra
  7. 7. © Sitra
  8. 8. Key solutions• Rounded shape (-10% envelope reduction) + external solar shading shield• Mechanical balanced ventilation with heat recovery• Room conditioning with chilled beams• Night ventilative cooling with mechanical exhaust ventilation from atrium• Adiabatic + compressor cooling• Large windows for max daylight, 2 W/m2 installed lighting power + task lighting, occupancy and daylight control Jarek Kurnitski 28.3.2012 © Sitra
  9. 9. Mechanical ventilation + ventilative coolingThree operation modes:1. In the heating season the heat recovery ventilation, i.e. air handling units are operated.2. Ventilative cooling: boost with façade intakes and low pressure atrium exhaust fans. Used in midseasons, when air handling Façade intake units are operated together with atrium low pressure exhaust fans.3. Night time ventilative cooling. Air handling units are stopped and only atrium low pressure fans are operated. Jarek Kurnitski 28.3.2012 © Sitra
  10. 10. Simulated and measured energy performance• Office appliances are the major component in the energy balance… Jarek Kurnitski 28.3.2012 © Sitra
  11. 11. Helsinki, Environmental CentreYmpäristötalo (Kurnitski REHVA Journal 2/2012) © Sitra
  12. 12. General data• Gross floor area 6791 m2• Construction cost: - 16.5 M€ (2430 €/m2)• nZEB extra cost: - 0.5-0.7 M€ - 3-4% of construction cost Jarek Kurnitski 28.3.2012 © Sitra
  13. 13. Key solutions• Compact massing• Window to wall ratio 23 %• South facing double facade with integrated PV (60 kW/570 m2 providing 17% of electricity use)• District heating• Air conditioning with balanced ventilation, heat recovery and chilled beams• Cooling is 100% free cooling from boreholes: - 25 boreholes each 250 m depth - 15/20C cooling water dimensioning for AHUs and chilled beams Jarek Kurnitski 28.3.2012 © Sitra
  14. 14. Key solutions• Large mechanical rooms on the top floor and low pressure ductwork• Specific fan power of main AHUs 1.4…1.6 kW/(m3/s)• Heat recovery (wheels) temperature ratio 78…80 % Jarek Kurnitski 28.3.2012 © Sitra
  15. 15. Integrated ventilation and AC with free cooling Air handling unit TE a) TC TC Supply TE Chilled beam Return Cooling water from boreholes Room TC TE controller Room a) ME TE Supply Thermostat Return District heat substation• CAV for cellular and open plan offices, DCV for other rooms• Active chilled beams in offices and passive chilled beams for other rooms for 24 h cooling (max cooling need 40 W/m2) Jarek Kurnitski 28.3.2012 © Sitra
  16. 16. Heat recovery from toilets – no separated exhausts• Separated exhaust fans replaced with a small 0.5 m³/s air handling unit with rotary heat exchanger• Supply air to toilets, heat recovery of 80% Jarek Kurnitski 28.3.2012 © Sitra
  17. 17. Room conditioning and lighting• Active chilled beams (CAV) in offices• Lighting fittings of T5 fluorescent lamps with 7 W/m² installed power.• Daylight, occupancy and time control is used in larger rooms, and occupancy and time control in cellular offices Jarek Kurnitski 28.3.2012 © Sitra
  18. 18. Energy performance (simulated) Net energy Delivered Energy Primary need energy carrier energy kWh/(m2 a) kWh/(m2 a) factor, - kWh/(m2 a)Space and ventilation heating 26,6 32,2 0,7 22,6Hot water heating 4,7 6,1 0,7 4,3Cooling 10,6 0,3 1,7 0,5Fans and pumps 9,4 9,4 1,7 16,0Lighting 12,5 12,5 1,7 21,3Appliances (plug loads) 19,3 19,3 1,7 32,7PV -7,1 1,7 -12,0Total 83 73 85Major differences compared to Central Europe:• much more heating (almost by factor 10)• only slightly less cooling• more lighting electricity Jarek Kurnitski 28.3.2012 © Sitra
  19. 19. Simple or complex ventilation systems?• Hybrid systems tend to be highly complicated (many actuators + complicated control) or are to be controlled by user – simulations provide often optimistic results compared to real operation• Mechanical systems centralized (as in two case studies) or decentralized• Centralized systems may be complex or not Jarek Kurnitski 28.3.2012 © Sitra
  20. 20. Example of decentralized ventilation(Achermann, IUCN building, REHVA J 3/2011)• Air intakes from facade, a filter unit, a fan and a heating/cooling coil• CO2 sensor located at the exhaust damper integrated into a panel mounted on the ceiling• No supply air ductwork Jarek Kurnitski 28.3.2012 © Sitra
  21. 21. Constant pressure nZEB compliant simple ventilation(Gräslund REHVA Journal 3/2011)• 1-2 step larger ducts and AHUs• No need for silencers and most of dampers Jarek Kurnitski 28.3.2012 © Sitra
  22. 22. nZEB solutions: Natural lighting and solar shading, (Scartezzini and Lamy REHVA AM 2011) 3.5 W/m2 installed lighting power achieved! Federation of European Heating, Ventilation and Air-conditioning Associations
  23. 23. nZEB solutions: Solar fired absorption chiller (Virta et al. REHVA GB 16 HVAC in sustainable office buildings)• An example of a free cooling solution – many possible solutions• The solar fired absorption chiller operates with hot water from the roof mounted concentrating solar collector and the wall mounted coil solar collectors Federation of European Heating, Ventilation and Air-conditioning Associations
  24. 24. nZEB case studies: common solutions• nZEB = demand reduction + effective systems + on site renewables• Energy sources used: heat pumps, DH, bio-CHP, solar PV and thermal• Heat recovery ventilation, often demand controlled, by centralized or decentralized systems sometimes combined with natural stack effect ventilation for ventilative cooling purposes• Free cooling solutions combined with mechanical cooling via boreholes, water to water HP, evaporative or ventilative cooling etc.• Optimized building envelope and effective external solar protection• Utilization of natural light + effective demand controlled lighting• High efficiency heat recovery and low specific fan power, CO2, presence and temperature control typical in nZEB• Water based distribution systems and VRV heat pumps• Utilization of thermal mass and other passive measures• Office appliances have become major component in energy balance… Jarek Kurnitski 28.3.2012 © Sitra
  25. 25. Key performance specification for nZEB(Virta et al. REHVA GB 16 HVAC in sustainable office buildings) Unit Low energy Nearly zero energy SFP of air handling unit kW/m3 /s < 2.0 < 1.5 Heat recovery efficiency % > 60 > 80 Demand controlled ventilation meeting rooms all spaces Installed lighting power W/m2 < 10 <5 Lighting control time, daylight time, daylight, occupancy U-value of window W/K,m2 < 1.2 < 1.0 g-value of window < 0.7 adaptable (seasons) Solar shading yes automated Infiltration (q50 ) m3 /h,m2 < 1.5 < 0.6 Share of renewable energy % > 10 >20• Some indicative values for key low and nZEB energy design criteria in cold and temperate climates Jarek Kurnitski 28.3.2012 © Sitra
  26. 26. Central Europe vs. North Europe• Large windows for max daylight to • Small windows for lowest acceptable save lighting electricity average daylight factor• Moderate insulation (Uwindow=1.1 , • Highly insulated envelope (Uwindow Uwall=0.30) =0.6…0.8, Uwall=0,15)• More cooling need than heating need • Slightly less cooling but a lot of heating• External solar shading • External shading for low solar angle• “Glass” buildings with external shading • Double façade to be used for “glass” possible buildings• Free cooling combined with • 100% free cooling possible with compressor cooling or solar cooling borehole water• Water based distribution system for • Water based distribution systems for cooling (or VRV) heating and cooling (or VRV)• Heat recovery ventilation • Heat recovery ventilation• Demand controlled ventilation and • Demand controlled ventilation and lighting lighting• PV panels • PV panels Jarek Kurnitski 28.3.2012 © Sitra
  27. 27. Experience from nZEB design process• Energy simulations needed in very early stage to compare massing alternatives (starting from scoping)• Reserving enough space for mechanical rooms and risers – 1-2 step larger AHUs and ductwork – this space may be difficult to find in a later stage• Simulations of a typical floor often enough for decision making of basic solutions (concept stage)• Facades to be optimized (concept stage) for a relevant combination of daylight, solar protection cooling and heating needs• To achieve targets, careful verification and commissioning needed• Sometimes official monthly based calculated methods may provide too optimistic results not achieved in practice Jarek Kurnitski 28.3.2012 © Sitra

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