Simulating Mixed-Mode Ventilation By Liam Buckley, IES Ltd.

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January 10, 2013

Simulating Mixed-Mode Ventilation By Liam Buckley, IES Ltd.

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ibpsanyc

January 10, 2013
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Transcript

  1. 2.

    Agenda • Introduction to mixed-mode ventilation • When to implement

    MM-Ventilation • Codes & Standards • Strategies for Natural & MM-Ventilation • Case-studies (throughout) and lessons learnt
  2. 4.

    Why Integrate MMV Systems March 2012: “At least 21 commercial

    buildings in the United States meet net-zero standards, according to a study released yesterday by the New Buildings Institute and the Zero Energy Commercial Building Consortium.” Ref: http://www.scientificamerican.com/article.cfm?id=net-zero-energy-buildings-in-us 1. Reduce energy consumption (EUI), carbon emissions and operating costs of buildings:
  3. 6.

    What % were naturally ventilated? Ref: http://newbuildings.org/sites/default/files/GettingtoZeroReport_0.pdf ECMs Daylight HE

    Lighting HE Envelope Hi R-value Glazing Natural Ventilation HE HVAC Heat Recovery Cool Roof Radiant GSHP UFAD / Displment Energy Conservation Measures Load Reduction Strategies
  4. 7.

    2. Green building certification (e.g. LEED …) • Optimize Energy

    Performance • Thermal Comfort • Increased Ventilation • Outdoor Air Delivery Monitoring • …… Why Integrate MMV Systems
  5. 8.

    3. Improve thermal comfort for occupants Section 5.3 Optional Method

    for Determining Acceptable Thermal Comfort in Naturally Conditioned Spaces Why Integrate MMV Systems
  6. 9.

    4. Improve ventilation/IAQ for occupants, and increase efficiency of building

    function (e.g. student performance in a school or patient recovery in healthcare). ASHRAE Standard 62.1 - Section 5.1 Natural Ventilation: Naturally ventilated spaces shall be permanently open to and within 8m (25 ft) of operable wall or roof openings to the outdoors. The opening area of which is a minimum of 4% of the net occupiable floor area. Where interior spaces without direct openings to the outdoors are ventilated through the adjoining rooms, the opening between rooms shall have a free area of 8% of the interior room, nor less than 25 sq.ft (2.3 m2). Why Integrate MMV Systems
  7. 10.

    When to Naturally (or MM) Ventilate • How many hours

    are there in one year? • Assume occupied hours 8am-6pm; Mon-Fri • Assumes no occupancy for national holidays
  8. 11.

    NV Potential in North America • Apply limits to 2490

    hours annually: New York (TMY2) 26% (644 hours)
  9. 15.

    Question: • Which office has the highest heating load? ALL:

    NYC – Office – VE1-2M – 40% Glazing 1 2 3 4 5 6 7 8
  10. 18.

    Codes & Standards • The Best: – CIBSE Applications Manual

    AM10 & AM13 – Natural Ventilation in non-domestic buildings Ref: www.cibse.org • The worst: – Paintshop! – Conceptually, ok.
  11. 20.

    CIBSE AM-10 Ventilation Strategies • CIBSE AM-10 rules of thumb:

    • Single sided: W≤(2*H) • Single sided with double opening: W≤(2.5*H) • Cross ventilation: W≤(5*H)
  12. 27.

    MM/Natural Ventilation Strategies 6. Atrium Design Office was awarded the

    highest ever BREEAM score of 87.55% when it opened in July 2007.
  13. 35.

    MM/Natural Ventilation Control • You can control pretty much anything

    • Allow buffers to avoid simultaneous heat/cool 9. Night Flushing Actuator Control
  14. 36.

    Window Controls Classroom 1 Classroom 2 Classroom 3 Classroom 4

    Operable Windows Control Variables 1. Internal temperature above 72°F AND external temperature above 60°F. 2. Internal temperature above 72°F AND external temperature range above 60°F and below 77°F. 3. Internal temperature above 72°F OR CO2 level above 1200 ppm. 4. Internal temperature above 72°F OR CO2 level above 1200 ppm; AND external temperature range above 60°F and below 77°F.
  15. 39.

    Mixed-mode Ventilation 10. MM: Sync HVAC Controllers with openings •

    Differential temperature, • high-limit override, • CO2-based control
  16. 40.

    Hybrid Ventilation • Summer TO = Outside Air Temperature (80°F)

    TG = Ground Temperature (47°F) TL = Leaving Air Temperature (65°F) TO = Outside Air Temperature (20°F) TG = Ground Temperature (47°F) TL = Leaving Air Temperature (40°F) • Winter
  17. 41.

    Hybrid Ventilation 11. Geothermal Labyrinth for ventilation air. • Free

    Heating • Free Cooling 12. Geometrically, solar chimney similar concept
  18. 42.

    Hybrid Ventilation • Increased ‘pre-treated’ ventilation air to AHU. •

    Air Temperature • Air Velocity Thermal mass concept
  19. 44.

    Lessons Learnt • Integrate to design as early as possible

    • Consider the negatives: noise, contamination, security & condensation • Study the climate and use accurate weather data • Include dynamic infiltration • Appropriate Loads Analysis • CIBSE AM10 & AM13! • Commissioning is essential for successful MMV